JP4528455B2 - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, in a bend orientation type liquid crystal display device, it is needed to make the whole of all pixels parts to be transferred from spray orientation states to bend orientation states uniformly before starting a normal display operation, but in a conventional method, since transition is not generated or even though transition is generated, an extremely long transition time is needed even applying a simple AC voltage to the pixel parts, display defects are apt to be generated due to defects of orientation. SOLUTION: This driving method is driving method of a liquid crystal display device in which OCB cells are used and, in the method, after all pixels are made to be transferred to bend orientation by repeatingly performing a process applying an AC voltage on which a bias voltage is superposed between electrodes 22 and pixel electrodes 23 and a process applying a zero voltage or a low voltage between the electrodes 22 and 23 alternately at a stage before the normal display operation is started, the display device is made to move to the normal display operation.

Description

【０３００】
表１より明らかなように、周波数が０．１Ｈｚから１０Ｈｚの範囲で且つデューティ比が２：１から１０００：１の範囲の場合に転移時間が極めて小さく、周波数が０．１Ｈｚから１００Ｈｚの範囲で且つデューティ比が１：１から１０００：１の範囲の場合であっても、十分に小さい転移時間となっていることが認められる。
【０３０１】
（実施の形態４）
図１２は実施の形態４に係る液晶表示装置の画素単位の構成概念図である。本実施の形態４では、本発明をアクティブマトリックス型液晶表示装置の駆動方法に適用した例が示されている。
【０３０２】
先ず、図１２を参照して、本実施の形態４に係る駆動方法に関連する液晶表示装置の構成を説明する。本実施の形態４に係る液晶表示装置は、駆動回路部を除いた構成に関して、一般的なＯＣＢセルを備えたアクティブマトリックス型液晶表示装置と同一の構成を有している。即ち、一対のガラス基板６０，６１と、ガラス基板６０，６１間に挟持された液晶層６６とを有する。ガラス基板６０，６１は、一定の間隔を隔てて対向配置されている。ガラス基板６０の内側面には、ＩＴＯの透明電極からなる共通電極６２が形成され、、ガラス基板６１の内側面には、画素スイッチング素子としての薄膜トランジスタ（ＴＦＴ）７０と、ＴＦＴ７０に接続したＩＴＯの透明電極からなる画素電極６３が形成されている。上記共通電極６２及び画素電極６３上には、ポリイミド膜からなる配向膜６４，６５が形成されており、この配向膜６４，６５は配向方向が互いに平行方向になるように配向処理されている。そして、配向膜６４，６５間には、Ｐ型のネマティック液晶からなる液晶層６６が挿入されている。また、配向膜６４，６５上の液晶分子のプレチルト角は約５度に設定されており、スプレイ配向からベンド配向へ転移する臨界電圧は２.６Ｖに設定されている。光学補償板６７のリターデーションはオン状態時に白あるいは黒表示となるように選択されている。なお、図中、６８，６９は偏光板である。
【０３０３】
また、図中、７１，７２は配向転移用駆動回路であり、この配向転移用駆動回路７１は共通電極６２に図１４に示す共通電極中心を基準として駆動電圧を印加し、且つ画素電極６３に０Ｖを印加する働きをなす。なお、他の構成として、配向転移用駆動回路７２は、共通電極６２及び画素電極６３に０Ｖを印加する働きをなす。また、７３は液晶表示用駆動回路であり、液晶表示用駆動回路７３は図１３に示す電圧波形を有する駆動電圧を共通電極６２及び画素電極６３に印加する働きをなす。即ち、液晶表示用駆動回路７３は、図１３の参照符号Ｍ１に示す電圧を画素電極６３に印加し、且つ図１３の参照符号Ｍ２に示す電圧を共通電極６２に印加する。なお、上記構成では、配向転移期間中において、画素電極６３に０Ｖを印加するようにしたけれども、これに代えて、配向転移期間中においても液晶表示用駆動回路７３から画素電極電圧を印加するようにしてもよい。
【０３０４】
また、７４ａ，７４ｂはスイッチ回路であり、７５はスイッチ回路７４ａ，７４ｂのスイッチング態様の切換えを制御するスイッチ制御回路である。前記スイッチ回路７４ａは、３つの個別接点Ｐ７，Ｐ８，Ｐ９，と、１つの共通接点Ｑ１を備えており、前記スイッチ回路７４ｂは、３つの個別接点Ｐ１０，１１，１２と、１つの共通接点Ｑ２を備えている。共通接点Ｑ１が個別接点Ｐ７に接続され且つ共通接点Ｑ２が個別接点Ｐ１０に接続された状態では、配向転移用駆動回路７１からの駆動電圧が電極６２，６３に印加されることになる。また、共通接点Ｑ１が個別接点Ｐ２に接続され且つ共通接点Ｑ２が個別接点Ｐ４に接続された状態では、液晶表示用駆動回路７３からの駆動電圧が電極６２，６３に印加されることになる。
【０３０５】
次いで、本実施の形態４に係る駆動方法について説明する。
【０３０６】
先ず、本来の画像信号に基づく液晶表示駆動に先立って、ベンド配向への転移のために、初期化処理を行う。先ず、電源投入により、スイッチ制御回路７５は、スイッチ回路７４ａにスイッチ切換信号を出力すると共に、スイッチ回路７４ｂにスイッチ切換信号を出力し、共通接点Ｑ１と個別接点Ｐ７とを接続状態とし、且つ共通接点Ｑ２と個別接点Ｐ１０とを接続状態する。これにより、配向転移用駆動回路７１から図１４に示す駆動電圧が共通電極６２に印加される。即ち、共通電極６２には、共通電極中心を基準として、バイアス電圧−ＧＶが重畳された、垂直同期信号に同期した交流電圧が印加される。なお、画素電極には０Ｖが印加される。そして、この交流電圧の印加を 期間Ｔ４維持する。
【０３０７】
次いで、交流電圧印加期間Ｔ４経過すると、スイッチ制御回路７５は、スイッチ回路７４ａにスイッチ切換信号を出力すると共に、スイッチ回路７４ｂにスイッチ切換信号を出力し、共通接点Ｑ１と個別接点Ｐ９とを接続状態とし、且つ共通接点Ｑ２と個別接点Ｐ１２とを接続状態する。これにより、配向転移用駆動回路７２から、図１４に示すように共通電極６２及び画素電極６３に０Ｖが印加される。そして、この０Ｖ電圧印加を期間Ｗ４維持する。
【０３０８】
次いで、０Ｖ電圧印加期間Ｗ４経過すると、スイッチ制御回路７５はスイッチ回路７４２ａにスイッチ切換信号を出力すると共にスイッチ回路７４ｂにスイッチ切換信号を出力し、再び、共通接点Ｑ１と個別接点Ｐ７とを接続状態とし且つ共通接点Ｑ２と個別接点Ｐ１０とを接続状態する。そして、このような交流電圧印加工程と０Ｖ電圧印加工程を交互に繰り返し、電源投入時から一定期間経過すると、電極全面が完全にベンド配向に転移する。
【０３０９】
そして、この一定期間経過時に、スイッチ制御回路７５は、スイッチ回路７４ａにスイッチ切換信号を出力すると共に、スイッチ回路７４ｂにスイッチ切換信号を出力し、共通接点Ｑ１と個別接点Ｐ８とを接続状態とし、且つ共通接点Ｑ２と個別接点Ｐ１１とを接続状態する。これにより、液晶表示用駆動回路７３からの駆動信号電圧が電極６２，６３に印加され、希望する画像が表示されることになる。ここで、液晶表示用駆動回路７３は、両電極間にベンド配向状態を維持する駆動電圧２.７Ｖを最低にしてこれをオフ状態とし、上限の電圧を７Ｖにしてこれをオン状態として、ＯＣＢパネルを表示する。
【０３１０】
上記駆動方法によって、広視野で高速応答のベンド配向型であるＯＣＢのアクティブマトリックス型の液晶表示装置が配向欠陥が全くなく高品質駆動表示できた。
【０３１１】
次いで、本発明者が、上記構成の液晶表示装置を作製し、上記駆動方法で初期化処理の実験を行ったので、その結果を述べる。なお、実験条件は以下のとおりである。
【０３１２】
セルギャップを約６μｍとし、バイアス電圧Ｇを−６Ｖとし、交流矩形波電圧の周波数及び振幅を７．９２ｋＨｚ、±１０Ｖとし、印加時間Ｔ３を０．５秒とした。また、０Ｖ電圧印加期間Ｗ４を０．５秒とした。
【０３１３】
上記実験結果によれば、上記液晶表示装置のパネル全画素内の配向転移がほぼ２秒以内で完了することができた。
【０３１４】
なお、バイアス電圧を重畳しないときには，表示面全体の配向状態を転移させるのに約２０秒必要であった。よって、本実施の形態４においても、バイアス電圧を重畳して駆動するのが、転移時間の短縮化を達成できることが認められる。
【０３１５】
（実施の形態５）
ＯＣＢモードのアクティブマトリックス型液晶表示装置の配向転移に関する駆動方法としては、上記の図１４に示す駆動電圧波形に代えて、図１５の駆動電圧波形を用いて駆動するようにしてもよい。即ち、交流電圧印加期間Ｔ４においては、共通電極６２に共通電極中心を基準として、直流電圧−１５Ｖを０．５秒間印加する。次いで、０Ｖ電圧印加期間Ｗ４においては、０Ｖを０．２秒間印加する。そして、直流電圧−１５Ｖ印加と０Ｖ電圧印加を交互に繰り返す。このよう駆動方法においても、転移を確実に且つ極めて短時間に完了することができる。
【０３１６】
なお、本発明者が上記駆動方法を用いて実験したところ、２秒以内の転移時間が得られた。
【０３１７】
（実施の形態６）
本実施の形態６は、上記実施の形態４，５に用いたアクティブマトリックス型の液晶表示装置に代えて、スイッチング素子の上に平坦化膜を配置し、その上に画素電極を構成するいわゆる平坦化膜構成の液晶表示装置に上記に実施の形態４，５の駆動方法を適用したことを特徴とするものである。駆動方法を具体的に説明すると、上記実施の形態４におけるバイアス重畳した配向転移用電圧を０．５秒印加し、次いで、オープン状態を０．５秒とし、これを交互に繰り返した。この駆動方法によると、転移時間は１秒以内で更に転移がスムーズに行えた。これは、平坦化膜構成により、画素電極間隔を小さくでき、この結果、スプレイ配向からベンド配向へスムーズに転移したものと考えられる。
【０３１８】
（その他の事項）
▲１▼上記実施の形態では、バイアス電圧を重畳した交流電圧を印加するようにしたけれども、直流電圧を印加するようにしてもよく、このようにすれば、片極性電圧でよいため、駆動回路が簡略化できる。
【０３１９】
▲２▼上記実施の形態では、バイアス電圧を重畳された交流電圧信号はバイアス電圧を直流として説明したが、信頼性向上のために、低周波の交流信号でもよい。
【０３２０】
▲３▼繰返し電圧の周波数及びデューティ比の最適範囲は、実施の形態３以外の他の実施の形態にも適用できる。
【０３２１】
▲４▼上記実施の形態では、発明の液晶表示装置の駆動法は透過型液晶表示装置で説明したが、反射型の液晶表示装置でもよい。また、これらはカラーフィルターを使用したフルカラー型の液晶表示装置や，カラフィルターレスの液晶表示装置でもよい。
【０３２２】
（実施の形態７） 図１６は本発明の実施の形態７に係る液晶表示装置の概略断面図、図１７は同じく概略平面図を示す。 図１６に示す液晶表示装置は、偏光板１０１・１０２と、該偏光板１０１の内側に配置された光学補償用の位相補償板１０３と、前記偏光板１０１・１０２の間に配置されたアクティブマトリックス型の液晶セル１０４とを有する。 前記液晶セル１０４は、ガラス等からなるアレー基板１０６と、該アレー基板１０６に対向する対向基板１０５とを有し、前記アレー基板１０６の内面上には透明電極である画素電極１０８が形成され、前記対向基板１０５の内面上には共通電極１０７が形成されている。さらに、該画素電極１０８上に配向膜１１０が形成され、共通電極１０７上には配向膜１０９が形成されている。
【０３２３】
また、前記アレー基板１０６上には、例えばａ−Ｓｉ系のＴＦＴ素子などからなるスイッチング素子１１１が配置され、該スイッチング素子１１１は前記画素電極１０８に接続されている。
【０３２４】
また、前記配向膜１０９・１１０の間には、図示せぬ直径５ミクロンのスペ−サ、および正の誘電率異方性のネマティック液晶材料からなる液晶層１１２が配置されている。また、前記配向膜１０９・１１０はその表面上の液晶分子のプレチルト角が正負逆の値を持ち、互いにほぼ平行方向になるよう同一方向に平行配向処理されている。従って、前記液晶層１１２は、無電圧印加状態では液晶分子が斜めに広がった配向領域からなるいわゆるスプレイ配向を形成している。
【０３２５】
また、前記配向膜１１０は、大きい値のプレチルト角Ｂ２（第３のプレチルト角）の配向膜１１０ａと、小さい値のプレチルト角Ａ２（第１のプレチルト角）の配向膜１１０ｂよりなる。また、前記配向膜１０９は、小さい値のプレチルト角Ｄ２（第４のプレチルト角）の配向膜１０９ａと、大きい値のプレチルト角Ｃ２（第２のプレチルト角）の配向膜１０９ｂよりなり、プレチルト角Ａ２に対向してプレチルト角Ｃ２が配置され、プレチルト角Ｂ２に対向してプレチルト角Ｄ２が配置されている。
【０３２６】
また、前記配向膜１０９・１１０は、ラビングクロスで信号電極線１１３とほぼ直角方向に、上下基板同一方向（図１６中の左側から右側に）に平行配向処理されている。
【０３２７】
また、図示せぬが、液晶表示装置には、液晶表示用駆動回路以外に、第１の電圧印加手段と第２の電圧印加手段とよりなる配向転移用駆動回路が設けられている。そして、前記第１の電圧印加手段により画素電極１０８と共通電極１０７の間に第１の電圧を印加して、第１の液晶セル領域と前記第２の液晶セル領域との境界付近においてディスクリネーション線を形成し、第２の電圧印加手段により画素電極１０８と対向電極１０７の間に前記第１の電圧よりも高い第２に電圧を印加して、ディスクリネーション線において転移核を発生させ、スプレイ配向からベンド配向へ転移させようにしている。
【０３２８】
次に、この液晶表示装置の製造方法について説明する。
【０３２９】
まず、アレー基板１０６の内面上に信号走査線１１３、スイッチング素子１１１および画素電極１０８を形成した。
【０３３０】
次に、前記画素電極１０８上に、日産化学工業（株）社製のポリアミック酸タイプの約５度の大きい値を持つ第３のプレチルト角としてのプレチルト角Ｂ２のポリイミド配向膜材料を塗布し、乾燥後焼成し、画素電極１０８上に配向膜１１０ａを形成した。
【０３３１】
次に、前記配向膜１１０ａの紙面上左側片側領域に紫外線を照射して、第１のプレチルト角としてのプレチルト角Ａ２の約２度の小さい値に変化させ、配向膜１１０ｂを形成した。
【０３３２】
対向基板１０５の内面上には、共通電極１０７を形成した。
【０３３３】
次に、前記共通電極１０７上には、日産化学工業（株）社製のポリアミック酸タイプの約５度の大きい値の第２のプレチルト角としてのプレチルト角Ｃ２を界面液晶分子に付与するポリイミド配向膜材料を塗布し、乾燥後焼成し、共通電極１０７上に配向膜１０９ｂを形成した。
【０３３４】
次に、前記配向膜１０９ｂの紙面上右側片側領域（プレチルト角の大きい値を持つプレチルト角Ｂ２に対向する領域）に、紫外線を照射して第４のプレチルト角としてのプレチルト角Ｄ２の約２度の小さい値に変化させ、配向膜１０９ａを形成した。
【０３３５】
以上のようにして、図１６の如く小さい値のプレチルト角Ａ２（第１のプレチルト角）に対向して大きい値のプレチルト角Ｃ２（第２のプレチルト角）を配置させ、大きい値のプレチルト角Ｂ２（第３のプレチルト角）に対向して小さい値のプレチルト角Ｄ２（第４のプレチルト角）を配置させることができた。
【０３３６】
また、以下のようにしてプレチルト角を制御することも可能である。
【０３３７】
即ち、図１８（ａ）に示すように、アレー基板１０６上にａ−Ｓｉ系のＴＦＴ素子などからなるアクティブマトリックス型のスイッチング素子（図示せぬ）と、それに接続して画素電極１０８を形成した。
【０３３８】
次に、図１８（ｂ）に示すように、前記画素電極１０８の左側領域にオゾン雰囲気下で紫外線を照射して、画素電極１０８の右側領域に比較して平坦化し、平坦化領域１０８ａを形成した。
【０３３９】
次に、図１８（ｃ）に示すように、前記画素電極１０８上にＪＳＲ社製のプレイミド型のポリイミド配向材料を塗布乾燥あるいは焼成して、配向膜１１０を形成した。
【０３４０】
このように形成した場合、画素電極１０８の平坦化領域１０８ａ上に位置する液晶分子１４０のプレチルト角は、未平坦化領域１０８ｂ上に位置する液晶分子１４０のプレチルト角よりも小さい値とすることができる。さらに、共通電極についても同様の処理を行うことによって、図１６と同様に、第１の液晶セル領域と、第２の液晶セル領域と、を同一画素内に有する液晶表示装置とすることができる。
【０３４１】
次に、図１６に示すように、前記のように形成した互いに大小のプレチルト角を付与する配向膜１０９および配向膜１１０の表面をラビングクロスで信号電極線１１３に対して直角方向に上下基板同一方向（図１６中の左側から右側）に平行配向処理し、正のネマティック液晶材料からなる液晶層１１２を配置した。
【０３４２】
このようにして作成された液晶表示装置において、前記画素電極１０８の配向元（ラビングの処理方向の上流側）には小さいプレチルト角Ａ２が、その対向する側には大きい値のプレチルト角Ｃ２が配置され、図１６の画素の（イ）領域（第１の液晶セル領域）には、共通電極１０７と画素電極１０８の間に第１の電圧として２．５Ｖを印加すると、液晶分子をアレー基板１０６側にスプレイ配向させたｂ−スプレイ配向１２０が、画素の（ロ）領域（第２の液晶セル領域）には液晶分子を対向基板１０５側にスプレイ配向させたｔ−スプレイ配向１２１が形成されやすくなる。
【０３４３】
即ち、図１６、図１７に示すように、前記液晶セル１０４のスイッチング素子１１１を通して共通電極１０７と画素電極１０８間に第１の電圧としての２．５Ｖを印加すると、画素内にｂ−スプレイ配向領域（第１の液晶セル領域）とｔ−スプレイ配向領域（第２の液晶セル領域）が形成され、その境界にディスクリネーション線１２３が信号電極線１１３に沿って、かつゲート電極線１１４・１１４’に渡って明瞭に形成された（ディスクリネーション線形成工程）。
【０３４４】
さらに、前記共通電極１０７と前記画素電極１０８との間に、第２の電圧として電圧−１５Ｖパルスを繰り返し印加することにより、図１７に示すようにディスクリネーション線１２３から転移核が発生してベンド配向１２４へ転移拡大し、ＴＦＴパネル画素全体は約３秒で速かに転移した（配向転移工程）。
【０３４５】
これは、ｂ−スプレイ配向状態とｔ−スプレイ配向領域の境界であるディスクネーション線領域は周囲より歪みのエネルギーが高くなっており、この状態に、上下電極間に高電圧が印加されることによって更にエネルギーが与えられスプレイ配向がベンド配向に転移したものと考えられる。
【０３４６】
（実施の形態８）
図１９は本発明の実施の形態８に係る液晶表示装置の概略図を示す。
【０３４７】
通常表示時には、ゲート電極線は線順次にオンされ走査されるが、通常の表示の前に、ゲート電極線を順次オンし、前記共通電極１０７と前記画素電極１０８との間に第２の電圧として電圧−１５Ｖパルスを繰り返し印加することにより、画素電極１０８とゲート電極線１１４、１１４’の間で電位差に起因する横電界が発生する。そして、前記横電界により、図１９の如くディスクリネーション線１２３とゲート電極線１１４、１１４’付近から転移核が発生してベンド配向へ転移拡大し、ＴＦＴパネル画素全体は約１秒で更に速かにベンド配向へ拡大転移した（配向転移工程）。
【０３４８】
これは、ｂ−スプレイ配向状態とｔ−スプレイ配向領域の境界であるディスクリネーション線領域が周囲より歪みのエネルギーが高くなっており、この状態に、横に配置されているゲート電極線からも前記ディスクリネーション線に横電界が印加されることによって更にエネルギーが与えられ、速く転移したものと考えられる。なお、転移が完了した後、ゲート電極線１１４・１１４’は通常の走査状態にもどる。
【０３４９】
なお、前記画素電極と共通電極の間に印加する第２の電圧は連続的に印加されてもよい。また、パルス状の電圧が繰り返し印加する場合は、その周波数が０．１Ｈｚから１００Ｈｚの範囲であり、且つ第２の電圧のデューティー比は少なくとも１：１から１０００：１の範囲で転移を速める効果が得られる。
【０３５０】
（その他の事項）
実施の形態７、８では、共通電極の配向先領域のプレチルト角Ｄ２を小さい値としたが、大きい値でも良い。また、画素電極の配向先領域のプレチルト角Ｂ２を大きい値としたが、横電界の影響でｔ−スプレイ配向となるため小さい値でも効果は得られる。
【０３５１】
また、一方の基板側のプレチルト角Ａ２の２度に対して対向のプレチルト角Ｃ２を５度としているが、その比が大きければ転移時間短縮の効果があり更に転移時間を速くすることができる。
【０３５２】
また、前記では、小さい方のプレチルト角Ａ２の値を２度としたが、ｂ−スプレイ配向させベンド配向へ容易に転移させるために、小さい値のプレチルト角Ａ２、Ｄ２の値として３度以下であれば良く、大きい値のプレチルト角Ｂ２、Ｃ２は４度以上であれば良い。
【０３５３】
また、配向処理方向を信号電極線１１３に対して直角方向に上下基板同一方向に平行配向処理したが、ゲート電極線１１４に対して直角方向（即ち、図１６のおける紙面に対して垂直方向）に上下基板同一方向に平行配向処理しても良い。
その際、ディスクリネーション線の形成場所が異なる。
【０３５４】
また、前記平行に配向処理される方向が、該画素電極に沿う電極線の直角方向から例えば約２度ずれて配向処理すると、画素内に形成されたディスクリネーション線に電極から横電界が斜めに印加されるため、スプレイ配向した液晶分子にねじれる力が加わりベンド配向へ転移しやすくなり、転移が確実に速い液晶表示装置となる。
【０３５５】
なお、第１の電圧としては、ディスクリネーション線を形成することが可能な電圧以上であれば良い。また、画素電極と共通電極の間に第２の電圧を印加するとしたが、共通電極に印加してもよい。
【０３５６】
また、前記配向膜材料としてポリイミド材料を使用したが、単分子膜材料などの他の材料でもよい。
【０３５７】
他の液晶表示装置においては、例えば、基板はプラスチック基板から形成することもできる。また、基板の一方を反射性基板から形成し、例えば、シリコンで形成してもよい。
【０３５８】
（実施の形態９）
本実施の形態は、信号電極線と画素電極、およびゲート電極線と画素電極に、それぞれ嵌合する形状の凹凸を形成したものである。
【０３５９】
図２０、図２１に、本実施の形態の液晶表示装置の要部を概念的に示す。
【０３６０】
本図は、アクティブマトリックス型のＯＣＢモードの液晶表示装置の画素を表示面上方（使用者側）から見たものである。
【０３６１】
図２０において、２０６は信号電極線（バスライン）であり、２０７はゲート電極線であり、２０８はスイッチングトランジスタ（素子）である。
【０３６２】
なお、図では信号電極線２０６とゲート電極線２０７は交差しているが、両方の電極線は絶縁膜（図示せぬ）を介して立体配置されているのは勿論である。
【０３６３】
また、ＴＦＴからなるスイッチングトランジスタ２０８は、図では略正方形状の画素電極２０２ａに接続されている。そして、信号電極線２０６、ゲート電極線２０７、スイッチングトランジスタ２０８、画素電極２０２ａの機能、動作、作用はＯＢＣモードのみならず従来の液晶表示装置と何等異ならない。
【０３６４】
また、最初に液晶分子２１１をスプレイ配向させるため、上下の配向膜２０３ａ・２０３ｂにラビングクロス等を使用しての配向処理がなされているのも同じである。
【０３６５】
更に、偏光板２０４ａ・２０４ｂ等の作用と共に、画素内のスプレイ配向状態から、液晶分子を対向基板間でベンド配向状態としたベンド配向領域に画素内の液晶分子全体を転移させる作用によって明暗の表示がなされるのも同じである。
【０３６６】
しかしながら、図２０（ａ）に示すように、略正方形状の画素電極２０２ａの各辺の略中央部に、凹部２２１ａおよび凸部２２２ａが形成されている。一方、これに近接して配線されている信号電極線２０６及びゲート電極線２０７は、前記凹部２２１ａおよび凸部２２２ａに嵌合するように凸部２６１・２７１と凹部２６２・２７２に変形した配線とされている。このため、画素電極２０２ａの上下、左右位置（図２０（ａ）における紙面上）に、変形した転移励起用の横電界印加部を形成することとなるのが、従来の液晶表示装置と相違する。
【０３６７】
次に、この液晶表示装置の製造方法について説明する。
【０３６８】
横電界印加部を含めた画素電極２０２ａ面上と共通電極２０２ｂ面上に、日産化学工業（株）社製のポリアミック酸タイプの約５度の大きさのプレチルト角のポリイミド配向膜材料を塗布乾燥焼成して、それぞれの電極面の液晶層２１０側に配向膜２０３ａ・２０３ｂを形成した。
【０３６９】
次に、前記配向膜２０３ａ・２０３ｂの表面を、共にラビングクロスで図２０（ａ）に示すように信号電極線２０６とほぼ直交する方向に配向処理した。
【０３７０】
以上のもとで、上下の基板間に正のネマティック液晶材料を真空注入して液晶層２１０を形成した。
【０３７１】
このため、図示せぬが、上下の配向膜２０３ａ・２０３ｂの表面では、液晶分子２１１が、そのプレチルト角が正負逆の値を持ち、しかも分子の直軸方向は互いにほぼ平行になるよう配向し、液晶層２１０はいわゆる無電圧印加状態で液晶分子が斜めに広がったいわゆるスプレイ配向となる。
【０３７２】
次に、液晶表示装置の表示のための動作について説明する。
【０３７３】
以上のもとで、共通電極２０２ｂと画素電極２０２ａ間に−１５Ｖという液晶分野では比較的電圧の高いパルス状の電圧を繰り返し印加すると共に、ゲート電極線２０７を通常の走査状態か、あるいは殆ど全てオンさせた状態にする。これにより、横電界印加部によって、ゲート電極線２０７、信号電極線２０６と画素電極２０２ａ間に周囲の通常の横電界より強い横電界が印加される。その結果、画素領域内のスプレイ配向領域において、信号電極線２０６とほぼ直交する方向にラビングした場合、主にゲート電極線２０７と画素電極２０２ａ間の横電界印加部を基点とした液晶層２９９にベンド配向への転移核が発生する。また、図２１に示すように、ゲート電極線２０７と直交する方向にラビングした場合、主に信号電極線２０６と画素電極２０２ａ間の横電界印加部を基点とした液晶層２９８にベンド配向への転移核が発生する。
【０３７４】
更に、この転移核をもとにベンド配向領域が拡大し、その結果画素領域全体を約０．５秒でベンド配向へ完了させることができた。
【０３７５】
なお、ＴＦＴパネル全体では、約２秒で速かに転移した。
【０３７６】
この機構であるが、上下電極間に高電圧が印加されて、図２０（ｂ）に示すように、液晶層２１０がｂ―スプレイ配向状態となり、周囲より歪みのエネルギーが高くなり、この液晶分子配向状態方向に横電界印加部からほぼ直角（図２０（ｂ）面垂直方向）に横電界が印加されるため、図２０（ｂ）のｂ―スプレイ配向における下基板側の液晶分子がねじれる力を受け、転移核の発生が起きるものと考えられる。
【０３７７】
以上の説明では、横電界印加部は、凹凹に変形した画素電極部と両方の信号電極線の凹凸部は、相互に嵌合するように形成されるものとしたが、図２２に示すように、画素電極２０２ａのみ、信号電極線２０６のみ、ゲート電極線２０７のみに形成されてもよいのは勿論である。
【０３７８】
即ち、本図においては、信号電極線２０６の凸部２６３、ゲート電極線２０７の凸部２７３、画素電極２０２ａの凸部２２３ａ・２２４ａはいずれか一方のみにあり、嵌合型となっていないのが図２０に示すものと相違する。
【０３７９】
また、凹凸部の平面形状は、図２０乃至図２２に示す三角形状、四角形状以外の形状、例えば台形形状、半円形状、円形状、楕円形状等であってもよいのは勿論である。
【０３８０】
更に、図２０乃至図２２では、横電界印加部は１画素の上下左右に合計４カ所設けているが、画素の大きさ等によっては上下の２個のみ、あるいは１個だけ設けても良く、更にまた電極縁にそって凹凸が連続的に形成されていてもよいのは勿論である。また、これまで、ラビング方向を信号電極線あるいはゲート電極線のほぼ直交するとしたが、ラビング方向を斜め方向にしても良い。この場合、信号およびゲート電極線と画素電極間の横電界印加部の液晶層からベンド配向へ転移が発生する。また、少なくとも、ラビング方向とほぼ直交する方向に横電界を印加できる横電界印加部を画素単位に少なくとも１個配置することが望ましい。
【０３８１】
また、図２０乃至図２２は平面図であるため、両電極線（信号電極線２０６およびゲート電極線２０７）と画素電極２０２ａは同一平面にあるように見えるが、これは少なくとも一方の電極線が画素電極とアレー基板上異なる高さに配置されていても良い。
【０３８２】
このように、画素電極の周辺の一部を基板面に平行な面内で凹凸に変形した電極変形部からなる横電界印加部は、平面視では０．５〜１０μｍ程度離れて、該横電界印加部の側方に存在する信号電極線若しくはゲート電極線の凸部や０．５〜１０μｍ程度凹んだ凹部の存在により、横電界を発生させる。
【０３８３】
（実施の形態１０）
本実施の形態は、横電界印加用の電極線を設けるものである。
【０３８４】
以下、図２３を参照しつつ本実施の形態を説明する。
【０３８５】
本図の（ａ）は、基板上面より見た平面図である。（ｂ）は、液晶表示装置のゲート電極線２０７に平行な面での断面図である。
【０３８６】
本図の（ａ）と（ｂ）において、２０９は、アレー基板２０１ａ上の信号電極線２０６のほぼ直下部分に横電界印加専用に布設された電線である。２１２は、前記横電界印加用線２０９と信号電極線２０６、ゲート電極線２０７等を絶縁するための透明絶縁膜である。従って、この画素を上部（表示面に直交する使用者側方向）から見た場合には、図２３（ａ）に示すごとく、画素の左右中央部にて横電界印加用線２０９の平面視三角形状の凸部２９１が信号電極線２０６の側方に突出している。なお、前記信号電極線２０６および画素電極２０２ａは従来技術のものと何等かわりがない。
【０３８７】
前記横電界印加用線２０９は、前記信号電極線２０６若しくはゲート電極線２０７が接続された駆動回路に接続され、さらに、前記横電界印加用線２０９は、配向転移後の通常の液晶表示時には、駆動回路と遮断されるよう構成されている。
【０３８８】
また、前記横電界印加用線２０９を、信号電極線２０６に対する上部の信号電極線とし、透明絶縁膜を介して画素電極に近接して設け、横電界印加の効果を増し、併せて透明絶縁膜中の図示していないコンタクトホールで電気的に接続されていてもよい。この場合、信号電極線が２本となるため冗長度が増し電気抵抗が低下するという効果もある。
【０３８９】
即ち、図２３（ｃ）に示すように、横電界印加用線２０９ａは、信号電極線２０６の直上に透明絶縁膜２１３を介して設けられている。なお、画素中央部への平面視三角形状の凸部２９１ａがあるのは同じである。
【０３９０】
また、図２３（ｄ）は、本実施の形態の他の例である。図に示すように、横電界印加用線２０９ｂが平坦化透明絶縁膜２１２ｂによって被覆され、さらに、専用線２０９ｂの下に信号電極線２０６が平坦化透明絶縁膜２１２ｃによって被覆され、画素電極２０２ａが前記平坦化透明絶縁膜２１２ｂの上に設けられている。なお、画素中央部への三角形状の凸部２９１ｂがあるのは同じである。
【０３９１】
また、図ではこの横電界印加用の専用線の凸部を三角形状としているが、これは画素電極に対向する部分全てに連続的に凸部を設けたり、更には上方へ突出した凸部を有する等、立体的な構造を有していてもよいのは勿論である。
【０３９２】
また、横電界印加用の専用線は信号電極線でなく、ゲート電極線の直下、直上に設けても良い。更には、両電極線の直下等に設けても良い。
【０３９３】
（実施の形態１１）
本実施の形態は、画素電極内に少なくとも１カ所の切欠きを設けて欠陥部を形成するものである。
【０３９４】
図２４に、本実施の形態の液晶表示装置の画素単位の平面と特徴を概念的に示す。本図に示すように、ＩＴＯ膜からなる画素電極２０２ａは、例えば数μｍ幅でエッチングにより除去されて平面視クランク形状の電極欠陥部２２５が形成されている。
【０３９５】
なお、この電極欠陥部２２５を含めた画素電極２０２ａ面上および図示せぬ共通電極面上には、日産化学工業（株）社製のポリアミック酸タイプの約５度の大きさのプレチルト角のポリイミド配向膜材料を塗布乾燥焼成して、それぞれ配向膜（図示せず）を形成し、更にそれらの表面をラビングクロスでゲート電極線２０７と直交する方向に配向処理がなされ、このため液晶分子のプレチルト角が正負逆の値を持ち、互いにほぼ平行方向になるよう同一方向に平行配向されているのは、第９および第１０の実施の形態と同じである。
【０３９６】
従って、液晶層はいわゆる無電圧印加状態で液晶分子が斜めに広がった配向領域からなるいわゆるスプレイ配向の液晶セルを形成しているのも同じである。
【０３９７】
しかしながら、表示前の画素の共通電極と画素電極間に１５Ｖ、あるいは共通電極に−１５Ｖの電圧のパルスを繰り返し印加すると共に、ゲート電極を通常の走査状態か、あるいは殆ど全てオンさせた状態にすると、画素単位には電極欠陥部２２５が存在するため、図２４（ｂ）に示すように、該電極欠陥部２２５の縁で強い歪みの斜め横電界２８０が発生する。
【０３９８】
このため、画素領域内のスプレイ配向は、この電極欠陥部２２５の液晶層２９９にベンド配向への転移核が発生し、更にこのベンド配向領域が拡大して画素領域全体を約０．５秒でベンド配向へ完了させる。また、ＴＦＴパネル全体では、約２秒で速かに転移する。
【０３９９】
これは、電極欠陥部２２５からなる横電界印加部で強い横電界を受け、この付近の液晶分子は基板面に水平状態に配向され、いわゆるｂ−スプレイ配向状態となり、周囲より歪みのエネルギーが高くなっており、この状態のもとで上下電極間に高電圧が印加されるため更にエネルギーが与えられ、その結果、電極欠陥部２２５において転移核が発生し、ベンド配向領域が拡大するものと考えられる。
【０４００】
なお、図２４では、平面視クランク形状の電極欠陥部２２５を１本形成しているが、２本以上としても良いのは勿論である。
【０４０１】
また、その形状は直線、角型や円形、楕円、更には三角形状等であっても良いのは勿論である。
【０４０２】
更に、電極欠陥部２２５は、共通電極側に形成しても良い。
【０４０３】
更にまた、画素電極および共通電極の両方に形成しても良いのも勿論である。
【０４０４】
（実施の形態１２）
本実施の形態は、横電界を発生させると共に、これに併せてあらかじめ画素平面内にチルト角の相違する領域を形成しておくものである。
【０４０５】
図２５に、本実施の形態の液晶表示装置の画素単位の構成と特徴を概念的に示す。本図の（ａ）は、ゲート電極線に平行な方向の画素の断面図であり、同一画素であるが、左側の（イ）と右側の（ロ）とで、チルト角が相違している様子を示す。
【０４０６】
図２５（ｂ）は、上（使用者側）方向より見た画素の平面図であり、画素電極２０２ａの上下左右に凹凸部２２１ａ・２２２ａが設けられ、更に信号電極線２０６およびゲート電極線２０７の対応する位置に前記凹凸部２２１ａ・２２２ａに相嵌合するように凹凸部２６１・２６２・２７１・２７２が設けられており、前述した実施の形態７と同様に、第１の電圧である２．５Ｖを印加して、図２５（ａ）の（イ）と（ロ）の境界にディスクリネーション線２２６が形成されている。
【０４０７】
以下、本実施の形態の液晶表示装置の製造方法について説明する。
【０４０８】
アクティブマトリックス型の液晶セルの対向する基板内面上にはそれぞれ配向膜２０３ａｍ・２０３ｂｍが形成され、この配向膜２０３ａｍ・２０３ｂｍは、液晶層２１０が無電圧印加状態でスプレイ配向を形成する処理がされていること、画素電極２０２ａやこれに近接して配線されているゲート電極線２０７等に転移励起用の横電界印加部を形成すること等は、先の第１の実施の形態と同じである。
【０４０９】
しかしながら、配向膜の処理が異なる。即ち、図２５（ａ）において、横電界印加部を含めた画素電極２０２ａ面上に、日産化学工業（株）社製のポリアミック酸タイプの約５度の大きい値を持つプレチルト角Ｂ２のポリイミド配向膜材料を塗布乾燥焼成し、配向膜２０３ａｍを形成する。
【０４１０】
次に、この配向膜２０３ａｍの左側片側領域２０３ａｈのみ、即ち、（イ）に示す方のみに紫外線を照射してプレチルト角Ｅ２が約２度の小さい値の配向膜に変化させる。
【０４１１】
これに対して、対向基板２０１ｂ上には日産化学工業（株）社製のポリアミック酸タイプの約５度の大きい値のプレチルト角Ｆ２を界面液晶分子に付与するポリイミド配向膜材料を塗布乾燥焼成し、共通電極２０２ｂ上に配向膜２０３ｂｈを形成する。
【０４１２】
次に、前記配向膜２０３ｂｈの右側片側領域２０３ｂｍのみ、即ち、（ロ）に示す方のみに紫外線を照射してプレチルト角Ｄ２の約２度の小さい値の配向膜に変化させる。
【０４１３】
このようにして、図２５（ａ）の（イ）に示す如くアレー基板２０１ａ側左半分の配向膜２０３ａｈの小さい値のプレチルト角Ｅ２に対向して対向基板２０１ｂ側左半分の配向膜２０３ｂｈの大きい値のプレチルト角Ｆ２を配置させ、（ロ）に示すごとくアレー基板側２０１ａ右半分の配向膜２０３ａｍの大きい値のプレチルト角Ｂ２に対向して対向基板２０１ｂ側右半分の配向膜２０３ｂｍの小さい値のプレチルト角Ｄ２を配置させる。
【０４１４】
更に、このようにして形成した互いに大小のプレチルト角を付与する配向膜の表面をラビングクロスで図２５（ｂ）に示すように信号電極６とほぼ直交する方向に上下基板同一方向に平行配向処理した。その後、正のネマティック液晶材料を充填して、これからなる液晶層２１０を配置した。
【０４１５】
以上の下で、画素電極２０２ａの配向元（ラビングの根本方向）には小さいプレチルト角Ｅ２が、該プレチルト角Ｅ２に対向する側には大きい値のプレチルト角Ｆ２が配置され、図２５（ａ）の画素の（イ）で示す領域には液晶分子を下基板側にスプレイ配向させたｂ−スプレイ配向２２７ｂが、画素の（ロ）で示す領域には液晶分子を上基板側にスプレイ配向させたｔ−スプレイ配向２２７ｔが形成されやすくなる。
【０４１６】
次に、液晶セルのスイッチングトランジスタ２０８を通して対向する電極間に転移臨界電圧付近の２．５Ｖを印加すると、上述の理由で同一の画素内にｂ−スプレイ配向領域とｔ−スプレイ配向領域が形成され、その境界にディスクリネーション線２２６が信号電極線２０６に沿って、かつゲート電極線２０７に渡って明瞭に形成された。
【０４１７】
この画素の共通電極と画素電極間に−１５Ｖのパルスを繰り返し印加した。そうすると、図２５（ｂ）に示すように、ディスクリネーション線２２６と横電界印加部付近の液晶層２９９から転移核が発生してベンド配向領域へ転移が拡大し、ＴＦＴパネル画素全体では約１秒で速かに転移した。
【０４１８】
これは、ｂ−スプレイ配向状態とｔ−スプレイ配向領域の境界であるディクリネーション線２２６領域は周囲より歪みのエネルギーが高くなっていて、この状態に加えて横電界印加部で発生する横電界によってスプレイ配向にねじれが発生して転移し易くなり、これに上下電極間に高電圧が印加されて更にエネルギーが与えられベンド転移したものと考えられる。
【０４１９】
以上、本発明を幾つかの実施の形態に基づいて説明してきたが、本発明は何もこれらに限定されないのは勿論である。即ち、例えば以下のようにしてもよい。
【０４２０】
１）画素電極と共通電極間に印加する電圧を連続的、あるいは間欠的とする。
【０４２１】
２）高電圧パルスが繰り返し印加される場合、その周波数は０．１Ｈｚから１００Ｈｚの範囲であり、且つ第２の電圧のデューティー比は少なくとも１：１から１０００：１の範囲で、転移を速める値を選択する。
【０４２２】
３）使用する基板をプラスチック製とし、電極として有機導電膜を採用する。
【０４２３】
４）基板の一方を反射性基板により形成し、例えばシリコンとしたり、あるいは、アルミニウム等の反射電極よりなる反射性基板により形成し、反射型液晶表示装置とする。
【０４２４】
５）画素電極、共通電極に基板面に直交する方向の強電極電界発生用突起を設ける等の手段をも併用する。
【０４２５】
６）両基板間を一定に保持する球状ガラスやシリカに換えて、そのための突起物を形成し、該突起物に液晶分子を配列させる機能を持たせる等の手段をも併用する。
【０４２６】
７）前記突起部の上部若しくは下部を前記強電極発生用突起に兼用する。
【０４２７】
８）画素電極の形状は、正方形状でなく、長方形状や３角形状とする。
【０４２８】
９）画素を液晶の配向の異なる領域に分割するのは２つではなく、３つや４つとしたりする。
【０４２９】
１０）プレチルト角に大小を付けるのに、透明電極をＯ2 アッシャー等で表面状態を変え、該透明電極に配向膜を形成する等の手段を採用している。
【０４３０】
（実施の形態１３）
図２６は実施の形態１３に係る液晶表示装置に用いられる液晶セルの構成外観図であり、図２７、および図２８は凸形状物作製を説明するための製造プロセスの一部である。
【０４３１】
ガラス基板３０８上にＪＳＲ株式会社製ＰＣ系レジスト材料を塗布形成し厚さ１μｍのレジスト薄膜を形成する。次にレジスト薄膜３２０に、矩形状のパターンの開口部３２２を設けたフォトマスク３２１を通して、平行光紫外線３２３で照射露光する。平行光で露光された上記レジスト薄膜３２０を現像、リンスし、９０℃でプリベークして図２８に示すように断面が凸状の形状物３１０を形成する。
【０４３２】
次に、前記基板上に、定法に従いＩＴＯ電極７を２０００Ａ製膜し、電極付ガラス基板３０８とした。その後、透明電極３０２を有するガラス基板３０１、および上記凸形状物の形成されたガラス基板３０８上に日産化学工業製配向膜塗料ＳＥ−７４９２をスピンコート法にて塗布し、恒温槽中１８０℃、１時間硬化させ配向膜３０３、３０６を形成する。その後、レーヨン製ラビング布を用いて図２９に示す方向にラビング処理を施し、積水ファインケミカル（株）製スペーサ５、およびストラクトボンド３５２Ａ（三井東圧化学（株）製シール樹脂の商品名）を用いて基板間隔が６．５μｍとなるように貼り合わせ、液晶セル３０９（液晶セルＡとする）を作成した。
【０４３３】
この時、配向膜界面での液晶プレチルト角が約５度となるようにラビング処理を行った。
【０４３４】
次に、液晶ＭＪ９６４３５（屈折率異方性Δn＝０．１３８）を真空注入法にて液晶セルＡに注入し、テストセルＡとした。
【０４３５】
次に、テストセルＡに、その偏光軸が配向膜のラビング処理方向と４５度の角度をなし、かつ、お互いの偏光軸方向が直交するように偏光板を貼合し、７Ｖ矩形波を印加してスプレイ配向からベンド配向への転移を観察したところ、約５秒で全電極領域がスプレイ配向からベンド領域へと転移した。
【０４３６】
凸形状物３１０の形成された領域では、液晶層厚が周囲の液晶層領域に比べて小さく実効的に電界強度が大きく、この部分よりベンド転移が確実に発生する。
発生したベンド配向は速やかに他の領域に広がっていく。
【０４３７】
即ち、確実かつ高速なスプレイ→ベンド転移が達成出来る。
【０４３８】
凸形状物としては、その断面形状が本実施例の如く矩形状のほか、台形状、三角状、半円状でも良いことは言うまでもない。
【０４３９】
比較例として、凸形状部３１０を有しない透明電極付きガラス基板を用いること以外、同様のプロセスで、スプレイ配向液晶セルＲを作製し、液晶ＭＪ９６４３５を封入してテストセルＲとした。このテストセルＲに７Ｖ矩形波を印加した時の、全電極領域がスプレイ配向からベンド領域へと転移するに要する時間は４２秒であり、本発明の効果は明らかである。
【０４４０】
（実施の形態１４）
図３０は実施の形態１４に係る液晶表示装置に用いられる液晶セルの構成外観図であり、図３１はその平面図である。図３０は図３１の矢視Ｘ１−Ｘ１から見た断面図である。実施の形態１４は、凸形状物３１０を、表示画素領域外に形成された透明電極３０７ａ上に設けたことを特徴とするものである。以下に、その作製手順を説明する。
【０４４１】
透明電極３０２を有するガラス基板３０１、および凸形状物の形成されたガラス基板３０８上に日産化学工業製配向膜塗料ＳＥ−７４９２をスピンコート法にて塗布し、恒温槽中１８０℃、１時間硬化させ配向膜３０３，３０６，３０６ａを形成する。その後、レーヨン製ラビング布を用いて図２９に示す方向にラビング処理を施し、積水ファインケミカル（株）製スペーサ５、およびストラクトボンド３５２Ａ（三井東圧化学（株）製シール樹脂の商品名）を用いて基板間隔が６．５μｍとなるように貼り合わせ、液晶セル（液晶セルＢとする）を作成した。
【０４４２】
この時、配向膜界面での液晶プレチルト角が約５度となるようにラビング処理を行った。
【０４４３】
次に、液晶ＭＪ９６４３５（屈折率異方性Δn＝０．１３８）を真空注入法にて液晶セルＢに注入した。
【０４４４】
次に、液晶セルＢに、その偏光軸が配向膜のラビング処理方向と４５度の角度をなし、かつ、お互いの偏光軸方向が直交するように偏光板を貼合し、７Ｖ矩形波を印加してスプレイ配向からベンド配向への転移を観察したところ、約７秒で全電極領域がスプレイ配向からベンド領域へと転移した。
【０４４５】
本実施の形態では、表示画素領域外に凸形状部を設け、表示画素領域外でベンド転移核発生をさせたものであるが、発生したベンド配向は表示画素領域外から表示画素領域内に速やかに広がっていくことが確認された。
【０４４６】
表示画素領域とベンド核発生用電極領域との間には、電界の印加されない（電極部を有しない）領域が存在するが、微小領域でありさえすればこの領域を越えてベンド配向は展開する。
【０４４７】
（実施の形態１５）
図３２は実施の形態１５に係る液晶表示装置に用いられる液晶セルの構成外観図であり、図２７、図２８、および図３３は凸形状物作製を説明するための製造プロセスの一部である。
【０４４８】
ガラス基板３０８上にＪＳＲ株式会社製ＰＣ系レジスト材料を塗布形成し厚さ１μｍのレジスト薄膜を形成する。次にレジスト薄膜３２０に、矩形状のパターンの開口部３２２を設けたフォトマスク３２１を通して、平行光紫外線３２３で照射露光する。平行光で露光された上記レジスト薄膜２０を現像、リンスし、９０℃でプリベークして図２８に示すように断面が凸状の形状物３１０を形成する。
【０４４９】
次に、上記レジスト薄膜材料のガラス転移点以上の１５０℃でポストベークして凸形状物３１０の肩をなだらかに順方向に傾斜させて、図３２に示すようにその断面形状を山形様に形成する工程で製造する。
【０４５０】
次に、前記基板上に、定法に従いＩＴＯ電極を２０００Åの厚みで製膜し、電極付ガラス基板３０８とした。その後、透明電極３０２を有するガラス基板３０１、および上記凸形状物の形成されたガラス基板３０８上に日産化学工業製配向膜塗料ＳＥ−７４９２をスピンコート法にて塗布し、恒温槽中１８０℃、１時間硬化させ配向膜３０３、３０６を形成する。その後、レーヨン製ラビング布を用いて図２９に示す方向にラビング処理を施し、積水ファインケミカル（株）製スペーサ３０５、およびストラクトボンド３５２Ａ（三井東圧化学（株）製シール樹脂の商品名）を用いて基板間隔が６．５μｍとなるように貼り合わせ、液晶セル３０９（液晶セルＣとする）を作成した。
【０４５１】
この時、配向膜界面での液晶プレチルト角が約５度となるようにラビング処理を行った。
【０４５２】
次に、液晶ＭＪ９６４３５（屈折率異方性Δn＝０．１３８）を真空注入法にて液晶セルＣに注入し、テストセルＣとした。
【０４５３】
次に、テストセルＣに、その偏光軸が配向膜のラビング処理方向と４５度の角度をなし、かつ、お互いの偏光軸方向が直交するように偏光板を貼合し、７Ｖ矩形波を印加してスプレイ配向からベンド配向への転移を観察したところ、約７秒で全電極領域がスプレイ配向からベンド領域へと転移した。
【０４５４】
本テストセルＣは、上記三角形状先端部に電界の集中が起こり、この部分よりベンド配向が発生する。また、三角形状物６０上部では、ラビング処理による擦り上げ部と擦り下げ部が存在するため、結果として液晶プレチルト角の符号が反対の領域が出来る。即ち前記凸形状部の近傍では液晶ダイレクタが基板面に水平になっており、このことも高速なスプレイ−ベンド転移に寄与しているものと思われる。
【０４５５】
本実施例では画素領域内に電界集中部を設けたが、画素領域外に設けても同様な効果が認められた。また、本実施例では電界集中部位は基板片側に配設したのみであるが、基板両側に配設しても良いことは言うまでもない。
【０４５６】
（実施の形態１６）
図３４は実施の形態１６に係る液晶表示装置に用いられる液晶セルの構成外観図であり、図３５は本実施の形態で用いたガラス基板３０２の電極パターンを表している。
【０４５７】
開口部３８０を有する透明電極３０２、及び開口部を有しない透明電極３０７を有する２枚のガラス基板３０１、３０８上に日産化学工業製配向膜塗料ＳＥ−７４９２をスピンコート法にて塗布し、恒温槽中１８０℃、１時間硬化させ配向膜３０３、３０６を形成する。その後、レーヨン製ラビング布を用いて図２９に示す方向にラビング処理を施し、積水ファインケミカル（株）製スペーサ３０５、およびストラクトボンド３５２Ａ（三井東圧化学（株）製シール樹脂の商品名）を用いて基板間隔が６．５μｍとなるように貼り合わせ、液晶セル３０９（液晶セルＤとする）を作成した。
【０４５８】
この時、配向膜界面での液晶プレチルト角が約５度となるようにラビング処理を行った。
【０４５９】
次に、液晶ＭＪ９６４３５（屈折率異方性Δn＝０．１３８）を真空注入法にて液晶セルＤに注入し、テストセルＤとした。
【０４６０】
次に、その偏光軸が配向膜のラビング処理方向と４５度の角度をなし、かつ、お互いの偏光軸方向が直交するように偏光板を貼合し、電圧を印加しながらスプレイ配向からベンド配向への転移を観察した。
【０４６１】
このテストセルＤに、ガラス基板８側電極に２Ｖ、３０Ｈｚ、矩形波を、ガラス基板１側電極に７Ｖ、３０Ｈｚ、矩形波を印加した時の、全電極領域がスプレイ配向からベンド領域へと転移するに要する時間は５秒であり、極めて高速なベンド転移が実現された。
【０４６２】
本実施例においては、二枚の電極間に挟持された液晶層に５Ｖ（＝７Ｖ−２Ｖ）の電界が印加されるが、電極開口部の液晶層には７Ｖ（＝７Ｖ−０Ｖ）の実効電界が印加されることになるため、ここよりベンド配向が発生する。
【０４６３】
本実施例では開口部形状を矩形としたが、円形、三角形状など他の形状でも良いことは言うまでもない。
【０４６４】
（実施の形態１７）
図３６は実施の形態１７に係る液晶表示装置に用いられる液晶セルの要部断面図であり、図３７はその一部の拡大図である。この液晶セルは、ガラス基板３０８上に画素スイッチング素子３８０、信号電極線３８１、ゲート信号線（図示せず）が形成されており、これらスイッチング素子３８０、信号電極線３８１及びゲート信号線を覆って平坦化膜３８２が形成されている。そして、平坦化膜３８２上に表示電極３０７が形成されており、この表示電極３０７とスイッチング素子３８０とは、平坦化膜３８２に開口したコンタクトホール３８３内を挿通する中継電極３８４を介して電気的に接続されている。中継電極３８４は、コンタクトホール３８３の上開口側の部分が、図３７に示すように凹部３８４ａとなっている。このような凹部３８４ａにより、表示電極３０７に開口が形成されることになり、この凹部３８４ａ付近で電界の集中を生じさせることが可能となる。よって、転移時間の短縮化を達成することができる。
【０４６５】
（実施の形態１８）
図３８は実施の形態１８に係る液晶表示装置の構成外観図である。
【０４６６】
実施の形態１６で作成したテストセルＤに、主軸がハイブリット配列した負の屈折率異方性もつ光学媒体よりなる位相差板３１２、３１５、負の一軸性位相差板３１１、３１４、正の一軸性位相差板３１９、偏光板３１３、３１６を図３９に示される配置で貼合し、液晶表示装置を作成した。
【０４６７】
この時の位相差板３１２、３１５、３１１、３１４、３１９のリターデーション値は波長５５０ｎｍの光に対して、それぞれ２６ｎｍ、２６ｎｍ、３５０ｎｍ、３５０ｎｍ、および１５０ｎｍであった。
【０４６８】
図４０は２５℃における液晶表示装置の正面での電圧−透過率特性である。１０Ｖの矩形波電圧を１０秒印加しベンド配向を確認した後、電圧を降下させながら測定した。本液晶表示素子ではベンド配向からスプレイ配向への転移が２．１Ｖで起こるため、実効的には２．２Ｖ以上の電圧で表示を行う必要がある。
【０４６９】
次に、白レベル電圧を２．２Ｖ、黒レベル電圧を７．２Ｖとした時のコントラスト比の視角依存性を測定したところ、上下１２６度、左右１６０度の範囲でコントラスト比１０：１以上が達成されており、基板配向膜面上に液晶ダイレクタ方位が周囲とは異なる部位を一部設けても、充分な広視野角特性が維持されることが確認された。また、目視観察においても、配向不良および表示品位不良は認められなかった。
【０４７０】
また、３Ｖ〜５Ｖ間の応答時間を測定したところ、立ち上がり時間は５ミリ秒、立ち下がり時間は６ミリ秒であった。
【０４７１】
以上より明らかなように、本発明液晶表示装置は、従来のＯＣＢモードの広視野角特性や応答特性を犠牲にすることなく、高速なスプレイ−ベンド配向転移を達成することが出来、その実用的な価値は極めて大きい。
【０４７２】
（実施の形態１９）
図４１は実施の形態１９に係る液晶表示装置の要部断面図である。ベンド配向型セルとして動作させる液晶セルは、２枚の平行な基板４００，４０１間に液晶層４０２を封入した、いわゆるサンドイッチセルである。通常、一方の基板には透明電極が、他方の基板には薄膜トランジスタを備えた画素電極が、各々形成されている。
【０４７３】
図４１（ａ）は、電場を印加しない初期状態の配向を示す模式図である。初期状態の配向は、液晶分子の分子軸が基板４００，４０１平面に対して若干の傾きを有しながらもほぼ平行に且つ実質的に一様に配向した状態、すなわちホモジニアス配向である。基板との界面に存在する液晶分子は、上下両基板４００，４０１において、互いに逆方向に傾斜している。すなわち、基板との界面に存在する液晶分子の配向角θ1およびθ2（すなわち、プレチルト角）は、互いに異符号となるように調整されている。なお、以下の説明において、配向角およびプレチルト角は、基板に平行な平面に対する液晶分子の分子軸の傾きを、基板に平行な平面を基準に反時計回りに正として表した角度である。
【０４７４】
図４１（ａ）の状態の液晶層４０２に、基板平面に対して垂直方向にある値を超える強さの電場を印加すると、液晶の配向状態が変化し、図４１（ｂ）に示すような配向へと転移する。
【０４７５】
図４１（ｂ）に示す配向は、ベンド配向と呼ばれるものであり、両基板表面付近においては基板平面に対する液晶分子の分子軸の傾き、すなわち配向角の絶対値が小さく、液晶層４０２の中心部分においては液晶分子の配向角の絶対値が大きくなっている。また、液晶層全体に渡って、実質的にねじれ構造を有してない。
【０４７６】
このような、ホモジニアス配向からベンド配向への転移を詳細に観察すると、まず、液晶層４０２の一部においてベンド配向の核が発生しており、この核が、ホモジニアス配向である他の領域を蚕食しながら次第に成長し、最終的には液晶層全体がベンド配向となる。換言すれば、液晶層のベンド配向への転移には、核の発生、すなわち微小領域でのホモジニアス配向からベンド配向への転移が必要である。
【０４７７】
そこで、発明者らは、液晶分子配向の単位ベクトル（以下、「ディレクター」とする。）の運動方程式を解くことにより、微小領域でのベンド配向への転移について解析し、核が容易に発生し得る条件を見出した。以下に、その手法について説明する。
【０４７８】
液晶の配向状態は、ディレクターによって記述される。なお、ディレクターｎは、［数１］で表される関数である。
【数１】

【０４７９】
液晶の自由エネルギー密度ｆは、［数２］に示すように、ディレクターｎの関数として表わすことができる。
【数２】

【０４８０】
ここで、ｋ11、ｋ22、ｋ33はFrankの弾性定数であり、各々、スプレイ、ツイスト、ベンドの弾性定数を表す。Δεは、液晶の分子軸方向の誘電率とそれに直交する方向の誘電率との差、すなわち誘電率異方性を表す。また、Ｅは、外部電場である。
【０４８１】
［数２］において、第１項、第２項、第３項は、各々、液晶の広がり、捻じれ、曲がりによる弾性エネルギーを表わす。また、第４項は、外部電場と液晶との電気的相互作用による電気エネルギーを表す。電気エネルギーは、Δε＞０であればｎがＥと平行となるときに最小となり、Δε＜０であればｎがＥに直交するときに最小となる。従って、ある特定の強さを超える電場Ｅが印加されると、液晶分子は、Δε＞０であれば分子長軸が電場方向に平行になるように配向し、Δε＜０であれば分子長軸が電場方向に直交するように配向する。
【０４８２】
初期状態の分子配向が外部電場による変形を受けたときの液晶の全自由エネルギーＦは、ｆの体積積分として表すことができる。
【数３】

［数３］に示すように、全自由エネルギーＦは、ディレクターを表す未知関数ｎ(ｘ)を変数として定義される関数（すなわち、汎関数）である。外部電場印加下において出現する液晶の配向状態は、適当な境界条件のもとで、全自由エネルギーＦを最小とするｎ(ｘ)で記述される。すなわち、Ｆを最小とするｎ(ｘ)が決まれば、液晶の配向状態を予測することができる。更に、適当な境界条件のもとでＦを最小とするような、時間変化をも考慮したディレクターn(ｘ，ｔ) を決めることができれば、光学定数などのデバイスのあらゆる挙動を予測することができる。これは、物理的にいえば典型的な最小作用の原理であり、数学的にいえば境界値付きの変分極小問題である。
【０４８３】
そこで、［数３］を原理的に解く。しかし、例えば、Eulerの方程式を用いるような解析的方法では、複雑な非線形方程式が現れるため、ディレクターｎ(ｘ)の関数形を簡単に決定することは困難である。
【０４８４】
そこで、［数３］を容易に解くために、次のような方法を採用する。まず、積分空間を有限要素法と同様の手法により離散化する。すなわち、全積分空間をｎｐ個の要素に分割し、［数３］を各要素の積分の和として表わす。
【数４】

【０４８５】
ここで、部分積分空間ΔＶにおけるディレクターn(ｘ)に対して、以下のような近似を行う。ｎx 、ｎy、ｎzは、［数２］式に示すように本来ならばｘ、ｙ、ｚの関数であるが、ΔＶにおいては一定であると仮定する。また、ｄｎx,j／ｄｘ＝（ｎx,j+1−ｄｎx,j）／Δｘと近似する。なお、ｎx,jは、第ｊ番目の要素中におけるｎxであり、前述したようにΔＶにおいては一定ではあるが、未知数である。この部分積分空間ΔＶにおけるn(ｘ)の近似は粗いものであるが、これを積分空間の分割を細かくすることによってカバーし、近似を高めることができる。
【０４８６】
上記近似によれば、［数４］において、ｎx,j、ｎy,j、ｎz,jは１つの要素中では定数であるため、積分自体は容易に計算できる。しかし、この段階でも、全自由エネルギーＦを表す式は、分割数に比例する多数の未知数ｎx,j、ｎy,j、ｎz,jの高次項および非線型項が存在し、依然として複雑である。但し、ｎx,0、ｎy,0、ｎz,0などの値は、境界条件として容易に与えることができる。
【０４８７】
上記近似によれば、全自由エネルギーＦは、
【数５】

という形に変換される。すなわち、全自由エネルギーＦは、未知関数ｎ(ｘ)を変数として定義される汎関数から、未知数ｎx,j、ｎy,j、ｎz,jの関数に変換される。未知数ｎx,j、ｎy,j、ｎz,jは、多次元のパラメーター空間内で、関数Ｆを最小とする値である。
【０４８８】
液晶のベンド配向は、前述したように、捻じれを実質的に有しない構造である。ディレクターｎは、前述したように本来はｘ、ｙ、ｚの関数であるが、配向角の関数として表すことが可能である。この場合、ベンド配向におけるディレクターｎは、
【数６】

で表される。但し、θは、基板に平行な平面に対する液晶分子の傾き、すなわち配向角である。また、θは、液晶分子の基板からの距離ｚのみに依存するものとする。図２は、このディレクターを示した模式図である。
【０４８９】
［数６］を［数４］に代入し、ｎｐ個の要素に分割して離散化を行い、各要素について、Ｆを最小化するようなθjを求める。すなわち、各要素について、
【数７】

なる方程式を満足するθjを求める。なお、ｄはＬ／ｎｐであり、Ｌは基板間距離である。
【０４９０】
しかし、［数７］のような複雑な非線型方程式を、ｎｐ個連立させて解くのは容易ではない。そこで、以下のような回路類推を行うことにより、［数７］を解く。ディレクターの運動方程式は、
【数８】

で表される。なお、ηは、液晶の粘性率である。[数８]について、以下のような回路類推を行う。
【数９】

[数８]は、
【数１０】

に変換される。[数１０]に対応する回路は、図３に示すように、ｎｐ個のＣＲ回路で構成されている。 [数１０]の第二項は、ＣＲ回路を流れる電流を表す。なお、Ｒjは放電緩和のための抵抗であって、ＣＲ回路を流れる電流（ｉ）を、ｉ＝∂Ｆ（Ｖj）／∂Ｖjとして規定する電圧制御抵抗である。
【０４９１】
電流ｉ（＝∂Ｆ／∂Ｖj）は、特定のＶjでゼロに収束する。すなわち、Ｖjは、回路シミュレーターでＣＲ回路を流れる電流がゼロとなるときの電圧を求めれば、自動的に求めることができる。
【０４９２】
このように、ディレクターの運動方程式を等価回路に置き換えることにより、液晶の配向現象を表現する非線型連立方程式を回路シミュレーター上で解析し、外部電場Ｅと配向状態（配向角θj）との関係を求めることができる。
【０４９３】
上記手法においては、配向現象を表現する非線型連立方程式を、電気回路的な類推によって回路に置き換えて回路シミュレーター上で解析するため、プログラム中には等価回路が設定されるだけで、方程式自身を解くための計算プロセスは含まれない。よって、プログラムの単純化および縮小を実現することができる。
【０４９４】
更に、上記手法に基づいて、外部電場Ｅの増加に伴う配向角θjの変化を計算すれば、配向角θjが突然変化するときの外部電場Ｅとして、液晶転移の臨界電場Ｅｃを求めることができる。
【０４９５】
図４４は、上記手法に基づく計算結果の一例であり、外部電場Ｅを時間とともに増加させたときの、θjの時間変化を表す。なお、図４の結果は、境界条件をθ0＝＋０．１rad、θnp-1＝−０．１radとして固定し、ｋ11＝６×１０^-7dyn、ｋ33＝１２×１０^-7dyn、Δε＝１０として計算した結果である。図４に示すように、電場印加初期においては、配向角θjがいずれも比較的小さく、液晶の配向状態がホモジニアス配向であることがわかる。しかし、一定時間経過後、すなわち外部電場Ｅが一定値を超えると（Ｅ＞Ｅｃ）、配向角θjが突然変化して転移が生じる。転移後の配向角θjは、両基板近傍から液晶層の中心部に向かってその絶対値が大きくなっており、転移後の液晶の配向状態がベンド配向であることがわかる。
【０４９６】
臨界電場Ｅｃが小さいほど、液晶の配向状態をホモジニアス配向からベンド配向へと速やかに転移させることができる。そこで、上記手法に基づいて、液晶の配向を決める条件を種々変化させて、各条件下での臨界電場Ｅｃを計算した。その結果、臨界電場Ｅｃは、特に、液晶の弾性定数（スプレイ弾性定数）、プレチルト角の非対称性に影響されることが見出された。
【０４９７】
図４５は、スプレイ弾性定数ｋ11と臨界電場Ｅｃとの関係を求めた結果を示したものである。なお、図４５は、境界条件をθ0＝＋０．１rad、θnp-1＝−０．１radとし、ｋ33＝１２×１０^-7dyn、Δε＝１０として計算した結果である。図４５に示すように、スプレイ弾性定数ｋ11が大きいほど、臨界電場Ｅｃが増大する。特に、ｋ11＞１０×１０^-7dynの範囲では、ｋ11の増大に伴って、Ｅｃが急激に増大する。
【０４９８】
従って、速やかな液晶転移を実現するためには、スプレイ弾性定数ｋ11を、１０×１０^-7dyn未満、好ましくは、８×１０^-7dyn以下とすることが有効である。
また、スプレイ弾性定数ｋ11の下限については、特に限定するものではないが、６×１０^-7dyn以上とすることが好ましい。ｋ11＜６×１０^-7dynの液晶材料を合成または調製することは、通常、困難であるからである。
【０４９９】
上記のようなスプレイ弾性定数ｋ11を有する液晶材料としては、特に限定するものではないが、例えば、ピリミジン系液晶、ジオキサン系液晶、ビフェニル系液晶などを挙げることができる。
【０５００】
プレチルト角の非対称性は、上下基板間でのプレチルト角の絶対値の差（Δθ）で表すことができる。また、前述したように、プレチルト角θ0およびθnp-1は互いに異符号とされるため、プレチルト角の絶対値の差（Δθ）は、Δθ＝｜θ0＋θnp-1｜で表すことができる。
【０５０１】
図４６（ａ）は、上下基板間でのプレチルト角の絶対値の差（Δθ）と臨界電場Ｅｃとの関係を求めた結果を示すものである。図６のａは、ｋ11＝６×１０^-7dyn、ｋ33＝１２×１０^-7dyn、Δε＝１０として計算した結果である。図４６（ａ）に示すように、プレチルト角の差Δθが大きいほど、臨界電場Ｅｃが低下する。特に、Δθ≧０．０００２radの範囲では、Δθの増大に伴って、Ｅｃが急激に低下する。
【０５０２】
従って、速やかな液晶転移を実現するためには、プレチルト角の差Δθを、０．０００２rad以上、好ましくは０．０３５rad以上とすることが有効である。また、プレチルト角の差Δθの上限については、特に限定するものではないが、通常、１．５７rad未満、好ましくは０．７８５rad以下とする。
【０５０３】
なお、プレチルト角θ0およびθnp-1は、その絶対値が、通常、０radを超え且つ１．５７rad未満、好ましくは０．０１７rad以上０．７８５rad以下となるように調整される。プレチルト角の調整は、基板表面に、斜方蒸着法およびラングミュア−ブロジェット（ＬＢ）法などの方法により、適当な液晶配向膜を形成することによって制御することができる。液晶配向膜としては、特に限定するものではないが、例えば、ポリイミド樹脂、ポリビニルアルコール、ポリスチレン樹脂、ポリシンナメート樹脂、カルコン系樹脂、ポリペプチド樹脂および高分子液晶などを挙げることができる。また、液晶配向膜の材料選択のほか、斜方蒸着法を採用する場合は蒸着方向の基板表面に対する傾きを調製することによって、ＬＢ法を採用する場合は基板の引き上げ速度などの条件を調整することによって、プレチルト角を制御することができる。
【０５０４】
また、臨界電場Ｅｃは、液晶層内の電場の不均一性に影響される。液晶層に発生する電場の歪みが、液晶分子の配向状態の安定性に影響するからである。なお、電場の不均一性は、液晶層に実質的に均一に印加される主電場Ｅ0と、不均一に印加される副電場Ｅ1との比（Ｅ1／Ｅ0）で表すことができる。なお、Ｅ1は、印加される副電場の最大値とする。
【０５０５】
電場の不均一性Ｅ1／Ｅ0と臨界電場Ｅｃとの関係は、前述した手法に基づいて、以下のようにして調べることができる。すなわち、液晶層に、外部電場Ｅとして均一電場である主電場Ｅ0を印加するとともに、不均一電場である副電場Ｅ1を重畳させて印加するという条件で、主電場Ｅ0の増加に伴う配向角θjの変化を計算する。このとき、副電場Ｅ1は、主電場Ｅ0の増加に伴って、Ｅ1／Ｅ0が所定の値で一定となるように増加させる。得られた計算結果より、配向角θjが突然変化するときの主電場Ｅ0として、液晶転移の臨界電場Ｅｃが求められる。
【０５０６】
図４７は、上記手法に基づいて、Ｅ1／Ｅ0の値を種々変化させて、各条件下での臨界電場Ｅｃを計算した計算結果の一例である。なお、図７の結果は、境界条件をθ0＝＋０．２６rad、θnp-1＝−０．２５radとして固定し、ｋ11＝６×１０^-7dyn、ｋ33＝１２×１０^-7dyn、Δε＝１０として計算した結果である。図４７に示すように、Ｅ1／Ｅ0が大きいほど、すなわち電場の不均一性が大きいほど、臨界電場Ｅｃが増大し、Ｅ1／Ｅ0＝１付近ではＥｃは無限小となる。これは、液晶層の電場に歪みが存在すると、電場が一様である場合に比べてホモジニアス配向が不安定となり、その結果、ベンド配向への転移が速やかに発現するからであると考えられる。
【０５０７】
従って、速やかな液晶転移を実現するためには、液晶層に、実質的に均一な主電場Ｅ0とともに、空間的に不均一な電場Ｅ1を印加することが有効である。特に、０．０１＜Ｅ1／Ｅ0＜１とすることが有効である。Ｅ1／Ｅ0≦０．０１の範囲では、不均一電場印加による液晶転移を促進する効果を十分に得ることは困難であり、Ｅ1／Ｅ0≧１の範囲では、印加電圧が大きくなり過ぎるため実際の使用に適当でないという問題があるからである。更には、０．５≦Ｅ1／Ｅ0≦１とすることが好ましい。
【０５０８】
不均一電場Ｅ1は、薄膜トランジスタのソース電極（またはゲート電極）と透明電極との間に印加した電圧を利用することにより、液晶層に対して基板に垂直な方向に印加することができる。また、不均一電場Ｅ1は、周波数１００ｋＨｚ以下の交流電場とすることが好ましく、更には、振幅を時間的に減衰させることが好ましい。
【０５０９】
臨界電場Ｅｃを低下させる条件である、スプレイ弾性定数（ｋ11）、プレチルト角の非対称性（Δθ）および電場の不均一性（Ｅ1／Ｅ0）という３条件のうち、２条件ないし３条件を組み合わせて満足させることが好ましい。これらの条件を組み合わせることにより、各条件を１つのみ満足させる場合に比べ、更に確実に臨界電場Ｅｃをより確実に低下させることができるからである。
【０５１０】
例えば、図４６（ｂ）は、実質的に均一な外部電場Ｅ0とともに、不均一な電場Ｅ1を印加すること以外は、図４６（ａ）と同条件で計算した結果である。なお、図４６（ｂ）は、Ｅ1／Ｅ0＝０．０３とした場合の結果である。図４６（ａ）および（ｂ）の比較からわかるように、プレチルト角の非対称性および電場の不均一性の２条件を組み合わせて満足させることにより、臨界電場Ｅｃをより低下させ、更に速やかな液晶転移を実現することができる。
【０５１１】
（実施の形態２０）
本実施の形態２０は上記実施の形態７と同様に第１の液晶セル領域と第２の液晶セル領域を形成し、その境界部のディスクリネーション線を核にしてベンド転移を容易に発生させることを特徴とするものである。但し、実施の形態７では、上下一対の基板それぞれに紫外線を照射し、局所的にプレチルト角を変化させる手法を用いた。しかし、本発明はこれに限るものではない。処理する基板は両方の基板であっても一方の基板であっても、第１と第２の液晶セル領域を形成することは可能であり、また、プレチルト角を変化させる手法としては紫外線を照射に限らない。以下に、具体的な内容を実施の形態２０−１〜実施の形態２０−５を例示して説明することにする。
【０５１２】
（実施の形態２０−１）
図４８は実施の形態２０−１の係る液晶表示装置の配向状態を示す概念図である。本実施の形態２０−１は、上下一対の基板のうちの一方だけＵＶ照射を行った例である。具体的には、実施の形態７と同様な方法でアレイ基板５００だけにＵＶ照射を行った。これにより、アレイ基板５００には実施の形態７と同様に、５度と２度のプレチルト領域が形成された。プレチルト角５度は図１６のＢ２に相当し、プレチルト角２度は図１６のＡ２に相当する。対向基板５０１の内側面及びアレイ側基板５００の内側面には、それぞれ同一材料からなる配向膜が形成されているが、アレイ基板５００側よりも対向基板５０１側でのラビング強度を上げることにより、対向基板５０１にはアレイ基板５００の２種のプレチルト角の中間的なプレチルト角を実現した。本実施の形態では３度であった。このように対向基板５０１のプレチルト角がアレイ側基板５００の２種ののプレチルト角の間にあることが本実施の形態２０−１の特徴である。
【０５１３】
電界を印加しない状態では、液晶層５０２には図４８（ａ）のように２つの領域H１，Ｈ２が発現する。ここでアレイ側基板５００のプレチルトが、右側領域Ｈ２で２度、左側領域Ｈ１で５度であり、対向基板５００のプレチルトが右側領域Ｈ２及び左側領域Ｈ１共に３度である。
【０５１４】
一般に電界を印加しない状態における、液晶パネルの厚み方向（セル厚方向）中央付近の液晶分子の配列方向は、上下のプレチルト角の平均的な値になる。なお、図４８において、液晶分子は参照符号５０３で示されている。よって、図４８（ａ）のようにアレイ側基板５００のプレチルトが対向基板５０１のプレチルトよりも高い左側領域Ｈ１では、上記中央付近の液晶５０３は図中右上がりの状態になる。逆にレイ側基板５００のプレチルトが対向基板５０１のプレチルトよりも小さい右側領域Ｈ２では、上記中央付近の液晶５０３は図中右下がりの状態になる。このようにアレイ基板５００にプレチルトの分布を持たせ、対向基板５０１側にはその中間的なプレチルトを持たせることで、液晶パネルの厚み方向中央部の液晶には２種類の配列を実現できる。なお、対向基板５０１にプレチルトの分布を持たせ、アレイ基板５００側にはその中間的なプレチルトを持たせるようにしてもよい。、
次いで、液晶パネルにベンド配向に転移する電界以下の電界を印加すると、図４８（ｂ）のような配向になる。本来の転移電圧は非常に高電圧であるため、かかる高電圧を印加すると１秒以下の時間でベンド配向に転移する。図４８（ｂ）のような配向は、本来の転移電圧を印加したときに、転移の初期に確認されたが、これは０．１秒以下の時間であった。
【０５１５】
そこで、この配向状態を詳細に観察するため、転移電圧以下の電圧を印加した。電圧印加時の配向状態は、電圧無印加時における液晶パネルの厚み方向中央部の液晶の配向状態が影響する。即ち、電圧無印加時において当該中央部の液晶分子が右上がり状態である左領域では、対向基板５０１付近にスプレイ変形部位を有するｔ−スプレイ配向が形成され、電圧無印加時において当該中央部の液晶分子が左上がりの右領域では、アレイ側基板５００付近にスプレイ変形部位を有するｂ−スプレイ配向が形成される。このｔ−スプレイ配向とｂ−スプレイ配向の境界部ではディスクリネーションが発生し、このディスクリネーション線を核にしてベンド転移が発生することを見出した。この現象については両側をＵＶ照射した実施の形態７と同じである。
【０５１６】
本実施の形態では、図４８（ｂ）に示すように、ラビング方向側から観察すると左側が比較的黒っぽく、右側が白っぽく見え、逆方向から観察すると左側が比較的白っぽく右側が比較的黒っぽく見えた。このことからｔ−スプレイ状態、ｂ−スプレイ状態と判断した。これは液晶層のセル厚方向で中央部の液晶の立ち方が非対称であり、例えば左側では液晶分子の長軸方向から観察するため、液晶の複屈折性は少なく、比較的黒っぽく見えたと考える。
【０５１７】
この液晶パネルに上記実施の形態１から６で述べた転移波形を印加すると、ディスクリネーション線を核にしてベンド配向が成長することが確認された。
【０５１８】
転移を高速化するためには、ベンド転移の核を確実に形成することが重要であり、本実施の形態では各画素ごとにＵＶ照射することで、各画素にｔ−スプレイ配向とｂ−スプレイ配向を形成し、ディスクリネーション線を発生させることで転移の高速化を実現できた。
【０５１９】
上述した例では、アレイ基板側に紫外線を照射しプレチルトの違う領域を形成したが、本発明はこれに限るものではない。対向基板に紫外線を照射し、プレチルトの異なる領域を形成しても良い。
【０５２０】
また本実施の形態ではプレチルトの異なる２つの領域に分割したが、本発明はこれに限るものではなく、少なくとも上下基板でプレチルトの大小関係が逆転している領域を有していればよい。また本発明は、各画素ごとにプレチルトの違う領域を形成したが、複数の画素ごとに当該領域を形成するようなしてもよい。、また、画素内に多数の領域があってもかまわない。ただし、ゲートラインなど画素電極がつながっていない領域では、各画素ごとに転移核を形成していることが望ましい。
【０５２１】
また本実施の形態では、プレチルトは５度、３度、２度のものを用いたが、本発明はこれに限るものではない。ただし、安定してディスクリネーションを発生させるためには基板内のプレチルトの最大と最小の差を１度以上にする必要が有り、より望ましくは２度以上にすることが望ましい。また安定にベンド配向するためには、プレチルトの最小値が１度以上が理想的であり、望ましくは２度以上が望ましい。
【０５２２】
（実施の形態２０−２）
本実施の形態２０−２では、ラビング強度に面内分布を持たせることで、プレチルト角に分布を持たせた。
【０５２３】
一般に液晶の配向処理にはラビング処理が行われている。これは均一な長さの繊維を用いて基板表面を擦ることで液晶の配向性を制御している。一般にラビング強度が強いとプレチルトが低いことが知られている。本実施の形態２０−２では、ラビングに用いる繊維の長さを不均一にすることでラビング強度に分布を持たせ、プレチルトを意図的に不均一にした。
【０５２４】
繊維の長さを変えるため、本実施の形態では、図４９に示す横幅５０μｍ高さ１００μｍの微小な段差５１０を有する基板５１１を用いて、均一な長さの繊維を有するラビング布５１２で、基板５１１上を１００回以上ラビングを行った。
段差５１０の高い部分ではラビング布５１２の損耗が激しく、これにより、図５０に示すようにラビング繊維の長さに分布を持ったラビング布５１１ａを得た。
【０５２５】
このラビング布５１１ａを用いるとプレチルト角に分布が発生し、プレチルトが２から５度までの領域がランダムに発生した。上下基板ともプレチルトに分布を持たせる処理を行った。この２枚の基板を組み合わせると、さまざまなプレチルトの組み合わせ領域が形成される。しかし、これらの領域は、大別すると電圧無印加状態において、セル厚方向中央部での液晶分子が斜め上方に向いているｂ−スプレイ配向に近似した配向領域と、セル厚方向中央部での液晶分子が斜め下方に向いているｔ−スプレイ配向に近似した配向領域の２種の領域に分けられる。本実施の形態では、このプレチルトの分布は画素よりも小さい領域で発生したため、この２種の領域を各画素に形成することができた。
【０５２６】
このような構成の液晶表示パネルに電圧を印加すると、ｂ−スプレイ配向とｔ−スプレイ配向の２種の配向領域が形成され、２種の配向領域の境界部でディスクリネーション線が発生し、これを核にしてベンド転移が確認された。
【０５２７】
本実施の形態２０−２ではラビング強度の分布を形成するために繊維の長さに分布を形成したが、本発明はこれに限るものではない。ラビング布の繊維質をコットンとレーヨンの混合にすることでラビング強度の分布を形成することができた。ここでは柔軟なコットンと剛直なレーヨンの繊維を独立に編み込むラビング布を実現した。
【０５２８】
（実施の形態２０−３）
図５１はアレイ配線によるラビングの影を示した概念図である。本実施の形態２０−３では、アレイ基板５００上に形成されている金属配線（ソース電極線５２０、ゲート電極線５２１）によるラビングの影を用いて局所的にラビング強度の弱い領域を形成した。なお、対向基板５０１側では、ラビング強度が均一な通常のラビング処理を行った。アレイ基板５００でのラビング方向はソース電極線５２０の延在方向から２０度傾けて行った。このとき、ゲート電極線５２１及びソース電極線５２０は画素電極部分よりも高くなっているため、ラビング処理をすると、ゲート電極線５２１及びソース電極線５２０のエッジ部分５２２でラビング強度が弱くなり、画素領域のその他の領域５２３に比べプレチルトが高くなった。
【０５２９】
ここで、対向基板５０１のプレチルト角は、前記した２つのプレチルトの中間的な値にした。このようなラビング処理により、電圧無印加時において、領域５２２にはセル厚方向中央部での液晶分子が斜め上方に向いているｂ−スプレイ配向に近似した配向が形成され、領域５２３にはセル厚方向中央部での液晶分子が斜め下方に向いているｔ−スプレイ配向に近似した配向が形成された。これにより、上記実施の形態と同様に電圧を印加すると、領域５２２にｂ−スプレイ配向が形成され、領域５２３にｔ−スプレイ配向が形成され、この２種の配向領域の境界部でディスクリネーション線が発生し、これを核にしてベンド転移が確認された。
【０５３０】
ところで、本実施の形態２０−３での画素電極は縦長の形状であった。このような縦長形状の画素電極の場合、上下方向にラビングすると、プレチルトの高い領域の面積は各画素では少ない。むしろ左右方向にラビングするとプレチルトの高い領域の面積は広く得られた。また上述した例のように、斜め方向にラビングしたときにプレチルトの高い領域の面積は最大に得られた。この結果から、ラビング方向はソース電極線５２０に対して角度を持ってラビングを行う方式がプレチルトの異なる領域を十分に形成でき、ベンド転移を効率よく実現することができる。
【０５３１】
また、ソース電極線と画素電極間、並びに、ゲート電極線と画素電極間のそれぞれに横電界が発生している場合には、以下に述べるように横電界の発生方向とラビング方向とが転移容易性に影響を与える。即ち、上下方向にラビングすると、ディスクリネーション線は横方向に発生する。このとき、ソース電極線と画素電極間に横電界が発生していると、この横電界効果によって転移が良好であった。また、左右方向にラビングすると、ディスクリネーション線は縦方向に発生する。このとき、ゲート電極線と画素電極間に横電界が発生していると転移が良好であった。また、斜め方向にラビングすると、ディスクリネーション線は図中の画素の左上から右下まで走り、このときにはソース電極線と画素電極間の横電界、並びに、ゲート電極線と画素電極間の横電界の双方が効果的であった。
【０５３２】
このように、上下方向のラビングではソース電極線と画素電極間の横電界が効果が有り、左右方向ラビングではゲート電極線と画素電極間の横電界が効果が有り、斜め方向ラビングではソースー画素、ゲートー画素間の双方の横電界が効果的である。従って、横電界による効果的を希望する場合には、横電界の方向を考慮してラビング方向を決定しておく必要がある。
【０５３３】
なお、本実施の形態２０−３では金属電極配線の影を用いたが、本発明はこれに限るものではない。後述する実施の形態２４に述べるような柱状スペーサや実施の形態１３、１４に述べたような突起物であってもかまわない。
【０５３４】
（実施の形態２０−４）
本実施の形態２０−４では、配向膜の膜厚に分布を持たせることでプレチルトに分布をもたせた。一般に配向膜の印刷は、図５２に示す印刷版５３０を用いて行っている。ここで、一般的に配向膜の印刷方法を図５２を参照して簡単に説明すると、配向膜の塗布液は、ディスペンサ５３１から回転しているドクターロール５３２とアニロックスロール５３３間に滴下供給される。この塗布液は、２つのロール５３２，５３３間で練られてアニロックスロール５３３の表面に液薄膜となって保持され、アニロックスロール５３３から版胴５３４上の印刷版５３０に移される。そして、テーブル５３５上に固定された基板５３６が版胴５３４の直下を通過するときに、塗布液が印刷版５３０から基板５３６に転写塗布される。ところで、このような配向膜の塗布工程において使用される印刷版５３０には、配向膜の膜厚を一定にする要請から一般的には均一な細かいメッシュが形成されている。本実施の形態では、上記要請とは逆に配向膜の膜厚に分布を持たせることが要請されているため、図５３及び図５４に示すようにメッシュサイズＬを大きくした印刷版５３０を使用した。これにより、印刷の不均一が生みだされ、膜厚に分布を持った配向膜が形成された。このようにして形成された配向膜は、膜厚が薄い領域ではプレチルトの値が低く、この領域ではｂ−ツイスト配向が発現しやすい傾向があった。配向膜の膜厚が厚い領域ではプレチルトの値が高く、ｔ−ツイスト配向が発現しやすい傾向があった。このようにして、 本実施の形態２０−４でも、比較的ランダムに配向膜の薄い領域、厚い領域が形成されるため、実施の形態２０−２と同様に２領域を形成することができ、ベンド転移核を有効に形成することができた。
【０５３５】
メッシュサイズＬとしては、１００μｍ以上とした場合に、配向膜に十分な膜厚分布を持たせることができた。なお、参考までに述べると、通常のメッシュサイズＬは５０μｍ程度である。
【０５３６】
また、上記の例では、配向膜に膜厚分布を持たせるために、メッシュサイズＬを大きくした印刷版を用いたけれども、メッシュサイズＬを不均一にした印刷版を用いてもよく、また、表面に凹凸をつけるようにした印刷版を用いてもよい。
【０５３７】
（実施の形態２０−５）
本実施の形態２０−５では、基板の表面処理等によってプレチルト角に分布を持たせた。具体的に説明すると、基板上に配向膜を均一に印刷し、硬化させた後、かかる配向膜が形成された基板を４５℃、９０％の高湿度雰囲気中に放置した。このとき湿度による表面処理によって配向膜の本来的に付与されたプレチルト角が局所的に低下した。次いで、従来と同様に配向膜表面をラビング処理することで、基板に３度から５度のプレチルト角の分布を実現することができた。
【０５３８】
上記の例では、配向膜が形成された基板を高湿度雰囲気中に放置してプレチルト角に分布を持たせたけれども、溶媒噴霧蒸気中を通すことや、溶媒を配向膜に噴霧吹き付け処理をすることでも実現できる。
【０５３９】
さらに、配向膜上に別種の配向膜を噴霧処理することでも実現できる。例えばプレチルト角５度の配向膜上にプレチルト角３度の配向膜を噴霧吹き付けすることで実現した。
【０５４０】
（実施の形態２１）
本実施の形態２１は、基板表面を凹凸状に形成にすることにより、ベンド転移を効率よく実現することを特徴とするものである。即ち、基板表面を凹凸状に形成して局所的に強い電界を印加することでｔ−スプレイ配向とｂ−スプレイ配向の領域の形成による効果と、凸部で強い電界が印加されることによる効果の両者により、ベンド転移核を良好に発生させることを特徴とするものである。具体的な構成は、以下の実施の形態２１−１〜実施の形態２１−４において説明することにする。
【０５４１】
（実施の形態２１−１）
前述した実施の形態１３は、凸部を形成しこの凸部に電界の強い領域を形成することにより、この電界の強い領域を転移の核にする方式であった。この方式を用いても、実施の形態２０と同様にｔ−スプレイ配向とｂ−スプレイ配向が形成され、、この異なる配向の境界部で発生するディスクリネーションを核に転移が発生する。以下、図５５を参照して、詳細に説明する。なお、図５５において、５３５は電気力線であり、５３６は凸部あり、５３７は画素電極、５３８は対向電極である。実施の形態１３の場合の電気力線５３５は、図５５（ａ）のようになる。凸部５３６での電界が強く、この電界は対向電極側５３８でさらに広がる。このため、図５５（ｂ）に示すように、凸部５３６の両側には横電界成分が発生する。この結果、図中左側では電界は左上方向に電気力線が向き、この方向に液晶分子が向こうとするため図のようにｂ−スプレイ配向が形成される。図の右側では、電気力線が右上方向に向くため、ｔ−スプレイ配向が形成される。従って、ｂ−スプレイ配向とｔ−スプレイ配向の境界部に発生するディスクリネーションを核にベンド転移が発生する。
【０５４２】
図５６は本実施の形態２１−１に係る液晶表示装置の駆動波形図である。この駆動波形は、ベンド転移への初期化処理期間において、低い電圧（０Ｖ）と高い電圧（−２５Ｖ）を交互に印加することを特徴とするものである。このような電圧波形を有する駆動電圧の印加により、転移を確実に実現することができる。
【０５４３】
なぜなら、転移が不確実な場合は、以下のプロセスが発生していると考えられる。即ち、電圧印加により、ｔ−スプレイ配向とｂ−スプレイ配向の２つのスプレイ配向状態が発生し、殆どの画素領域ではこの２つの配向の境界部からベンド配向が発生する。しかしながら、何らかの理由によりベンド配向する前に、１つのスプレイ配向状態ににってしまった場合、転移は発生しにくく、この画素では転移が起こらない。
【０５４４】
そこで、低い電圧を印加することで、液晶の配向を一旦初期状態に戻し、再度転移波形を印加することで次回の転移を確実化するのが、この波形の特徴である。よって、この低い電圧はスプレイ配向に戻る電圧であることが最低条件であり、望ましくは絶対値で１Ｖ以下、更に望ましくは０Ｖにするのがよい。
【０５４５】
この低い電圧期間を、初期に印加することが望ましく、これによって初期にどのようなノイズが入っても確実な転移が実現する。なお、パルス幅は、０．１秒〜１０秒が望ましかった。
【０５４６】
（実施の形態２１−２）
本実施の形態２１−２では各画素に凹凸形状を形成した。図５７は凹凸形状の形成を概念的に説明した図であり、図５７（ａ）は従来の画素構造を表わし、ここでは各画素は金属配線５４０（ゲート電極線又はソース電極線）に挟まれた領域である。この金属配線５４０上には窒化シリコン等による絶縁膜５４１が形成されている。ただし、画素電極５４２上には、絶縁膜５４１は一般に形成されていない。
【０５４７】
図５７（ｂ）は本実施の形態２１−２を示す断面図であり、画素電極５４２の中央部で画素電極５４２上に島状にフォトレジスト樹脂からなる凸部５４３を形成されている。この凸部５４３は、画素電極５４２上に塗布されたフォトレジスト樹脂膜をフォトリソグラフィーによって部分的に残すことにより形成されたものである。凸部５４３の高さは１μｍ、幅が２０μｍとした。このとき画素の幅は５０μｍであった。このように凹凸形状を形成すると、凸部（又は凹部）の左右両側でｂ−ツイストとｔ−ツイスト領域が形成され、良好なベンド転移が実現できた。
【０５４８】
凸部５４３の変形例として、図５７（ｂ）では凸部５４３は画素電極５４２の上に形成しているが、画素電極５４２の下に形成しても良い。
【０５４９】
また、凸部５４３の形状は、図５７（ｂ）に示す形状に限らず、図５７（ｃ）に示す山形状であってもよい。図５７（ｃ）に示す山形状の凸部５４３は、例えばフォトリソグラフィーによって部分的に残された樹脂部分を熱処理により溶融させて形状をなだらかにして作製することができる。特に、図５７（ｃ）に示す形状の凸部５４３は、良好なベンド転移が実現できた。これは断面形状がななめに傾斜しているので、この傾斜角が液晶のプレチルトに加算される。このため実施の形態２０のようにプレチルトに分布を持たせるのと同様の効果が得られたものと考えられる。図５７（ｂ）に示したような急峻な形状でも液晶の配向は連続的に穏やかに変化するため、図５７（ｃ）と同様の効果が得られたものと考える。
【０５５０】
さらに画素電極５４２を凸部５４３の上に形成すると、図５２（ｄ）の形状が形成できた。このような変形例では画素電極５４２を凸部５４３上に形成することで、凸部５４３の電界強度を強くする効果が追加されるため、転移が更に良好に実現できた。
【０５５１】
また、凸部の更に他の変形例としては、図５７（ｅ）に示すように、アレイ基板５４５上に窒化シリコンからなる凸部５４３が形成されている。この凸部５４３は、凹凸形状を形成するために金属配線５４０上に形成した窒化シリコン膜を部分的に残すことにより得られたものである。本方式では作製プロセスが増加しないメリットがある。なお、凸部５４３の段差は１μｍ程度を実現できた。
【０５５２】
また、凸部の更に他の変形例としては、アレイ基板５００の表面に透明樹脂層５４６を形成し、透明樹脂層５４６上にＩＴＯ電極を形成する手法も用いた。図５７（ｆ）がこのときの構成である。この構成では金属配線５４０上の透明樹脂層５４６は盛り上がっているため、この透明樹脂層５４６上に形成された画素電極５４２は凹構造になる。この凹構造部の傾斜によって２つのツイスト領域が形成できた。さらにこの透明樹脂層５４６をパターニングして、この層に凹凸構造を形成しても良い。
【０５５３】
（実施の形態２１−３）
本実施の形態２１−３では、基板上に凹凸を密に形成した。
【０５５４】
本発明は基板上に凹凸形状を形成し、これによってｂ−スプレイとｔ−スプレイの領域を形成することにある。よって凹凸形状は実施の形態１３のように各画素に点在させても、また画素に複数形成しても、さらに画素内に密に形成しても良い。
【０５５５】
本実施の形態では基板上に密に形成するために、基板表面上を荒らす処理を行った。基板のＩＴＯ表面をＯ２アッシャーで処理し、凹凸形状を最大０．２μｍの深さとした。基板の凹凸の深さは０．１μｍ以上あれば転移の向上に効果があった。
【０５５６】
また本発明はこの手法に限るものではなく、凹凸形状を形成できれば良い。例えばＩＴＯの蒸着条件を速くする、膜厚を厚くする等の処理によってＩＴＯ表面の凹凸を形成することができた。なお、このとき、ＩＴＯの結晶粒界は５０ｎｍであり、通常のＩＴＯの結晶粒界が１０ｎｍ以下であるのに比べて十分な凹凸状が得られていることが理解される。
【０５５７】
また凹凸パターンをアミ点印刷しても良い。また基板をプレス成形しても良い。
【０５５８】
（実施の形態２１−４）
その他簡易な手法として、通常の配向膜の中あるいは上にセル厚以下の大きさの粒子を分散させることで、基板表面に凹凸構造を形成してもよい。
【０５５９】
（実施の形態２２）
図５８は実施の形態２２に係る液晶表示装置の要部断面図であり、図５９は実施の形態２２に係る液晶表示装置の画素電極付近の平面図である。本実施の形態は、上記実施の形態１１と同様に画素電極及び対向電極の少なくとも一方の電極に、電極欠落部を形成することを特徴とするものである。但し、本実施の形態では、ラビング方向を考慮して電極欠落部の形成方向を決定することを特徴とする。ここで、図５８おいて、５５０は画素電極を示し、５５１は対向電極を示し、５５２はアレイ基板を示し、５５３は対向基板を示し、５５４は電極欠落部を示し、５５５は電気力線を示し、５５６は液晶分子を示す。本実施の形態２２における電極欠落部５５２の作用効果について、上記の実施の形態１１と重複説明となるが、ここで再度説明しておくことにする。電極欠落部５５４を有する箇所の電気力線分布は図５８（ａ）のようになり、このとき液晶の配列は図５８（ｂ）のようにｔ−スプレイ配向とｂ−スプレイ配向ｔが形成され、その境界部のディスクリネーション線からベンド転移が発生する。よって、各画素に電極欠落部５５４を形成することでベンド転移を容易にすることができる。この欠落部５５４は、画素電極のみならず、対向電極に形成してもよく、また画素電極及び対向電極の両者に形成するようにしてもよい。横電界の形成の状態は同様である。
【０５６０】
ここで、電極欠落部５５４の形成方向とラビング方向との関係について考察する。電極欠落部５５４の形成方向は、デスクリネーションラインの発生方向と一致する。そこで、欠落部がないときに発生するディスクリネーション線の箇所に欠落部を形成することが安定して転移を行うためには重要であった。例えば実施の形態２０−３で述べたように、ラビング方向によって発生するディスクリネーション線の方向が異なる場合がある。よってラビング方向と最適な欠落部５５４の形成方向には相関関係が存在する。
【０５６１】
上下方向にラビングする場合にはディスクリネーション線は左右方向に形成されるため、欠落部５５４は画素の左右方向に形成することが望ましい。左右方向のラビングではディスクリネーション線は上下方向に形成されるため、欠落部５５４は画素の上下方向に形成するのが望ましい。斜め方向にラビングする場合には、欠落部５５４は画素の斜め方向に形成することが望ましかった。
【０５６２】
本実施の形態では欠落部は１本としたが、複数本を形成しても良い。また、欠落部は図５９（ａ）のように矩形のスリットを空けても良く、また画素周辺に図５９（ｂ）のように切り込みを入れても良い。なお、５９（ａ）及び図５９（ｂ）において、５５８はゲート電極線であり、５５９はソース電極線である。
【０５６３】
（実施の形態２３）
本実施の形態は横電界を形成することで、ｂ−スプレイとｔ−スプレイを形成しベンド転移を確実化することを実現した。図６０を参照して説明すると、画素電極５６０は金属電極線５６１（ソース電極線またはゲート電極線）に挟まれた状態になっている。ここで画素電極５６０の電位が金属電極線５６１の電位よりも低い場合、矢印５６２のように横電界が発生する。この影響で液晶５６３の配向に異方性が発生し、図６０のようにｂ−スプレイ配向とｔ−スプレイ配向が発生する。
【０５６４】
ここで、この横電界が画素電極５６０の両側から印加されることが特徴であり、方向性が逆になるため非対称なスプレイ配向が発生する。なお、ラビング方向と横電界方向とが略一致することが、転移の促進の観点から望ましい。以下に、横電界を形成させるための具体的な駆動について実施の形態２３−１〜実施の形態２３−３を例示して説明することにする。
【０５６５】
（実施の形態２３−１）
本実施の形態２３−１では、ラビング方向を上下方向（図６０の左右方向）にし、横電界はゲート電極線−画素電極間に印加するようにした。図６１にその駆動波形の概念図を示す。電位レベルにはゲートレベルの高いレベル（ＧＨ）、ゲートレベルの低いレベル（ＧＬ）、ソースレベルの高いレベル（ＳＨ）とソースの低いレベル（ＳＬ）を有している。ゲートレベルは前記したレベルから２種選択、ソースレベルはＳＨレベルとＳＬレベルの間の電位をとることができる。転移波形を印加するための対向電位も別に有している。対向電極にはソースレベルよりも低い電圧を印加し、これで画素電極と対向電極間に転移波形を印加する。
この転移波形は実施の形態１から６に記載したものなどである。
【０５６６】
ここで、本実施の形態では、ソース電極線の電圧を低いレベル（ＳＬ）とし、また、ゲート電極線の電圧を高いレベルＧＨとした。ゲート電極線がレベルＧＨであるため、画素トランジスタは導通状態となる。これにより、画素電極はソース電極線と同電位になる。このとき、画素電極よりもゲート電極線の電圧が高いため、画素電極−ゲート電極線間に電圧Ｖ１に対応する横電界が印加される。そして、画素の上方のゲート電極線（図６０の右側の金属電極線）及び下方のゲート電極線（図６０の右側の金属電極線）との間で電界方向が相互に逆方向となる横電界が発生するため、本実施の形態では、上方部（図６０の右側部分）でｂ−スプレイ配向が下方部でｔ−スプレイ配向が形成された。これによってベンド転移が良好に行われた。
【０５６７】
また、補助電極層を有する構造の場合は、横電界の効果を向上するため、図６２又は図６３に示す構成とするのがよい。通常、図６２に示すようにゲート電極線５７０上には補助電極層５７１が設けられ、この補助電極層５７１は補助容量を形成している。この構成では補助電極層５７１はゲート電界を遮蔽する効果があるため、ゲート電極線５７０と画素電極５８０の間に横電界を有効に発生させるためには、この補助電極層５７１を仮想線で示す従来例の大きさから破線で示す大きさのように小さくするか、又は、図６３に示すように画素中央部に形成するとより横電界の効果が高かった。
【０５６８】
（実施の形態２３−２）
本実施の形態２３−２は、上記実施の形態２３−１と同様にゲートー画素間に横電界を印加したが、ゲートレベルを下げて実現した。図６４にその駆動波形の概念図を示す。電位レベルは、基本的には実施の形態２３−１と同様である。但し、上記実施の形態２３−１ではゲート電極線の電圧は高いレベルＧＨのままであったけれども、本実施の形態２３−２では、ゲート電極線の電圧は画素の充電期間中は高いレベルＧＨとし、画素の充電期間以外の期間（画素電位を保持している期間）は低いレベルＧＬとした。即ち、対向電極に電圧を印加し充電が十分になされる期間は、ソース電極線をレベルＳＨとするが、充電期間後はソース電極線をレベルＳＬとした。これにより、電圧Ｖ２（＞Ｖ１）に対応する横電界を画素電極とゲート電極間に印加することができた。なお、本実施の形態では、画素電極よりもゲート電極電圧が低いため、上記実施の形態２３−１とは逆の配向状態、即ち、上方部（図６０の右側部分）でｔ−スプレイが下方部（図６０の左側部分）でｂ−スプレイが形成された。なお、
（実施の形態２３−３）
本実施の形態２３−３ではソースー画素間に横電界を印加したことを特徴とするものである。図６５にその駆動波形の概念図を示す。本実施の形態では、対向電極の電位が変化し充電が完了するまでの画素の充電期間は画素トランジスタを導通状態にするためゲート電極線を高いレベルＧＨとし、それ以外の期間（画素電位を保持している期間）はゲート電極線を低いレベルＧＬにする。ゲート電極線がレベルＧＬのときはソース電極線と画素電極は導通していないため、ソース電極線と画素電極とは異なる電位に保つことができる。そこで、画素電極は電位の高い状態に保ちながら、ゲート電極線がレベルＧＬとなった段階でソース電極線をレベルＳＬとすることにより、ソース電極線と画素電極間に電圧Ｖ３に対応する横電界を印加した。これによって画素−ソース間に横電界を印加して２つのスプレイ配向状態を形成し、ベンド転移を良好に行うことができた。
【０５６９】
本実施の形態２３−３ではラビング方向を横方向（図６０の紙面に垂直方向）にするとより効果的であった。また、上記の例では、画素電位を保持している期間の全ての期間中、ソース電極線をレベルＳＬとしたけれども、画素電位を保持している期間の一部の期間のみソース電極線をレベルＳＬとするうにしてもよい。
【０５７０】
（実施の形態２４）
本実施の形態２４は、画素領域にスペーサを形成しないことでベンド転移を良好に行うことを特徴とするものである。従来は、図６６（ａ）に示すように画素領域５９１内に球状のビーズ５９０を分散させて基板間の距離を保っていた。
【０５７１】
ベンド転移の挙動において、このビーズ５９０によってベンド転移が阻害される現象を我々は見出した。そこで本実施の形態では、表示部である画素領域５９１においてこのビーズ５９０をなくすことで転移を良好に行うことを実現した。
【０５７２】
具体的には、図６６（ｂ）及び図６７に示すように、表示部以外の非表示領域５９２にフォトリソグラフィー工程を用いて厚み５μｍのスペーサ柱５９３を形成し、これをスペーサビーズの代わりに用いた。このような構成により、ベンド転移が阻害されることなく、良好に転移が行われた。なお、図６６及び図６７において、５９４はゲート電極線を示し、５９５はソース電極線を示す。また、スペーサ柱５９３の配置は、図６６（ｂ）に限定されるものではなく、非表示領域に形成されていればよい。
【０５７３】
【発明の効果】
以上のように本発明によれば，ＯＣＢセルを用いた液晶表示装置の駆動方法で，一対の基板に、バイアス電圧を重畳した交流電圧を印加して、これを連続印加することにより、または、一対の基板に、バイアス電圧を重畳した交流電圧を印加する工程とオープン状態もしくは低電圧を印加する工程を交互に繰り返すことにより，スプレイ配向からベンド配向への転移をほぼ確実にかつ極めて短時間に完了でき、表示欠陥の無い、応答速度が速く動画像表示に適した，かつ広視野のベンド配向型ＯＣＢの液晶表示装置を得ることができる。
【０５７４】
また、本発明によれば、スプレイ配向からベンド配向への転移を確実に速くし易い、表示欠陥の無いアクティブマトリックス型の液晶セルからなる高速応答広視野で高画質のＯＣＢ表示モードの液晶表示装置を得ることが出来るという効果が得られる。
【０５７５】
また、本発明によれば、初期化期間中に配向状態が異なる複数の液晶領域を発現させることにより、その液晶領域の境界部でディスクリネーション線を形成することができ、迅速且つ確実にベンド配向への転移が達成できる。
【０５７６】
また、本発明によれば、アレー基板と対向基板の間の液晶層上下界面の液晶のプレチルト角が正負逆で、互いに平行に配向処理されたスプレイ配向の液晶セルで、電圧無印加時にはスプレイ配向となっており、液晶表示駆動に先立って、電圧印加によりスプレイ配向からベンド配向に転移させる初期化処理が行われ、この初期化されたベンド配向状態で液晶表示駆動を行うアクティブマトリックス型の液晶表示装置において、１画素内に、少なくとも１つの転移励起用の横電界印加部を有し、該横電界印加部によって横電界を発生させるとともに、画素電極と共通電極間に連続的または間欠的に電圧を印加し、画素毎に転移核を発生させ画素全体をスプレイ配向からベンド配向に転移させることにより、スプレイ配向からベンド配向への転移を速く確実に起こさせ、これにより表示欠陥のないしかも高速応答で広視野高画質のＯＣＢ表示モードの液晶表示装置を提供することが可能となる。
【０５７７】
また、本発明によれば、ＯＣＢ表示モードの配向液晶表示素子は、一対の基板間に挟持される液晶層と、基板の外側に配設される位相補償板とを含むパラレル配向液晶表示素子であり、確実かつ高速なスプレイ−ベンド配向転移を達成することができ、その実用的価値は極めて大きい。
【０５７８】
また、本発明によれば、互いに対向する第１の基板と第２の基板との間に保持された液晶に電場を印加し、前記液晶の配向をベンド配向に転移させる方法であって、前記液晶のスプレイ弾性定数ｋ11を、１０×１０^-7ｄｙｎ≧ｋ11≧６×１０^-7ｄｙｎの範囲とし、且つ、前記第１の基板に対する前記液晶のプレチルト角の絶対値をθ1とし、前記第２の基板に対する前記液晶のプレチルト角の絶対値をθ2としたとき、１．５７ｒａｄ＞｜θ1−θ2｜≧０．０００２ｒａｄなる関係を満たすため、液晶をベンド配向に速やかに転移させることができる。
【０５７９】
また、本発明によれば、互いに対向する第１の基板と第２の基板との間に保持された液晶に電場を印加し、前記液晶の配向をベンド配向に転移させる方法であって、前記液晶のスプレイ弾性定数ｋ11を、１０×１０^-7ｄｙｎ≧ｋ11≧６×１０^-7ｄｙｎの範囲とし、且つ、前記電場が、空間的に均一に印加される主電場に、空間的に不均一に印加される副電場を重畳させた電場であり、前記主電場をＥ0とし、前記副電場の最大値をＥ1としたとき、１．０＞Ｅ1／Ｅ0＞１／１００なる関係を満たすため、液晶をベンド配向に速やかに転移させることができる。
【０５８０】
また、本発明によれば、互いに対向する第１の基板と第２の基板との間に保持された液晶に電場を印加し、前記液晶の配向をベンド配向に転移させる方法であって、前記第１の基板に対する前記液晶のプレチルト角の絶対値をθ1とし、前記第２の基板に対する前記液晶のプレチルト角の絶対値をθ2としたとき、１．５７ｒａｄ＞｜θ1−θ2｜≧０．０００２ｒａｄなる関係を満たし、且つ、前記電場が、空間的に均一に印加される主電場に、空間的に不均一に印加される副電場を重畳させた電場であり、前記主電場をＥ0とし、前記副電場の最大値をＥ1としたとき、１．０＞Ｅ1／Ｅ0＞１／１００なる関係を満たすため、液晶をベンド配向に速やかに転移させることができる。
【０５８１】
また、本発明によれば、互いに対向する第１の基板と第２の基板との間に保持された液晶に電場を印加し、前記液晶の配向をベンド配向に転移させる方法であって、前記液晶のスプレイ弾性定数ｋ11を１０×１０^-7ｄｙｎ≧ｋ11≧６×１０^-7ｄｙｎの範囲とし、前記第１の基板に対する前記液晶のプレチルト角の絶対値をθ1とし、前記第２の基板に対する前記液晶のプレチルト角の絶対値をθ2としたとき、１．５７ｒａｄ＞｜θ1−θ2｜≧０．０００２ｒａｄなる関係を満たし、且つ、前記電場が、空間的に均一に印加される主電場に、空間的に不均一に印加される副電場を重畳させた電場であり、前記主電場をＥ0とし、前記副電場の最大値をＥ1としたとき、１．０＞Ｅ1／Ｅ0＞１／１００なる関係を満たすため、液晶をベンド配向に速やかに転移させることができる。
【図面の簡単な説明】
【図１】ベンド配向型のＯＣＢセルを備えた液晶表示装置の一部分を示す斜視図である。
【図２】スプレイ配向からベンド配向へ転移する様子を説明する液晶セルの断面図である。
【図３】本発明の実施の形態１に係る液晶表示装置の駆動法による画素単位の構成概念図である。
【図４】本発明の実施の形態１で使用した配向転移用電圧波形図である。
【図５】本発明の実施の形態１におけるバイアス電圧と転移時間の関係図である。
【図６】本発明の実施の形態２に係る液晶表示装置の駆動法による画素単位の構成概念図である。
【図７】本発明の実施の形態２で使用した配向転移用電圧波形図である。
【図８】本発明の実施の形態２におけるバイアス電圧と転移時間の関係図である。
【図９】本発明の実施の形態３に係る液晶表示装置の駆動法による画素単位の構成概念図である。
【図１０】本発明の実施の形態３で使用した配向転移用電圧波形図である。
【図１１】本発明の実施の形態３におけるバイアス電圧と転移時間の関係図である。
【図１２】本発明の実施の形態４に係る液晶表示装置の駆動法による画素単位の構成概念図である。
【図１３】本発明の実施の形態４に係る液晶表示装置の通常駆動電圧波形図である。
【図１４】本発明の実施の形態４で使用した配向転移用電圧波形図である。
【図１５】本発明の実施の形態５で使用した配向転移用電圧波形図である。
【図１６】本発明の実施の形態７に係る液晶表示装置の概略断面図である。
【図１７】本発明の実施の形態７に係る液晶表示装置の概略平面図である。
【図１８】本発明の実施の形態７に係る液晶表示装置の製造方法を示す図である。
【図１９】本発明の実施の形態８に係る液晶表示装置を示す図であり、図１９（ａ）は液晶表示装置の概略断面図、図１９（ｂ）は液晶表示装置の概略平面図である。
【図２０】本発明の実施の形態９に係る液晶表示装置の構成を概念的に示した図であり、図２０（ａ）は液晶表示装置の概略平面図、図２０（ｂ）は液晶表示装置の概略断面図である。
【図２１】本発明の実施の形態９に係る液晶表示装置の構成を概念的に示した図である。
【図２２】本発明の実施の形態９に係る液晶表示装置の他の例を示す図である。
【図２３】本発明の実施の形態１０に係る液晶表示装置の構成を概念的に示した図であり、図２３（ａ）は液晶表示装置の概略平面図、図２３（ｂ）は液晶表示装置の概略断面図、図２３（ｃ）は他の例の液晶表示装置の概略断面図、図２３（ｄ）は他の例の液晶表示装置の概略断面図である。
【図２４】本発明の実施の形態１１に係る液晶表示装置の構成を概念的に示した図であり、図２４（ａ）は液晶表示装置の概略平面図、図２４（ｂ）は電界の歪みを示す概略図である。
【図２５】本発明の実施の形態１２に係る液晶表示装置の構成を概念的に示した図であり、図２５（ａ）は液晶表示装置の概略断面図、図２５（ｂ）は概略平面図である。
【図２６】本発明の実施の形態１３に係る液晶表示装置の断面構成を概念的に示す図である。
【図２７】本発明に係わる液晶表示装置の実施の形態１３，１４のガラス基板上に形成された凸形状物の製造プロセスを説明するための図である。
【図２８】本発明に係わる図２７に続く凸形状物の製造プロセスを説明するための図である。
【図２９】本発明の実施の形態１３に用いた基板のラビング方向を示す図である。
【図３０】本発明に係わる実施の形態１４の構成外観図である。
【図３１】本発明に係わる実施の形態１４の平面図である。
【図３２】本発明の実施の形態１５に係る液晶表示装置に備えられる液晶セルの構成外観図である。
【図３３】本発明の実施の形態１５に係る液晶セルの凸形状物の製造プロセスを説明するための図である。
【図３４】本発明の実施の形態１６に係る液晶表示装置に備えられる液晶セルの断面構成を概念的に示す図である。
【図３５】本発明の実施の形態１６に係る液晶セルに用いた透明電極のパターンを概念的に示す図である。
【図３６】本発明の実施の形態１７に係る液晶表示装置に備えられる液晶セルの要部断面図である。
【図３７】図３６の一部の拡大図である。
【図３８】本発明の実施の形態１８に係る液晶表示装置に備えられる液晶セルの要部断面図である。
【図３９】本発明の実施の形態１８に係る液晶表示装置に備えられる液晶セルでの光学素子の配置を説明するための図である。
【図４０】本発明の実施の形態１８に係る液晶表示装置に備えられる液晶セルの電圧−透過率特性を示す図である。
【図４１】図４１（ａ）はモジニアス配向を示す模式図（ａ）であり、図４１（ｂ）はベンド配向を示す模式図（ｂ）である。
【図４２】液晶層のディレクターを示す図である。
【図４３】ＣＲ等価回路を示す図である。
【図４４】時間とともに増加する外部電場下での液晶の配向角（θj）の時間変化を示す図である。
【図４５】スプレイ弾性定数（ｋ11）と臨界電場（Ｅｃ）との関係を示す図である。
【図４６】プレチルト角の絶対値の差（Δθ）と臨界電場（Ｅｃ）との関係を示す図である。
【図４７】電場の不均一性（Ｅ1／Ｅ0）と臨界電場（Ｅｃ）との関係を示す図である。
【図４８】図４８は実施の形態２０−１の係る液晶表示装置の配向状態を示す概念図である。
【図４９】段差５１０を有する基板５１１の斜視図である。
【図５０】ラビング繊維の長さに分布を持ったラビング布５１１ａの拡大図である。
【図５１】実施の形態２０−３におけるアレイ配線によるラビングの影を示した概念図である。
【図５２】配向膜の塗布装置を示す図である。
【図５３】印刷版５３０の表面の部分拡大平面図である。
【図５４】印刷版５３０の表面の部分拡大断面図である。
【図５５】実施の形態２１−２の係る液晶表示装置の電気力線分布と液晶の配向状態を示す概念図であり、図５５（ａ）は電気力線分布図であり、図５５（ｂ）は液晶の配向状態を示す図である。
【図５６】本実施の形態２１−１に係る液晶表示装置の駆動波形図である。
【図５７】本実施の形態２１−２に係る液晶表示装置の構造を示す概念図でおり、図５７（ａ）は従来例の画素構造を示す図であり、図５７（ａ）は画素の凹凸構造を示す図であり、図５７（ｂ）は画素の凹凸構造の変形例を示す図であり、図５７（ｃ）は画素の凹凸構造の変形例を示す図であり、図５７（ｄ）は画素の凹凸構造の他の変形例を示す図であり、図５７（ｅ）は画素の凹凸構造の他の変形例を示す図であり、図５７（ｆ）は画素の凹凸構造の他の変形例を示す図である。
【図５８】実施の形態２２に係る液晶表示装置の要部断面図である。
【図５９】実施の形態２２に係る液晶表示装置の画素電極付近の平面図である。
【図６０】実施の形態２３に係る液晶表示装置の動作を示す概念図である。
【図６１】実施の形態２３−１に係る液晶表示装置の転移電圧波形を示す概念図である。
【図６２】補助電極層５７１の形状を示す平面図である。
【図６３】補助電極層５７１の他の形状を示す平面図である。
【図６４】実施の形態２３−２に係る液晶表示装置の転移電圧波形を示す概念図である。
【図６５】実施の形態２３−３に係る液晶表示装置の転移電圧波形を示す概念図である。
【図６６】実施の形態２４に係るスペーサを説明するための基板平面図であり、図６６（ａ）は従来例のスペーサを示す図であり、図６６（ｂ）は本発明のスペーサを示す図である。
【図６７】実施の形態２４に係るスペーサを説明するための基板断面図である。
【図６８】従来例の断面図である。
【符号の説明】
２０，２１ 基板
２２，２３ 電極
２４，２５ 配向膜
２６ 液晶層
３０，４０，５０，７１，７２ 配向転移用駆動回路
３１ 液晶表示駆動回路
１０１・１０２ 偏光板
１０３ 位相補償板
１０４ 液晶セル
１０５ 対向基板
１０６ アレー基板
１０７ 共通電極
１０８ 画素電極
１０９・１１０ 配向膜
１１１ スイッチング素子
１１２ 液晶層
１１３ 信号電極線
１１４・１１４’ ゲート電極線
１２０ ｂ−スプレイ配向
１２１ ｔ−スプレイ配向
１２３ ディスクリネーション線
１２４ ベンド配向
Ａ２・Ｂ２・Ｃ２・Ｄ２ プレチルト角
２０１ａ アレー基板
２０１ｂ 対向基板
２０２ａ 画素電極
２２１ａ 画素電極の凹部
２２２ａ 画素電極の凸部
２２３ａ 画素電極の非嵌合型凸部
２２４ａ 画素電極の非嵌合型凸部
２０２ｂ 共通電極
２０３ａ 配向膜
２０３ａｍ 配向膜
２０３ａｈ 配向膜
２０３ｂ 配向膜
２０３ｂｍ 配向膜
２０３ｂｈ 配向膜
２０４ａ 偏光板
２０４ｂ 偏光板
２０５ 位相補償板
２０６ 信号電極線
２６１ 信号電極線の凸部
２６２ 信号電極線の凹部
２６３ 信号電極線の非嵌合型凸部
２０７ ゲート電極線
２７１ ゲート電極線の凸部
２７２ ゲート電極線の凹部
２７３ ゲート電極線の非嵌合型凸部
２０８ スイッチングトランジスタ（素子）
２０９ 横電界印加用線
２９１ 横電界印加用線の凸部
２０９ａ 横電界印加用線
２９１ａ 横電界印加用線の凸部
２１０ 液晶層
２９８ 液晶層
２９９ 液晶層
２１１ 液晶分子
２１２ 透明絶縁膜
２２５ 電極欠陥部
２２６ ディスクリネーション線
２２７ｂ ｂ−スプレイ配向
２２７ｔ ｔ−スプレイ配向
３０１，３０８ ガラス基板
３０２，３０７ 透明電極
３０３，３０６ 配向膜
３０４ 液晶層
３０４ａ 電圧無印加時の液晶配向（スプレイ配向）
３０４ｂ 電圧印加時の液晶配向（ベンド配向）
３０５ スペーサ
３０９ テストセル
３１０ 凸形状物
３１１，３１４ 負の一軸性フィルム位相板
３１２，３１５ 主軸がハイブリッド配列した負の屈折率異方性を有する光学媒体よりなる位相差板
３１３，３１６ 偏光板
３１７，３１８ 位相補償板
３１９ 正の一軸性フィルム位相板
３２０ レジスト薄膜
３２１ フォトマスク
３２２ フォトマスク開口部
３２３ 平行紫外線
３６０ 三角形状物
３８０ 電極開口部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an OCB mode liquid crystal display device with a high-speed response and a wide field of view for displaying television images, personal computers, and multimedia images, a manufacturing method thereof, and a driving method of the liquid crystal display device.
[0002]
[Prior art]
Conventionally, as a liquid crystal display device, for example, as a liquid crystal display mode, a twisted nematic (TN) mode liquid crystal display element using a nematic liquid crystal having a positive dielectric anisotropy has been put into practical use, but the response is slow. There are disadvantages such as narrow viewing angle. There are also display modes such as ferroelectric liquid crystal (FLC) and anti-ferroelectric liquid crystal that have a fast response and a wide viewing angle. However, they have major drawbacks in image sticking, shock resistance, and temperature dependence of characteristics. . In addition, although there is an in-plane switching (IPS) mode in which the viewing angle is extremely wide and the liquid crystal molecules are driven in a horizontal electric field in the plane, the response is slow and the aperture ratio is low and the luminance is low. When trying to display full-color movies on a large screen, a liquid crystal mode with a wide field of view, high brightness, and high-speed display performance is required, but there is currently a practical liquid crystal display mode that satisfies this perfectly at the same time. do not do.
[0003]
Conventionally, as a liquid crystal display device aiming at high brightness with at least a wide field of view, there is one in which the above-mentioned TN mode liquid crystal region is divided into two orientations and the viewing angle is expanded vertically (SID92 DIGEST P798-801). That is, nematic liquid crystal having positive dielectric anisotropy is used in each display pixel of the liquid crystal display device, and two liquid crystal regions having different orientation directions of liquid crystal molecules are formed in the TN mode. It expands the viewing angle.
[0004]
FIG. 68 shows a conceptual diagram of the configuration of the conventional liquid crystal display device. In FIG. 68, 701 and 702 are glass substrates, 703 and 704 are electrodes, and 705, 705 ′, 706, and 706 ′ are alignment films. In one alignment region A, nematic liquid crystal molecules 707 and 707 ′ having a slight dielectric anisotropy slightly inclined from the opposing upper and lower substrate interfaces form large and small pretilt angles, and in the other alignment region B, The size of the pretilt angle with respect to the upper and lower substrate interfaces is set opposite to that of the alignment region A. The large and small pretilt angles are set to have a difference of several degrees. As an example of a conventional manufacturing method for forming alignment regions having different pretilt angles on the upper and lower substrates, a photoresist is applied to the alignment film, masking is performed using a photolithographic technique, and a desired alignment film surface is rubbed in a predetermined direction. There are methods such as repeating the work. By such a method, as shown in FIG. 68, the orientation of the liquid crystal molecules in the central portion of the liquid crystal layer is opposite to each other in the orientation regions A and B, and the liquid crystal molecules in each orientation region rise up in reverse with voltage application. Thus, the refractive index anisotropy is averaged with respect to the incident light beam in units of pixels, and the viewing angle can be expanded. In the above-described conventional orientation-divided TN mode, the viewing angle is larger than in the normal TN mode, and the vertical viewing angle is about ± 35 degrees with a contrast of 10.
[0005]
However, the response speed is about 50 mS with essentially no change from the TN mode. As described above, the viewing angle and response are insufficient in the conventional two-divided TN mode.
[0006]
In addition, there is a liquid crystal display mode that uses a so-called homeotropic alignment mode in which liquid crystal molecules are aligned almost vertically at the alignment film interface, and there is a liquid crystal display device with a wide field of view and high-speed response by adding a film retardation plate and alignment division technology However, the response speed between binary values of black and white takes about 25 ms, especially the response speed between gray gradations is slow at 50 to 80 ms, which is longer than about 1/30 s, which is referred to as the visual speed of human eyes, and the moving image flows. Looks.
[0007]
On the other hand, a bend alignment type liquid crystal display device (OCB mode liquid crystal display device) using a change in refractive index due to a change in the rising angle of each liquid crystal molecule in a state where the liquid crystal molecules between the substrates are bend aligned has been proposed. Yes. The liquid crystal molecules with bend alignment are much faster in the on-state and off-state alignment change speed than the on-off state of the TN type liquid crystal display device, and the response speed is high. It can be a display device. Furthermore, since the liquid crystal display device of the bend alignment type is entirely bend-aligned between the upper and lower substrates, the bend alignment type liquid crystal display device can self-compensate in terms of optical phase difference, and also compensates for phase difference with a film phase difference plate. This has the potential to become a wide-field LCD device.
[0008]
[Problems to be solved by the invention]
By the way, the above-mentioned liquid crystal display device is usually produced by placing liquid crystal molecules in a splay alignment state between substrates under no voltage. In order to change the refractive index using bend alignment, the entire display unit needs to be uniformly transferred from the splay alignment state to the bend alignment state before the use of the liquid crystal display device is started. When a voltage is applied between the opposing display electrodes, the place where the transition nuclei from the splay alignment to the bend alignment are generated is not uniform, such as around the dispersed spacers, or alignment unevenness, scratches, etc. at the alignment film interface. . Further, since the transition nucleus is not always generated from a certain place, a display defect is likely to occur when the transition occurs or does not occur. Therefore, it is extremely important that the entire display unit is uniformly transferred from the splay alignment to the bend alignment before the start of use.
[0009]
However, conventionally, even if a simple AC voltage is applied, the transition does not occur or even if it occurs, it takes a very long transition time.
[0010]
An object of the present invention is to provide a bend alignment type liquid crystal that is capable of bend alignment transition almost certainly and has no display defects due to completion of the transition in a very short time, has a high response speed and is suitable for moving image display and has a wide field of view. A display device, a manufacturing method thereof, and a driving method of a liquid crystal display device are proposed.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention applies a voltage waveform between a substrate and a bias voltage superimposed on a drive voltage for orientation transition as a driving method for orientation transition.
[0012]
In addition, the present invention provides a plurality of liquid crystal regions having different alignment states during the initialization period for alignment transition (particularly, in an alignment state in which the tilt angles of liquid crystal molecules in the central portion between the upper and lower pair of substrates are opposite to each other). Two liquid crystal regions) can be developed. This is because a disclination line can be formed at the boundary portion of the liquid crystal region, and a transition to bend alignment can be achieved quickly and reliably.
[0013]
Hereinafter, a specific configuration of the present invention will be described.
[0048]
Claim 1 The described invention includes a pair of upper and lower substrates and a liquid crystal layer sandwiched between the substrates, and prior to liquid crystal display driving, the initial alignment of the liquid crystal layer is bent from the splay alignment state by applying a voltage between the substrates. In a liquid crystal display device that performs liquid crystal display driving in the initialized bend alignment state during an initialization process for transferring to the bend alignment state, during the initialization process for transferring to the bend alignment state, A means for causing a liquid crystal region having two types of splay alignment states, a b-spray alignment region and a t-spray alignment region, to appear in the liquid crystal layer, is generated at the boundary between the b-spray alignment region and the t-spray alignment region. The transition from the disclination line to bend to the bend orientation state occurs or expands. It is characterized by that.
[0049]
As described above, when a plurality of liquid crystal regions having different alignment states are developed, a disclination line can be formed at the boundary between the liquid crystal regions, and a transition to bend alignment can be achieved quickly and reliably. The alignment state is not limited to the splay alignment, and for example, a vertical alignment may be expressed in a partial region of the splay alignment region.
[0093]
Claim 2 The described invention Claim 1 In the liquid crystal display De A transverse electric field forming means for excitation of transition is provided in the vicinity of the scintillation line.
[0094]
The transition is promoted by the action of the transverse electric field by the transverse electric field forming means.
[0122]
According to a 69th aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the 66th aspect, the uneven shape forming step is a step of forming an uneven shape using a printing method.
[0184]
Claim 3 The described invention 3. The liquid crystal display device according to claim 2, wherein the lateral electric field forming means is At least one in one pixel Features that are provided It is said.
[0185]
With the above configuration, the following operations are performed.
[0186]
A voltage sufficiently higher than the transition voltage is applied between the pixel electrode and the common electrode, and at least one transition excitation lateral electric field application unit provided in one pixel applies a lateral electric field to the liquid crystal layer, thereby The horizontal electric field application part becomes the starting point from the splay alignment of the liquid crystal layer in the pixel to the bend alignment (that is, the transition nucleus can be surely generated in the liquid crystal layer around the horizontal electric field application part), and thus the splay alignment quickly The transition from orientation to bend orientation can be performed.
[0238]
DETAILED DESCRIPTION OF THE INVENTION
The present invention was obtained as a result of paying attention to the transition mechanism from splay alignment to bend alignment described below in a liquid crystal display device including a bend alignment type OCB cell. Therefore, first, the transfer mechanism will be described in detail, and then the specific contents of the present invention will be described using embodiments.
[0239]
FIG. 1 is a perspective view showing a part of a liquid crystal display device having a bend-oriented OCB cell. Referring to FIG. 1, the configuration of a liquid crystal display device having a bend-oriented OCB cell will be briefly described. A liquid crystal layer 13 including liquid crystal molecules 12 is disposed between substrates 10 and 11 arranged in parallel to each other. Has been inserted. Although not shown in the drawing, display electrodes for applying an electric field to the liquid crystal layer 13 and alignment films for regulating the alignment of liquid crystal molecules are formed on the mutually opposing surfaces of the substrates 10 and 11, respectively. Yes. As shown in the figure, the alignment film is pre-tilted with about 5 to 7 degrees of liquid crystal molecules 12 in the vicinity of the substrate interface, and is aligned so that the alignment directions in the substrate surface are in the same direction, that is, parallel alignment. . As the distance from the surfaces of the substrates 10 and 11 increases, the liquid crystal molecules 12 gradually rise to a bend alignment in which the tilt angle of the liquid crystal molecules is 90 degrees at approximately the center in the thickness direction of the liquid crystal layer 13. Polarizing plates 15 and 16 and optical compensation plates 17 and 18 are arranged outside the substrates 10 and 11, and the two polarizing plates 15 and 16 are arranged such that their polarization axes are orthogonal to or parallel to each other. The axis and the orientation direction of the liquid crystal molecules are arranged at an angle of 45 degrees. Then, using the difference in refractive index anisotropy of the liquid crystal layer between the on state where a high voltage is applied and the off state where a low voltage is applied, the polarization state is changed through the polarizing plate and the optical compensator. The transmittance is controlled and displayed.
[0240]
In the liquid crystal display device having the bend alignment type OCB cell, since the liquid crystal layer is in the splay alignment before use, the liquid crystal layer is changed from the splay alignment state to the bend alignment state by applying a voltage before driving the liquid crystal display. It is necessary to transfer to.
[0241]
FIG. 2 schematically shows the mechanism of the alignment transition in which the liquid crystal layer transitions from the splay alignment to the bend alignment when a high voltage equal to or higher than the transition critical voltage is applied for the alignment transition.
[0242]
FIG. 2 is a cross-sectional view of a liquid crystal cell conceptually showing a liquid crystal molecule arrangement by schematically showing liquid crystal molecules when two substrates are arranged in parallel.
[0243]
FIG. 2A shows an initial spray arrangement state. When there is no electric field between the substrates, the major axis of the liquid crystal molecules 12 at the center of the liquid crystal layer 13 is in a splay alignment state with a low energy state that is substantially parallel to the substrate surface. Here, for convenience of explanation, liquid crystal molecules parallel to the substrate are denoted by reference numeral 12a.
[0244]
Next, FIG. 2B shows a liquid crystal molecule alignment state when a high voltage is started to be applied between electrodes (not shown) formed on the substrates 10 and 11. The liquid crystal molecules 12 at the center in the liquid crystal layer 13 begin to slightly tilt due to the electric field, and as a result, the liquid crystal molecules 12a oriented parallel to the substrate surface move toward one substrate surface (to the substrate 11 side in the figure). Go.
[0245]
Next, FIG.2 (c) shows a liquid crystal molecule arrangement state when time passes, after applying a voltage. The liquid crystal molecules 12 at the center of the liquid crystal layer 13 are further tilted with respect to the substrate surface. On the other hand, the liquid crystal molecules 12a oriented substantially parallel to the substrate surface come near the substrate interface and are strongly regulated from the alignment film. Receive power.
[0246]
Next, FIG.2 (d) shows the liquid crystal molecular arrangement | sequence state in which the energy state shifted to the bend alignment. The liquid crystal molecules 12 at the center of the liquid crystal layer 13 are perpendicular to the substrate surface, and the liquid crystal molecules in contact with the alignment film (not shown) interface on the substrate 10 receive a strong regulating force from the alignment film and are tilted. The state is maintained, and at this time, the liquid crystal molecules 12a oriented parallel to the substrate surface existing in FIGS.
[0247]
When a further time elapses from FIG. 2D, the alignment state shifts to the bend alignment state shown in FIG. 1 between the substrates, and the transition is completed.
[0248]
As described above, the transition from the splay alignment to the bend alignment that occurs when a voltage is applied can be considered as described above.
[0249]
However, the place where this occurs usually does not occur in the entire liquid crystal layer in the substrate surface at once, but is a part where energy is easily transferred in a part of the alignment region, and is usually a spacer dispersed in the gap. Transition nuclei are generated in the surrounding area and the alignment uneven part, and the bend alignment region is expanded therefrom. Accordingly, in order to change the alignment in the OCB cell, a transition nucleus is generated in at least a part of the liquid crystal layer in the substrate surface, and a bend alignment state having higher energy than the splay alignment state by applying energy from the outside. It is necessary to transition to and maintain this.
[0250]
As a result of considering the mechanism of such alignment transition, the present inventors have developed a liquid crystal display device that reliably generates transition nuclei and completes the transition in an extremely short time, a manufacturing method thereof, and a driving method of the liquid crystal display device. It came to be completed. Specific contents will be described based on the embodiment.
[0251]
(Embodiment 1)
FIG. 3 is a conceptual diagram of a pixel unit configuration by the driving method of the liquid crystal display device according to the first embodiment of the present invention. First, the configuration of the liquid crystal display device related to the driving method according to the first embodiment will be described with reference to FIG. The liquid crystal display device according to the first embodiment has the same configuration as a liquid crystal display device including a general OCB cell with respect to the configuration excluding the drive circuit unit. That is, it has a pair of glass substrates 20 and 21 and a liquid crystal layer 26 sandwiched between the glass substrates 20 and 21. The glass substrates 20 and 21 are arranged to face each other with a certain interval. A common electrode 22 made of an ITO transparent electrode is formed on the inner surface of the glass substrate 20, and a pixel electrode 23 made of an ITO transparent electrode is formed on the inner surface of the glass substrate 21. Alignment films 24 and 25 made of a polyimide film are formed on the common electrode 22 and the pixel electrode 23, and the alignment films 24 and 25 are aligned so that the alignment directions are parallel to each other. A liquid crystal layer 26 made of P-type nematic liquid crystal is inserted between the alignment films 24 and 25. The pretilt angle of the liquid crystal molecules on the alignment films 24 and 25 is set to about 5 degrees, and the critical voltage for transition from the splay alignment to the bend alignment is set to 2.5V. The retardation of the optical compensator 29 is selected so that white or black is displayed in the on state. In FIG. 1, reference numerals 27 and 28 denote polarizing plates.
[0252]
In the figure, reference numeral 30 denotes an alignment transition driving circuit, and reference numeral 31 denotes a liquid crystal display driving circuit. 32a and 32b are switch circuits, and 33 is a switch control circuit for controlling switching of the switching mode of the switch circuits 32a and 32b. The switch circuit 32a includes two individual contacts P1, P2, and one common contact Q1, and the switch circuit 32b includes two individual contacts P3, P4 and one common contact Q2. Yes. The common contact Q1 is connected to one of the individual contacts P1 and P2 in response to the switch switching signal S1 from the switch control circuit 33. Similarly, the common contact Q2 is connected to any of the individual contacts P3 and P4 in response to the switch switching signal S2 from the switch control circuit 33. In a state where the common contact Q1 is connected to the individual contact P1 and the common contact Q2 is connected to the individual contact P3, the drive voltage from the alignment transition drive circuit 30 is applied to the electrodes 22 and 23. In the state where the common contact Q1 is connected to the individual contact P2 and the common contact Q2 is connected to the individual contact P4, the drive voltage from the liquid crystal display drive circuit 33 is applied to the electrodes 22 and 23.
[0253]
Next, a driving method according to the first embodiment will be described.
[0254]
First, prior to liquid crystal display driving based on the original image signal, initialization processing is performed for transition to bend alignment. First, when the power is turned on, the switch control circuit 33 outputs switch switching signals S1, S2 to the switch circuits 32a, 32b, the common contact Q1 is connected to the individual contact P1, and the common contact Q2 is connected to the individual contact P3. And As a result, the driving voltage shown in FIG. 4 is applied between the electrodes 22 and 23 from the alignment transition driving circuit 30. This drive voltage is an AC voltage in which an AC rectangular wave voltage A is superimposed on a bias voltage B as shown in FIG. 4, and the value of the drive voltage is necessary to cause a transition from a splay alignment to a bend alignment. It is set to a voltage value larger than the critical voltage, which is a minimum voltage. By applying such a drive voltage, the transition time can be significantly shortened compared to the conventional example in which a simple AC voltage is applied. The reason why the transition time is shortened will be described later. In this way, the initialization process regarding the transition to the bend alignment is completed.
[0255]
Next, when the transition time during which the entire electrode surface completely transitions to the bend orientation elapses, the switch control circuit 33 outputs a switching signal S1 for switching the common contact Q1 to the individual contact P2 side to the switch circuit 32a and the common contact Q2 individually. A switching signal S2 for switching to the contact P4 side is output to the switch circuit 32b. As a result, the common contact Q1 and the individual contact P2 are connected, and the common contact Q2 and the individual contact P4 are connected, and the drive signal voltage from the liquid crystal display drive circuit 31 is applied between the electrodes 22 and 23. The desired image is displayed. Here, the liquid crystal display driving circuit 31 maintains the bend alignment state by setting a rectangular wave voltage of 2.7 V at 30 Hz to turn it off, and turns on the rectangular wave voltage 7 V at 30 Hz to display the OCB panel. .
[0256]
Next, the present inventor manufactured a liquid crystal display device having the above-described configuration and conducted an initialization process experiment with the above driving method. The experimental conditions are as follows.
[0257]
2cm electrode area ² The cell gap was about 6 μm, the frequency of the AC rectangular wave voltage A was 30 Hz, and the amplitude was ± 4V.
[0258]
Under the above conditions, the transition times were measured when the bias voltage B was set to four types of voltages of 0V, 2V, 4V, and 5V. The results are shown in FIG. Here, the transition time means the time required to complete the alignment transition in the entire area of the electrode area.
[0259]
As apparent from FIG. 5, when the bias voltage B is 0 V, the transition time is 140 seconds. On the other hand, when the bias voltage B is 4 V, the transition time can be shortened to 8 seconds. This is because the bias voltage overlaps the liquid crystal molecule orientation of the liquid crystal layer due to the bias voltage, causing a shift between the substrates as shown in FIG. 2 (d), generating more transition nuclei, and further increasing the effective voltage. It is thought that the transition time was increased by up.
[0260]
As described above, by continuously applying the AC voltage with bias superimposed thereon, the transition time can be shortened compared to the case of simple AC voltage application.
[0261]
In the above experimental example, the AC rectangular wave voltage signal has a frequency of 30 Hz and a value of ± 4 V. However, the present invention is not limited to this, and may be any frequency at which the liquid crystal operates. Of course, if the amplitude of the AC voltage A is increased, the transition time will be faster. At this time, the higher the bias voltage B is, the faster it is. However, in consideration of lowering the drive voltage, it is desirable to set the bias voltage to an optimum voltage level according to the desired transition time. Moreover, although the rectangular wave was used as a waveform, you may use the alternating current waveform from which duty ratio differs.
[0262]
For reference, a driving method for applying an alternating voltage is disclosed in Japanese Patent Laid-Open No. 9-185032. However, in this prior art, a normal positive / negative symmetrical alternating voltage is merely applied. On the other hand, in the present invention, the bias voltage is superimposed on the AC voltage to break the positive / negative symmetry of the AC voltage, and an asymmetric waveform is applied to the liquid crystal layer to disturb the orientation of the liquid crystal molecules and promote the generation of transition nuclei. It is easy to promote. In the prior art, since a positive / negative symmetrical alternating voltage is applied, the alignment of the liquid crystal molecules cannot be disturbed, and the change of the alignment state stops midway, and there is a possibility that no transition nucleus is generated. In contrast, in the present invention, transition nuclei are generated quickly and reliably. Accordingly, the present invention is essentially different from the prior art.
[0263]
(Embodiment 2)
FIG. 6 is a conceptual diagram of a pixel unit of the liquid crystal display device according to the second embodiment. In the second embodiment, a step of applying an alternating voltage superimposed with a bias voltage between the substrates and a step of electrically opening the substrates between the substrates (open state) are alternately repeated, so that the liquid crystal layer is formed. The splay alignment is changed to the bend alignment.
[0264]
In the liquid crystal display device according to the second embodiment, the same components as those of the liquid crystal display device according to the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the second embodiment, the alignment transition drive circuit 40, the switch circuit 42a, and the switch control circuit 43 are used in place of the alignment transition drive circuit 30, the switch circuit 32a, and the switch control circuit 32 of the first embodiment. It is done. The switch circuit 42a is a three-terminal changeover switch circuit including an individual contact P5 in addition to the individual contacts P1 and P2. The switching of the switch circuit 42a is controlled by a switch control circuit 43. The alignment transition driving circuit 40 applies the driving voltage shown in FIG. This drive voltage is an AC voltage in which an AC rectangular wave voltage C is superimposed on a bias voltage D as shown in FIG. 7, and the value of the drive voltage is necessary to cause a transition from the splay alignment to the bend alignment. It is set to a voltage value larger than the critical voltage, which is a minimum voltage.
[0265]
The common contact Q1 of the switch circuit 42a is connected to any one of the individual contacts P1, P2, and P5 by a switch switching signal S3 from the switch control circuit 42. In a state in which the common contact Q1 is connected to the individual contact P5, the electrodes 22 and 23 are in an open state separated from the alignment transition drive circuit 40. In a state where the common contact Q1 is connected to the individual contact P1 and the common contact Q2 is connected to the individual contact P3, the drive voltage from the alignment transition drive circuit 40 is applied to the electrodes 22 and 23. In the state where the common contact Q1 is connected to the individual contact P2 and the common contact Q2 is connected to the individual contact P4, the drive voltage from the liquid crystal display drive circuit 31 is applied to the electrodes 22 and 23.
[0266]
Next, a driving method according to the second embodiment will be described.
[0267]
First, prior to liquid crystal display driving based on the original image signal, initialization processing is performed for transition to bend alignment. First, when the power is turned on, the switch control circuit 43 outputs a switch switching signal S3 to the switch circuit 42a and also outputs a switch switching signal S2 to the switch circuit 32b, thereby connecting the common contact Q1 and the individual contact P1. In addition, the common contact Q2 and the individual contact P3 are connected. As a result, the drive voltage shown in FIG. 7 is applied between the electrodes 22 and 23 from the alignment transition drive circuit 30. Then, when a certain period T2 has elapsed, the switch control circuit 43 outputs a switch switching signal S3 to the switch circuit 42a, and puts the common contact Q1 and the individual contact P5 into a connected state. As a result, the electrodes 22 and 23 are disconnected from the alignment transition drive circuit 40 and are in an open state. Such an open state is maintained for the period W2, and during this open state period W2, the electrodes 22 and 23 are in a charge holding state.
[0268]
When the open state period W2 elapses, the switch control circuit 43 outputs a switch switching signal S3 to the switch circuit 42a, and sets the common contact Q1 and the individual contact P1 in the connected state again. Then, such an alignment transition drive and an open state are alternately repeated, and when a certain period of time elapses after the power is turned on, the entire surface of the electrode is completely transitioned to bend alignment.
[0269]
When the fixed period has elapsed, the switch control circuit 43 outputs the switch switching signal S3 to the switch circuit 42a and also outputs the switch switching signal S2 to the switch circuit 32b, so that the common contact Q1 and the individual contact P2 are connected. And the common contact Q2 and the individual contact P43 are connected. As a result, the drive signal voltage from the liquid crystal display drive circuit 31 is applied between the electrodes 20 and 21, and a desired image is displayed. Here, the liquid crystal display drive circuit 31 maintains the bend alignment state by setting the rectangular wave voltage of 2.7 V to 30 Hz as in the first embodiment, turns it off, and turns on the rectangular wave voltage 7 V of 30 Hz. The OCB panel is displayed as the state.
[0270]
Next, the present inventor manufactured a liquid crystal display device having the above-described configuration and conducted an initialization process experiment with the above driving method. The experimental conditions are as follows.
[0271]
2cm electrode area ² The cell gap was about 6 μm, the bias voltage B was 2 V, the frequency and amplitude of the AC rectangular wave voltage D were 30 Hz and ± 4 V, and the application time T2 was fixed at 2 seconds.
[0272]
Under the above conditions, the open state time W2 was changed to 0 seconds, 0.2 seconds, 2 seconds, and 3 seconds, and the transition time was measured when the voltage application state and the open state were alternately repeated. The result is shown in FIG. Here, the transition time means the time required to complete the alignment transition in the entire area of the electrode area.
[0273]
As is clear from FIG. 8, when the open state time W2 was 0 seconds, that is, when an alternating voltage superimposed with a bias voltage was continuously applied, the transition time required 80 seconds. On the other hand, when the open state time W2 was set to 0.2 seconds and the AC voltage superimposed with the bias was alternately switched, the transition time was shortened to 40 seconds. However, when the open state time W2 is 2 seconds, the transition time is as long as 420 seconds, and when W2 is 3 seconds, the transition cannot be completed.
[0274]
Further, when the transition time was measured under the same conditions as in the above experimental example except that the application time T2 was 0.3 seconds and the open state period W2 was 0.3 seconds, the transition time was 28 seconds.
[0275]
Incidentally, when T2 was fixed to 2 seconds and W2 was set to 0.1 second or more and 0.5 second or less, good results were obtained.
[0276]
It can be considered that the state transition time from the splay alignment to the bend alignment became extremely short by repeatedly switching the biased alternating voltage and the open state as described above for the following reason. That is, by applying an alternating voltage with a bias superimposed, the liquid crystal molecule orientation of the liquid crystal layer is shaken and is displaced between the substrates as shown in FIG. 2D, and then the transition nucleus is formed by switching to the short open state. It is thought that this occurred and the transition time became faster.
[0277]
The effect can be obtained even if another voltage signal is further added and then the open state is entered next before or after the step of applying the AC voltage on which the bias is superimposed.
[0278]
Further, the voltage value of the bias voltage and the AC voltage, the application time, the open state maintenance time, and the like can be selected according to the desired transition time. The frequency of the AC voltage may be a frequency at which the liquid crystal operates, and may be a value such as 10 kHz. Although a rectangular wave is used as the waveform, alternating waveforms with different duty ratios may be used.
[0279]
(Embodiment 3)
FIG. 9 is a conceptual diagram of a pixel unit of the liquid crystal display device according to the third embodiment. In the third embodiment, the step of applying an alternating voltage superimposed with a bias voltage between the substrates and the step of applying a zero voltage or a low voltage between the substrates are alternately repeated, so that the liquid crystal layer is removed from the splay alignment. It is characterized by transitioning to bend alignment.
[0280]
In the liquid crystal display device according to the third embodiment, the same components as those of the liquid crystal display device according to the second embodiment are denoted by the same reference numerals, and description thereof is omitted. In the third embodiment, a switch circuit 42b and a switch control circuit 53 are used instead of the switch circuit 32b and the switch control circuit 43 of the second embodiment. In the third embodiment, in addition to the alignment transition drive circuit 40, an alignment transition drive circuit 50 for applying a low voltage between the electrodes 22 and 23 is provided.
[0281]
The switch circuit 42b is a three-terminal changeover switch circuit provided with individual contacts P6 in addition to the individual contacts P3 and P4. The switch switching of the switch circuit 42b is controlled by the switch control circuit 53. The common contact Q2 of the switch circuit 42b is connected to any one of the individual contacts P3, P4, and P6 by the switch switching signal S4 from the switch control circuit 53.
[0282]
In the state where the common contact Q1 is connected to the individual contact P5 and the common contact Q2 is connected to the individual contact P3, the drive voltage from the alignment transition drive circuit 40 is applied to the electrodes 22 and 23. In the state where the common contact Q1 is connected to the individual contact P5 and the common contact Q2 is connected to the individual contact P6, the drive voltage from the alignment transition drive circuit 50 is applied to the electrodes 22 and 23. . Further, in the state where the common contact Q1 is connected to the individual contact P2 and the common contact Q2 is connected to the individual contact P4, the drive voltage from the liquid crystal display drive circuit 31 is applied to the electrodes 22 and 23.
[0283]
Next, a driving method according to the third embodiment will be described.
[0284]
First, prior to liquid crystal display driving based on the original image signal, initialization processing is performed for transition to bend alignment. First, when the power is turned on, the switch control circuit 53 outputs a switch switching signal S3 to the switch circuit 42a and also outputs a switch switching signal S4 to the switch circuit 42b, thereby connecting the common contact Q1 and the individual contact P1. In addition, the common contact Q2 and the individual contact P3 are connected. Accordingly, the drive voltage shown in FIG. 10 is applied between the electrodes 22 and 23 from the alignment transition drive circuit 40. When a predetermined period T3 elapses, the switch control circuit 53 outputs the switch switching signal S3 to the switch circuit 42a and also outputs the switch switching signal S4 to the switch circuit 42b, and the common contact Q1 and the individual contact P5 are connected. And the common contact Q2 and the individual contact P6 are connected. Accordingly, the low voltage shown in FIG. 10 is applied between the electrodes 22 and 23 from the alignment transition drive circuit 50. Such low voltage application is maintained for the period W3.
[0285]
Next, when the low voltage application period W3 elapses, the switch control circuit 53 outputs the switch switching signal S3 to the switch circuit 42a and also outputs the switch switching signal S4 to the switch circuit 42b, and again connects the common contact Q1 and the individual contact P1. The connection state is set and the common contact Q2 and the individual contact P3 are connected. Then, such an alternating voltage application process and a low voltage application process are alternately repeated, and when a certain period of time elapses after the power is turned on, the entire surface of the electrode completely transitions to bend alignment.
[0286]
When this fixed period has elapsed, the switch control circuit 53 outputs the switch switching signal S3 to the switch circuit 42a and also outputs the switch switching signal S4 to the switch circuit 42b, and the common contact Q1 and the individual contact P2 are connected. And the common contact Q2 and the individual contact P43 are connected. As a result, the drive signal voltage from the liquid crystal display drive circuit 31 is applied between the electrodes 20 and 21, and a desired image is displayed. Here, the liquid crystal display drive circuit 31 maintains the bend alignment state by setting the rectangular wave voltage of 2.7 V to 30 Hz as in the first embodiment, turns it off, and turns on the rectangular wave voltage 7 V of 30 Hz. The OCB panel is displayed as the state.
[0287]
Next, the present inventor manufactured a liquid crystal display device having the above-described configuration and conducted an initialization process experiment with the above driving method. The experimental conditions are as follows.
[0288]
2cm electrode area ² The cell gap was about 6 μm, the bias voltage D was 2 V, the frequency and amplitude of the AC rectangular wave voltage C were 30 Hz, ± 4 V, and the application time T3 was fixed at 1 second. The applied voltage during the low voltage application period W3 was a DC voltage of -2V.
[0289]
Under the above conditions, the transition time when the low voltage application period W3 was changed and the alternating voltage application state and the applied voltage application state were alternately repeated was measured, and the result is shown in FIG.
[0290]
As is clear from FIG. 11, when the low voltage application time was 0 seconds, that is, when an alternating voltage superimposed with a bias voltage was continuously applied, the transition time required about 80 seconds. On the other hand, when the low voltage application time W3 was set to 0.1 second and the AC voltage superimposed with the bias was alternately switched, the transition time was shortened to 60 seconds. However, when the low voltage application time W3 is 1 second, the transition time becomes 360 seconds, and when W3 is 3 seconds, the transition cannot be completed.
[0291]
In addition, the transition was completed within 50 seconds at the shortest in repeated switching between the AC voltage ± 4 V with the bias voltage superimposed on 2 V and the DC voltage 0 V. In addition, the transition time within 50 seconds at the shortest was obtained by repeated switching between the AC voltage ± 4 V superimposed with the bias 2 V and the AC low voltage ± 2 V.
[0292]
Incidentally, when T3 was fixed to 1 second and W2 was set to 0.1 second or more and 0.5 second or less, good results were obtained.
[0293]
As described above, the transition time from the splay alignment to the bend alignment is shortened by repeatedly switching between the bias voltage-applied AC voltage application and the low voltage application, rather than simply applying the AC voltage with the bias superimposed. . This is due to the application of an alternating voltage with bias superimposed, and the liquid crystal molecule orientation of the liquid crystal layer is shaken and is displaced between the substrates as shown in FIG. 2 (d), and then switched to a short low voltage application state. It is thought that transition nuclei were generated and the transition time was faster.
[0294]
Further, the voltage value of the bias voltage and the AC voltage, the application time, the low voltage value, the application time, and the like can be selected and changed depending on the desired transition time, not the above values. The frequency of the AC voltage may be a frequency at which the liquid crystal operates, and may be a value such as 10 kHz. Although a rectangular wave is used as the waveform, alternating waveforms with different duty ratios may be used.
[0295]
In the above example, a low voltage of −2V is applied during the low voltage application period W3, but 0V may be applied.
[0296]
Next, the ratio between the AC voltage application period T3 and the low voltage application period W3 and the number of repetitions of AC voltage application and low voltage application per second will be described. Here, for convenience of explanation, the voltage in the low voltage application period W3 is assumed to be 0V, and alternating repetition of alternating voltage application and 0V application is considered as one transition voltage as indicated by a broken line L in FIG. In such a case, in order to shorten the transition time, it is necessary to set the frequency of the transition voltage L in the range of 0.1 Hz to 100 Hz and the duty ratio of the transition voltage L in the range of 1: 1 to 1000: 1. There is. Further, it is desirable that the frequency of the transition voltage L is in the range of 0.1 Hz to 10 Hz, and the duty ratio of the transition voltage L is in the range of 2: 1 to 1000: 1. The reason will be described in detail below.
[0297]
In a duty ratio range (for example, a duty ratio range of 1: 1 to 1:10, etc.) in which the duty ratio of the repetitively applied voltage is larger in the voltage application pause period than in the voltage application period, the transition nucleus is obtained by applying the pulse width. Even if this occurs, it is considered that the transition is relieved in the voltage application pause state at the subsequent pulse interval, and returns to the splay alignment, and the transition is not completed. Therefore, it is necessary to set the duty ratio so that the voltage application period is larger than the voltage application pause period. In order to enlarge the transition region, the duty ratio is in the range of 1: 1 to 1000: 1 where the pulse width is wider than the pulse interval, preferably 2: 1 to 100: 1. When DC is continuously applied from 1000: 1, it is considered that the pulse repetitive application is almost eliminated, so that the opportunity for generation of transition nuclei decreases and the transition becomes slightly longer.
[0298]
The repetition frequency of the voltage application for transition may be from continuous to about 100 Hz. Desirably, a pulse interval of about 10 ms or more with a duty ratio of 1000: 1 from 10 Hz at which a pulse width of about 100 ms or more is obtained for transition expansion. Up to 0.1 Hz is preferable.
[0299]
The inventor measured the transition time when a voltage was applied to the liquid crystal cell while changing the repetition frequency and duty ratio under alternating repetition conditions of DC-15V and 0V, and the results are shown in Table 1. .
[Table 1]

[0300]
As is clear from Table 1, when the frequency is in the range of 0.1 Hz to 10 Hz and the duty ratio is in the range of 2: 1 to 1000: 1, the transition time is extremely small, and the frequency is in the range of 0.1 Hz to 100 Hz. Even when the duty ratio is in the range of 1: 1 to 1000: 1, it is recognized that the transition time is sufficiently small.
[0301]
(Embodiment 4)
FIG. 12 is a conceptual diagram of a pixel unit of the liquid crystal display device according to the fourth embodiment. In the fourth embodiment, an example in which the present invention is applied to a driving method of an active matrix liquid crystal display device is shown.
[0302]
First, the configuration of the liquid crystal display device related to the driving method according to the fourth embodiment will be described with reference to FIG. The liquid crystal display device according to the fourth embodiment has the same configuration as that of an active matrix liquid crystal display device including a general OCB cell with respect to the configuration excluding the drive circuit unit. That is, it has a pair of glass substrates 60 and 61 and a liquid crystal layer 66 sandwiched between the glass substrates 60 and 61. The glass substrates 60 and 61 are arranged to face each other with a certain interval. A common electrode 62 made of an ITO transparent electrode is formed on the inner surface of the glass substrate 60, and a thin film transistor (TFT) 70 as a pixel switching element and an ITO electrode connected to the TFT 70 are formed on the inner surface of the glass substrate 61. A pixel electrode 63 made of a transparent electrode is formed. Alignment films 64 and 65 made of a polyimide film are formed on the common electrode 62 and the pixel electrode 63, and the alignment films 64 and 65 are subjected to an alignment process so that the alignment directions are parallel to each other. A liquid crystal layer 66 made of P-type nematic liquid crystal is inserted between the alignment films 64 and 65. The pretilt angle of the liquid crystal molecules on the alignment films 64 and 65 is set to about 5 degrees, and the critical voltage for transition from the splay alignment to the bend alignment is set to 2.6V. The retardation of the optical compensator 67 is selected so that white or black is displayed in the on state. In the figure, reference numerals 68 and 69 denote polarizing plates.
[0303]
In the figure, reference numerals 71 and 72 denote alignment transition drive circuits. The alignment transition drive circuit 71 applies a drive voltage to the common electrode 62 with reference to the center of the common electrode shown in FIG. It works to apply 0V. As another configuration, the alignment transition drive circuit 72 functions to apply 0 V to the common electrode 62 and the pixel electrode 63. Reference numeral 73 denotes a liquid crystal display driving circuit. The liquid crystal display driving circuit 73 serves to apply a driving voltage having a voltage waveform shown in FIG. 13 to the common electrode 62 and the pixel electrode 63. That is, the liquid crystal display driving circuit 73 applies the voltage indicated by the reference symbol M1 in FIG. 13 to the pixel electrode 63, and applies the voltage indicated by the reference symbol M2 in FIG. In the above configuration, 0 V is applied to the pixel electrode 63 during the alignment transition period, but instead, the pixel electrode voltage is applied from the liquid crystal display driving circuit 73 during the alignment transition period. It may be.
[0304]
Reference numerals 74a and 74b denote switch circuits, and reference numeral 75 denotes a switch control circuit that controls switching of the switching mode of the switch circuits 74a and 74b. The switch circuit 74a includes three individual contacts P7, P8, P9 and one common contact Q1, and the switch circuit 74b includes three individual contacts P10, 11, 12 and one common contact Q2. It has. In a state where the common contact Q1 is connected to the individual contact P7 and the common contact Q2 is connected to the individual contact P10, the drive voltage from the alignment transition drive circuit 71 is applied to the electrodes 62 and 63. In the state where the common contact Q1 is connected to the individual contact P2 and the common contact Q2 is connected to the individual contact P4, the drive voltage from the liquid crystal display drive circuit 73 is applied to the electrodes 62 and 63.
[0305]
Next, a driving method according to the fourth embodiment will be described.
[0306]
First, prior to liquid crystal display driving based on the original image signal, initialization processing is performed for transition to bend alignment. First, when the power is turned on, the switch control circuit 75 outputs a switch switching signal to the switch circuit 74a and also outputs a switch switching signal to the switch circuit 74b so that the common contact Q1 and the individual contact P7 are connected, and The contact Q2 and the individual contact P10 are connected. Thereby, the drive voltage shown in FIG. 14 is applied to the common electrode 62 from the alignment transition drive circuit 71. In other words, an alternating voltage synchronized with the vertical synchronizing signal on which the bias voltage −GV is superimposed is applied to the common electrode 62 with the common electrode center as a reference. Note that 0 V is applied to the pixel electrode. Then, the application of the AC voltage is maintained for a period T4.
[0307]
Next, when the AC voltage application period T4 elapses, the switch control circuit 75 outputs a switch switching signal to the switch circuit 74a and also outputs a switch switching signal to the switch circuit 74b to connect the common contact Q1 and the individual contact P9. And the common contact Q2 and the individual contact P12 are connected. As a result, 0 V is applied from the alignment transition drive circuit 72 to the common electrode 62 and the pixel electrode 63 as shown in FIG. Then, this 0V voltage application is maintained for a period W4.
[0308]
Next, when the 0V voltage application period W4 elapses, the switch control circuit 75 outputs a switch switching signal to the switch circuit 742a and outputs a switch switching signal to the switch circuit 74b, and again connects the common contact Q1 and the individual contact P7. And the common contact Q2 and the individual contact P10 are connected. Then, the AC voltage application process and the 0V voltage application process are alternately repeated, and when a certain period of time elapses after the power is turned on, the entire surface of the electrode completely transitions to bend alignment.
[0309]
Then, when this fixed period has elapsed, the switch control circuit 75 outputs a switch switching signal to the switch circuit 74a and also outputs a switch switching signal to the switch circuit 74b so that the common contact Q1 and the individual contact P8 are connected, In addition, the common contact Q2 and the individual contact P11 are connected. As a result, the drive signal voltage from the liquid crystal display drive circuit 73 is applied to the electrodes 62 and 63, and a desired image is displayed. Here, the liquid crystal display driving circuit 73 sets the driving voltage 2.7V for maintaining the bend alignment state between both electrodes to the lowest value to turn it off, and sets the upper limit voltage to 7V to turn it on, Display the panel.
[0310]
By the above driving method, the OCB active matrix type liquid crystal display device of the bend alignment type with a wide field of view and high-speed response was able to display a high quality drive without any alignment defects.
[0311]
Next, the present inventor manufactured a liquid crystal display device having the above-described configuration and conducted an initialization process experiment with the above driving method. The experimental conditions are as follows.
[0312]
The cell gap was about 6 μm, the bias voltage G was −6 V, the frequency and amplitude of the AC rectangular wave voltage were 7.92 kHz, ± 10 V, and the application time T3 was 0.5 seconds. The 0V voltage application period W4 was set to 0.5 seconds.
[0313]
According to the experimental result, the alignment transition in all the pixels of the panel of the liquid crystal display device could be completed within about 2 seconds.
[0314]
When the bias voltage is not superimposed, it takes about 20 seconds to shift the alignment state of the entire display surface. Therefore, also in the fourth embodiment, it can be recognized that driving by superimposing the bias voltage can reduce the transition time.
[0315]
(Embodiment 5)
As a driving method related to the orientation transition of the OCB mode active matrix liquid crystal display device, the driving voltage waveform shown in FIG. 14 may be used instead of the driving voltage waveform shown in FIG. That is, in the AC voltage application period T4, a DC voltage of −15 V is applied to the common electrode 62 with respect to the center of the common electrode for 0.5 seconds. Next, in the 0V voltage application period W4, 0V is applied for 0.2 seconds. And DC voltage -15V application and 0V voltage application are repeated alternately. Even in such a driving method, the transfer can be completed reliably and in a very short time.
[0316]
In addition, when this inventor experimented using the said drive method, the transition time within 2 second was obtained.
[0317]
(Embodiment 6)
In the sixth embodiment, instead of the active matrix type liquid crystal display device used in the fourth and fifth embodiments, a flattening film is disposed on a switching element and a pixel electrode is formed thereon, so-called flattening. The driving method according to the fourth and fifth embodiments is applied to a liquid crystal display device having a chemical film structure. The driving method will be described in detail. The bias-superposed alignment transition voltage in the fourth embodiment is applied for 0.5 seconds, then the open state is set to 0.5 seconds, and this is repeated alternately. According to this driving method, the transition time was within 1 second, and the transition could be performed more smoothly. This is thought to be due to the smooth transition from the splay alignment to the bend alignment as a result of being able to reduce the pixel electrode spacing due to the planarization film configuration.
[0318]
(Other matters)
(1) In the above embodiment, an AC voltage superimposed with a bias voltage is applied. However, a DC voltage may be applied. In this case, a unipolar voltage may be used. Can be simplified.
[0319]
{Circle around (2)} In the above embodiment, the AC voltage signal on which the bias voltage is superimposed is described as the bias voltage being a DC, but a low-frequency AC signal may be used to improve reliability.
[0320]
(3) The optimum range of the frequency and duty ratio of the repetitive voltage can be applied to other embodiments other than the third embodiment.
[0321]
{Circle over (4)} In the above embodiment, the driving method of the liquid crystal display device of the present invention has been described for the transmissive liquid crystal display device, but a reflective liquid crystal display device may be used. These may be a full-color liquid crystal display device using a color filter or a color filter-less liquid crystal display device.
[0322]
Embodiment 7 FIG. 16 is a schematic sectional view of a liquid crystal display device according to Embodiment 7 of the present invention, and FIG. 17 is a schematic plan view thereof. The liquid crystal display device shown in FIG. 16 includes polarizing plates 101 and 102, a phase compensation plate 103 for optical compensation disposed inside the polarizing plate 101, and an active matrix disposed between the polarizing plates 101 and 102. Type liquid crystal cell 104. The liquid crystal cell 104 includes an array substrate 106 made of glass or the like, and a counter substrate 105 facing the array substrate 106. A pixel electrode 108, which is a transparent electrode, is formed on the inner surface of the array substrate 106. A common electrode 107 is formed on the inner surface of the counter substrate 105. Further, an alignment film 110 is formed on the pixel electrode 108, and an alignment film 109 is formed on the common electrode 107.
[0323]
A switching element 111 made of, for example, an a-Si TFT element is disposed on the array substrate 106, and the switching element 111 is connected to the pixel electrode 108.
[0324]
Between the alignment films 109 and 110, a spacer (not shown) having a diameter of 5 microns and a liquid crystal layer 112 made of a nematic liquid crystal material having a positive dielectric anisotropy are disposed. The alignment films 109 and 110 are subjected to parallel alignment treatment in the same direction so that the pretilt angles of the liquid crystal molecules on the surfaces thereof have positive and negative values and become substantially parallel to each other. Therefore, the liquid crystal layer 112 forms a so-called splay alignment composed of alignment regions in which liquid crystal molecules spread obliquely when no voltage is applied.
[0325]
The alignment film 110 includes an alignment film 110a having a large pretilt angle B2 (third pretilt angle) and an alignment film 110b having a small pretilt angle A2 (first pretilt angle). The alignment film 109 includes an alignment film 109a having a small pretilt angle D2 (fourth pretilt angle) and an alignment film 109b having a large pretilt angle C2 (second pretilt angle). The pretilt angle C2 is disposed opposite to the pretilt angle B2, and the pretilt angle D2 is disposed opposite the pretilt angle B2.
[0326]
Further, the alignment films 109 and 110 are subjected to parallel alignment processing in the same direction as the signal electrode lines 113 by rubbing cross in the same direction of the upper and lower substrates (from the left side to the right side in FIG. 16).
[0327]
Although not shown, the liquid crystal display device is provided with an alignment transition driving circuit including a first voltage applying unit and a second voltage applying unit in addition to the liquid crystal display driving circuit. Then, a first voltage is applied between the pixel electrode 108 and the common electrode 107 by the first voltage applying means, and a discretion is made in the vicinity of the boundary between the first liquid crystal cell region and the second liquid crystal cell region. Forming a transition line in the disclination line by forming a nation line and applying a second voltage higher than the first voltage between the pixel electrode 108 and the counter electrode 107 by the second voltage applying means. The splay alignment is changed to the bend alignment.
[0328]
Next, a method for manufacturing the liquid crystal display device will be described.
[0329]
First, the signal scanning line 113, the switching element 111 and the pixel electrode 108 were formed on the inner surface of the array substrate 106.
[0330]
Next, a polyimide alignment film material having a pretilt angle B2 as a third pretilt angle having a large value of about 5 degrees of a polyamic acid type manufactured by Nissan Chemical Industries, Ltd. is applied on the pixel electrode 108, After drying, firing was performed to form an alignment film 110 a on the pixel electrode 108.
[0331]
Next, the alignment film 110b was formed by irradiating the left side region on the paper surface of the alignment film 110a with ultraviolet rays to change the pretilt angle A2 as the first pretilt angle to a small value of about 2 degrees.
[0332]
A common electrode 107 was formed on the inner surface of the counter substrate 105.
[0333]
Next, on the common electrode 107, a polyimide alignment that imparts to the interface liquid crystal molecules a pretilt angle C2 as a second pretilt angle having a large value of about 5 degrees of a polyamic acid type manufactured by Nissan Chemical Industries, Ltd. A film material was applied, dried, and baked to form an alignment film 109 b on the common electrode 107.
[0334]
Next, the right side of the alignment film 109b on the right side of the paper (region facing the pretilt angle B2 having a large pretilt angle) is irradiated with ultraviolet rays to obtain a pretilt angle D2 of about 2 degrees as a fourth pretilt angle. Thus, the orientation film 109a was formed.
[0335]
As described above, a large pretilt angle C2 (second pretilt angle) is arranged opposite to a small pretilt angle A2 (first pretilt angle) as shown in FIG. A small pre-tilt angle D2 (fourth pre-tilt angle) could be arranged opposite to (third pre-tilt angle).
[0336]
In addition, the pretilt angle can be controlled as follows.
[0337]
That is, as shown in FIG. 18A, an active matrix type switching element (not shown) made of an a-Si TFT element and the like and a pixel electrode 108 are formed on the array substrate 106 and connected thereto. .
[0338]
Next, as shown in FIG. 18B, the left side region of the pixel electrode 108 is irradiated with ultraviolet rays in an ozone atmosphere to flatten it compared to the right side region of the pixel electrode 108 to form a flattened region 108a. did.
[0339]
Next, as shown in FIG. 18C, an alignment film 110 was formed by applying and drying or baking a premide type polyimide alignment material manufactured by JSR on the pixel electrode 108.
[0340]
When formed in this manner, the pretilt angle of the liquid crystal molecules 140 positioned on the planarized region 108a of the pixel electrode 108 is set to a value smaller than the pretilt angle of the liquid crystal molecules 140 positioned on the non-planarized region 108b. it can. Further, by performing the same process on the common electrode, a liquid crystal display device having the first liquid crystal cell region and the second liquid crystal cell region in the same pixel can be obtained as in FIG. .
[0341]
Next, as shown in FIG. 16, the surfaces of the alignment film 109 and the alignment film 110 that are formed as described above and that give a pretilt angle of the same size are rubbed with the upper and lower substrates in the direction perpendicular to the signal electrode line 113. A liquid crystal layer 112 made of a positive nematic liquid crystal material was disposed by parallel alignment in the direction (from left to right in FIG. 16).
[0342]
In the liquid crystal display device thus produced, a small pretilt angle A2 is arranged at the orientation source (upstream side in the rubbing processing direction) of the pixel electrode 108, and a large pretilt angle C2 is arranged on the opposite side. Then, when 2.5 V is applied as a first voltage between the common electrode 107 and the pixel electrode 108 to the (a) region (first liquid crystal cell region) of the pixel in FIG. The b-spray alignment 120 with the splay alignment on the side and the t-spray alignment 121 with the liquid crystal molecules splayed on the counter substrate 105 side are easily formed in the (b) region (second liquid crystal cell region) of the pixel. Become.
[0343]
That is, as shown in FIGS. 16 and 17, when 2.5 V as the first voltage is applied between the common electrode 107 and the pixel electrode 108 through the switching element 111 of the liquid crystal cell 104, the b-spray orientation is formed in the pixel. A region (first liquid crystal cell region) and a t-spray alignment region (second liquid crystal cell region) are formed, and a disclination line 123 is formed along the signal electrode line 113 and a gate electrode line 114. 114 'was clearly formed (disclination line forming step).
[0344]
Further, by repeatedly applying a voltage −15 V pulse as the second voltage between the common electrode 107 and the pixel electrode 108, a transition nucleus is generated from the disclination line 123 as shown in FIG. The transition to the bend alignment 124 was expanded, and the entire TFT panel pixel was quickly transitioned in about 3 seconds (alignment transition step).
[0345]
This is because the discnation line region that is the boundary between the b-spray alignment state and the t-spray alignment region has higher strain energy than the surroundings, and a high voltage is applied between the upper and lower electrodes in this state. It is considered that energy was further applied and the splay alignment was changed to the bend alignment.
[0346]
(Embodiment 8)
FIG. 19 is a schematic view of a liquid crystal display device according to Embodiment 8 of the present invention.
[0347]
At the time of normal display, the gate electrode lines are turned on and scanned in sequence, but before normal display, the gate electrode lines are sequentially turned on and a second voltage is applied between the common electrode 107 and the pixel electrode. As a result, by repeatedly applying the voltage −15V pulse, a horizontal electric field caused by the potential difference is generated between the pixel electrode 108 and the gate electrode lines 114 and 114 ′. Then, due to the lateral electric field, as shown in FIG. 19, transition nuclei are generated from the vicinity of the disclination line 123 and the gate electrode lines 114 and 114 ′, and the transition is expanded to bend alignment, and the entire TFT panel pixel is further accelerated in about 1 second. Expanded transition to crab bend alignment (alignment transition process).
[0348]
This is because the disclination line region, which is the boundary between the b-spray alignment state and the t-spray alignment region, has higher strain energy than the surroundings, and in this state also from the gate electrode line arranged horizontally It is considered that energy was given further by applying a lateral electric field to the disclination line, and the energy was transferred quickly. After the transfer is completed, the gate electrode lines 114 and 114 ′ are returned to the normal scanning state.
[0349]
The second voltage applied between the pixel electrode and the common electrode may be applied continuously. Further, when a pulsed voltage is repeatedly applied, the frequency is in the range of 0.1 Hz to 100 Hz, and the duty ratio of the second voltage is at least 1: 1 to 1000: 1. Is obtained.
[0350]
(Other matters)
In the seventh and eighth embodiments, the pretilt angle D2 of the alignment destination region of the common electrode is set to a small value, but may be a large value. Further, although the pretilt angle B2 of the alignment destination region of the pixel electrode is set to a large value, the effect can be obtained even with a small value because the t-spray alignment is caused by the influence of the lateral electric field.
[0351]
Further, although the opposing pretilt angle C2 is set to 5 degrees with respect to the pretilt angle A2 of one substrate side, if the ratio is large, the transition time can be shortened and the transition time can be further increased.
[0352]
In the above description, the value of the smaller pretilt angle A2 is set to 2 degrees. However, in order to make b-spray alignment and easy transition to bend alignment, the values of the small pretilt angles A2 and D2 are 3 degrees or less. The pretilt angles B2 and C2 having large values may be 4 degrees or more.
[0353]
In addition, the alignment processing direction is the direction perpendicular to the signal electrode line 113 and parallel alignment processing in the same direction of the upper and lower substrates, but the direction perpendicular to the gate electrode line 114 (ie, the direction perpendicular to the paper surface in FIG. Alternatively, parallel alignment treatment may be performed in the same direction on the upper and lower substrates.
At that time, the formation place of the disclination line is different.
[0354]
In addition, when the alignment process is performed with the parallel alignment process shifted by, for example, about 2 degrees from the perpendicular direction of the electrode line along the pixel electrode, a lateral electric field is obliquely applied from the electrode to the disclination line formed in the pixel. Therefore, a twisting force is applied to the splay-aligned liquid crystal molecules and the transition to bend alignment is facilitated, so that a liquid crystal display device in which the transition is surely fast can be obtained.
[0355]
Note that the first voltage may be equal to or higher than a voltage at which a disclination line can be formed. In addition, although the second voltage is applied between the pixel electrode and the common electrode, it may be applied to the common electrode.
[0356]
Further, although a polyimide material is used as the alignment film material, other materials such as a monomolecular film material may be used.
[0357]
In other liquid crystal display devices, for example, the substrate can be formed from a plastic substrate. Further, one of the substrates may be formed from a reflective substrate, for example, silicon.
[0358]
(Embodiment 9)
In this embodiment, concaves and convexes having shapes to be fitted to the signal electrode line and the pixel electrode, and the gate electrode line and the pixel electrode, respectively, are formed.
[0359]
20 and 21 conceptually show the main part of the liquid crystal display device of this embodiment.
[0360]
This figure shows a pixel of an active matrix type OCB mode liquid crystal display device as viewed from above the display surface (user side).
[0361]
In FIG. 20, 206 is a signal electrode line (bus line), 207 is a gate electrode line, and 208 is a switching transistor (element).
[0362]
In the figure, the signal electrode line 206 and the gate electrode line 207 intersect, but it goes without saying that both electrode lines are three-dimensionally arranged via an insulating film (not shown).
[0363]
In addition, the switching transistor 208 made of TFT is connected to a pixel electrode 202a having a substantially square shape in the drawing. The functions, operations, and actions of the signal electrode line 206, the gate electrode line 207, the switching transistor 208, and the pixel electrode 202a are not different from those of the conventional liquid crystal display device as well as the OBC mode.
[0364]
In addition, the alignment treatment using the rubbing cloth or the like is performed on the upper and lower alignment films 203a and 203b in order to first splay align the liquid crystal molecules 211.
[0365]
Further, together with the action of the polarizing plates 204a, 204b, etc., light and dark display is achieved by the action of transferring the entire liquid crystal molecules in the pixel from the splay alignment state in the pixel to the bend alignment region in which the liquid crystal molecules are bent between the opposing substrates. It is the same that is done.
[0366]
However, as shown in FIG. 20A, a concave portion 221a and a convex portion 222a are formed at substantially the center of each side of the substantially square pixel electrode 202a. On the other hand, the signal electrode line 206 and the gate electrode line 207 which are wired in the vicinity of the wiring line are deformed into convex portions 261 and 271 and concave portions 262 and 272 so as to be fitted into the concave portions 221a and the convex portions 222a. Has been. For this reason, it is different from a conventional liquid crystal display device in that a deformed lateral excitation application unit for transition excitation is formed above and below the pixel electrode 202a and on the left and right positions (on the paper surface in FIG. 20A). .
[0367]
Next, a method for manufacturing the liquid crystal display device will be described.
[0368]
A polyimide alignment film material having a pretilt angle of about 5 degrees of polyamic acid type manufactured by Nissan Chemical Industries, Ltd. is applied and dried on the surface of the pixel electrode 202a including the lateral electric field applying portion and the surface of the common electrode 202b. Baking was performed to form alignment films 203a and 203b on the liquid crystal layer 210 side of the respective electrode surfaces.
[0369]
Next, both the surfaces of the alignment films 203a and 203b were subjected to an alignment process in a direction substantially orthogonal to the signal electrode lines 206 as shown in FIG.
[0370]
Under the above conditions, a liquid crystal layer 210 was formed by vacuum injection of a positive nematic liquid crystal material between the upper and lower substrates.
[0371]
For this reason, although not shown, the liquid crystal molecules 211 are aligned on the surfaces of the upper and lower alignment films 203a and 203b so that the pretilt angles have positive and negative values and the perpendicular directions of the molecules are substantially parallel to each other. The liquid crystal layer 210 has a so-called splay alignment in which liquid crystal molecules spread obliquely in a so-called no-voltage application state.
[0372]
Next, an operation for display of the liquid crystal display device will be described.
[0373]
Based on the above, in the liquid crystal field of −15 V between the common electrode 202b and the pixel electrode 202a, a pulse voltage having a relatively high voltage is repeatedly applied, and the gate electrode line 207 is in a normal scanning state or almost all. Turn it on. Thereby, a lateral electric field stronger than the surrounding normal lateral electric field is applied between the gate electrode line 207, the signal electrode line 206, and the pixel electrode 202a by the lateral electric field applying unit. As a result, in the splay alignment region in the pixel region, when rubbing in a direction substantially orthogonal to the signal electrode line 206, the liquid crystal layer 299 mainly based on the lateral electric field application portion between the gate electrode line 207 and the pixel electrode 202a is formed. Transition nuclei to bend alignment are generated. In addition, as shown in FIG. 21, when rubbing in a direction orthogonal to the gate electrode line 207, the liquid crystal layer 298 mainly having a lateral electric field application portion between the signal electrode line 206 and the pixel electrode 202a has a bend alignment. A transition nucleus is generated.
[0374]
Further, the bend alignment region was expanded based on the transition nucleus, and as a result, the entire pixel region could be completed to bend alignment in about 0.5 seconds.
[0375]
The entire TFT panel was quickly transferred in about 2 seconds.
[0376]
In this mechanism, a high voltage is applied between the upper and lower electrodes, and as shown in FIG. 20 (b), the liquid crystal layer 210 is in a b-splay alignment state, and the strain energy is higher than the surroundings. Since the lateral electric field is applied at a substantially right angle (vertical direction in FIG. 20B) in the orientation state direction, the force for twisting the liquid crystal molecules on the lower substrate side in the b-spray orientation of FIG. It is thought that the generation of transition nuclei occurs.
[0377]
In the above description, the horizontal electric field applying portion is formed so that the pixel electrode portion deformed into the concave and convex portions and the concavo-convex portions of both signal electrode lines are fitted to each other, as shown in FIG. Of course, only the pixel electrode 202a, only the signal electrode line 206, and only the gate electrode line 207 may be formed.
[0378]
That is, in this figure, the convex portion 263 of the signal electrode line 206, the convex portion 273 of the gate electrode line 207, and the convex portions 223a and 224a of the pixel electrode 202a are only in one of them, and are not of a fitting type. Is different from that shown in FIG.
[0379]
Of course, the planar shape of the concavo-convex portion may be a shape other than the triangular shape or the quadrangular shape shown in FIGS. 20 to 22, for example, a trapezoidal shape, a semicircular shape, a circular shape, an elliptical shape, or the like.
[0380]
Furthermore, in FIG. 20 to FIG. 22, a total of four horizontal electric field application units are provided on the top, bottom, left and right of one pixel. However, depending on the size of the pixel, only the top and bottom two or only one may be provided. Of course, irregularities may be formed continuously along the electrode edge. Further, until now, the rubbing direction is almost orthogonal to the signal electrode line or the gate electrode line, but the rubbing direction may be an oblique direction. In this case, transition from the liquid crystal layer of the lateral electric field application portion between the signal and gate electrode line and the pixel electrode to bend alignment occurs. In addition, it is desirable that at least one lateral electric field applying unit that can apply a lateral electric field in a direction substantially orthogonal to the rubbing direction is arranged for each pixel.
[0381]
20 to 22 are plan views, both electrode lines (the signal electrode line 206 and the gate electrode line 207) and the pixel electrode 202a appear to be on the same plane. This is because at least one of the electrode lines is The pixel electrode and the array substrate may be arranged at different heights.
[0382]
As described above, the lateral electric field applying unit composed of the electrode deformed portion in which a part of the periphery of the pixel electrode is deformed into a concavo-convex shape in a plane parallel to the substrate surface is separated by about 0.5 to 10 μm in plan view. A lateral electric field is generated by the presence of a convex portion of the signal electrode line or gate electrode line present on the side of the application portion or a concave portion recessed by about 0.5 to 10 μm.
[0383]
(Embodiment 10)
In the present embodiment, an electrode wire for applying a lateral electric field is provided.
[0384]
Hereinafter, the present embodiment will be described with reference to FIG.
[0385]
(A) of this figure is the top view seen from the board | substrate upper surface. FIG. 6B is a cross-sectional view taken along a plane parallel to the gate electrode line 207 of the liquid crystal display device.
[0386]
In (a) and (b) of this figure, reference numeral 209 denotes an electric wire provided exclusively for applying a lateral electric field in a portion almost directly below the signal electrode line 206 on the array substrate 201a. A transparent insulating film 212 insulates the horizontal electric field applying line 209 from the signal electrode line 206, the gate electrode line 207, and the like. Therefore, when this pixel is viewed from the top (the direction of the user side perpendicular to the display surface), as shown in FIG. A convex portion 291 having a shape protrudes to the side of the signal electrode line 206. The signal electrode line 206 and the pixel electrode 202a are not different from those of the prior art.
[0387]
The horizontal electric field applying line 209 is connected to a driving circuit to which the signal electrode line 206 or the gate electrode line 207 is connected. Further, the horizontal electric field applying line 209 is used for normal liquid crystal display after orientation transition. It is configured to be disconnected from the drive circuit.
[0388]
Further, the horizontal electric field applying line 209 is an upper signal electrode line with respect to the signal electrode line 206, and is provided close to the pixel electrode through the transparent insulating film to increase the effect of applying the horizontal electric field, and at the same time, the transparent insulating film It may be electrically connected through a contact hole (not shown). In this case, since there are two signal electrode lines, there is an effect that the redundancy is increased and the electric resistance is lowered.
[0389]
That is, as shown in FIG. 23C, the horizontal electric field applying line 209 a is provided directly above the signal electrode line 206 via the transparent insulating film 213. It is the same that there is a convex portion 291a having a triangular shape in plan view at the center of the pixel.
[0390]
FIG. 23D shows another example of this embodiment. As shown in the figure, the horizontal electric field applying line 209b is covered with the flattened transparent insulating film 212b, and further, the signal electrode line 206 is covered with the flattened transparent insulating film 212c under the dedicated line 209b, and the pixel electrode 202a is formed. It is provided on the planarized transparent insulating film 212b. It is the same that there is a triangular protrusion 291b to the center of the pixel.
[0390]
In the figure, the convex portion of the dedicated line for applying the horizontal electric field has a triangular shape, but this may be provided with a continuous convex portion on all the portions facing the pixel electrode, or a convex portion protruding upward. Of course, it may have a three-dimensional structure.
[0392]
In addition, the dedicated line for applying the horizontal electric field may be provided directly below or directly above the gate electrode line instead of the signal electrode line. Further, it may be provided directly below both electrode lines.
[0393]
(Embodiment 11)
In the present embodiment, a defective portion is formed by providing at least one notch in a pixel electrode.
[0394]
FIG. 24 conceptually shows the plane and features of the pixel unit of the liquid crystal display device of the present embodiment. As shown in this figure, the pixel electrode 202a made of an ITO film is removed by etching with a width of, for example, several μm to form an electrode defect portion 225 having a crank shape in plan view.
[0395]
In addition, on the surface of the pixel electrode 202a including the electrode defect portion 225 and on the common electrode surface (not shown), a polyamic acid type polyimide having a pretilt angle of about 5 degrees manufactured by Nissan Chemical Industries, Ltd. Alignment film materials are applied, dried and fired to form alignment films (not shown), and the surface of the alignment films is further rubbed with a rubbing cloth in a direction perpendicular to the gate electrode lines 207. Therefore, pretilt of liquid crystal molecules is performed. As in the ninth and tenth embodiments, the angles have opposite values and are oriented in parallel in the same direction so as to be substantially parallel to each other.
[0396]
Therefore, the liquid crystal layer forms a so-called splay alignment liquid crystal cell composed of alignment regions in which liquid crystal molecules spread obliquely in a so-called no-voltage application state.
[0397]
However, when a pulse of a voltage of 15 V or -15 V is repeatedly applied between the common electrode and the pixel electrode of the pixel before display, and the gate electrode is in a normal scanning state or almost all turned on. Since the electrode defect portion 225 exists in the pixel unit, as shown in FIG. 24B, an oblique lateral electric field 280 having a strong distortion is generated at the edge of the electrode defect portion 225.
[0398]
For this reason, in the splay alignment in the pixel area, transition nuclei to bend alignment are generated in the liquid crystal layer 299 of the electrode defect portion 225, and the bend alignment area is further expanded to make the entire pixel area in about 0.5 seconds. Complete to bend alignment. In addition, the entire TFT panel transitions quickly in about 2 seconds.
[0399]
This is because a horizontal electric field is applied to the horizontal electric field applying portion composed of the electrode defect portion 225, and the liquid crystal molecules in the vicinity thereof are aligned in a horizontal state on the substrate surface, so that a so-called b-spray alignment state is obtained. In this state, a high voltage is applied between the upper and lower electrodes, so that further energy is applied. As a result, transition nuclei are generated in the electrode defect portion 225 and the bend alignment region is expanded. It is done.
[0400]
In FIG. 24, one electrode defect portion 225 having a crank shape in plan view is formed, but it is needless to say that two or more electrode defect portions 225 may be formed.
[0401]
Of course, the shape may be a straight line, a square, a circle, an ellipse, or a triangle.
[0402]
Further, the electrode defect portion 225 may be formed on the common electrode side.
[0403]
Of course, it may be formed on both the pixel electrode and the common electrode.
[0404]
(Embodiment 12)
In the present embodiment, a horizontal electric field is generated, and a region with a different tilt angle is formed in advance in the pixel plane in accordance with this.
[0405]
FIG. 25 conceptually shows the configuration and characteristics of each pixel of the liquid crystal display device of this embodiment. (A) of this figure is a cross-sectional view of a pixel in a direction parallel to the gate electrode line. Although it is the same pixel, the left (A) and the right (B) have different tilt angles. Show the state.
[0406]
FIG. 25B is a plan view of the pixel viewed from the upper (user side) direction. The pixel electrode 202a is provided with concave and convex portions 221a and 222a, and further, the signal electrode line 206 and the gate electrode line 207. Are provided with concavo-convex portions 261, 262, 271 and 272 so as to be phase-fitted with the concavo-convex portions 221a and 222a, and is the first voltage 2 as in the seventh embodiment. A disclination line 226 is formed at the boundary between (a) and (b) in FIG.
[0407]
Hereinafter, a method for manufacturing the liquid crystal display device of the present embodiment will be described.
[0408]
Alignment films 203am and 203bm are formed on the opposing substrate inner surfaces of the active matrix type liquid crystal cell, respectively, and the alignment films 203am and 203bm are processed to form a splay alignment in a state where no voltage is applied to the liquid crystal layer 210. That is, the formation of a transverse electric field application section for transfer excitation in the pixel electrode 202a or the gate electrode line 207 or the like wired close to the pixel electrode 202a is the same as in the first embodiment.
[0409]
However, the treatment of the alignment film is different. That is, in FIG. 25A, on the surface of the pixel electrode 202a including the lateral electric field applying portion, a polyimide orientation with a pretilt angle B2 having a large value of about 5 degrees of a polyamic acid type manufactured by Nissan Chemical Industries, Ltd. The film material is applied, dried, and baked to form the alignment film 203am.
[0410]
Next, only the left side region 203ah of the alignment film 203am, that is, only the direction shown in (a) is irradiated with ultraviolet rays so that the pretilt angle E2 is changed to an alignment film having a small value of about 2 degrees.
[0411]
On the other hand, on the counter substrate 201b, a polyimide alignment film material that imparts a pretilt angle F2 of about 5 degrees of a polyamic acid type manufactured by Nissan Chemical Industries, Ltd. to the interface liquid crystal molecules is applied, dried and fired. An alignment film 203bh is formed on the common electrode 202b.
[0412]
Next, only the right side region 203bm of the alignment film 203bh, that is, only the direction shown in (b) is irradiated with ultraviolet rays to change the alignment film to a small value of about 2 degrees of the pretilt angle D2.
[0413]
In this way, as shown in FIG. 25A (a), the left half alignment film 203bh on the counter substrate 201b side is larger than the small pretilt angle E2 of the alignment film 203ah on the left half side of the array substrate 201a. The pretilt angle F2 of the value is arranged, and the small value of the alignment film 203bm of the right half of the counter substrate 201b is opposed to the large pretilt angle B2 of the alignment film 203am of the right half of the array substrate side 201a as shown in FIG. A pretilt angle D2 is arranged.
[0414]
Further, the surfaces of the alignment films formed in this way giving a large and small pretilt angle are rubbed with a parallel alignment process in the same direction of the upper and lower substrates in a direction substantially perpendicular to the signal electrode 6 as shown in FIG. did. Thereafter, a positive nematic liquid crystal material was filled, and a liquid crystal layer 210 made of the same was disposed.
[0415]
Under the above, a small pretilt angle E2 is arranged at the orientation source (rubbing root direction) of the pixel electrode 202a, and a large pretilt angle F2 is arranged on the side facing the pretilt angle E2, and FIG. The b-splay alignment 227b in which liquid crystal molecules are splay-oriented on the lower substrate side is provided in the area indicated by (a) of the pixel, and the liquid crystal molecules are splay-oriented on the upper substrate side in the area indicated by (b) of the pixel. The t-spray orientation 227t is easily formed.
[0416]
Next, when 2.5 V near the transition critical voltage is applied between the opposing electrodes through the switching transistor 208 of the liquid crystal cell, a b-spray alignment region and a t-spray alignment region are formed in the same pixel for the above-described reason. The disclination line 226 is clearly formed along the signal electrode line 206 and across the gate electrode line 207 at the boundary.
[0417]
A pulse of −15 V was repeatedly applied between the common electrode and the pixel electrode of this pixel. Then, as shown in FIG. 25 (b), transition nuclei are generated from the disclination line 226 and the liquid crystal layer 299 in the vicinity of the lateral electric field applying portion, and the transition is expanded to the bend alignment region. Transitioned quickly in seconds.
[0418]
This is because, in the declination line 226 region, which is the boundary between the b-spray alignment state and the t-spray alignment region, the strain energy is higher than that of the surroundings. Thus, it is considered that twisting occurs in the splay alignment and the transition easily occurs, and a high voltage is applied between the upper and lower electrodes to further apply energy and bend transition.
[0419]
As mentioned above, although this invention has been demonstrated based on some embodiment, of course, this invention is not limited to these at all. That is, for example, the following may be performed.
[0420]
1) The voltage applied between the pixel electrode and the common electrode is continuous or intermittent.
[0421]
2) When a high voltage pulse is repeatedly applied, the frequency is in the range of 0.1 Hz to 100 Hz, and the duty ratio of the second voltage is at least in the range of 1: 1 to 1000: 1. Select.
[0422]
3) The substrate to be used is made of plastic, and an organic conductive film is adopted as an electrode.
[0423]
4) One of the substrates is formed of a reflective substrate, for example, silicon, or a reflective substrate made of a reflective electrode such as aluminum to form a reflective liquid crystal display device.
[0424]
5) A means for providing a projection for generating a strong electrode electric field in a direction orthogonal to the substrate surface is also used in combination with the pixel electrode and the common electrode.
[0425]
6) Instead of spherical glass or silica that keeps the distance between both substrates constant, means for forming a protrusion for the purpose and providing the protrusion with a function of aligning liquid crystal molecules is also used.
[0426]
7) The upper part or the lower part of the protrusion is also used as the strong electrode generating protrusion.
[0427]
8) The shape of the pixel electrode is not square but rectangular or triangular.
[0428]
9) The pixel is not divided into two regions with different liquid crystal orientations, but three or four.
[0429]
10) In order to increase or decrease the pretilt angle, means such as changing the surface state of the transparent electrode with an O2 asher and forming an alignment film on the transparent electrode is employed.
[0430]
(Embodiment 13)
FIG. 26 is a structural external view of a liquid crystal cell used in the liquid crystal display device according to Embodiment 13, and FIGS. 27 and 28 are part of a manufacturing process for explaining the production of a convex object.
[0431]
A PC-based resist material manufactured by JSR Corporation is applied and formed on a glass substrate 308 to form a resist thin film having a thickness of 1 μm. Next, the resist thin film 320 is exposed and irradiated with parallel ultraviolet rays 323 through a photomask 321 provided with a rectangular pattern of openings 322. The resist thin film 320 exposed with the parallel light is developed and rinsed, and pre-baked at 90 ° C. to form a shape 310 having a convex cross section as shown in FIG.
[0432]
Next, 2000 A of ITO electrode 7 was formed on the substrate according to a conventional method to obtain a glass substrate 308 with an electrode. Thereafter, an alignment film coating SE-7492 manufactured by Nissan Chemical Industries, Ltd. was applied by spin coating on the glass substrate 301 having the transparent electrode 302 and the glass substrate 308 on which the above-mentioned convex shape was formed. The alignment films 303 and 306 are formed by curing for 1 hour. After that, rubbing treatment was performed in the direction shown in FIG. 29 using a rayon rubbing cloth, and spacer 5 manufactured by Sekisui Fine Chemical Co., Ltd. and Structbond 352A (trade name of seal resin manufactured by Mitsui Toatsu Chemical Co., Ltd.) were used. Thus, a liquid crystal cell 309 (referred to as liquid crystal cell A) was prepared by bonding the substrates so that the distance between the substrates was 6.5 μm.
[0433]
At this time, the rubbing process was performed so that the liquid crystal pretilt angle at the alignment film interface was about 5 degrees.
[0434]
Next, a liquid crystal MJ96435 (refractive index anisotropy Δn = 0.138) was injected into the liquid crystal cell A by a vacuum injection method to obtain a test cell A.
[0435]
Next, a polarizing plate is bonded to test cell A so that the polarization axis forms an angle of 45 degrees with the rubbing treatment direction of the alignment film and the polarization axis directions are orthogonal to each other, and a 7 V rectangular wave is applied. Then, when the transition from the splay alignment to the bend alignment was observed, the entire electrode region transitioned from the splay alignment to the bend region in about 5 seconds.
[0436]
In the region where the convex object 310 is formed, the liquid crystal layer thickness is smaller than that of the surrounding liquid crystal layer region, and the electric field strength is effectively large, and the bend transition surely occurs from this portion.
The generated bend orientation quickly spreads to other regions.
[0437]
That is, a reliable and fast spray-to-bend transition can be achieved.
[0438]
Needless to say, the convex shape may have a trapezoidal shape, a triangular shape, or a semicircular shape as well as a rectangular shape as in this embodiment.
[0439]
As a comparative example, a splay alignment liquid crystal cell R was produced by the same process except that a glass substrate with a transparent electrode not having the convex portion 310 was used, and a liquid crystal MJ96435 was sealed to obtain a test cell R. When a 7V rectangular wave is applied to the test cell R, the time required for the entire electrode region to transition from the splay alignment to the bend region is 42 seconds, and the effect of the present invention is clear.
[0440]
(Embodiment 14)
30 is a structural external view of a liquid crystal cell used in the liquid crystal display device according to Embodiment 14, and FIG. 31 is a plan view thereof. 30 is a cross-sectional view seen from the arrow X1-X1 in FIG. The fourteenth embodiment is characterized in that the convex object 310 is provided on the transparent electrode 307a formed outside the display pixel region. The production procedure will be described below.
[0441]
An alignment film coating SE-7492 made by Nissan Chemical Industries, Ltd. is applied by spin coating on a glass substrate 301 having a transparent electrode 302 and a glass substrate 308 having a convex shape, and cured at 180 ° C. for 1 hour in a thermostatic bath. Alignment films 303, 306, and 306a are formed. After that, rubbing treatment was performed in the direction shown in FIG. 29 using a rayon-made rubbing cloth, and spacer 5 made by Sekisui Fine Chemical Co., Ltd. and Structbond 352A (trade name of Mitsui Toatsu Chemical Co., Ltd. seal resin) were used. Thus, a liquid crystal cell (referred to as liquid crystal cell B) was prepared by bonding the substrates so that the distance between the substrates was 6.5 μm.
[0442]
At this time, the rubbing process was performed so that the liquid crystal pretilt angle at the alignment film interface was about 5 degrees.
[0443]
Next, liquid crystal MJ96435 (refractive index anisotropy Δn = 0.138) was injected into liquid crystal cell B by vacuum injection.
[0444]
Next, a polarizing plate is bonded to the liquid crystal cell B so that its polarization axis forms an angle of 45 degrees with the rubbing treatment direction of the alignment film, and the polarization axis directions are orthogonal to each other, and a 7 V rectangular wave is applied. Then, when the transition from the splay alignment to the bend alignment was observed, the entire electrode region shifted from the splay alignment to the bend region in about 7 seconds.
[0445]
In the present embodiment, a convex portion is provided outside the display pixel area and bend transition nuclei are generated outside the display pixel area. The generated bend orientation is quickly generated from outside the display pixel area into the display pixel area. It was confirmed to spread to.
[0446]
Between the display pixel region and the bend nucleus generating electrode region, there is a region to which no electric field is applied (having no electrode part), but the bend alignment develops beyond this region as long as it is a minute region. .
[0447]
(Embodiment 15)
FIG. 32 is a structural external view of a liquid crystal cell used in the liquid crystal display device according to the fifteenth embodiment, and FIGS. 27, 28, and 33 are part of a manufacturing process for explaining the fabrication of a convex object. .
[0448]
A PC-based resist material manufactured by JSR Corporation is applied and formed on a glass substrate 308 to form a resist thin film having a thickness of 1 μm. Next, the resist thin film 320 is exposed and irradiated with parallel ultraviolet rays 323 through a photomask 321 provided with a rectangular pattern of openings 322. The resist thin film 20 exposed with parallel light is developed, rinsed, and pre-baked at 90 ° C. to form a shape 310 having a convex cross section as shown in FIG.
[0449]
Next, post-baking is performed at 150 ° C. above the glass transition point of the resist thin film material, and the shoulder of the convex object 310 is gently inclined in the forward direction, so that the cross-sectional shape is formed in a mountain shape as shown in FIG. Manufactured in the process of.
[0450]
Next, an ITO electrode having a thickness of 2000 mm was formed on the substrate according to a conventional method to obtain a glass substrate 308 with an electrode. Thereafter, an alignment film coating SE-7492 manufactured by Nissan Chemical Industries, Ltd. was applied by spin coating on the glass substrate 301 having the transparent electrode 302 and the glass substrate 308 on which the above-mentioned convex shape was formed. The alignment films 303 and 306 are formed by curing for 1 hour. After that, rubbing treatment was performed in the direction shown in FIG. 29 using a rayon rubbing cloth, and spacers 305 made by Sekisui Fine Chemical Co., Ltd. and Structbond 352A (trade name of seal resin made by Mitsui Toatsu Chemical Co., Ltd.) were used. Thus, a liquid crystal cell 309 (referred to as a liquid crystal cell C) was prepared by bonding the substrates so that the distance between the substrates was 6.5 μm.
[0451]
At this time, the rubbing process was performed so that the liquid crystal pretilt angle at the alignment film interface was about 5 degrees.
[0452]
Next, a liquid crystal MJ96435 (refractive index anisotropy Δn = 0.138) was injected into the liquid crystal cell C by a vacuum injection method to obtain a test cell C.
[0453]
Next, a polarizing plate is bonded to the test cell C so that its polarization axis forms an angle of 45 degrees with the rubbing treatment direction of the alignment film, and the polarization axis directions are orthogonal to each other, and a 7 V rectangular wave is applied. Then, when the transition from the splay alignment to the bend alignment was observed, the entire electrode region shifted from the splay alignment to the bend region in about 7 seconds.
[0454]
In this test cell C, electric field concentration occurs at the triangular tip, and bend alignment occurs from this portion. In addition, at the upper part of the triangular object 60, there are a rubbing portion and a rubbing portion due to the rubbing process, and as a result, regions having opposite signs of the liquid crystal pretilt angle are formed. That is, in the vicinity of the convex portion, the liquid crystal director is horizontal to the substrate surface, which also seems to contribute to the high-speed spray-bend transition.
[0455]
In the present embodiment, the electric field concentration portion is provided in the pixel region, but the same effect is recognized even if it is provided outside the pixel region. Further, in this embodiment, the electric field concentration portion is only disposed on one side of the substrate, but it goes without saying that it may be disposed on both sides of the substrate.
[0456]
(Embodiment 16)
FIG. 34 is a structural external view of a liquid crystal cell used in the liquid crystal display device according to Embodiment 16, and FIG. 35 shows an electrode pattern of the glass substrate 302 used in this embodiment.
[0457]
An alignment film coating SE-7492 manufactured by Nissan Chemical Industries, Ltd. is applied by spin coating on two glass substrates 301 and 308 having a transparent electrode 302 having an opening 380 and a transparent electrode 307 having no opening. The alignment films 303 and 306 are formed by curing in a bath at 180 ° C. for 1 hour. After that, rubbing treatment was performed in the direction shown in FIG. 29 using a rayon rubbing cloth, and spacers 305 made by Sekisui Fine Chemical Co., Ltd. and Structbond 352A (trade name of seal resin made by Mitsui Toatsu Chemical Co., Ltd.) were used. Thus, a liquid crystal cell 309 (referred to as a liquid crystal cell D) was prepared by bonding the substrates so that the distance between the substrates was 6.5 μm.
[0458]
At this time, the rubbing process was performed so that the liquid crystal pretilt angle at the alignment film interface was about 5 degrees.
[0459]
Next, a liquid crystal MJ96435 (refractive index anisotropy Δn = 0.138) was injected into the liquid crystal cell D by a vacuum injection method to obtain a test cell D.
[0460]
Next, a polarizing plate is bonded so that the polarization axis forms an angle of 45 degrees with the rubbing treatment direction of the alignment film, and the polarization axis directions are orthogonal to each other, and from the splay alignment to the bend alignment while applying a voltage. The transition to was observed.
[0461]
When 2 V, 30 Hz, rectangular wave is applied to the glass substrate 8 side electrode and 7 V, 30 Hz, rectangular wave is applied to the glass substrate 1 side electrode, the entire electrode region transitions from the splay alignment to the bend region. The time required for this was 5 seconds, and an extremely fast bend transition was realized.
[0462]
In this embodiment, an electric field of 5V (= 7V-2V) is applied to the liquid crystal layer sandwiched between two electrodes, but an effective voltage of 7V (= 7V-0V) is applied to the liquid crystal layer in the electrode opening. Since an electric field is applied, bend alignment occurs from here.
[0463]
In this embodiment, the shape of the opening is rectangular, but it is needless to say that other shapes such as a circle and a triangle may be used.
[0464]
(Embodiment 17)
FIG. 36 is a fragmentary cross-sectional view of a liquid crystal cell used in the liquid crystal display device according to Embodiment 17, and FIG. 37 is a partial enlarged view thereof. In this liquid crystal cell, a pixel switching element 380, a signal electrode line 381, and a gate signal line (not shown) are formed on a glass substrate 308, and covers the switching element 380, the signal electrode line 381, and the gate signal line. A planarizing film 382 is formed. A display electrode 307 is formed on the planarization film 382. The display electrode 307 and the switching element 380 are electrically connected via a relay electrode 384 inserted through the contact hole 383 opened in the planarization film 382. It is connected to the. In the relay electrode 384, a portion on the upper opening side of the contact hole 383 is a recess 384a as shown in FIG. Such a recess 384a forms an opening in the display electrode 307, and an electric field can be concentrated in the vicinity of the recess 384a. Therefore, shortening of the transition time can be achieved.
[0465]
(Embodiment 18)
FIG. 38 is a structural external view of a liquid crystal display device according to the eighteenth embodiment.
[0466]
Phase difference plates 312 and 315, negative uniaxial phase difference plates 311 and 314, and positive uniaxial layers made of an optical medium having negative refractive index anisotropy in which principal axes are hybrid-arranged in test cell D created in the sixteenth embodiment The phase difference plate 319 and the polarizing plates 313 and 316 were bonded together in the arrangement shown in FIG. 39 to produce a liquid crystal display device.
[0467]
The retardation values of the retardation films 312, 315, 311, 314, and 319 at this time were 26 nm, 26 nm, 350 nm, 350 nm, and 150 nm, respectively, with respect to light having a wavelength of 550 nm.
[0468]
FIG. 40 shows voltage-transmittance characteristics in front of the liquid crystal display device at 25 ° C. A 10 V rectangular wave voltage was applied for 10 seconds to confirm the bend orientation, and the measurement was performed while decreasing the voltage. In the present liquid crystal display element, the transition from the bend alignment to the splay alignment occurs at 2.1 V, so that it is necessary to effectively display at a voltage of 2.2 V or more.
[0469]
Next, when the viewing angle dependency of the contrast ratio when the white level voltage is 2.2 V and the black level voltage is 7.2 V is measured, the contrast ratio is 10: 1 or more in the range of 126 degrees up and down and 160 degrees left and right. It has been achieved, and it has been confirmed that sufficient wide viewing angle characteristics can be maintained even when a part of the liquid crystal director direction different from the surrounding is provided on the substrate alignment film surface. Further, even in visual observation, neither orientation failure nor display quality failure was observed.
[0470]
Moreover, when the response time between 3V-5V was measured, the rise time was 5 milliseconds and the fall time was 6 milliseconds.
[0471]
As is clear from the above, the liquid crystal display device of the present invention can achieve a high-speed splay-bend alignment transition without sacrificing the wide viewing angle characteristics and response characteristics of the conventional OCB mode, and its practical use. The value is extremely great.
[0472]
(Embodiment 19)
FIG. 41 is a cross-sectional view of a principal part of the liquid crystal display device according to the nineteenth embodiment. A liquid crystal cell operated as a bend alignment type cell is a so-called sandwich cell in which a liquid crystal layer 402 is sealed between two parallel substrates 400 and 401. Usually, a transparent electrode is formed on one substrate, and a pixel electrode including a thin film transistor is formed on the other substrate.
[0473]
FIG. 41 (a) is a schematic diagram showing the orientation in the initial state where no electric field is applied. The alignment in the initial state is a state in which the molecular axes of the liquid crystal molecules are aligned substantially in parallel and substantially uniformly while having a slight inclination with respect to the planes of the substrates 400 and 401, that is, homogeneous alignment. Liquid crystal molecules present at the interface with the substrate are inclined in opposite directions in the upper and lower substrates 400 and 401. That is, the alignment angles θ1 and θ2 (that is, the pretilt angle) of the liquid crystal molecules present at the interface with the substrate are adjusted to have different signs. In the following description, the orientation angle and the pretilt angle are angles that represent the inclination of the molecular axes of liquid crystal molecules with respect to a plane parallel to the substrate as positive in the counterclockwise direction with respect to the plane parallel to the substrate.
[0474]
When an electric field with a strength exceeding a certain value in a direction perpendicular to the substrate plane is applied to the liquid crystal layer 402 in the state of FIG. 41A, the alignment state of the liquid crystal changes, as shown in FIG. Transition to orientation.
[0475]
The orientation shown in FIG. 41B is called bend orientation, and the inclination of the molecular axis of the liquid crystal molecules relative to the substrate plane, that is, the absolute value of the orientation angle is small in the vicinity of the surfaces of both substrates. In, the absolute value of the orientation angle of liquid crystal molecules is large. In addition, the entire liquid crystal layer has substantially no twisted structure.
[0476]
When the transition from the homogeneous alignment to the bend alignment is observed in detail, first, a bend alignment nucleus is generated in a part of the liquid crystal layer 402, and this nucleus engulfs another region having the homogeneous alignment. However, it gradually grows and finally the entire liquid crystal layer becomes bend alignment. In other words, the transition from the liquid crystal layer to the bend alignment requires the generation of nuclei, that is, the transition from the homogeneous alignment to the bend alignment in a minute region.
[0477]
Therefore, the inventors analyzed the transition to the bend alignment in a minute region by solving the equation of motion of the liquid crystal molecular alignment unit vector (hereinafter referred to as “director”), and the nucleus was easily generated. We found the conditions to obtain. The method will be described below.
[0478]
The alignment state of the liquid crystal is described by the director. Director n is a function represented by [Equation 1].
[Expression 1]

[0479]
The free energy density f of the liquid crystal can be expressed as a function of the director n as shown in [Equation 2].
[Expression 2]

[0480]
Here, k11, k22, and k33 are Frank's elastic constants, which respectively represent the splay, twist, and bend elastic constants. Δε represents the difference between the dielectric constant in the molecular axis direction of the liquid crystal and the dielectric constant in the direction orthogonal thereto, that is, dielectric anisotropy. E is an external electric field.
[0481]
In [Equation 2], the first term, the second term, and the third term respectively represent elastic energy due to the spread, twist, and bend of the liquid crystal. The fourth term represents the electrical energy due to the electrical interaction between the external electric field and the liquid crystal. The electrical energy is minimized when n is parallel to E if Δε> 0, and is minimized when n is orthogonal to E if Δε <0. Therefore, when an electric field E exceeding a certain intensity is applied, the liquid crystal molecules are aligned so that the molecular long axis is parallel to the electric field direction if Δε> 0, and the molecular length if Δε <0. Oriented so that the axis is orthogonal to the electric field direction.
[0482]
The total free energy F of the liquid crystal when the initial molecular orientation is deformed by an external electric field can be expressed as a volume integral of f.
[Equation 3]

As shown in [Formula 3], the total free energy F is a function (that is, a functional) defined with an unknown function n (x) representing the director as a variable. The alignment state of the liquid crystal that appears under the application of an external electric field is described by n (x) that minimizes the total free energy F under appropriate boundary conditions. That is, if n (x) that minimizes F is determined, the alignment state of the liquid crystal can be predicted. Furthermore, if the director n (x, t) considering the time change that minimizes F under an appropriate boundary condition can be determined, all behaviors of the device such as optical constants can be predicted. it can. This is the principle of typical minimum action in physical terms, and it is a small variable polarization problem with boundary values in mathematical terms.
[0483]
Therefore, [Equation 3] is solved in principle. However, for example, in an analytical method using Euler's equation, since a complicated nonlinear equation appears, it is difficult to easily determine the functional form of the director n (x).
[0484]
Therefore, in order to easily solve [Equation 3], the following method is adopted. First, the integration space is discretized by the same method as the finite element method. That is, the entire integration space is divided into np elements, and [Equation 3] is expressed as the sum of the integrals of each element.
[Expression 4]

[0485]
Here, the following approximation is performed on the director n (x) in the partial integration space ΔV. It is assumed that nx, ny, and nz are functions of x, y, and z as originally shown in [Expression 2], but are constant in ΔV. Further, it is approximated as dnx, j / dx = (nx, j + 1−dnx, j) / Δx. Note that nx, j is nx in the j-th element, and as described above, although ΔV is constant, it is an unknown number. The approximation of n (x) in this partial integration space ΔV is rough, but this can be covered by making the division of the integration space fine, and the approximation can be enhanced.
[0486]
According to the above approximation, in [Equation 4], nx, j, ny, j, nz, j are constants in one element, so that the integration itself can be easily calculated. However, even at this stage, the expression representing the total free energy F is still complicated because there are a large number of unknown terms nx, j, ny, j, nz, j that are proportional to the number of divisions and nonlinear terms. However, values such as nx, 0, ny, 0, nz, 0 can be easily given as boundary conditions.
[0487]
According to the above approximation, the total free energy F is
[Equation 5]

Is converted into the form. That is, the total free energy F is converted from a functional defined with the unknown function n (x) as a variable into a function of unknowns nx, j, ny, j, nz, j. The unknowns nx, j, ny, j, nz, j are values that minimize the function F in a multidimensional parameter space.
[0488]
As described above, the bend alignment of the liquid crystal has a structure substantially free of twist. The director n is originally a function of x, y, and z as described above, but can be expressed as a function of the orientation angle. In this case, the director n in the bend orientation is
[Formula 6]

It is represented by Here, θ is the inclination of the liquid crystal molecules with respect to the plane parallel to the substrate, that is, the orientation angle. Also, θ depends only on the distance z of the liquid crystal molecules from the substrate. FIG. 2 is a schematic diagram showing this director.
[0489]
Substituting [Formula 6] into [Formula 4], dividing it into np elements, and performing discretization, find θj that minimizes F for each element. That is, for each element
[Expression 7]

Find θj that satisfies the following equation. Here, d is L / np, and L is the distance between the substrates.
[0490]
However, it is not easy to solve a complex nonlinear equation such as [Equation 7] by np simultaneous equations. Therefore, [Equation 7] is solved by performing the following circuit analogy. Director's equation of motion is
[Equation 8]

It is represented by Note that η is the viscosity of the liquid crystal. For [Equation 8], the following circuit analogy is performed.
[Equation 9]

[Equation 8] is
[Expression 10]

Is converted to As shown in FIG. 3, the circuit corresponding to [Equation 10] is composed of np CR circuits. The second term of [Expression 10] represents the current flowing through the CR circuit. Rj is a resistance for discharge mitigation, and is a voltage control resistor that defines the current (i) flowing through the CR circuit as i = ∂F (Vj) / ∂Vj.
[0491]
The current i (= ∂F / ∂Vj) converges to zero at a specific Vj. That is, Vj can be automatically obtained by obtaining a voltage when the current flowing through the CR circuit becomes zero by a circuit simulator.
[0492]
Thus, by replacing the director's equation of motion with an equivalent circuit, the nonlinear simultaneous equations expressing the liquid crystal orientation phenomenon are analyzed on the circuit simulator, and the relationship between the external electric field E and the orientation state (orientation angle θj) is shown. Can be sought.
[0493]
In the above method, the nonlinear simultaneous equations expressing the orientation phenomenon are replaced with circuits by analogy of electric circuits and analyzed on the circuit simulator. The calculation process for solving is not included. Therefore, simplification and reduction of the program can be realized.
[0494]
Furthermore, if the change in the orientation angle θj accompanying the increase in the external electric field E is calculated based on the above method, the critical electric field Ec of the liquid crystal transition can be obtained as the external electric field E when the orientation angle θj changes suddenly. .
[0495]
FIG. 44 is an example of a calculation result based on the above method, and represents a time change of θj when the external electric field E is increased with time. The results shown in FIG. 4 indicate that the boundary conditions are fixed as θ0 = + 0.1 rad, θnp−1 = −0.1 rad, and k11 = 6 × 10. ^-7 dyn, k33 = 12 × 10 ^-7 This is a calculation result with dyn, Δε = 10. As shown in FIG. 4, it can be seen that at the initial stage of electric field application, the orientation angle θj is relatively small, and the orientation state of the liquid crystal is homogeneous orientation. However, after a lapse of a certain time, that is, when the external electric field E exceeds a certain value (E> Ec), the orientation angle θj suddenly changes and a transition occurs. The orientation angle θj after the transition increases from the vicinity of both substrates toward the center of the liquid crystal layer, and it can be seen that the orientation state of the liquid crystal after the transition is bend orientation.
[0496]
As the critical electric field Ec is smaller, the alignment state of the liquid crystal can be quickly transferred from the homogeneous alignment to the bend alignment. Therefore, based on the above method, the critical electric field Ec under each condition was calculated by changing various conditions for determining the alignment of the liquid crystal. As a result, it has been found that the critical electric field Ec is particularly affected by the elastic constant (splay elastic constant) of the liquid crystal and the asymmetry of the pretilt angle.
[0497]
FIG. 45 shows the result of determining the relationship between the splay elastic constant k11 and the critical electric field Ec. In FIG. 45, the boundary conditions are θ0 = + 0.1 rad, θnp−1 = −0.1 rad, and k33 = 12 × 10. ^-7 This is a calculation result with dyn, Δε = 10. As shown in FIG. 45, the critical electric field Ec increases as the splay elastic constant k11 increases. In particular, k11> 10 × 10 ^-7 In the range of dyn, Ec increases rapidly as k11 increases.
[0498]
Therefore, in order to realize a quick liquid crystal transition, the splay elastic constant k11 is set to 10 × 10. ^-7 less than dyn, preferably 8 × 10 ^-7 It is effective to set it below dyn.
The lower limit of the splay elastic constant k11 is not particularly limited, but is 6 × 10. ^-7 It is preferable to set it to dyn or more. k11 <6 × 10 ^-7 This is because it is usually difficult to synthesize or prepare dyn liquid crystal materials.
[0499]
The liquid crystal material having the splay elastic constant k11 as described above is not particularly limited, and examples thereof include pyrimidine liquid crystal, dioxane liquid crystal, and biphenyl liquid crystal.
[0500]
The asymmetry of the pretilt angle can be expressed by the difference (Δθ) in absolute value of the pretilt angle between the upper and lower substrates. As described above, since the pretilt angles θ0 and θnp-1 are different from each other, the difference between the absolute values of the pretilt angles (Δθ) can be expressed by Δθ = | θ0 + θnp-1 |.
[0501]
FIG. 46A shows the result of obtaining the relationship between the absolute value difference (Δθ) of the pretilt angle between the upper and lower substrates and the critical electric field Ec. FIG. 6A shows k11 = 6 × 10. ^-7 dyn, k33 = 12 × 10 ^-7 This is a calculation result with dyn, Δε = 10. As shown in FIG. 46A, the critical electric field Ec decreases as the pretilt angle difference Δθ increases. In particular, in the range of Δθ ≧ 0.0002 rad, Ec rapidly decreases as Δθ increases.
[0502]
Therefore, in order to realize quick liquid crystal transition, it is effective to set the difference Δθ in the pretilt angle to 0.0002 rad or more, preferably 0.035 rad or more. The upper limit of the difference Δθ in the pretilt angle is not particularly limited, but is usually less than 1.57 rad, preferably 0.785 rad or less.
[0503]
Note that the pretilt angles θ0 and θnp-1 are adjusted so that their absolute values are usually greater than 0 rad and less than 1.57 rad, preferably 0.017 rad to 0.785 rad. The adjustment of the pretilt angle can be controlled by forming an appropriate liquid crystal alignment film on the substrate surface by a method such as oblique vapor deposition or Langmuir-Blodget (LB). The liquid crystal alignment film is not particularly limited, and examples thereof include polyimide resin, polyvinyl alcohol, polystyrene resin, polycinnamate resin, chalcone resin, polypeptide resin, and polymer liquid crystal. In addition to selecting the material for the liquid crystal alignment film, by adjusting the inclination of the deposition direction with respect to the substrate surface when using the oblique deposition method, adjusting the conditions such as the substrate pulling rate when using the LB method. Thus, the pretilt angle can be controlled.
[0504]
In addition, the critical electric field Ec is affected by the non-uniformity of the electric field in the liquid crystal layer. This is because the distortion of the electric field generated in the liquid crystal layer affects the stability of the alignment state of the liquid crystal molecules. The non-uniformity of the electric field can be expressed by a ratio (E1 / E0) between the main electric field E0 applied to the liquid crystal layer substantially uniformly and the sub-electric field E1 applied nonuniformly. E1 is the maximum value of the applied sub electric field.
[0505]
The relationship between the electric field non-uniformity E1 / E0 and the critical electric field Ec can be examined as follows based on the above-described method. That is, the orientation angle θj accompanying the increase in the main electric field E0 is applied to the liquid crystal layer under the condition that the main electric field E0 which is a uniform electric field is applied as the external electric field E and the sub electric field E1 which is a nonuniform electric field is superimposed and applied. Calculate the change in. At this time, the sub electric field E1 is increased so that E1 / E0 becomes constant at a predetermined value as the main electric field E0 increases. From the obtained calculation result, the critical electric field Ec of the liquid crystal transition is obtained as the main electric field E0 when the orientation angle θj changes suddenly.
[0506]
FIG. 47 is an example of calculation results obtained by calculating the critical electric field Ec under each condition by changing the value of E1 / E0 variously based on the above method. The results shown in FIG. 7 indicate that the boundary conditions are fixed as θ0 = + 0.26 rad, θnp−1 = −0.25 rad, and k11 = 6 × 10. ^-7 dyn, k33 = 12 × 10 ^-7 This is a calculation result with dyn, Δε = 10. As shown in FIG. 47, the greater E1 / E0, that is, the greater the electric field non-uniformity, the greater the critical electric field Ec. Ec becomes infinitely small in the vicinity of E1 / E0 = 1. This is presumably because when the electric field of the liquid crystal layer is distorted, the homogeneous alignment becomes unstable as compared with the case where the electric field is uniform, and as a result, the transition to the bend alignment is quickly developed.
[0507]
Therefore, in order to realize quick liquid crystal transition, it is effective to apply a spatially nonuniform electric field E1 to the liquid crystal layer together with a substantially uniform main electric field E0. In particular, it is effective to satisfy 0.01 <E1 / E0 <1. In the range of E1 / E0 ≦ 0.01, it is difficult to sufficiently obtain the effect of promoting the liquid crystal transition due to the application of the non-uniform electric field. In the range of E1 / E0 ≧ 1, the applied voltage becomes too large, so that the actual voltage is too high. This is because there is a problem that it is not suitable for use. Furthermore, it is preferable that 0.5 ≦ E1 / E0 ≦ 1.
[0508]
The non-uniform electric field E1 can be applied in a direction perpendicular to the substrate with respect to the liquid crystal layer by using a voltage applied between the source electrode (or gate electrode) of the thin film transistor and the transparent electrode. Further, the non-uniform electric field E1 is preferably an alternating electric field having a frequency of 100 kHz or less, and further, the amplitude is preferably attenuated in terms of time.
[0509]
A combination of two or three conditions among the three conditions that reduce the critical electric field Ec: the spray elastic constant (k11), the pretilt angle asymmetry (Δθ), and the electric field non-uniformity (E1 / E0). It is preferable to satisfy. This is because by combining these conditions, the critical electric field Ec can be more reliably reduced more reliably than when only one of the conditions is satisfied.
[0510]
For example, FIG. 46B shows the result of calculation under the same conditions as FIG. 46A except that the non-uniform electric field E1 is applied together with the substantially uniform external electric field E0. FIG. 46B shows the result when E1 / E0 = 0.03. As can be seen from the comparison of FIGS. 46 (a) and 46 (b), by satisfying a combination of the two conditions of asymmetry of the pretilt angle and non-uniformity of the electric field, the critical electric field Ec is further reduced, and the liquid crystal can be further rapidly Transition can be realized.
[0511]
(Embodiment 20)
In the twentieth embodiment, as in the seventh embodiment, the first liquid crystal cell region and the second liquid crystal cell region are formed, and the bend transition is easily generated with the disclination line at the boundary as the nucleus. It is characterized by this. However, in the seventh embodiment, a method is used in which the pair of upper and lower substrates are irradiated with ultraviolet rays to locally change the pretilt angle. However, the present invention is not limited to this. It is possible to form the first and second liquid crystal cell regions regardless of whether the substrate to be processed is one or both substrates, and ultraviolet rays are used as a method for changing the pretilt angle. Not limited to. The specific contents will be described below by exemplifying Embodiment 20-1 to Embodiment 20-5.
[0512]
(Embodiment 20-1)
FIG. 48 is a conceptual diagram showing the alignment state of the liquid crystal display device according to Embodiment 20-1. The present embodiment 20-1 is an example in which only one of the pair of upper and lower substrates is irradiated with UV. Specifically, only the array substrate 500 was irradiated with UV by the same method as in the seventh embodiment. As a result, 5 ° and 2 ° pre-tilt regions were formed on the array substrate 500 as in the seventh embodiment. The pretilt angle of 5 degrees corresponds to B2 in FIG. 16, and the pretilt angle of 2 degrees corresponds to A2 in FIG. An alignment film made of the same material is formed on the inner side surface of the counter substrate 501 and the inner side surface of the array side substrate 500. By increasing the rubbing strength on the counter substrate 501 side than on the array substrate 500 side, The counter substrate 501 realized an intermediate pretilt angle between the two types of pretilt angles of the array substrate 500. In this embodiment, it was 3 degrees. As described above, the feature of the present embodiment 20-1 is that the pretilt angle of the counter substrate 501 is between the two types of pretilt angles of the array-side substrate 500.
[0513]
In a state where no electric field is applied, two regions H1 and H2 appear in the liquid crystal layer 502 as shown in FIG. Here, the pretilt of the array side substrate 500 is 2 degrees in the right region H2 and 5 degrees in the left region H1, and the pretilt of the counter substrate 500 is 3 degrees in both the right region H2 and the left region H1.
[0514]
In general, the alignment direction of the liquid crystal molecules near the center of the thickness direction (cell thickness direction) of the liquid crystal panel in a state where no electric field is applied is an average value of the upper and lower pretilt angles. In FIG. 48, the liquid crystal molecules are denoted by reference numeral 503. Therefore, as shown in FIG. 48A, in the left region H1 where the pretilt of the array side substrate 500 is higher than the pretilt of the counter substrate 501, the liquid crystal 503 near the center is in a state of rising to the right in the drawing. On the contrary, in the right region H2 where the pretilt of the ray-side substrate 500 is smaller than the pretilt of the counter substrate 501, the liquid crystal 503 near the center is in a state of lowering right in the figure. As described above, by providing the array substrate 500 with a pretilt distribution and having an intermediate pretilt on the counter substrate 501 side, two types of alignment can be realized in the liquid crystal at the central portion in the thickness direction of the liquid crystal panel. The counter substrate 501 may have a pretilt distribution, and the array substrate 500 may have an intermediate pretilt. ,
Next, when an electric field equal to or lower than the electric field transitioning to bend alignment is applied to the liquid crystal panel, the alignment is as shown in FIG. Since the original transition voltage is a very high voltage, when such a high voltage is applied, it transitions to bend alignment in a time of 1 second or less. The orientation as shown in FIG. 48 (b) was confirmed at the initial stage of the transition when the original transition voltage was applied, but this time was 0.1 second or less.
[0515]
Therefore, in order to observe this orientation state in detail, a voltage equal to or lower than the transition voltage was applied. The alignment state at the time of voltage application is influenced by the alignment state of the liquid crystal at the center in the thickness direction of the liquid crystal panel when no voltage is applied. That is, in the left region where the liquid crystal molecules in the central portion are in a right-up state when no voltage is applied, a t-spray alignment having a splay deformation site is formed in the vicinity of the counter substrate 501, and in the central portion when no voltage is applied. In the right region where the liquid crystal molecules rise to the left, b-spray alignment having a splay deformation site is formed in the vicinity of the array-side substrate 500. It has been found that disclination occurs at the boundary between the t-splay alignment and the b-splay alignment, and that a bend transition occurs with the disclination line serving as a nucleus. This phenomenon is the same as in the seventh embodiment in which both sides are irradiated with UV.
[0516]
In this embodiment, as shown in FIG. 48 (b), the left side looks relatively blackish when viewed from the rubbing direction side, the right side looks whitish, and the left side looks relatively whitish and the right side looks relatively blackish when viewed from the opposite direction. . From this, it was judged as a t-spray state and a b-spray state. This is because the liquid crystal layer is asymmetric in the center of the liquid crystal layer in the cell thickness direction. For example, the left side is observed from the long axis direction of the liquid crystal molecules.
[0517]
When the transition waveform described in the first to sixth embodiments was applied to this liquid crystal panel, it was confirmed that the bend alignment grew with the disclination line as a nucleus.
[0518]
In order to speed up the transition, it is important to reliably form the nucleus of the bend transition. In this embodiment, each pixel is irradiated with UV light, so that each pixel has t-spray orientation and b-spray alignment. By forming the orientation and generating the disclination line, it was possible to increase the speed of the transition.
[0519]
In the above-described example, the array substrate side is irradiated with ultraviolet rays to form regions with different pretilts, but the present invention is not limited to this. The counter substrate may be irradiated with ultraviolet rays to form regions with different pretilts.
[0520]
In the present embodiment, the region is divided into two regions having different pretilts. However, the present invention is not limited to this, and it is sufficient that at least the upper and lower substrates have regions where the magnitude relation of the pretilt is reversed. In the present invention, a region having a different pretilt is formed for each pixel, but the region may be formed for each of a plurality of pixels. In addition, there may be a large number of regions in a pixel. However, it is desirable that a transition nucleus is formed for each pixel in a region where the pixel electrode is not connected, such as a gate line.
[0521]
In this embodiment, the pretilt is 5 degrees, 3 degrees, or 2 degrees, but the present invention is not limited to this. However, in order to stably generate disclination, it is necessary to set the difference between the maximum and minimum pretilts in the substrate to 1 degree or more, and more desirably to 2 degrees or more. For stable bend alignment, the minimum pretilt value is ideally 1 degree or more, and desirably 2 degrees or more.
[0522]
(Embodiment 20-2)
In the present embodiment 20-2, the pretilt angle is given a distribution by giving the rubbing intensity an in-plane distribution.
[0523]
In general, a rubbing process is performed for the alignment process of the liquid crystal. This controls the orientation of the liquid crystal by rubbing the substrate surface using fibers of uniform length. In general, it is known that the pretilt is low when the rubbing strength is high. In this Embodiment 20-2, the length of the fiber used for rubbing is made non-uniform so that the rubbing strength is distributed and the pretilt is intentionally non-uniform.
[0524]
In order to change the length of the fiber, in this embodiment mode, a substrate 511 having a minute step 510 having a width of 50 μm and a height of 100 μm shown in FIG. 49 is used to form a substrate with a rubbing cloth 512 having a uniform length of fiber. The rubbing on 511 was performed 100 times or more.
The rubbing cloth 512 was heavily worn at the high portion of the step 510, and as a result, a rubbing cloth 511a having a distribution in the length of the rubbing fibers as shown in FIG. 50 was obtained.
[0525]
When this rubbing cloth 511a was used, a distribution occurred in the pretilt angle, and a region where the pretilt was 2 to 5 degrees was randomly generated. The upper and lower substrates were processed to have a pretilt distribution. When these two substrates are combined, various pretilt combination regions are formed. However, these regions can be broadly divided into an alignment region approximated to b-spray alignment in which liquid crystal molecules in the cell thickness direction central portion are obliquely upward in a state in which no voltage is applied, and a cell thickness direction central portion. The liquid crystal molecules can be divided into two types of alignment regions that approximate the t-splay alignment in which the liquid crystal molecules are directed obliquely downward. In the present embodiment, since the pretilt distribution is generated in a region smaller than the pixel, these two types of regions can be formed in each pixel.
[0526]
When a voltage is applied to the liquid crystal display panel having such a configuration, two types of alignment regions, b-spray alignment and t-spray alignment, are formed, and a disclination line is generated at the boundary between the two alignment regions. Bend transition was confirmed with this as the nucleus.
[0527]
In the present embodiment 20-2, the distribution is formed in the fiber length in order to form the distribution of the rubbing strength, but the present invention is not limited to this. The rubbing strength distribution could be formed by mixing the fiber of the rubbing cloth with cotton and rayon. Here, a rubbing cloth that independently knits flexible cotton and rigid rayon fibers has been realized.
[0528]
(Embodiment 20-3)
FIG. 51 is a conceptual diagram showing the shadow of rubbing by array wiring. In the present embodiment 20-3, a region where the rubbing strength is locally weak is formed using the rubbing shadow by the metal wiring (source electrode line 520, gate electrode line 521) formed on the array substrate 500. Note that a normal rubbing process with uniform rubbing strength was performed on the counter substrate 501 side. The rubbing direction on the array substrate 500 was performed by tilting 20 degrees from the extending direction of the source electrode line 520. At this time, since the gate electrode line 521 and the source electrode line 520 are higher than the pixel electrode portion, when rubbing is performed, the rubbing strength is weakened at the edge portion 522 of the gate electrode line 521 and the source electrode line 520, and the pixel The pretilt was higher than the other region 523 in the region.
[0529]
Here, the pretilt angle of the counter substrate 501 was set to an intermediate value between the two pretilts described above. By such rubbing treatment, when no voltage is applied, the region 522 is formed with an alignment that approximates the b-splay alignment in which the liquid crystal molecules in the center in the cell thickness direction are obliquely upward, and the region 523 has a cell orientation. An alignment approximated to the t-spray alignment in which the liquid crystal molecules at the center in the thickness direction are directed obliquely downward was formed. Thus, when a voltage is applied in the same manner as in the above embodiment, a b-spray alignment is formed in the region 522 and a t-spray alignment is formed in the region 523, and the disclination is made at the boundary between the two types of alignment regions. A line was generated and the bend transition was confirmed using this as a nucleus.
[0530]
By the way, the pixel electrode in the present embodiment 20-3 has a vertically long shape. In the case of such a vertically long pixel electrode, the area of the high pretilt region is small in each pixel when rubbing in the vertical direction. Rather, when the rubbing was performed in the left-right direction, a large pretilt area was obtained. Further, as in the example described above, the area of the high pretilt area was maximized when rubbing in an oblique direction. From this result, the rubbing direction having an angle with respect to the source electrode line 520 can sufficiently form regions having different pretilts, and bend transition can be efficiently realized.
[0531]
In addition, when a horizontal electric field is generated between the source electrode line and the pixel electrode and between the gate electrode line and the pixel electrode, the generation direction of the horizontal electric field and the rubbing direction are easily changed as described below. Affects sex. That is, when rubbing in the vertical direction, disclination lines are generated in the horizontal direction. At this time, when a lateral electric field was generated between the source electrode line and the pixel electrode, the transition was good due to the lateral electric field effect. When rubbing in the left-right direction, disclination lines are generated in the vertical direction. At this time, the transition was good when a lateral electric field was generated between the gate electrode line and the pixel electrode. In addition, when rubbing in an oblique direction, the disclination line runs from the upper left to the lower right of the pixel in the figure. At this time, the horizontal electric field between the source electrode line and the pixel electrode, and the horizontal electric field between the gate electrode line and the pixel electrode. Both were effective.
[0532]
Thus, the horizontal electric field between the source electrode line and the pixel electrode is effective in the vertical rubbing, the horizontal electric field is effective between the gate electrode line and the pixel electrode in the horizontal rubbing, and the source pixel is effective in the diagonal rubbing. Both lateral electric fields between the gate and the pixel are effective. Therefore, in the case where the effect by the horizontal electric field is desired, it is necessary to determine the rubbing direction in consideration of the direction of the horizontal electric field.
[0533]
Although the shadow of the metal electrode wiring is used in the present embodiment 20-3, the present invention is not limited to this. Columnar spacers as described in a twenty-fourth embodiment described later or protrusions as described in the thirteenth and fourteenth embodiments may be used.
[0534]
(Embodiment 20-4)
In the present embodiment 20-4, the pretilt has a distribution by providing a distribution in the film thickness of the alignment film. In general, the alignment film is printed using a printing plate 530 shown in FIG. Here, in general, the alignment film printing method will be briefly described with reference to FIG. 52. The alignment film coating solution is supplied dropwise from the dispenser 531 between the rotating doctor roll 532 and the anilox roll 533. . The coating liquid is kneaded between the two rolls 532 and 533 and held as a liquid film on the surface of the anilox roll 533, and is transferred from the anilox roll 533 to the printing plate 530 on the plate cylinder 534. Then, when the substrate 536 fixed on the table 535 passes just below the plate cylinder 534, the coating liquid is transferred and applied from the printing plate 530 to the substrate 536. By the way, a uniform fine mesh is generally formed on the printing plate 530 used in such an alignment film coating process in order to keep the thickness of the alignment film constant. In this embodiment, contrary to the above request, since it is required to have a distribution in the film thickness of the alignment film, a printing plate 530 having a larger mesh size L as shown in FIGS. 53 and 54 is used. did. As a result, non-uniform printing was produced, and an alignment film having a distribution in film thickness was formed. The alignment film thus formed has a low pretilt value in a thin region, and the b-twist alignment tends to develop easily in this region. In the region where the film thickness of the alignment film is thick, the pretilt value is high and the t-twist alignment tends to be easily developed. Thus, in the present embodiment 20-4, since the thin region and the thick region of the alignment film are formed relatively randomly, two regions can be formed as in the case of the embodiment 20-2. Bend transition nuclei could be formed effectively.
[0535]
When the mesh size L was 100 μm or more, the alignment film could have a sufficient film thickness distribution. For reference, the normal mesh size L is about 50 μm.
[0536]
In the above example, in order to give the alignment film a film thickness distribution, a printing plate having a larger mesh size L may be used. However, a printing plate having a non-uniform mesh size L may be used, You may use the printing plate which made the surface uneven | corrugated.
[0537]
(Embodiment 20-5)
In the present Embodiment 20-5, the pretilt angle is distributed by surface treatment of the substrate. More specifically, after the alignment film was uniformly printed on the substrate and cured, the substrate on which the alignment film was formed was left in a high humidity atmosphere at 45 ° C. and 90%. At this time, the pretilt angle originally imparted to the alignment film was locally reduced by the surface treatment with humidity. Next, by rubbing the surface of the alignment film in the same manner as in the past, a pretilt angle distribution of 3 to 5 degrees could be realized on the substrate.
[0538]
In the above example, the substrate on which the alignment film is formed is left in a high-humidity atmosphere to have a distribution in the pretilt angle. However, the substrate is passed through a solvent spray vapor or a solvent is sprayed onto the alignment film. Can also be realized.
[0539]
Furthermore, it can also be realized by spraying another type of alignment film on the alignment film. For example, it was realized by spraying an alignment film having a pretilt angle of 3 degrees on an alignment film having a pretilt angle of 5 degrees.
[0540]
(Embodiment 21)
The twenty-first embodiment is characterized in that the bend transition is efficiently realized by forming the substrate surface in an uneven shape. That is, the effect of forming a region of t-spray alignment and b-spray alignment by applying a strong electric field locally by forming the substrate surface in an uneven shape, and the effect of applying a strong electric field at the convex portion Both of these are characterized in favorably generating bend transition nuclei. A specific configuration will be described in the following Embodiment 21-1 to Embodiment 21-4.
[0541]
(Embodiment 21-1)
In the thirteenth embodiment described above, a convex portion is formed, and a region having a strong electric field is formed on the convex portion, whereby the region having a strong electric field is used as a nucleus of transition. Even if this method is used, t-splay alignment and b-splay alignment are formed in the same manner as in the twentieth embodiment, and a transition occurs with the disclination generated at the boundary portion of the different orientations as a nucleus. Hereinafter, this will be described in detail with reference to FIG. In FIG. 55, 535 is a line of electric force, 536 is a projection, 537 is a pixel electrode, and 538 is a counter electrode. The electric lines of force 535 in the case of the thirteenth embodiment are as shown in FIG. The electric field at the convex portion 536 is strong, and this electric field further spreads on the counter electrode side 538. For this reason, as shown in FIG. 55B, a lateral electric field component is generated on both sides of the convex portion 536. As a result, on the left side in the figure, the electric field lines are directed in the upper left direction, and the liquid crystal molecules are directed in this direction, so that b-spray alignment is formed as shown in the figure. On the right side of the figure, since the electric lines of force are directed in the upper right direction, t-spray orientation is formed. Therefore, a bend transition occurs with the disclination occurring at the boundary between the b-splay alignment and the t-splay alignment as a nucleus.
[0542]
FIG. 56 is a drive waveform diagram of the liquid crystal display device according to the present Embodiment 21-1. This drive waveform is characterized in that a low voltage (0 V) and a high voltage (−25 V) are alternately applied during the initialization process period for bend transition. By applying a driving voltage having such a voltage waveform, the transition can be reliably realized.
[0543]
This is because when the transition is uncertain, the following process is considered to have occurred. That is, two splay alignment states of t-splay alignment and b-splay alignment are generated by voltage application, and bend alignment is generated from the boundary between the two alignments in most pixel regions. However, if, for some reason, one splay alignment state is reached before bend alignment, the transition is unlikely to occur, and the transition does not occur in this pixel.
[0544]
Therefore, the feature of this waveform is that the orientation of the liquid crystal is once returned to the initial state by applying a low voltage, and the next transition is ensured by applying the transition waveform again. Therefore, it is a minimum condition that this low voltage is a voltage that returns to the splay alignment, preferably 1 V or less, more preferably 0 V in absolute value.
[0545]
It is desirable to apply this low voltage period in the early stage, so that a reliable transition can be realized regardless of any noise in the initial stage. The pulse width was desirably 0.1 seconds to 10 seconds.
[0546]
(Embodiment 21-2)
In this Embodiment 21-2, an uneven shape is formed in each pixel. FIG. 57 is a diagram conceptually illustrating the formation of the concavo-convex shape. FIG. 57A shows a conventional pixel structure, in which each pixel is sandwiched between metal wirings 540 (gate electrode lines or source electrode lines). Area. An insulating film 541 made of silicon nitride or the like is formed on the metal wiring 540. However, the insulating film 541 is generally not formed over the pixel electrode 542.
[0547]
FIG. 57B is a cross-sectional view showing the present embodiment 21-2. A convex portion 543 made of a photoresist resin is formed in an island shape on the pixel electrode 542 at the center of the pixel electrode 542. The convex portion 543 is formed by partially leaving a photoresist resin film applied on the pixel electrode 542 by photolithography. The height of the convex portion 543 was 1 μm and the width was 20 μm. At this time, the width of the pixel was 50 μm. When the concavo-convex shape was formed in this way, b-twist and t-twist regions were formed on the left and right sides of the convex portion (or concave portion), and good bend transition could be realized.
[0548]
As a modification of the convex portion 543, the convex portion 543 is formed on the pixel electrode 542 in FIG. 57B, but may be formed below the pixel electrode 542.
[0549]
Further, the shape of the convex portion 543 is not limited to the shape shown in FIG. 57B, and may be a mountain shape shown in FIG. The convex portion 543 having a mountain shape shown in FIG. 57C can be manufactured by melting a resin portion partially left by photolithography, for example, by heat treatment. In particular, the convex portion 543 having the shape shown in FIG. Since the cross-sectional shape is slantingly inclined, this inclination angle is added to the pretilt of the liquid crystal. For this reason, it is considered that the same effect as the distribution of the pretilt as in the twentieth embodiment is obtained. Even with a steep shape as shown in FIG. 57 (b), the orientation of the liquid crystal changes continuously and gently, so it is considered that the same effect as in FIG. 57 (c) was obtained.
[0550]
Further, when the pixel electrode 542 is formed on the convex portion 543, the shape of FIG. 52 (d) can be formed. In such a modified example, by forming the pixel electrode 542 on the convex portion 543, an effect of increasing the electric field strength of the convex portion 543 is added, so that the transition can be realized more satisfactorily.
[0551]
As still another modification of the convex portion, a convex portion 543 made of silicon nitride is formed on the array substrate 545 as shown in FIG. The convex portion 543 is obtained by partially leaving the silicon nitride film formed on the metal wiring 540 in order to form the concave-convex shape. This method has an advantage that the manufacturing process does not increase. In addition, the level | step difference of the convex part 543 has implement | achieved about 1 micrometer.
[0552]
As another modification of the convex portion, a method of forming a transparent resin layer 546 on the surface of the array substrate 500 and forming an ITO electrode on the transparent resin layer 546 was also used. FIG. 57 (f) shows the configuration at this time. In this configuration, since the transparent resin layer 546 on the metal wiring 540 is raised, the pixel electrode 542 formed on the transparent resin layer 546 has a concave structure. Two twist regions could be formed by the inclination of the concave structure. Furthermore, the transparent resin layer 546 may be patterned to form a concavo-convex structure in this layer.
[0553]
(Embodiment 21-3)
In the present Embodiment 21-3, the unevenness was densely formed on the substrate.
[0554]
The present invention is to form an uneven shape on a substrate, thereby forming b-spray and t-spray regions. Therefore, the concavo-convex shape may be scattered in each pixel as in the thirteenth embodiment, or a plurality of uneven shapes may be formed in the pixel, or more densely formed in the pixel.
[0555]
In this embodiment mode, a process for roughening the surface of the substrate is performed in order to form the substrate densely on the substrate. The ITO surface of the substrate was treated with an O2 asher, and the uneven shape had a maximum depth of 0.2 μm. If the depth of the unevenness of the substrate was 0.1 μm or more, there was an effect in improving the transition.
[0556]
Further, the present invention is not limited to this method, and it is only necessary to form an uneven shape. For example, the unevenness of the ITO surface could be formed by a process such as increasing the deposition conditions of ITO or increasing the film thickness. At this time, the crystal grain boundary of ITO is 50 nm, and it is understood that sufficient unevenness is obtained as compared with the case where the crystal grain boundary of normal ITO is 10 nm or less.
[0557]
Further, the uneven pattern may be printed with halftone dots. The substrate may be press-molded.
[0558]
(Embodiment 21-4)
As another simple method, a concavo-convex structure may be formed on the substrate surface by dispersing particles having a cell thickness or less in or on a normal alignment film.
[0559]
(Embodiment 22)
58 is a cross-sectional view of a principal part of the liquid crystal display device according to the twenty-second embodiment. FIG. 59 is a plan view of the vicinity of the pixel electrode of the liquid crystal display device according to the twenty-second embodiment. This embodiment is characterized in that an electrode missing portion is formed in at least one of the pixel electrode and the counter electrode as in the case of the eleventh embodiment. However, the present embodiment is characterized in that the formation direction of the electrode missing portion is determined in consideration of the rubbing direction. Here, in FIG. 58, 550 indicates a pixel electrode, 551 indicates a counter electrode, 552 indicates an array substrate, 553 indicates a counter substrate, 554 indicates a missing electrode portion, 555 indicates a line of electric force. Reference numeral 556 denotes a liquid crystal molecule. The operational effect of the electrode missing portion 552 in the present embodiment 22 will be redundantly described with respect to the above embodiment 11, but will be described again here. The distribution of electric lines of force at the portion having the electrode missing part 554 is as shown in FIG. 58 (a). At this time, the liquid crystal alignment is formed with t-spray alignment and b-spray alignment t as shown in FIG. 58 (b). The bend transition occurs from the disclination line at the boundary. Therefore, the bend transition can be facilitated by forming the electrode missing portion 554 in each pixel. The missing portion 554 may be formed not only on the pixel electrode but also on the counter electrode, or may be formed on both the pixel electrode and the counter electrode. The state of formation of the transverse electric field is the same.
[0560]
Here, the relationship between the formation direction of the electrode missing part 554 and the rubbing direction will be considered. The formation direction of the electrode missing part 554 coincides with the generation direction of the disclination line. Therefore, it has been important to form a missing portion at a position of a disclination line generated when there is no missing portion in order to perform stable transition. For example, as described in the embodiment 20-3, the direction of the disclination line generated may differ depending on the rubbing direction. Therefore, there is a correlation between the rubbing direction and the optimal formation direction of the missing portion 554.
[0561]
In the case of rubbing in the vertical direction, the disclination line is formed in the left-right direction, so that the missing portion 554 is preferably formed in the left-right direction of the pixel. Since the disclination line is formed in the vertical direction in rubbing in the horizontal direction, it is desirable to form the missing portion 554 in the vertical direction of the pixel. When rubbing in an oblique direction, it is desirable to form the missing portion 554 in the oblique direction of the pixel.
[0562]
In this embodiment, the number of missing portions is one, but a plurality of missing portions may be formed. Further, the missing portion may be a rectangular slit as shown in FIG. 59 (a), or may be cut around the pixel as shown in FIG. 59 (b). In FIG. 59 (a) and FIG. 59 (b), 558 is a gate electrode line, and 559 is a source electrode line.
[0563]
(Embodiment 23)
In the present embodiment, by forming a transverse electric field, b-spray and t-spray are formed and bend transition is ensured. Referring to FIG. 60, the pixel electrode 560 is sandwiched between metal electrode lines 561 (source electrode lines or gate electrode lines). Here, when the potential of the pixel electrode 560 is lower than the potential of the metal electrode line 561, a horizontal electric field is generated as indicated by an arrow 562. Due to this influence, anisotropy occurs in the alignment of the liquid crystal 563, and b-spray alignment and t-spray alignment occur as shown in FIG.
[0564]
Here, the lateral electric field is applied from both sides of the pixel electrode 560, and since the directionality is reversed, asymmetric splay alignment occurs. Note that it is desirable that the rubbing direction and the horizontal electric field direction substantially coincide from the viewpoint of promoting transition. Hereinafter, specific driving for forming a lateral electric field will be described by exemplifying Embodiment 23-1 to Embodiment 23-3.
[0565]
(Embodiment 23-1)
In the present Embodiment 23-1, the rubbing direction is the vertical direction (the horizontal direction in FIG. 60), and the lateral electric field is applied between the gate electrode line and the pixel electrode. FIG. 61 shows a conceptual diagram of the drive waveform. The potential level includes a high gate level (GH), a low gate level (GL), a high source level (SH), and a low source level (SL). Two kinds of gate levels can be selected from the above-mentioned levels, and the source level can take a potential between the SH level and the SL level. A counter potential for applying the transition waveform is also provided. A voltage lower than the source level is applied to the counter electrode, thereby applying a transition waveform between the pixel electrode and the counter electrode.
This transition waveform is the one described in the first to sixth embodiments.
[0566]
Here, in this embodiment, the voltage of the source electrode line is set to a low level (SL), and the voltage of the gate electrode line is set to a high level GH. Since the gate electrode line is at the level GH, the pixel transistor becomes conductive. As a result, the pixel electrode has the same potential as the source electrode line. At this time, since the voltage of the gate electrode line is higher than that of the pixel electrode, a lateral electric field corresponding to the voltage V1 is applied between the pixel electrode and the gate electrode line. Then, a horizontal electric field in which the electric field directions are opposite to each other between the gate electrode line above the pixel (the right metal electrode line in FIG. 60) and the lower gate electrode line (the right metal electrode line in FIG. 60). Therefore, in the present embodiment, the b-spray alignment is formed in the upper part (the right part in FIG. 60) and the t-splay alignment is formed in the lower part. As a result, the bend transition was successfully performed.
[0567]
In the case of a structure having an auxiliary electrode layer, the structure shown in FIG. 62 or 63 is preferably used in order to improve the effect of the transverse electric field. Normally, as shown in FIG. 62, an auxiliary electrode layer 571 is provided on the gate electrode line 570, and this auxiliary electrode layer 571 forms an auxiliary capacitance. In this configuration, since the auxiliary electrode layer 571 has an effect of shielding the gate electric field, the auxiliary electrode layer 571 is indicated by a virtual line in order to effectively generate a lateral electric field between the gate electrode line 570 and the pixel electrode 580. If the size of the conventional example is reduced to the size indicated by the broken line, or if it is formed at the center of the pixel as shown in FIG. 63, the effect of the lateral electric field is higher.
[0568]
(Embodiment 23-2)
In the present embodiment 23-2, a lateral electric field is applied between the gate and the pixel as in the above embodiment 23-1, but this is realized by lowering the gate level. FIG. 64 shows a conceptual diagram of the drive waveform. The potential level is basically the same as that in the embodiment 23-1. However, in Embodiment 23-1, the voltage of the gate electrode line remains at the high level GH. However, in Embodiment 23-2, the voltage of the gate electrode line remains at the high level GH during the pixel charging period. The period GL other than the pixel charging period (the period in which the pixel potential is held) is set to a low level GL. That is, the source electrode line is set to level SH during a period in which voltage is applied to the counter electrode and charging is sufficiently performed, but after the charging period, the source electrode line is set to level SL. As a result, a lateral electric field corresponding to the voltage V2 (> V1) could be applied between the pixel electrode and the gate electrode. In this embodiment, since the gate electrode voltage is lower than that of the pixel electrode, the orientation state opposite to that of the above embodiment 23-1, that is, the t-spray is lower in the upper portion (right side portion in FIG. 60). The b-spray was formed at the part (left side of FIG. 60). In addition,
(Embodiment 23-3)
Embodiment 23-3 is characterized in that a lateral electric field is applied between the source pixel and the pixel. FIG. 65 shows a conceptual diagram of the drive waveform. In this embodiment mode, the charge period of the pixel until the charge of the counter electrode is changed and the charging is completed is set to a high level GH in order to make the pixel transistor conductive, and the other period (the pixel potential is maintained). The gate electrode line is set to a low level GL during the period of time. When the gate electrode line is at the level GL, since the source electrode line and the pixel electrode are not conductive, the source electrode line and the pixel electrode can be kept at different potentials. Therefore, the horizontal electric field corresponding to the voltage V3 is generated between the source electrode line and the pixel electrode by setting the source electrode line to the level SL when the gate electrode line reaches the level GL while keeping the pixel electrode in a high potential state. Was applied. As a result, a horizontal electric field was applied between the pixel and the source to form two splay alignment states, and the bend transition was successfully performed.
[0569]
In this Embodiment 23-3, it was more effective to set the rubbing direction to the lateral direction (perpendicular to the paper surface of FIG. 60). In the above example, the source electrode line is set to the level SL during the entire period in which the pixel potential is held, but the source electrode line is set to the level only in a part of the period in which the pixel potential is held. SL may be used.
[0570]
(Embodiment 24)
The twenty-fourth embodiment is characterized in that the bend transition is favorably performed by not forming a spacer in the pixel region. Conventionally, as shown in FIG. 66A, spherical beads 590 are dispersed in the pixel region 591 to maintain the distance between the substrates.
[0571]
In the behavior of bend transition, we have found a phenomenon in which bend transition is inhibited by this bead 590. Therefore, in this embodiment, it is possible to perform the transfer well by eliminating the beads 590 in the pixel region 591 which is a display portion.
[0572]
Specifically, as shown in FIGS. 66B and 67, a spacer column 593 having a thickness of 5 μm is formed in a non-display region 592 other than the display portion by using a photolithography process, and this spacer pillar is replaced with a spacer bead. Using. With such a configuration, the transfer was successfully performed without inhibiting the bend transfer. 66 and 67, 594 indicates a gate electrode line, and 595 indicates a source electrode line. In addition, the arrangement of the spacer columns 593 is not limited to that shown in FIG. 66B, and may be formed in the non-display area.
[0573]
【The invention's effect】
As described above, according to the present invention, in the method for driving a liquid crystal display device using OCB cells, an alternating voltage on which a bias voltage is superimposed is applied to a pair of substrates and applied continuously, or By alternately repeating the process of applying an alternating voltage with a bias voltage superimposed on a pair of substrates and the process of applying an open state or a low voltage, the transition from the splay alignment to the bend alignment is almost reliably performed in an extremely short time. A bend-oriented OCB liquid crystal display device that can be completed, has no display defects, has a high response speed, is suitable for moving image display, and has a wide field of view can be obtained.
[0574]
In addition, according to the present invention, the OCB display mode liquid crystal display device having a high-speed response wide field of view and high image quality composed of an active matrix type liquid crystal cell free from display defects, which is easy to ensure a fast transition from splay alignment to bend alignment. The effect that can be obtained.
[0575]
Further, according to the present invention, by causing a plurality of liquid crystal regions having different alignment states to appear during the initialization period, a disclination line can be formed at the boundary between the liquid crystal regions, and the bend can be made quickly and reliably. A transition to orientation can be achieved.
[0576]
Further, according to the present invention, the liquid crystal cell of the splay alignment in which the pretilt angles of the liquid crystal at the upper and lower interfaces of the liquid crystal layer between the array substrate and the counter substrate are opposite to each other and aligned in parallel with each other. Prior to the liquid crystal display driving, an initialization process for changing from the splay alignment to the bend alignment is performed by applying a voltage, and the active matrix liquid crystal display that drives the liquid crystal display in the initialized bend alignment state. In the apparatus, at least one lateral electric field applying unit for excitation of transition is provided in one pixel, and a horizontal electric field is generated by the horizontal electric field applying unit, and a voltage is continuously or intermittently applied between the pixel electrode and the common electrode. From the splay alignment to the bend alignment by generating transition nuclei for each pixel and transferring the entire pixel from the splay alignment to the bend alignment. Fast it was surely caused, and thereby possible to provide a liquid crystal display device of the OCB display mode with a wide viewing quality at no addition fast response display defect.
[0577]
According to the present invention, the OCB display mode alignment liquid crystal display element is a parallel alignment liquid crystal display element including a liquid crystal layer sandwiched between a pair of substrates and a phase compensation plate disposed outside the substrate. Yes, a reliable and fast spray-bend alignment transition can be achieved, and its practical value is extremely large.
[0578]
According to the present invention, there is provided a method of applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other, and transferring the alignment of the liquid crystal to a bend alignment, The splay elastic constant k11 of the liquid crystal is 10 × 10 ^-7 dyn ≧ k11 ≧ 6 × 10 ^-7 When the absolute value of the pretilt angle of the liquid crystal with respect to the first substrate is θ1 and the absolute value of the pretilt angle of the liquid crystal with respect to the second substrate is θ2, the range is 1.57 rad> | Since the relationship θ1−θ2 | ≧ 0.0002 rad is satisfied, the liquid crystal can be quickly transferred to the bend alignment.
[0579]
According to the present invention, there is provided a method of applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other, and transferring the alignment of the liquid crystal to a bend alignment, The splay elastic constant k11 of the liquid crystal is 10 × 10 ^-7 dyn ≧ k11 ≧ 6 × 10 ^-7 dyn, and the electric field is an electric field obtained by superimposing a spatially non-uniformly applied sub-electric field on a spatially non-uniformly applied main electric field, and the main electric field is E0, When the maximum value of the sub electric field is E1, the relationship of 1.0> E1 / E0> 1/100 is satisfied, so that the liquid crystal can be quickly transferred to the bend alignment.
[0580]
According to the present invention, there is provided a method of applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other, and transferring the alignment of the liquid crystal to a bend alignment, When the absolute value of the pretilt angle of the liquid crystal relative to the first substrate is θ1, and the absolute value of the pretilt angle of the liquid crystal relative to the second substrate is θ2, 1.57 rad> | θ1−θ2 | ≧ 0.0002 rad And the electric field is an electric field in which a sub-electric field applied spatially non-uniformly is superimposed on a main electric field applied spatially uniformly, and the main electric field is E0, When the maximum value of the sub-electric field is E1, the relationship of 1.0> E1 / E0> 1/100 is satisfied, so that the liquid crystal can be quickly transferred to the bend alignment.
[0581]
According to the present invention, there is provided a method of applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other, and transferring the alignment of the liquid crystal to a bend alignment, The splay elastic constant k11 of the liquid crystal is 10 × 10 ^-7 dyn ≧ k11 ≧ 6 × 10 ^-7 When the absolute value of the pretilt angle of the liquid crystal with respect to the first substrate is θ1 and the absolute value of the pretilt angle of the liquid crystal with respect to the second substrate is θ2, the range is 1.57 rad> | θ1− θ2 | ≧ 0.0002 rad, and the electric field is an electric field obtained by superimposing a sub-electric field applied spatially non-uniformly on a main electric field applied spatially uniformly, When the electric field is E0 and the maximum value of the sub-electric field is E1, the relationship of 1.0> E1 / E0> 1/100 is satisfied, so that the liquid crystal can be quickly transferred to the bend alignment.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a part of a liquid crystal display device including a bend alignment type OCB cell.
FIG. 2 is a cross-sectional view of a liquid crystal cell for explaining a transition from splay alignment to bend alignment.
FIG. 3 is a conceptual diagram of a pixel unit by a driving method of the liquid crystal display device according to the first embodiment of the present invention.
FIG. 4 is a voltage waveform diagram for orientation transition used in Embodiment 1 of the present invention.
FIG. 5 is a relationship diagram between a bias voltage and a transition time in the first embodiment of the present invention.
FIG. 6 is a conceptual diagram of a pixel unit by a driving method of a liquid crystal display device according to a second embodiment of the present invention.
FIG. 7 is a voltage waveform diagram for alignment transition used in Embodiment 2 of the present invention.
FIG. 8 is a relationship diagram between a bias voltage and a transition time in Embodiment 2 of the present invention.
FIG. 9 is a conceptual diagram of a pixel unit by a driving method of a liquid crystal display device according to a third embodiment of the present invention.
FIG. 10 is a voltage waveform diagram for alignment transition used in Embodiment 3 of the present invention.
FIG. 11 is a relationship diagram between a bias voltage and a transition time in Embodiment 3 of the present invention.
12 is a conceptual diagram of a pixel unit configuration by a driving method of a liquid crystal display device according to a fourth embodiment of the present invention. FIG.
FIG. 13 is a normal drive voltage waveform diagram of the liquid crystal display device according to the fourth embodiment of the present invention.
FIG. 14 is a voltage waveform diagram for alignment transition used in Embodiment 4 of the present invention.
FIG. 15 is a voltage waveform diagram for alignment transition used in the fifth embodiment of the present invention.
FIG. 16 is a schematic cross-sectional view of a liquid crystal display device according to a seventh embodiment of the present invention.
FIG. 17 is a schematic plan view of a liquid crystal display device according to a seventh embodiment of the present invention.
FIG. 18 is a diagram showing a method of manufacturing the liquid crystal display device according to the seventh embodiment of the present invention.
19A and 19B are diagrams showing a liquid crystal display device according to an eighth embodiment of the present invention. FIG. 19A is a schematic cross-sectional view of the liquid crystal display device, and FIG. 19B is a schematic plan view of the liquid crystal display device. is there.
20 is a diagram conceptually showing the configuration of a liquid crystal display device according to a ninth embodiment of the present invention. FIG. 20 (a) is a schematic plan view of the liquid crystal display device, and FIG. 20 (b) is a liquid crystal display. It is a schematic sectional drawing of an apparatus.
FIG. 21 is a diagram conceptually showing the structure of the liquid crystal display device according to the ninth embodiment of the present invention.
FIG. 22 is a diagram showing another example of a liquid crystal display device according to the ninth embodiment of the present invention.
23 is a diagram conceptually showing the configuration of a liquid crystal display device according to a tenth embodiment of the present invention. FIG. 23 (a) is a schematic plan view of the liquid crystal display device, and FIG. 23 (b) is a liquid crystal display. FIG. 23C is a schematic cross-sectional view of another example of the liquid crystal display device, and FIG. 23D is a schematic cross-sectional view of another example of the liquid crystal display device.
24 is a diagram conceptually showing the configuration of a liquid crystal display device according to an eleventh embodiment of the present invention. FIG. 24 (a) is a schematic plan view of the liquid crystal display device, and FIG. It is the schematic which shows distortion.
25 is a diagram conceptually showing the configuration of a liquid crystal display device according to Embodiment 12 of the present invention. FIG. 25 (a) is a schematic sectional view of the liquid crystal display device, and FIG. 25 (b) is a schematic plan view. FIG.
FIG. 26 is a diagram conceptually showing a cross-sectional structure of a liquid crystal display device according to a thirteenth embodiment of the present invention.
FIG. 27 is a diagram for explaining a process for manufacturing a convex object formed on the glass substrate of the thirteenth and fourteenth embodiments of the liquid crystal display device according to the present invention.
FIG. 28 is a view for explaining a process for manufacturing a convex object subsequent to FIG. 27 according to the present invention.
FIG. 29 is a diagram showing the rubbing direction of the substrate used in the thirteenth embodiment of the present invention.
FIG. 30 is a structural external view of a fourteenth embodiment according to the present invention.
FIG. 31 is a plan view of a fourteenth embodiment according to the present invention.
FIG. 32 is a structural external view of a liquid crystal cell provided in a liquid crystal display device according to Embodiment 15 of the present invention.
FIG. 33 is a diagram for explaining a manufacturing process for the convex object of the liquid crystal cell according to the fifteenth embodiment of the present invention.
FIG. 34 is a diagram conceptually showing a cross-sectional structure of a liquid crystal cell provided in a liquid crystal display device according to Embodiment 16 of the present invention.
FIG. 35 is a diagram conceptually showing a pattern of a transparent electrode used in a liquid crystal cell according to Embodiment 16 of the present invention.
FIG. 36 is a cross-sectional view of a principal part of a liquid crystal cell provided in the liquid crystal display device according to Embodiment 17 of the present invention.
FIG. 37 is an enlarged view of a part of FIG. 36.
FIG. 38 is a cross-sectional view of main parts of a liquid crystal cell provided in a liquid crystal display device according to an eighteenth embodiment of the present invention.
FIG. 39 is a diagram for explaining an arrangement of optical elements in a liquid crystal cell provided in a liquid crystal display device according to an eighteenth embodiment of the present invention.
FIG. 40 is a diagram showing voltage-transmittance characteristics of a liquid crystal cell included in a liquid crystal display device according to an eighteenth embodiment of the present invention.
FIG. 41 (a) is a schematic diagram (a) showing a motivated orientation, and FIG. 41 (b) is a schematic diagram (b) showing a bend orientation.
FIG. 42 is a diagram illustrating a director of a liquid crystal layer.
FIG. 43 is a diagram showing a CR equivalent circuit.
FIG. 44 is a diagram showing a temporal change in the alignment angle (θj) of the liquid crystal under an external electric field that increases with time.
FIG. 45 is a diagram showing a relationship between a splay elastic constant (k11) and a critical electric field (Ec).
FIG. 46 is a diagram showing the relationship between the absolute value difference (Δθ) of the pretilt angle and the critical electric field (Ec).
FIG. 47 is a diagram showing the relationship between electric field inhomogeneity (E1 / E0) and critical electric field (Ec).
FIG. 48 is a conceptual diagram showing an alignment state of the liquid crystal display device according to the embodiment 20-1.
49 is a perspective view of a substrate 511 having a step 510. FIG.
FIG. 50 is an enlarged view of a rubbing cloth 511a having a distribution in the length of the rubbing fiber.
FIG. 51 is a conceptual diagram showing the shadow of rubbing by array wiring in the embodiment 20-3.
FIG. 52 is a view showing an alignment film coating apparatus.
53 is a partially enlarged plan view of the surface of the printing plate 530. FIG.
54 is a partially enlarged cross-sectional view of the surface of the printing plate 530. FIG.
55 is a conceptual diagram showing an electric force line distribution and a liquid crystal alignment state of the liquid crystal display device according to Embodiment 21-2. FIG. 55 (a) is an electric force line distribution diagram, and FIG. ) Is a diagram showing the alignment state of the liquid crystal.
FIG. 56 is a drive waveform chart of the liquid crystal display device according to the present embodiment 21-1.
FIG. 57 is a conceptual diagram showing the structure of the liquid crystal display device according to the present embodiment 21-2. FIG. 57 (a) is a diagram showing a pixel structure of a conventional example, and FIG. FIG. 57B is a diagram showing a modification of the concavo-convex structure of the pixel, FIG. 57C is a diagram showing a modification of the concavo-convex structure of the pixel, and FIG. ) Is a diagram showing another modification example of the concavo-convex structure of the pixel, FIG. 57E is a diagram showing another modification example of the concavo-convex structure of the pixel, and FIG. FIG.
58 is a main-portion cross-sectional view of the liquid crystal display device according to Embodiment 22. FIG.
FIG. 59 is a plan view of the vicinity of a pixel electrode of a liquid crystal display device according to a twenty-second embodiment.
FIG. 60 is a conceptual diagram showing an operation of the liquid crystal display device according to the twenty-third embodiment.
61 is a conceptual diagram showing transition voltage waveforms of a liquid crystal display device according to Embodiment 23-1. FIG.
62 is a plan view showing the shape of the auxiliary electrode layer 571. FIG.
63 is a plan view showing another shape of the auxiliary electrode layer 571. FIG.
FIG. 64 is a conceptual diagram showing transition voltage waveforms of the liquid crystal display device according to the embodiment 23-2.
FIG. 65 is a conceptual diagram showing transition voltage waveforms of the liquid crystal display device according to Embodiment 23-3.
66 is a plan view of a substrate for explaining a spacer according to Embodiment 24, FIG. 66 (a) is a view showing a conventional spacer, and FIG. 66 (b) is a view showing a spacer according to the present invention. FIG.
FIG. 67 is a cross-sectional view of a substrate for explaining a spacer according to the twenty-fourth embodiment;
FIG. 68 is a sectional view of a conventional example.
[Explanation of symbols]
20, 21 substrate
22, 23 electrodes
24, 25 Alignment film
26 Liquid crystal layer
30, 40, 50, 71, 72 Orientation transition drive circuit
31 Liquid crystal display drive circuit
101 ・ 102 Polarizing plate
103 Phase compensator
104 Liquid crystal cell
105 Counter substrate
106 Array substrate
107 Common electrode
108 Pixel electrode
109/110 Alignment film
111 Switching element
112 Liquid crystal layer
113 Signal electrode wire
114/114 'gate electrode line
120 b-splay orientation
121 t-spray orientation
123 Disclination wire
124 Bend orientation
A2, B2, C2, D2 pretilt angles
201a array substrate
201b Counter substrate
202a pixel electrode
221a Recess of pixel electrode
222a Convex part of pixel electrode
223a Non-fitting type convex part of pixel electrode
224a Non-fitting type convex part of pixel electrode
202b Common electrode
203a Alignment film
203am alignment film
203ah alignment film
203b Alignment film
203bm alignment film
203bh alignment film
204a Polarizing plate
204b Polarizing plate
205 Phase compensator
206 Signal electrode wire
261 Convex part of signal electrode wire
262 Signal electrode wire recess
263 Non-fitting type convex part of signal electrode wire
207 Gate electrode line
271 Convex part of gate electrode line
272 Recess of gate electrode line
273 Non-fitting type convex part of gate electrode line
208 Switching transistor (element)
209 Line for applying horizontal electric field
291 Convex part of horizontal electric field application line
209a Horizontal electric field application line
291a Convex part of horizontal electric field application line
210 Liquid crystal layer
298 Liquid crystal layer
299 Liquid crystal layer
211 Liquid crystal molecules
212 Transparent insulation film
225 Electrode defect
226 Disclination wire
227b b-spray orientation
227t t-splay orientation
301,308 Glass substrate
302,307 Transparent electrode
303,306 Alignment film
304 Liquid crystal layer
304a Liquid crystal alignment when no voltage is applied (splay alignment)
304b Liquid crystal alignment during voltage application (bend alignment)
305 Spacer
309 test cell
310 Convex object
311,314 Negative uniaxial film phase plate
312 and 315 A retardation plate made of an optical medium having negative refractive index anisotropy in which main axes are arranged in a hybrid arrangement
313,316 Polarizing plate
317,318 Phase compensation plate
319 Positive Uniaxial Film Phase Plate
320 resist thin film
321 photomask
322 Photomask opening
323 Parallel UV
360 Triangular object
380 Electrode opening

Claims (3)

Including a pair of upper and lower substrates and a liquid crystal layer sandwiched between the substrates, and prior to liquid crystal display driving, the initial alignment of the liquid crystal layer is transferred from the splay alignment state to the bend alignment state by applying a voltage between the substrates. In the liquid crystal display device that performs the initialization process and performs the liquid crystal display drive in the initialized bend alignment state,
Means for causing a liquid crystal region having two types of splay alignment states, a b-spray alignment region and a t-spray alignment region, to develop in the liquid crystal layer during the initialization process of transition to the bend alignment state; A liquid crystal display device characterized in that a transition from a disclination line generated at a boundary between a splay alignment region and a t-spray alignment region to a bend alignment state occurs or expands . 2. The liquid crystal display device according to claim 1, wherein a transverse electric field forming means for transfer excitation is provided in the vicinity of the disclination line . 3. The liquid crystal display device according to claim 2, wherein at least one horizontal electric field forming unit is provided in one pixel .

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