JP4255521B2

JP4255521B2 - Liquid crystal display element and manufacturing method thereof

Info

Publication number: JP4255521B2
Application number: JP19352097A
Authority: JP
Inventors: 直樹加藤; 米治田窪
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1997-07-18
Filing date: 1997-07-18
Publication date: 2009-04-15
Anticipated expiration: 2017-07-18
Also published as: JPH1138441A

Description

【０００１】
【発明の属する技術分野】
本発明は液晶表示素子、特に、優れた視角特性を有する横方向電界駆動方式の液晶表示素子に関する。
【０００２】
【従来の技術】
近年、アクティブマトリクス型液晶表示装置は目ざましい進歩を遂げ、ＣＲＴ(陰極線管)と同等の高表示品位となり、薄型軽量、低消費電力などの特徴を有することからＣＲＴに代わる表示装置として、ノート型パソコン，小型ＴＶなどに積極的に応用されている。
【０００３】
このようなアクティブマトリクス型液晶表示素子において広く用いられているのがＴＮ(Twisted Nematic)方式のＮＷ(Normally White)モードである。ＴＮ方式とは、基板間で液晶分子が90゜ねじれた構成をもつ液晶パネルを２枚の偏光板ではさんだものである。また、２枚の偏光板の偏光軸方向が、互いに直交し、一方の偏光子の偏光軸が一方の基板に接している液晶分子の長軸方向と平行あるいは垂直になるように貼り合わせているモードがＮＷモードである。このＴＮ方式のＮＷモードの場合、電圧無印加、またはあるしきい値電圧付近の低電圧において白表示、それより高い電圧において黒表示となる。このＴＮ方式の液晶表示素子では、基板間に電圧を印加することにより、液晶分子はねじれ構造をほどきながら電界方向に配向しようとするが、このときの液晶分子の配向状態によりパネルを通過してくる光の偏光状態が変化し、光の透過率が調節される。ところで、液晶分子の配向状態が同じでも、液晶パネルに入射してくる光の入射方向によって光の偏光状態が変化するため、あらゆる入射方向に対して光の透過率は異なってくる。すなわち、液晶パネルは視角依存性をもつ。この視角依存性は次のような特徴を持っている。ＮＷモードの場合、電圧を印加して液晶分子が基板面に対して完全に垂直に立ち上がれば、基板に垂直な方向から見て、真の黒となるはずである。これは、液晶分子は、分子の長軸方向が光の進行方向に平行な時には、光学的な位相差は生じず、光は偏光成分を変化することなく液晶層を通過するためである。実際には電圧をある程度印加しても、基板界面付近の液晶分子は、基板との相互作用が強く立ち上がりにくい。また、液晶層中心部の液晶分子も完全には立ち上がらないので、基板に垂直な方向に進行する光に対して、光学的な位相差はなくならず、真の黒とはならない。一方、このような配向状態では、液晶層中心部の長軸方向にほぼ等しい進行方向の光の方が、基板に垂直な方向に進行する光より光学的な位相差が小さくなる。したがって、基板に対して垂直より数度、上下いずれかの方向に傾けて光を入射させた方が黒が沈み込み、コントラスト比の良好な表示が得られる。ところがこの時、この入射角度と基板法線に対して対称な角度から入射した光は急激に黒が沈み込まなくなる。したがって実際の液晶パネルは、基板法線を中心として画面の上下方向に対して、その視角特性は著しく非対称になってしまっている。
【０００４】
このため近年、アクティブマトリクス型液晶表示素子では視野角の拡大を図る技術の開発が盛んに行われている。例えば、ドレイン電極と共通電極を同一基板上に形成し、ドレイン電極と共通電極間の横方向電界によって液晶を駆動する方式(例えばアジアディスプレイ’95，第577頁から第580頁(ASIA DISPLAY '95 P.577-580))が提案されている。この方式では、視角による光学的な位相差の変化が少ないため、視野角の拡大を図ることができる。
【０００５】
【発明が解決しようとする課題】
しかしながら、従来のこの横方向電界によって液晶を駆動する方式の液晶表示素子は、そのしきい値電圧が(数１)に表されるように、電極間距離Ｌに依存している。
【０００６】
【数１】

【０００７】
このため、ドレイン電極と共通電極が異なる層に形成される場合、露光時のアライメントずれ等により、パネル面内で、ドレイン電極と共通電極間の距離が異なる領域が生じる可能性があり、そして、ドレイン電極と共通電極間の距離が異なる領域では、(数１)より明らかなように電気光学特性が異なるために、表示ムラとして認識されてしまうという問題点がある。
【０００８】
本発明は上記従来の問題点を解決するものであり、パネル面内でドレイン電極と共通電極間の距離が異なる領域が生じても、表示ムラとして認識されにくい液晶表示素子を提供することを目的とする。
【０００９】
【課題を解決するための手段】
本発明の液晶表示素子は単位画素内にドレイン電極と共通電極により複数グループの横方向電界領域を形成し、かつ、分割露光の境界部で表示ムラとなるドレイン電極と共通電極間距離のずれが生じても、他のグループの横方向電界領域で互いに補償されるように、各グループの電極間距離を設定したものである。
【００１０】
この本発明によれば、電極間距離のずれが生じても、他の横方向電界領域で互いに補償されるために、表示ムラとして認識されにくくなる。
【００１１】
【発明の実施の形態】
以下、本発明の各実施の形態について図面を参照しながら説明する。なお、各実施の形態に共通する部分については同一符号を用いるものとする。
【００１２】
(実施の形態１)
図１は本発明の液晶表示素子の実施の形態１における１画素部の平面図であり、図２は本発明の液晶表示素子の実施の形態１における構成を示す断面図である。ここで図１に示す１画素部のドレイン電極と共通電極間の距離は(表１)に示すようにマスク設計されている。
【００１３】
【表１】

【００１４】
本実施の形態に係る液晶表示素子は、これら図１及び図２に示されるように、ガラス基板１上にＣｒからなるゲート電極２及び共通電極３が形成され、これらの電極を覆うようにＳｉＮｘからなるゲート絶縁膜４が形成されている。ゲート電極２上にゲート絶縁膜４を介してａ−Ｓｉ膜５が形成され、トランジスタの能動層となっている。ａ−Ｓｉ膜５のパターンの一部に重畳するようにＭｏからなるソース電極６、ドレイン電極７が形成され、これらすべてを覆うようにＳｉＮｘからなる絶縁膜８が形成されている。ここで、いずれの層も分割露光によりパターニングされているが、ドレイン電極７は図１において、そのアライメントが左方向にずれることはあっても右方向には決してずれないように装置の設定がなされているものとする。このように形成された単位画素をマトリクス状に配置したアクティブマトリクス基板上にポリイミドからなる配向膜９を塗布した後、ラビング処理が施されている。対向基板10上にもポリイミドからなる配向膜９を塗布した後、ラビング処理が施されている。前記アクティブマトリクス基板と対向基板間に液晶11が封入され、２枚の基板の外表面に偏光板12が配置されている。
【００１５】
このようにして作製した液晶表示素子は、分割露光の境界部でもドレイン電極７と共通電極３間の距離の相違に起因する表示ムラはほとんど観察されず、また、その視角特性を評価したところ、上下左右共に70°以上(コントラスト比10以上)という優れた視角特性が得られているが、以下この点について検証する。
【００１６】
図３は本発明の液晶表示素子の実施の形態１における電圧−透過率特性のシミュレーションの際想定した電極構成の説明図で(表２)に具体的電極間隔を示す。図４は最大透過率差の定義を示すためのドレイン電極と共通電極との距離のずれが生じた場合の電圧−透過率特性図、図５は本発明の液晶表示素子の実施の形態１におけるドレイン電極と共通電極との距離のずれ量と最大透過率差の関係図であり、以下、これらの各図を参照して説明する。
【００１７】
【表２】

【００１８】
本実施の形態における液晶表示素子において、ドレイン電極と共通電極間の距離のずれが生じた場合の透過率変化量を明確にするために、図３に示すような電極構成を想定し、(表２)に示すような電極間隔の場合の液晶セルの電圧−透過率特性をシミュレーションし、基準(電極間距離がずれていない場合)との透過率差が最大となるところの透過率差ΔＴmax(図４参照)を求めた。
【００１９】
図５はこの結果から求めたずれ量と最大透過率差ΔＴmaxの関係である。これから、本実施の形態における液晶表示素子では、ドレイン電極と共通電極間の距離が設計値から最大ｄ(0.5μm)までずれる可能性がある場合でも、単位画素内にドレイン電極と共通電極により４つのグループに分割される横方向電界領域を形成し、かつ、ドレイン電極と共通電極間の距離のずれが生じても、他の横方向電界領域で互いに補償されるように、各グループの電極間距離をＬ(12μm)，Ｌ(12μm)，Ｌ＋ｄ(12+0.5=12.5μm)，Ｌ−ｄ(12-0.5=11.5μm)と設定することにより、最大透過率差ΔＴmaxは約１％以下に抑えることが可能であることがわかる。
【００２０】
(比較例)
前記液晶表示素子との比較を行うために、ドレイン電極と共通電極間の距離が、(表３)に示すようにマスク設計されていることを除いては、実施の形態１に係る液晶表示素子と同様である液晶表示素子(以下「比較例」という)を前記実施の形態１の液晶表示素子と同様の方法により作製した。
【００２１】
【表３】

【００２２】
この比較例に係る液晶表示素子では、分割露光の境界でドレイン電極と共通電極間の距離の相違に起因すると思われる表示ムラが観察された。
【００２３】
この比較例に係る液晶表示素子において、ドレイン電極と共通電極間の距離のずれが生じた場合の透過率変化量を明確にするために、実施の形態１と同様の方法によりずれ量と最大透過率差ΔＴmaxの関係を求めた。図６は比較例における液晶表示素子のドレイン電極と共通電極間の距離のずれ量と最大透過率差との関係図であり、この図６から、比較例に係る液晶表示素子では、ドレイン電極と共通電極間の距離が設計値から最大0.5μmずれた場合、最大透過率差ΔＴmaxは実施の形態１による液晶表示素子の場合に比べて、約２倍の２％程度と大きくなることがわかる。
【００２４】
以上のように、本実施の形態によれば、ドレイン電極と共通電極間の距離が製造上、設計値よりも最大ｄずれる可能性がある場合、単位画素内にドレイン電極と共通電極により４つのグループからなる４の整数倍個の横方向電界領域を形成し、かつ、ドレイン電極と共通電極間の距離のずれが生じても、他の横方向領域で互いに補償するように、各グループの電極間距離をＬ，Ｌ，Ｌ＋ｄ，Ｌ−ｄに設定することにより、ドレイン電極と共通電極間の距離の相違が生じてもその相違が表示ムラとして認識されにくくすることができる。
【００２５】
(実施の形態２)
図７は本発明の液晶表示素子の実施の形態２における１画素部の平面図であり、図８は本発明の液晶表示素子の実施の形態２におけるドレイン電極と共通電極との距離のずれ量と最大透過率差の関係図である。ここで図７に示すドレイン電極と共通電極間の距離は(表４)に示すようにマスク設計されている。
【００２６】
【表４】

【００２７】
本実施の形態に係る液晶表示素子の断面構造は前記図２に示した実施の形態１と同様であり、ドレイン電極と共通電極間の距離が(表４)に示すようにマスク設計されている点のみが相違する。このような構成の液晶表示素子を実施の形態１と同様の方法により作製した。ここで、ドレイン電極７は実施の形態１と同様に図７において、そのアライメントが左方向にずれることはあっても右方向には決してずれないように、装置の設定がなされているものとする。
【００２８】
このようにして作製した液晶表示素子では、分割露光の境界部でもドレイン電極７と共通電極３間の距離の相違に起因する表示ムラはほとんど観察されず、また、この液晶表示素子の視角特性を評価したところ、上下左右共に70°以上(コントラスト比10以上)という優れた視角特性が得られているが、以下この点について検証する。
【００２９】
本実施の形態の液晶表示素子におけるドレイン電極と共通電極間の距離のずれが生じた場合の透過率変化量を明確にするために、実施の形態１と同様の方法によりずれ量と最大透過率差ΔＴmaxの関係を求めた。その結果は図８に示す通りであり、本実施の形態における液晶表示素子では、ドレイン電極と共通電極間の距離が設計値から最大ｄ(0.5μm)までずれる可能性がある場合でも、単位画素内に、ドレイン電極と共通電極により６つのグループからなる６の整数倍個の横方向電界領域を形成し、かつ、ドレイン電極と共通電極間の距離のずれが生じても、他の横方向電界領域で互いに補償されるように、各グループの電極間距離をＬ(12μm)，Ｌ(12μm)，Ｌ＋ｄ(12+0.5=12.5μm)，Ｌ−ｄ(12-0.5=11.5μm)，Ｌ＋ｄ／２(12+0.5/2=12.25μm)，Ｌ−ｄ／２(12-0.5/2=11.75μm)と設定することにより、最大透過率差ΔＴmaxを、前記の比較例に係る液晶表示素子の場合に比べて４分の１以下の0.5％以下に抑えることが可能であることがわかる。
【００３０】
以上のように、本実施の形態によれば、単位画素内に６の整数倍個の横方向電界領域を形成しかつ、前記の電極間距離をＬ，Ｌ，Ｌ＋ｄ，Ｌ−ｄ，Ｌ＋ｄ／２，Ｌ−ｄ／２に設定したことにより、ドレイン電極と共通電極間の距離の相違が生じてもその相違が表示ムラとして認識されにくくすることができる。
【００３１】
(実施の形態３)
図９は本発明の液晶表示素子の実施の形態３における１画素部の平面図であり、図10は本発明の液晶表示素子の実施の形態３におけるドレイン電極と共通電極との距離のずれ量と最大透過率差の関係図である。ここで図７に示すドレイン電極と共通電極間の距離は(表５)に示すようにマスク設計されている。
【００３２】
【表５】

【００３３】
本実施の形態に係る液晶表示素子の断面構造は前記図２に示した実施の形態１と同様であり、ドレイン電極と共通電極間の距離が(表５)に示すようにマスク設計されている点のみが相違する。このような構成の液晶表示素子を実施の形態１と同様の方法により作製した。ここで、ドレイン電極７は実施の形態１と同様に図７において、そのアライメントが左方向にずれることはあっても右方向には決してずれないように、装置の設定がなされているものとする。
【００３４】
このようにして作製した液晶表示素子では、分割露光の境界部でもドレイン電極７と共通電極３間の距離の相違に起因する表示ムラはほとんど観察されず、また、この液晶表示素子の視角特性を評価したところ、上下左右共に70°以上(コントラスト比10以上)という優れた視角特性が得られているが、以下この点について検証する。
【００３５】
本実施の形態の液晶表示素子におけるドレイン電極と共通電極間の距離のずれが生じた場合の透過率変化量を明確にするために、実施の形態１と同様の方法によりずれ量と最大透過率差ΔＴmaxの関係を求めた。その結果は図10に示す通りであり、この本実施の形態における液晶表示素子では、ドレイン電極と共通電極間の距離が設計値から最大ｄ(0.5μm)までずれる可能性がある場合でも、単位画素内に、ドレイン電極と共通電極により８つのグループからなる８の整数倍個の横方向電界領域を形成し、かつ、ドレイン電極と共通電極間の距離のずれが生じても、他の横方向電界領域で互いに補償されるように、各グループの電極間距離をＬ(12μm)，Ｌ(12μm)，Ｌ＋ｄ(12+0.5=12.5μm)，Ｌ−ｄ(12-0.5=11.5μm)，Ｌ＋ｄ／２(12+0.5/2=12.25μm)，Ｌ−ｄ／２(12-0.5/2=11.75μm)，Ｌ＋ｄ／４(12+0.5/4=12.125μm)，Ｌ−ｄ／４(12-0.5/4=11.875μm)と設定することにより、最大透過率差ΔＴmaxを、前記の比較例に係る液晶表示素子の場合に比べて５分の１以下の0.4％以下に抑えることが可能であることがわかる。
【００３６】
以上のように、本実施の形態によれば、単位画素内に８の整数倍個の横方向電界領域を形成しかつ、前記電極間距離をＬ，Ｌ，Ｌ＋ｄ，Ｌ−ｄ，Ｌ＋ｄ／２，Ｌ−ｄ／２，Ｌ＋ｄ／４，Ｌ−ｄ／４に設定することにより、ドレイン電極と共通電極間の距離の相違が生じてもその相違が表示ムラとして認識されにくくすることができる。
【００３７】
【発明の効果】
以上のように本発明によれば、単位画素内にドレイン電極と共通電極により複数の横方向電界領域を形成し、かつ、ドレイン電極と共通電極間の距離の相違が生じても他の横方向電界領域によって互いに補償するように各領域の電極間距離を設定することにより、前記電極間距離の相違が表示ムラとして認識されにくくなり、視角特性も優れている等、液晶表示素子としての表示品位を向上させることができるという有利な効果が得られる。
【図面の簡単な説明】
【図１】本発明の液晶表示素子の実施の形態１における１画素部の平面図である。
【図２】本発明の液晶表示素子の実施の形態１における構成を示す断面図である。
【図３】本発明の液晶表示素子の実施の形態１における電圧−透過率特性のシミュレーションの際想定した電極構成の説明図である。
【図４】最大透過率差の定義を示すためのドレイン電極と共通電極との距離のずれが生じた場合の電圧−透過率特性図である。
【図５】本発明の液晶表示素子の実施の形態１におけるドレイン電極と共通電極との距離のずれ量と最大透過率差の関係図である。
【図６】本発明の比較例における液晶表示素子のドレイン電極と共通電極間の距離のずれ量と最大透過率差との関係図である。
【図７】本発明の液晶表示素子の実施の形態２における１画素部の平面図である。
【図８】本発明の液晶表示素子の実施の形態２におけるドレイン電極と共通電極との距離のずれ量と最大透過率差の関係図である。
【図９】本発明の液晶表示素子の実施の形態３における１画素部の平面図である。
【図１０】本発明の液晶表示素子の実施の形態３におけるドレイン電極と共通電極との距離のずれ量と最大透過率差の関係図である。
【符号の説明】
１…ガラス基板、２…ゲート電極、３…共通電極、４…ゲート絶縁膜、５…ａ−Ｓｉ膜、６…ソース電極、７…ドレイン電極、８…絶縁膜、９…配向膜、 10…対向基板、 11…液晶、 12…偏光板。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display element, and more particularly to a lateral electric field drive type liquid crystal display element having excellent viewing angle characteristics.
[0002]
[Prior art]
In recent years, active matrix liquid crystal display devices have made remarkable progress and have high display quality equivalent to that of CRTs (cathode ray tubes), and are thin, light, and have low power consumption. It is actively applied to small TVs.
[0003]
A TN (Twisted Nematic) NW (Normally White) mode is widely used in such active matrix liquid crystal display elements. In the TN system, a liquid crystal panel having a configuration in which liquid crystal molecules are twisted by 90 ° between substrates is sandwiched between two polarizing plates. Also, the two polarizing plates are bonded so that the polarization axis directions are orthogonal to each other, and the polarization axis of one polarizer is parallel or perpendicular to the major axis direction of the liquid crystal molecules in contact with one substrate. The mode is the NW mode. In the TN type NW mode, no voltage is applied or white is displayed at a low voltage near a certain threshold voltage, and black is displayed at a higher voltage. In this TN liquid crystal display element, when a voltage is applied between the substrates, the liquid crystal molecules attempt to align in the electric field direction while untwisting the twisted structure, but the liquid crystal molecules pass through the panel depending on the alignment state of the liquid crystal molecules at this time. The polarization state of the incoming light changes and the light transmittance is adjusted. By the way, even when the alignment state of the liquid crystal molecules is the same, the light polarization state changes depending on the incident direction of the light incident on the liquid crystal panel, and thus the light transmittance varies with any incident direction. That is, the liquid crystal panel has viewing angle dependency. This viewing angle dependency has the following characteristics. In the NW mode, when a voltage is applied and the liquid crystal molecules rise completely perpendicular to the substrate surface, the black color should be true when viewed from the direction perpendicular to the substrate. This is because the liquid crystal molecules have no optical phase difference when the major axis direction of the molecules is parallel to the light traveling direction, and light passes through the liquid crystal layer without changing the polarization component. Actually, even when a voltage is applied to some extent, the liquid crystal molecules near the substrate interface have a strong interaction with the substrate and are difficult to rise. In addition, since the liquid crystal molecules at the center of the liquid crystal layer do not stand up completely, the optical phase difference is not lost for the light traveling in the direction perpendicular to the substrate, and the true black is not obtained. On the other hand, in such an alignment state, light traveling in a direction substantially equal to the major axis direction of the central portion of the liquid crystal layer has a smaller optical phase difference than light traveling in a direction perpendicular to the substrate. Therefore, when the light is incident on the substrate at an angle of several degrees from the vertical direction, black sinks, and a display with a good contrast ratio can be obtained. However, at this time, the black incident on the incident light from an angle symmetric with respect to the incident angle and the substrate normal line does not suddenly sink. Therefore, an actual liquid crystal panel has a viewing angle characteristic that is remarkably asymmetric with respect to the vertical direction of the screen around the substrate normal.
[0004]
For this reason, in recent years, active matrix liquid crystal display elements have been actively developed for increasing the viewing angle. For example, a drain electrode and a common electrode are formed on the same substrate, and a liquid crystal is driven by a lateral electric field between the drain electrode and the common electrode (for example, Asia Display '95, pages 577 to 580 (ASIA DISPLAY '95 P.577-580)) has been proposed. In this method, since the change in the optical phase difference due to the viewing angle is small, the viewing angle can be increased.
[0005]
[Problems to be solved by the invention]
However, the conventional liquid crystal display element that drives the liquid crystal by the lateral electric field depends on the inter-electrode distance L as represented by (Equation 1).
[0006]
[Expression 1]

[0007]
For this reason, when the drain electrode and the common electrode are formed in different layers, there may be a region where the distance between the drain electrode and the common electrode is different in the panel surface due to misalignment at the time of exposure, and In the region where the distance between the drain electrode and the common electrode is different, the electro-optical characteristics are different as apparent from (Equation 1), so that there is a problem that it is recognized as display unevenness.
[0008]
The present invention solves the above-described conventional problems, and an object thereof is to provide a liquid crystal display element that is less likely to be recognized as display unevenness even when regions having different distances between the drain electrode and the common electrode occur in the panel surface. And
[0009]
[Means for Solving the Problems]
In the liquid crystal display element of the present invention, a plurality of groups of horizontal electric field regions are formed in a unit pixel by a drain electrode and a common electrode, and the distance between the drain electrode and the common electrode that causes display unevenness at the boundary of divided exposure is Even if it occurs, the distance between the electrodes of each group is set so as to compensate each other in the lateral electric field region of the other group .
[0010]
According to the present invention, even if the inter-electrode distance shift occurs, it is less likely to be recognized as display unevenness because it is compensated for in other lateral electric field regions.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol shall be used about the part which is common in each embodiment.
[0012]
(Embodiment 1)
FIG. 1 is a plan view of one pixel portion in the first embodiment of the liquid crystal display element of the present invention, and FIG. 2 is a cross-sectional view showing the configuration in the first embodiment of the liquid crystal display element of the present invention. Here, the distance between the drain electrode and the common electrode of one pixel portion shown in FIG. 1 is designed as a mask as shown in (Table 1).
[0013]
[Table 1]

[0014]
In the liquid crystal display element according to the present embodiment, as shown in FIGS. 1 and 2, a gate electrode 2 and a common electrode 3 made of Cr are formed on a glass substrate 1, and SiNx is covered so as to cover these electrodes. A gate insulating film 4 made of is formed. An a-Si film 5 is formed on the gate electrode 2 via a gate insulating film 4 and serves as an active layer of the transistor. A source electrode 6 and a drain electrode 7 made of Mo are formed so as to overlap a part of the pattern of the a-Si film 5, and an insulating film 8 made of SiNx is formed so as to cover all of them. Here, although all the layers are patterned by divided exposure, in FIG. 1, the apparatus is set so that the drain electrode 7 is never shifted in the right direction even if the alignment is shifted in the left direction. It shall be. A rubbing process is performed after applying the alignment film 9 made of polyimide on the active matrix substrate in which the unit pixels formed in this manner are arranged in a matrix. After the alignment film 9 made of polyimide is applied also to the counter substrate 10, a rubbing process is performed. Liquid crystal 11 is sealed between the active matrix substrate and the counter substrate, and a polarizing plate 12 is disposed on the outer surfaces of the two substrates.
[0015]
In the liquid crystal display device thus fabricated, display unevenness due to the difference in distance between the drain electrode 7 and the common electrode 3 is hardly observed even at the boundary of the divided exposure, and the viewing angle characteristics are evaluated. An excellent viewing angle characteristic of 70 ° or more (contrast ratio of 10 or more) is obtained in both the top, bottom, left, and right.
[0016]
FIG. 3 is an explanatory diagram of an electrode configuration assumed in the simulation of the voltage-transmittance characteristics in the liquid crystal display element according to Embodiment 1 of the present invention, and (Table 2) shows specific electrode intervals. FIG. 4 is a voltage-transmittance characteristic diagram when the distance between the drain electrode and the common electrode is different to show the definition of the maximum transmittance difference, and FIG. 5 is the first embodiment of the liquid crystal display element of the present invention. FIG. 4 is a relationship diagram of a distance shift amount between a drain electrode and a common electrode and a maximum transmittance difference, and will be described below with reference to these drawings.
[0017]
[Table 2]

[0018]
In the liquid crystal display element in this embodiment, in order to clarify the transmittance change amount when the distance between the drain electrode and the common electrode is shifted, an electrode configuration as shown in FIG. 2) The voltage-transmittance characteristics of the liquid crystal cell in the case of the electrode spacing as shown in FIG. 2) are simulated, and the transmittance difference ΔTmax (where the transmittance difference from the reference (when the distance between the electrodes is not shifted) is maximized). (See FIG. 4).
[0019]
FIG. 5 shows the relationship between the deviation obtained from this result and the maximum transmittance difference ΔTmax. From this, in the liquid crystal display element according to the present embodiment, even if the distance between the drain electrode and the common electrode may deviate from the design value up to the maximum d (0.5 μm), the drain electrode and the common electrode within the unit pixel are 4 In order to form a lateral electric field region divided into two groups and to compensate each other in the other lateral electric field regions even if a deviation in the distance between the drain electrode and the common electrode occurs, By setting the distance to L (12 μm), L (12 μm), L + d (12 + 0.5 = 12.5 μm), Ld (12-0.5 = 11.5 μm), the maximum transmittance difference ΔTmax is about 1% or less. It can be seen that it can be suppressed.
[0020]
(Comparative example)
In order to make a comparison with the liquid crystal display element, the liquid crystal display element according to the first embodiment is different except that the distance between the drain electrode and the common electrode is designed as a mask as shown in (Table 3). A liquid crystal display element similar to the above (hereinafter referred to as “comparative example”) was produced by the same method as the liquid crystal display element of the first embodiment.
[0021]
[Table 3]

[0022]
In the liquid crystal display element according to this comparative example, display unevenness that was attributed to the difference in the distance between the drain electrode and the common electrode was observed at the boundary of the divided exposure.
[0023]
In the liquid crystal display element according to this comparative example, in order to clarify the amount of change in transmittance when the distance between the drain electrode and the common electrode is shifted, the shift amount and the maximum transmission are obtained by the same method as in the first embodiment. The relationship of the rate difference ΔTmax was determined. FIG. 6 is a relationship diagram of the amount of shift in the distance between the drain electrode and the common electrode of the liquid crystal display element in the comparative example and the maximum transmittance difference. From FIG. 6, in the liquid crystal display element according to the comparative example, It can be seen that when the distance between the common electrodes deviates by a maximum of 0.5 μm from the design value, the maximum transmittance difference ΔTmax is about 2%, which is about twice that of the liquid crystal display element according to the first embodiment.
[0024]
As described above, according to the present embodiment, when there is a possibility that the distance between the drain electrode and the common electrode may be shifted by a maximum d from the design value, four drain electrodes and the common electrode are included in the unit pixel. An electrode of each group is formed so as to form a lateral electric field region that is an integral multiple of 4 groups, and to compensate each other in the other lateral regions even if a deviation in distance between the drain electrode and the common electrode occurs. By setting the distances to L, L, L + d, and L−d, even if a difference in distance between the drain electrode and the common electrode occurs, the difference can be made difficult to be recognized as display unevenness.
[0025]
(Embodiment 2)
FIG. 7 is a plan view of one pixel portion in the second embodiment of the liquid crystal display element of the present invention, and FIG. 8 is a shift amount of the distance between the drain electrode and the common electrode in the second embodiment of the liquid crystal display element of the present invention. FIG. Here, the distance between the drain electrode and the common electrode shown in FIG. 7 is designed as a mask as shown in (Table 4).
[0026]
[Table 4]

[0027]
The cross-sectional structure of the liquid crystal display element according to the present embodiment is the same as that of the first embodiment shown in FIG. 2, and the mask is designed so that the distance between the drain electrode and the common electrode is shown in (Table 4). Only the point is different. A liquid crystal display element having such a configuration was manufactured by the same method as in the first embodiment. Here, as in the first embodiment, the drain electrode 7 is set in FIG. 7 so that the alignment is not shifted in the right direction even if the alignment is shifted in the left direction. .
[0028]
In the liquid crystal display device thus manufactured, display unevenness due to the difference in distance between the drain electrode 7 and the common electrode 3 is hardly observed even at the boundary portion of the divided exposure, and the viewing angle characteristics of the liquid crystal display device are As a result of evaluation, an excellent viewing angle characteristic of 70 ° or more (contrast ratio of 10 or more) is obtained in both the upper, lower, left, and right directions.
[0029]
In order to clarify the transmittance change amount when the distance between the drain electrode and the common electrode in the liquid crystal display element of the present embodiment is changed, the amount of shift and the maximum transmittance are obtained by the same method as in the first embodiment. The relationship of the difference ΔTmax was obtained. The result is as shown in FIG. 8, and in the liquid crystal display element according to the present embodiment, even when the distance between the drain electrode and the common electrode may deviate from the design value to the maximum d (0.5 μm), the unit pixel An integral multiple of 6 lateral field regions composed of 6 groups are formed by the drain electrode and the common electrode, and another lateral field is generated even if the distance between the drain electrode and the common electrode is shifted. The distances between the electrodes in each group are L (12 μm), L (12 μm), L + d (12 + 0.5 = 12.5 μm), L−d (12−0.5 = 11.5 μm), L + d / 2 (12 + 0.5 / 2 = 12.25 μm) and Ld / 2 (12-0.5 / 2 = 11.75 μm), the maximum transmittance difference ΔTmax is set to the value of the liquid crystal display device according to the comparative example. It can be seen that it can be suppressed to 0.5% or less, which is 1/4 or less than the case.
[0030]
As described above, according to the present embodiment, an integral multiple of six horizontal electric field regions are formed in a unit pixel, and the distance between the electrodes is set to L, L, L + d, Ld, L + d / By setting to 2, L−d / 2, even if a difference in distance between the drain electrode and the common electrode occurs, the difference can be hardly recognized as display unevenness.
[0031]
(Embodiment 3)
FIG. 9 is a plan view of one pixel portion in the third embodiment of the liquid crystal display element of the present invention, and FIG. 10 is a shift amount of the distance between the drain electrode and the common electrode in the third embodiment of the liquid crystal display element of the present invention. FIG. The distance between the drain electrode and the common electrode shown in FIG. 7 is designed as a mask as shown in (Table 5).
[0032]
[Table 5]

[0033]
The cross-sectional structure of the liquid crystal display element according to the present embodiment is the same as that of the first embodiment shown in FIG. 2, and the mask is designed so that the distance between the drain electrode and the common electrode is shown in (Table 5). Only the point is different. A liquid crystal display element having such a configuration was manufactured by the same method as in the first embodiment. Here, as in the first embodiment, the drain electrode 7 is set in FIG. 7 so that the alignment is not shifted in the right direction even if the alignment is shifted in the left direction. .
[0034]
In the liquid crystal display device thus manufactured, display unevenness due to the difference in distance between the drain electrode 7 and the common electrode 3 is hardly observed even at the boundary portion of the divided exposure, and the viewing angle characteristics of the liquid crystal display device are As a result of evaluation, an excellent viewing angle characteristic of 70 ° or more (contrast ratio of 10 or more) is obtained in both the upper, lower, left, and right directions.
[0035]
In order to clarify the transmittance change amount when the distance between the drain electrode and the common electrode in the liquid crystal display element of the present embodiment is changed, the amount of shift and the maximum transmittance are obtained by the same method as in the first embodiment. The relationship of the difference ΔTmax was obtained. The result is as shown in FIG. 10. In the liquid crystal display element according to the present embodiment, even when the distance between the drain electrode and the common electrode may deviate from the design value to the maximum d (0.5 μm), the unit An integer multiple of eight lateral electric field regions consisting of eight groups are formed in the pixel by the drain electrode and the common electrode, and another lateral direction is generated even if the distance between the drain electrode and the common electrode is shifted. The distance between the electrodes in each group is L (12 μm), L (12 μm), L + d (12 + 0.5 = 12.5 μm), L−d (12−0.5 = 11.5 μm), L + d so as to compensate each other in the electric field region. / 2 (12 + 0.5 / 2 = 12.25 μm), Ld / 2 (12-0.5 / 2 = 11.75 μm), L + d / 4 (12 + 0.5 / 4 = 12.125 μm), Ld / 4 (12 -0.5 / 4 = 11.875μm), the maximum transmittance difference ΔTmax can be suppressed to 0.4% or less, which is 1/5 or less compared to the case of the liquid crystal display element according to the comparative example. Ah I understand that
[0036]
As described above, according to the present embodiment, an integral multiple of eight horizontal electric field regions are formed in a unit pixel, and the distance between the electrodes is set to L, L, L + d, L-d, L + d / 2. , L−d / 2, L + d / 4, and L−d / 4, even if a difference in distance between the drain electrode and the common electrode occurs, the difference can be made difficult to be recognized as display unevenness.
[0037]
【The invention's effect】
As described above, according to the present invention, a plurality of lateral electric field regions are formed in the unit pixel by the drain electrode and the common electrode, and other lateral directions are generated even if the distance between the drain electrode and the common electrode is different. By setting the distance between the electrodes in each region so as to compensate each other depending on the electric field region, the difference in the distance between the electrodes becomes difficult to be recognized as display unevenness, and the display quality as a liquid crystal display element is excellent. It is possible to obtain an advantageous effect that it can be improved.
[Brief description of the drawings]
FIG. 1 is a plan view of one pixel portion in a first embodiment of a liquid crystal display element of the present invention.
FIG. 2 is a cross-sectional view showing the configuration of the liquid crystal display element according to the first embodiment of the present invention.
FIG. 3 is an explanatory diagram of an electrode configuration assumed in the simulation of voltage-transmittance characteristics in the first embodiment of the liquid crystal display element of the present invention.
FIG. 4 is a voltage-transmittance characteristic diagram in the case where there is a shift in the distance between the drain electrode and the common electrode for illustrating the definition of the maximum transmittance difference.
FIG. 5 is a relationship diagram between the amount of deviation of the distance between the drain electrode and the common electrode and the maximum transmittance difference in the liquid crystal display element according to the first embodiment of the present invention.
FIG. 6 is a relational diagram between the amount of shift in the distance between the drain electrode and the common electrode of the liquid crystal display element and the maximum transmittance difference in the comparative example of the present invention.
7 is a plan view of one pixel portion in a second embodiment of the liquid crystal display element of the present invention. FIG.
FIG. 8 is a relational diagram between the amount of shift in the distance between the drain electrode and the common electrode and the maximum transmittance difference in the liquid crystal display element according to the second embodiment of the present invention.
FIG. 9 is a plan view of one pixel portion in a third embodiment of the liquid crystal display element of the present invention.
FIG. 10 is a relationship diagram between a deviation amount of a distance between a drain electrode and a common electrode and a maximum transmittance difference in Embodiment 3 of the liquid crystal display element of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Gate electrode, 3 ... Common electrode, 4 ... Gate insulating film, 5 ... a-Si film, 6 ... Source electrode, 7 ... Drain electrode, 8 ... Insulating film, 9 ... Alignment film, 10 ... Counter substrate, 11 ... liquid crystal, 12 ... polarizing plate.

Claims

Liquid crystal is sandwiched between a first substrate and a second substrate having a drain electrode and a common electrode that is at least partially opposed to the drain electrode and formed on a different layer from the drain electrode through an insulating film. In a lateral electric field drive type liquid crystal display element that drives liquid crystal molecules by a lateral electric field between the drain electrode and the common electrode in a direction substantially parallel to the substrate, the distance between the drain electrode and the common electrode is more In the case where there is a possibility that the maximum d is shifted , an integer multiple of four lateral electric field regions consisting of four groups are formed in the unit pixel by the drain electrode and the common electrode, and display unevenness is caused at the boundary of the divided exposure. even if the deviation of the distance between the common electrode and the drain electrode made occurs, as is compensated each other in the horizontal electric field region of the other group, L a distance between electrodes of each group, respectively, L, L + d, L The liquid crystal display element characterized in that it is set to d.

Liquid crystal is sandwiched between a first substrate and a second substrate having a drain electrode and a common electrode that is at least partially opposed to the drain electrode and formed on a different layer from the drain electrode through an insulating film. In a lateral electric field drive type liquid crystal display element that drives liquid crystal molecules by a lateral electric field between the drain electrode and the common electrode in a direction substantially parallel to the substrate, the distance between the drain electrode and the common electrode is more If there is a possibility that even deviate up to d, to form a lateral electric field region of 6 integers Baiko of six groups by the common electrode and the drain electrode in the unit pixel, and the display unevenness at the boundary of the divided exposure The distance between the electrodes in each group is L, L, L + d, L so that even if a deviation in the distance between the drain electrode and the common electrode is compensated for in the lateral electric field region of the other group, d, a liquid crystal display element characterized in that it is set to L + d / 2, L- d / 2.

Liquid crystal is sandwiched between a first substrate and a second substrate having a drain electrode and a common electrode that is at least partially opposed to the drain electrode and formed on a different layer from the drain electrode through an insulating film. In a lateral electric field drive type liquid crystal display element that drives liquid crystal molecules by a lateral electric field between the drain electrode and the common electrode in a direction substantially parallel to the substrate, the distance between the drain electrode and the common electrode is more If there is a possibility that the maximum d is shifted, a horizontal electric field region divided into eight groups by the drain electrode and the common electrode is formed in the unit pixel, and the drain electrode that causes display unevenness at the boundary of the divided exposure even if the deviation of the distance between the common electrode occurs, as is compensated with each other by the lateral electric field region of the other group, the distance between the electrodes of each group are L, L, L + d, L- , L + d / 2, L -d / 2, L + d / 4, a liquid crystal display element characterized in that it is set to L-d / 4.

4. The electrode according to claim 1 , wherein the common electrode and the drain electrode are formed on the first substrate by using an apparatus in which only one direction is misaligned. The manufacturing method of the liquid crystal display element as described in any one .