JP3663783B2 - Liquid crystal display - Google Patents
Liquid crystal display Download PDFInfo
- Publication number
- JP3663783B2 JP3663783B2 JP28409196A JP28409196A JP3663783B2 JP 3663783 B2 JP3663783 B2 JP 3663783B2 JP 28409196 A JP28409196 A JP 28409196A JP 28409196 A JP28409196 A JP 28409196A JP 3663783 B2 JP3663783 B2 JP 3663783B2
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- optical compensation
- compensation layer
- refractive index
- crystal cell
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Liquid Crystal (AREA)
- Polarising Elements (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、視野角特性、特に、表示コントラストおよび階調反転の視野角特性が改善された液晶表示装置に関するものである。
【０００２】
【従来の技術】
液晶表示装置（以下、ＬＣＤと表わす）として現在最もよく用いられているものは、透明電極を形成した一対のガラス基板の間に、ガラス基板の法線方向に螺旋軸を有し、そのネジレ角度が約９０度であるような配向構造を有したネマチック液晶を挟持した液晶セルが、吸収軸が直交となるように配置された一対の直線偏光フィルムの間に挟まれた、ノーマリホワイト（以下、ＮＷと表わす）モードのツイステッドネマチック型ＬＣＤ（以下、ＴＮ−ＬＣＤと表わす）である。ＮＷモードのＴＮ−ＬＣＤは、電圧を印加しない状態では入射した直線偏光が液晶セルの旋光性により９０度回転して出射されるため白状態となり、電圧を印加した状態では液晶分子がガラス基板に対して起き上がり、旋光性が消失し入射した直線偏光はその状態を保ったまま出射されるため黒状態となる。また、この白状態、黒状態とその中間状態を利用することで、階調表示を行っている。
【０００３】
しかし、ＬＣＤに用いられるネマチック液晶は、分子構造が棒状で、分子軸方向の屈折率が大きい正の屈折率異方性を示すものであり、ＬＣＤを斜めに通過する光の偏光状態の変化は、この液晶の屈折率異方性による位相差のためにＬＣＤの法線方向とは異なったものとなる。このため、ＬＣＤの法線方向から外れた角度から表示を見た場合、コントラストの低下や、階調表示が逆転する階調反転などの現象が起こるという視野角特性を示す。
【０００４】
この視野角特性は液晶分子の屈折率異方性が原因であることから、液晶分子の屈折率異方性による位相差を補償するために、液晶とは逆の屈折率異方性を示す位相差フィルムを用いた改良が検討されている。視野角特性の改良は、主として黒表示、即ち電圧印加状態における視野角特性を改良することで、大きな効果が得られる。電圧印加状態では液晶分子はガラス基板に垂直に近い状態に配向していることから、この状態をガラス基板法線方向に光学軸を有する正の屈折率異方体と見なし、これを補償する位相差フィルムとして、フィルム法線方向に光学軸を有しかつ負の屈折率異方性を有する位相差フィルムを用いる方法が、特開平２−０１５２３９号公報や特開平３−１０３８２３号公報などに開示されている。しかしながら、実際のＬＣＤにおいては、電圧印加状態にあっても、ガラス基板付近の液晶分子は基板の配向膜の拘束力に起因して、ガラス基板に近い部分では傾斜状態のままであるため、フィルム法線方向に光学軸を有しかつ負の屈折率異方性を有する位相差フィルムでは、液晶セルによりもたらされる偏光状態を十分に補償することは難しい。
【０００５】
このような傾斜状態の液晶分子をも併せて補償するため、光学軸がフィルム法線方向から傾斜した方向にありかつ負の屈折率異方性を有する位相差フィルムを用いる方法も、特開昭６３−２３９４２１号公報や特開平６−２１４１１６号公報などに記載されている。しかし、これらの方法では、電圧印加状態の液晶セルに対する補償状態は改善されるものの、印加電圧がより低いために傾斜状態の液晶部分が増加してより複雑な配向形態をとる中間階調表示状態においては、補償が不完全となるため、表示コントラストの視野角は改善されるが、階調反転現象を改善することは困難であり、結果として不完全な視野角特性しか得ることができない。
【０００６】
また別の方法として、液晶と同じ正の屈折率異方性を持ちながらも、光学軸をフィルム法線方向から傾斜させた状態とした位相差板を用いても視野角特性を改良できることが、特開平５−０８０３２３号公報、特開平７−３０６４０６号公報やＷＯ９６／１０７７３号公報などに記載されている。これらの報告では、正の屈折率異方性を有しかつ光学軸をフィルム法線方向から傾斜させた状態とした位相差板を用いることが液晶セルの階調反転を抑制するのに有効であることが示されているが、いかなる形態で使用した場合にその効果が発現されるのかに関しては何ら具体的には言及されていない。
【０００７】
【発明が解決しようとする課題】
このようにＴＮ−ＬＣＤの視野角特性の改良に用いられる光学補償板については、表示コントラストのみならず階調反転も合わせたトータルでの視野角特性を飛躍的に改善できるものは見いだされていない状況にあった。かかる状況に鑑み、本発明者らが鋭意検討した結果、光学的に正の屈折率異方性を有しかつ光学軸がフィルム法線方向から２０〜７０°傾斜している特性を有する光学補償層に対し、フィルム面内に屈折率異方性が殆ど存在せず、フィルム厚み方向の屈折率が面内の屈折率より小さい特性を有する光学補償層、および、正の屈折率異方性を有する一軸配向性の光学補償層を組合せ、さらにこれら３種の特性の異なる光学補償層を偏光板と液晶セルに対して特定の順序で積層して用いることにより、表示コントラストと階調反転の両方の視野角特性を大幅に改善できることを見い出し、本発明を完成するに至った。
【０００８】
【課題を解決するための手段】
すなわち本発明は、ツイスト角が略９０°のねじれネマチック型液晶セルおよびこのセルの両側に配置された２枚の偏光板からなるノーマリーホワイトモードの液晶表示装置において、
(1) フィルム面内に屈折率異方性が殆ど存在せず、フィルム厚み方向の屈折率が面内の屈折率より小さい特性を有する光学補償層（Ａ）、
(2) 光学的に正の屈折率異方性を有しかつ光学軸がフィルム法線方向から２０〜７０°傾斜している特性を有する光学補償層（Ｂ）、および
(3) 光学的に正の屈折率異方性を有する一軸配向性の光学補償層（Ｃ）
の３種の特性の異なる光学補償層がそれぞれ少なくとも１層ずつ、液晶セルとその両側の偏光板との間に、偏光板／光学補償層（Ａ）／光学補償層（Ｂ）／光学補償層（Ｃ）／液晶セル／光学補償層（Ｃ）／光学補償層（Ｂ）／光学補償層（Ａ）／偏光板、の順に積層されていることを特徴とする液晶表示装置に関するものである。
【０００９】
【発明の実施の形態】
本発明に用いる、フィルム面内に屈折率異方性が殆ど存在せず、フィルム厚み方向の屈折率が面内の屈折率より小さい特性を有する光学補償層（Ａ）としては、必要な光学特性を満たすものであれば特に限定されるものではなく、例えば、溶剤キャスト法による製膜時の高分子の配向により、フィルム面内のレターデーションは小さく、かつフィルム厚み方向の屈折率（ｎt ）がフィルム面内の平均屈折率（ｎp ）よりも小さいという屈折率構造を持たせた透明高分子のキャストフィルムや、透明高分子の二軸延伸フィルム、特開平５−１９６８１９号公報に記載されている無機層状化合物を用いた位相差板、特開平５−２４９４５７号公報に記載されている屈折率の異なる物質の交互多層薄膜による補償板等を用いることができる。
【００１０】
フィルム面内に屈折率異方性が殆ど存在せず、フィルム厚み方向の屈折率が面内の屈折率より小さい特性を有する光学補償層（Ａ）の光学特性は、面内のレターデーション値（ＲA ）、および厚み方向のレターデーション値（ＲA'＝(ｎp−ｎt)×ｄ、ｄ：フィルム厚み）により規定される。これらの値は、使用する液晶セルの光学特性および最終的に必要とされる視野角特性により適宜選択されるが、通常はＲA ＝０〜１００nm、ＲA'＝５０〜２５０nmの範囲で用いられる。
【００１１】
本発明に用いる、光学的に正の屈折率異方性を有しかつ光学軸がフィルム法線方向から２０〜７０°傾斜している特性を有する光学補償層（Ｂ）としては、必要な光学特性を満たすものであれば特に限定されるものではなく、例えば、特開平４−１２０５１２号公報や特開平６−２２２２１３号公報に記載されている熱可塑性樹脂を電場や磁場印加あるいは異周速圧延により配向させた傾斜配向シート、特開平７−１５２０３５号公報や特開平７−１９１２１６号公報に記載されている電場や磁場等の印加下あるいは配向膜による配向制御下での配向固定による液晶性重合体の傾斜配向層、また、ＷＯ９６／１０７７３号公報に記載されている透明基板上への無機誘電体等の斜方蒸着による光学異方性層等を用いることができる。
【００１２】
光学的に正の屈折率異方性を有しかつ光学軸がフィルム法線方向から２０〜７０°傾斜している特性を有する光学補償層（Ｂ）の光学特性は、光学軸の液晶セル基板の法線方向からの傾斜角度（θ）、および光学補償層正面から測定した場合のレターデーション値（ＲB ）により規定される。これらの値は、使用する液晶セルの光学特性および最終的に必要とされる視野角特性により適宜選択されるが、通常はθ＝２０〜７０°、ＲB ＝２０〜２００nmの範囲で用いられる。
【００１３】
本発明に用いる、光学的に正の屈折率異方性を有する一軸配向性の光学補償層（Ｃ）としては、必要な光学特性を満たすものであれば特に限定されるものではなく、例えば、一般的に位相差板として用いられている熱可塑性樹脂の一軸延伸フィルムや、液晶性物質の面内一軸配向層等を用いることができる。
【００１４】
光学的に正の屈折率異方性を有する一軸配向性の光学補償層（Ｃ）の光学特性は、補償層面内のレターデーション値（ＲC ）により規定され、この値は、使用する液晶セルの光学特性および最終的に必要とされる視野角特性により適宜選択されるが、通常は ＲC＝１０〜１００nmの範囲である。
【００１５】
３種の特性の異なる光学補償層は、液晶セルとその両側の偏光板との間に、偏光板／光学補償層（Ａ）／光学補償層（Ｂ）／光学補償層（Ｃ）／液晶セル／光学補償層（Ｃ）／光学補償層（Ｂ）／光学補償層（Ａ）／偏光板、の順に積層される。各々の光学補償層（Ａ）、（Ｂ）、（Ｃ）は、前述の各光学補償層がそれぞれ１枚ずつであってもよいし、必要であれば各層内に複数の光学補償層を用いてもよい。
【００１６】
本発明の光学補償層の積層構成においては、液晶セルの光入射側および光出射側の各基板のラビング方向と、各々の側に配置される光学的に正の屈折率異方性を有しかつ光学軸がフィルム法線方向から２０〜７０°傾斜している特性を有する光学補償層（Ｂ）の光学軸の方向との関係が、視野角特性の改良効果に大きな影響を与える。光学軸の方向は、使用する液晶セルの光学特性および最終的に必要とされる視野角特性により適宜選択されるが、液晶セルの光出射側から見た場合に光学補償層（Ｂ）の光学軸の上側になる方向が、液晶セルの光入射側および光出射側においてそれぞれに近い側の液晶セル基板のラビング方向に対して、液晶セルの光出射側から見て左回りの方向を正としたときに略＋１８０°の関係になるよう設定した場合、視野角改良効果が最も大きく発現する。
【００１７】
さらに、本発明の光学補償層の積層構成においては、液晶セルの光入射側および光出射側の各基板のラビング方向と、光学的に正の屈折率異方性を有する一軸配向性の光学補償層（Ｃ）の遅相軸の方向の関係が、視野角特性の改良効果に大きな影響を与える。遅相軸の方向は、使用する液晶セルの光学特性および最終的に必要とされる視野角特性により適宜選択されるが、液晶セルの光入射側および光出射側においてそれぞれに近い側の液晶セル基板のラビング方向に対して略垂直の関係になるよう設定した場合、視野角改良効果がより大きく発現する。
【００１８】
セル両側の偏光板の吸収軸方向は、最終的に必要とされるＬＣＤの光学特性に応じて、光入射側および光出射側のいずれもそれぞれに近い側の液晶セル基板のラビング方向に対して略垂直（Ｅモード）あるいは略平行（Ｏモード）のいずれかより選択される。なお、本発明における光学補償層のレターデーション値（ＲA 、ＲA'、ＲB 、ＲC ）および光学軸の傾斜方向は、当業者においては常法に基づく測定により得られるものである。
【００１９】
【発明の効果】
本発明により、表示コントラストおよび階調反転の視野角特性が著しく改善されたＴＮ−ＬＣＤを得ることができる。
【００２０】
【実施例】
以下、実施例により本発明を詳細に説明するが、本発明はこれに限定されるものではない。
【００２１】
実施例１
特開平５−１９６８１９号公報に記載された方法に基づき、フィルム面内に屈折率異方性が殆ど存在せずフィルム厚み方向の屈折率が面内の屈折率より小さい特性を有する光学補償層（Ａ１）を作製した。また、ＷＯ９６／１０７７３号公報に記載された方法に基づき、光学的に正の屈折率異方性を有しかつ光学軸がフィルム法線方向から４５°傾斜している特性を有する光学補償層（Ｂ１）を作製した。さらに、溶剤キャスト法により製膜されたポリカーボネートフィルムを一軸延伸することにより、光学的に正の屈折率異方性を有する一軸配向性の光学補償層（Ｃ１）を作製した。シャープ（株）製のＴＦＴ−ＴＮ液晶テレビ（ＣＲＹＳＴＡＬＴＲＯＮ、４Ｅ−Ｌ１）の液晶セルとその両側の偏光板との間に、上記の３種の光学補償層を、偏光板／光学補償層（Ａ１）／光学補償層（Ｂ１）／光学補償層（Ｃ１）／液晶セル／光学補償層（Ｃ１）／光学補償層（Ｂ１）／光学補償層（Ａ１）／偏光板の順に積層してＴＮ−ＬＣＤを作製した。このとき、液晶セルの光出射側から見た場合に光学補償層（Ｂ１）の光学軸の上側になる方向が、液晶セルの光入射側および光出射側においてそれぞれに近い側の液晶セル基板のラビング方向に対して＋１８０°の関係になり、かつ、光学補償層（Ｃ１）の遅相軸の方向が液晶セルの光入射側および光出射側においてそれぞれに近い側の液晶セル基板のラビング方向に対して垂直の関係になるように設定した。このＴＮ−ＬＣＤにおいては、表示コントラストおよび階調反転の視野角特性はいずれも上下左右すべての方向で良好であり、従来のＴＮ−ＬＣＤと比較してはるかに優れたものであった。
【００２２】
実施例２
ＷＯ９６／１０７７３号公報に記載された方法に基づき、光学的に正の屈折率異方性を有しかつ光学軸がフィルム法線方向から６５°傾斜している特性を有する光学補償層（Ｂ２）を作製した。光学補償層（Ｂ）として上記の光学補償層（Ｂ２）を用いたほかは実施例１と同様にして、３種の光学補償層を積層したＴＮ−ＬＣＤを作製した。このＴＮ−ＬＣＤにおいては、表示コントラストおよび階調反転の視野角特性はいずれも上下左右すべての方向で良好であり、従来のＴＮ−ＬＣＤと比較してはるかに優れたものであった。
【００２３】
比較例１
光学補償層の積層順序を、偏光板／光学補償層（Ｃ１）／光学補償層（Ｂ１）／光学補償層（Ａ１）／液晶セル／光学補償層（Ａ１）／光学補償層（Ｂ１）／光学補償層（Ｃ１）／偏光板の順にしたほかは実施例１と同様にして、３種の光学補償層を積層したＴＮ−ＬＣＤを作製した。このＴＮ−ＬＣＤにおいては、左右および下方向の表示コントラストの視野角は良好であったが、上方向は悪く、また階調反転の視野角特性は上下左右ともあまり良好ではなかった。[0001]
BACKGROUND OF THE INVENTION
The present invention, viewing angle characteristics, in particular, to a liquid crystal display device which viewing angle characteristics of display contrast and gray scale inversion is improved.
[0002]
BACKGROUND of technology]
The liquid crystal display device (hereinafter, referred to as LCD) those currently used most frequently as is between a pair of glass substrates forming a transparency electrode has a helical axis in the normal direction of the glass substrate, the torsion A normally white liquid crystal cell in which a nematic liquid crystal having an alignment structure with an angle of about 90 degrees is sandwiched between a pair of linearly polarizing films arranged so that the absorption axes are orthogonal to each other ( This is a twisted nematic type LCD (hereinafter referred to as NW) mode (hereinafter referred to as TN-LCD). In the TN-LCD in NW mode, when no voltage is applied, the incident linearly polarized light is rotated 90 degrees due to the optical rotation of the liquid crystal cell and is emitted, and in a state where the voltage is applied, the liquid crystal molecules are applied to the glass substrate. On the other hand, it rises, the optical rotation disappears, and the incident linearly polarized light is emitted while maintaining this state, so that it becomes a black state. Further, gradation display is performed by utilizing the white state, the black state, and the intermediate state.
[0003]
However, nematic Ji click liquid crystal used in the LCD, the molecular structure is rod-shaped, which shows a positive refractive index anisotropy is large refractive index of the molecular axis direction, the polarization state of the light passing through the LCD obliquely changes, becomes different from the normal direction of the LCD for a phase difference due to a refractive index anisotropy of the liquid crystal. Therefore, it is shown when viewing the display from an angle deviating from the normal direction of the LCD, lowering of contrast, viewing angle characteristic that phenomenon occurs, such as a tone reversal that gradation display is reversed.
[0004]
This viewing angle characteristic is caused by the refractive index anisotropy of the liquid crystal molecules. Therefore, in order to compensate for the phase difference due to the refractive index anisotropy of the liquid crystal molecules, the viewing angle characteristic has a refractive index anisotropy opposite to that of the liquid crystal. Improvements using phase difference films are being studied. Improvement of viewing angle characteristics are primarily black display, i.e., to improve the viewing angle characteristics in the voltage applied state, a large effect is obtained. Since the liquid crystal molecules in the voltage applied state are oriented state nearly vertical to the glass substrate, to considered this an positive refractive index anisotropic material having an optical axis in a glass substrate normal direction, compensate for this to as a retardation film, a method of using a retardation film having a and negative refractive index anisotropy has an optical axis in a film normal direction, JP-a-2-015239 Publication and JP-a-3-103823 discloses such Is disclosed. However, in an actual LCD, even when a voltage is applied , the liquid crystal molecules in the vicinity of the glass substrate remain tilted near the glass substrate due to the binding force of the alignment film on the substrate. In a retardation film having an optical axis in the normal direction and negative refractive index anisotropy, it is difficult to sufficiently compensate the polarization state caused by the liquid crystal cell.
[0005]
To compensate also allowed 併 the liquid crystal molecules in such a tilted state, a method of using a retardation film having there and negative refractive index anisotropy in the direction in which light science axis is inclined from the film normal direction, especially This is described in, for example, Japanese Unexamined Patent Publication No. 63-239421 and Japanese Unexamined Patent Publication No. Hei 6-214116. However, in these methods, although the compensation state for the liquid crystal cell of the voltage application state is improved, halftone display state the liquid crystal portion of the inclined state applied voltage to lower is increased take a more complex orientation form in order to compensate is incomplete, but the viewing angle of the display contrast is improved, it is difficult to improve the gradation inversion phenomenon, it is only possible to obtain an incomplete viewing angle characteristics as a result.
[0006]
As another method, while having the same positive refractive index anisotropy as liquid crystal, the viewing angle characteristics can be improved even by using a retardation plate in which the optical axis is inclined from the film normal direction. It is described in JP-A-5-080323, JP-A-7-306406, WO96 / 10773, and the like. In these reports, the use of a retardation plate having a positive refractive index anisotropy and an optical axis inclined from the normal direction of the film is effective in suppressing gradation reversal of the liquid crystal cell. Although it has been shown, there is no specific mention regarding what form the effect is manifested when used.
[0007]
[Problems to be solved by the invention]
Thus, no optical compensator used for improving the viewing angle characteristics of the TN-LCD has been found to dramatically improve the total viewing angle characteristics including not only display contrast but also gradation inversion. Was in the situation. In view of this situation, as a result of intensive studies by the present inventors, optical compensation has a characteristic of having an optically positive refractive index anisotropy and an optical axis inclined by 20 to 70 ° from the film normal direction. to the layer, the refractive index anisotropy scarcely present in the film plane, an optical compensation layer where the refractive index of the film thickness direction has a smaller characteristic than the refractive index in the plane, and, the positive refractive index anisotropy both uniaxial orientation combining optical compensation layer, further by using laminated in a specific order with respect to the different optical compensation layer of these three characteristics polarizing plate and the liquid crystal cell, display contrast and gray scale inversion with It was found that the viewing angle characteristics can be greatly improved, and the present invention has been completed.
[0008]
[Means for Solving the Problems]
That is, the present invention relates to a normally white mode liquid crystal display device comprising a twisted nematic liquid crystal cell having a twist angle of approximately 90 ° and two polarizing plates disposed on both sides of the cell.
(1) an optical compensation layer (A) having almost no refractive index anisotropy in the film plane and having a characteristic that the refractive index in the film thickness direction is smaller than the refractive index in the plane ;
(2) an optical compensation layer (B) having an optically positive refractive index anisotropy and an optical axis inclined by 20 to 70 ° from the film normal direction ; and
(3) Uniaxially oriented optical compensation layer having optically positive refractive index anisotropy (C)
Each of the three types of optical compensation layers having different properties is provided between the liquid crystal cell and the polarizing plates on both sides thereof, and polarizing plate / optical compensation layer (A) / optical compensation layer (B) / optical compensation layer. (C) / liquid crystal cell / optical compensation layer (C) / the optical compensation layer (B) / it is relates to a liquid crystal display equipment, characterized in that the optical compensation layer (a) / the polarizing plate, which is of laminated in this order is there.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The optical compensation layer (A) used in the present invention has almost no refractive index anisotropy in the plane of the film, and the refractive index in the film thickness direction is smaller than the refractive index in the plane. It is not particularly limited as long as it satisfies, for example, by the orientation of the polymer during film by the solvent casting method, a small retardation in the film plane, and the film thickness direction of the refractive index (n t) Is described in JP-A-5-196819, a transparent polymer cast film having a refractive index structure that is smaller than the average refractive index (n p ) in the film plane, and a biaxially stretched film of a transparent polymer. A retardation plate using an inorganic layered compound, a compensation plate made of alternating multilayer thin films of substances having different refractive indexes, and the like described in JP-A-5-249457 can be used.
[0010]
The optical properties of the optical compensation layer (A) having almost no refractive index anisotropy in the film plane and the refractive index in the film thickness direction being smaller than the refractive index in the plane are in-plane retardation values ( RA), and the thickness direction retardation value (RA '= (n p -n t) × d, d: is defined by the film thickness). These values may be selected as appropriate by the viewing angle characteristics are optical characteristics Contact and ultimately required of the liquid crystal cell to be used is usually within a range of RA = 0~100nm, RA '= 50~250nm It is done.
[0011]
The optical compensation layer (B) used in the present invention has an optically positive refractive index anisotropy and an optical axis tilted by 20 to 70 ° from the film normal direction. The material is not particularly limited as long as it satisfies the characteristics. For example, the thermoplastic resin described in JP-A-4-120512 and JP-A-6-222213 is applied with an electric field, a magnetic field, or different peripheral speed rolling. liquid crystal due to the orientation fixed under orientation control of applied under or alignment film has that electric field or a magnetic field or the like is described in inclined orientation sheet, JP-a-7-152035 and JP-a-7-191216 discloses that was oriented by An optically anisotropic layer formed by oblique vapor deposition of an inorganic dielectric or the like on a transparent substrate described in WO96 / 10773 can be used.
[0012]
The optical characteristic of the optical compensation layer (B) having the optically positive refractive index anisotropy and the characteristic that the optical axis is inclined by 20 to 70 ° from the film normal direction is the liquid crystal cell substrate of the optical axis. Is defined by the inclination angle (θ) from the normal direction and the retardation value (RB) when measured from the front of the optical compensation layer. Use these values is suitably selected according to the viewing angle characteristics are optical characteristics Contact and ultimately required of the liquid crystal cell to be used, usually theta = 20 to 70 °, in the range of RB = 20 to 200 nm I can .
[0013]
The uniaxially oriented optical compensation layer (C) having an optically positive refractive index anisotropy used in the present invention is not particularly limited as long as it satisfies the necessary optical characteristics. A uniaxially stretched thermoplastic resin film generally used as a retardation plate, an in-plane uniaxial alignment layer of a liquid crystalline substance, or the like can be used.
[0014]
The optical characteristics of the uniaxially oriented optical compensation layer (C) having optically positive refractive index anisotropy are defined by the retardation value (RC) in the compensation layer surface, and this value is the value of the liquid crystal cell used. it is appropriately selected according to the viewing angle characteristics which are finally required optical characteristics Contact and typically in the range of RC = 10 to 100 nm.
[0015]
The three types of optical compensation layers having different characteristics are polarizing plate / optical compensation layer (A) / optical compensation layer (B) / optical compensation layer (C) / liquid crystal cell between the liquid crystal cell and the polarizing plates on both sides thereof. / Optical compensation layer (C) / Optical compensation layer (B) / Optical compensation layer (A) / Polarizing plate. Each of the optical compensation layers (A), (B), and (C) may include one optical compensation layer described above, and if necessary, a plurality of optical compensation layers may be used in each layer. May be.
[0016]
The laminated structure of the optical compensation layer of the present invention has a rubbing direction of each substrate on the light incident side and light emitting side of the liquid crystal cell and an optically positive refractive index anisotropy disposed on each side. In addition, the relationship with the direction of the optical axis of the optical compensation layer (B) having the characteristic that the optical axis is inclined by 20 to 70 ° from the normal direction of the film has a great influence on the effect of improving the viewing angle characteristic. Direction of the optical axis is appropriately selected according to the viewing angle characteristics are optical characteristics Contact and ultimately required of the liquid crystal cell used, the optical compensation layer when viewed from the light emission side of the liquid crystal cell (B The direction on the upper side of the optical axis of the liquid crystal cell is counterclockwise as viewed from the light emitting side of the liquid crystal cell with respect to the rubbing direction of the liquid crystal cell substrate on the light incident side and light emitting side of the liquid crystal cell. When the angle is set so as to be approximately + 180 °, the viewing angle improvement effect is most pronounced.
[0017]
Further, in the laminated structure of the optical compensation layer of the present invention, the rubbing direction of each substrate on the light incident side and the light emitting side of the liquid crystal cell and optical compensation of uniaxial orientation having optically positive refractive index anisotropy. The relationship of the slow axis direction of the layer (C) has a great influence on the effect of improving the viewing angle characteristics. The direction of the slow axis of the liquid crystal cell to be used is appropriately selected according to the optical characteristics Contact and viewing angle characteristic that is finally required, the side close to each in the light incident side and light outgoing side of the liquid crystal cell When the liquid crystal cell substrate is set so as to have a substantially perpendicular relationship with the rubbing direction, the effect of improving the viewing angle is more greatly exhibited.
[0018]
Absorption axis Direction of cells on both sides of the polarizing plate, depending on the optical characteristics of the LCD, which is finally required, none of the light incident side and the light emitting side with respect to the rubbing direction of the liquid crystal cell substrate on the side closer to each And selected from either substantially vertical (E mode) or substantially parallel (O mode) . Na us, the retardation value of the optical compensation layer of the present invention (RA, RA ', RB, RC) and the inclination direction of the optical axis is obtained by measurement based on a conventional method to those skilled in the art.
[0019]
【The invention's effect】
According to the present invention, it is possible to obtain a TN-LCD in which display contrast and gradation angle viewing angle characteristics are remarkably improved.
[0020]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this.
[0021]
Example 1
Based on the method described in Japanese Patent Application Laid-Open No. Hei 5-196919, an optical compensation layer having almost no refractive index anisotropy in the film plane and having a characteristic that the refractive index in the film thickness direction is smaller than the refractive index in the plane ( A1) was prepared. Further , based on the method described in WO96 / 10773, an optical compensation layer (optical compensation layer having an optically positive refractive index anisotropy and an optical axis inclined at 45 ° from the film normal direction) B1) was produced. Further, the polycarbonate film formed by the solvent casting method was uniaxially stretched to produce a uniaxially oriented optical compensation layer (C1) having optically positive refractive index anisotropy. Between the liquid crystal cell of TFT-TN liquid crystal television (CRYSTALTRON, 4E-L1) manufactured by Sharp Corporation and the polarizing plates on both sides thereof, the above three types of optical compensation layers are connected to the polarizing plate / optical compensation layer (A1). ) / optical compensation layer (B1) / optical compensation layer (C1) / liquid crystal cell / optical compensation layer (C1) / the optical compensation layer (B1) / optical compensation layer (A1) / stacked in this order polarizer TN-LCD Was made. At this time, the liquid direction that the upper side of the optical axis of the optical compensation layer (B1) when viewed from the light emission side of the crystal cell, the liquid crystal cell closer to each the light incident side and the light emitting side of the liquid crystal cell substrate And the rubbing direction of the liquid crystal cell substrate on the side where the slow axis direction of the optical compensation layer (C1) is close to the light incident side and the light emitting side of the liquid crystal cell. Was set to be perpendicular to In this TN-LCD, the display contrast and the viewing angle characteristics of gradation inversion are both good in all directions, up, down, left, and right, and far superior to the conventional TN-LCD.
[0022]
Example 2
Based on the method described in WO96 / 10773, an optical compensation layer (B2) having optically positive refractive index anisotropy and an optical axis inclined at 65 ° from the film normal direction Was made. A TN-LCD in which three types of optical compensation layers were laminated was prepared in the same manner as in Example 1 except that the optical compensation layer (B2) was used as the optical compensation layer (B). In this TN-LCD, the display contrast and the viewing angle characteristics of gradation inversion are both good in all directions, up, down, left, and right, and far superior to the conventional TN-LCD.
[0023]
Comparative Example 1
The order of lamination of the optical compensation layers is as follows: polarizing plate / optical compensation layer (C1) / optical compensation layer (B1) / optical compensation layer (A1) / liquid crystal cell / optical compensation layer (A1) / optical compensation layer (B1) / optical. Except for the order of compensation layer (C1) / polarizing plate, a TN-LCD in which three types of optical compensation layers were laminated was produced in the same manner as in Example 1. In this TN-LCD, the viewing angle of the display contrast in the left and right and down directions was good, but the up direction was bad, and the viewing angle characteristics of gradation inversion were not so good in the top and bottom and left and right.
Claims (3)
(1) フィルム面内に屈折率異方性が殆ど存在せず、フィルム厚み方向の屈折率が面内の屈折率より小さい特性を有する光学補償層（Ａ）、
(2) 光学的に正の屈折率異方性を有しかつ光学軸がフィルム法線方向から２０〜７０°傾斜している特性を有する光学補償層（Ｂ）、および
(3) 光学的に正の屈折率異方性を有する一軸配向性の光学補償層（Ｃ）
の３種の特性の異なる光学補償層がそれぞれ少なくとも１層ずつ、液晶セルとその両側の偏光板との間に、偏光板／光学補償層（Ａ）／光学補償層（Ｂ）／光学補償層（Ｃ）／液晶セル／光学補償層（Ｃ）／光学補償層（Ｂ）／光学補償層（Ａ）／偏光板、の順に積層されていることを特徴とする液晶表示装置。In a normally white mode liquid crystal display device comprising a twisted nematic liquid crystal cell with a twist angle of approximately 90 ° and two polarizing plates disposed on both sides of the cell,
(1) an optical compensation layer (A) having almost no refractive index anisotropy in the film plane and having a characteristic that the refractive index in the film thickness direction is smaller than the refractive index in the plane ;
(2) an optical compensation layer (B) having an optically positive refractive index anisotropy and an optical axis inclined by 20 to 70 ° from the film normal direction ; and
(3) Uniaxially oriented optical compensation layer having optically positive refractive index anisotropy (C)
Each of the three types of optical compensation layers having different properties is provided between the liquid crystal cell and the polarizing plates on both sides thereof, and polarizing plate / optical compensation layer (A) / optical compensation layer (B) / optical compensation layer. A liquid crystal display device comprising: (C) / liquid crystal cell / optical compensation layer (C) / optical compensation layer (B) / optical compensation layer (A) / polarizing plate.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28409196A JP3663783B2 (en) | 1996-10-25 | 1996-10-25 | Liquid crystal display |
| SG1997003728A SG63759A1 (en) | 1996-10-25 | 1997-10-13 | Liquid crystal display device |
| TW086115065A TW470860B (en) | 1996-10-25 | 1997-10-14 | Normally white mode liquid crystal display device |
| EP97118532A EP0838713A3 (en) | 1996-10-25 | 1997-10-24 | Liquid crystal display device |
| KR1019970054968A KR100485430B1 (en) | 1996-10-25 | 1997-10-24 | Liquid crystal display device |
| US08/957,780 US6208396B1 (en) | 1996-10-25 | 1997-10-24 | Normally white mode twisted nematic liquid crystal display device having improved viewing angle characteristics |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28409196A JP3663783B2 (en) | 1996-10-25 | 1996-10-25 | Liquid crystal display |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10123506A JPH10123506A (en) | 1998-05-15 |
| JP3663783B2 true JP3663783B2 (en) | 2005-06-22 |
Family
ID=17674117
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28409196A Expired - Fee Related JP3663783B2 (en) | 1996-10-25 | 1996-10-25 | Liquid crystal display |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3663783B2 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001042127A (en) * | 1999-08-04 | 2001-02-16 | Nitto Denko Corp | Composite phase difference plate, optical compensation polarizing plate and liquid crystal display device |
| AU7654700A (en) * | 1999-09-16 | 2001-04-17 | Merck Patent Gmbh | Optical compensator and liquid crystal display ii |
| WO2001020395A1 (en) * | 1999-09-16 | 2001-03-22 | Merck Patent Gmbh | Optical compensator and liquid crystal display |
| JP2001091745A (en) | 1999-09-22 | 2001-04-06 | Nitto Denko Corp | Composite phase difference plate, optical compensation polarizing plate and liquid crystal display device |
| US7006184B2 (en) * | 2002-04-12 | 2006-02-28 | Eastman Kodak Company | Bend aligned namatic liquid crystal imaging display with compensation film |
| WO2008059721A1 (en) | 2006-11-17 | 2008-05-22 | Nippon Oil Corporation | Elliptic polarizing plate and vertically aligned liquid crystal display using the same |
| JP2009075533A (en) | 2007-08-31 | 2009-04-09 | Nippon Oil Corp | Elliptic polarization plate and liquid crystal display device |
| JP2009300760A (en) | 2008-06-13 | 2009-12-24 | Nippon Oil Corp | Elliptical light polarization plate and vertically oriented type liquid crystal display using the same |
| JP5427595B2 (en) * | 2009-12-25 | 2014-02-26 | 富士フイルム株式会社 | Twisted orientation mode liquid crystal display |
-
1996
- 1996-10-25 JP JP28409196A patent/JP3663783B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10123506A (en) | 1998-05-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2485084B1 (en) | In-plane switching liquid crystal display comprising compensation film for angular field of view using negative biaxial retardation film and (+) C-plate | |
| JP2982869B2 (en) | Liquid crystal display | |
| US5016988A (en) | Liquid crystal display device with a birefringent compensator | |
| TW200528875A (en) | Complex light-compensation c plate with two or more of c plates different in dispersion ratio value and liquid crystal display using the same | |
| US6208396B1 (en) | Normally white mode twisted nematic liquid crystal display device having improved viewing angle characteristics | |
| WO2004068225A1 (en) | Vertically aligned liquid crystal display having negative compensation film | |
| EP2693243B1 (en) | Integrated O Film for Improving viewing angle of TN-LCD, and Polarizer Plate and TN-LCD including the same | |
| US20100177267A1 (en) | Integrated Wide Viewing Film and in-Plane Switching Liquid Crystal Display with the Same | |
| JP2002040429A (en) | Wide viewing angle liquid crystal display device utilizing compensation film | |
| JP3924955B2 (en) | Liquid crystal display device in which retardation film is arranged | |
| JP3663783B2 (en) | Liquid crystal display | |
| US7110071B2 (en) | Liquid crystal display device and electronic apparatus | |
| JP3330742B2 (en) | Optical compensation sheet and liquid crystal display device using the same | |
| KR100485430B1 (en) | Liquid crystal display device | |
| US6188455B1 (en) | Liquid crystal display with two optical compensation units | |
| JP2767382B2 (en) | Optical compensation sheet | |
| JP2006292787A (en) | Liquid crystal display panel and device | |
| JPH10133195A (en) | Liquid crystal display device | |
| JPH08101381A (en) | Liquid crystal display element | |
| JPH0756156A (en) | Liquid crystal display element | |
| JP3118054B2 (en) | Liquid crystal display device | |
| JPH0850270A (en) | Liquid crystal display element formed by using optically anisotropic element | |
| JPH09203895A (en) | Liquid crystal display element and optical anisotropic element | |
| JPH07333599A (en) | Liquid crystal display element | |
| JPH0996810A (en) | Liquid crystal display element and optically anisotropic element |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20040917 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20040928 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20041125 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20041125 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20050308 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20050321 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080408 Year of fee payment: 3 |
|
| RD05 | Notification of revocation of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: R3D05 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090408 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090408 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100408 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110408 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120408 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130408 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130408 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140408 Year of fee payment: 9 |
|
| LAPS | Cancellation because of no payment of annual fees |