JPH02304526A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To decrease the dependency of a display characteristic on visual sensation by nearly paralleling the plane direction of a double refractive layer consisting of planar liquid crystal molecules with the plane direction of the planar liquid crystal molecules. CONSTITUTION:A part held in place by a lower substrate 8 and an intermediate substrate 5 is an ordinary driving cell. A voltage is impressed on a 2nd liquid crystal layer 11 oriented by an oriented film 6 by using an electrode 12, by which the orientation state of the liquid crystal is changed and optical modulation is executed. On the other hand, the part held in place by an upper substrate 2 and the intermediate substrate 5 is a visual angle compensation cell sealed with a liquid crystal consisting of the planar molecules and the plane direction of the planar molecules of the 1st liquid crystal layer 10 is paralleled approximately with the oriented film 3 by the oriented film 3. The double refractive layer which is isotropic and smaller in the refractive index in the the thickness direction than the refractive index within the plane and is homogeneous is, therefore, obtd. The dependency of the display characteristic on the visual sensation is decreased in this way.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は液晶表示素子に関する。[Detailed description of the invention] [Industrial application field] The present invention relates to a liquid crystal display element.

〔従来の技術及び発明が解決しようとする課題〕電圧を
印加することによって液晶層の複屈折の大きさを変化さ
せ、光変調を行うタイプの液晶表示素子は既に公知であ
る。ところが、このタイプの液晶表示素子では、視角に
よって光が実際に通過する液晶層内の距離が変化するこ
と、みかけの複屈折の大きさが液晶分子の配向方向と視
角方向の相対角によって変化することなどにより、表示
特性の視角依存性が著しく大きく、表示の視認可能な角
度範囲は非常に小さい。[Prior Art and Problems to be Solved by the Invention] Liquid crystal display elements of a type that modulate light by changing the magnitude of birefringence of a liquid crystal layer by applying a voltage are already known. However, in this type of liquid crystal display element, the distance through which light actually passes through the liquid crystal layer changes depending on the viewing angle, and the magnitude of the apparent birefringence changes depending on the relative angle between the alignment direction of the liquid crystal molecules and the viewing angle direction. For this reason, the viewing angle dependence of the display characteristics is extremely large, and the angular range in which the display can be viewed is extremely small.

このような表示特性の視角依存性を低減させるために、
液晶層と偏光子との間に複屈折層を設けることが提案さ
れている０例えば、特開昭６２−２１０４２３号公報に
は、垂直配向させた液晶層に電圧を印加し、液晶層の複
屈折の大きさを変化させることによって光変調を行うＤ
ＡＰ方式のＥＣＢ型液晶表示素子において、光学異方性
が負となるように作ったポリマーフィルムを複屈折層と
して設け、該複屈折層により視角補償を行うことが開示
されている。一般に、このような視角補償用複屈折層に
要求される特性は、液晶表示素子のモード（ＳＴＮ、　
ｌｌＩＣ［３，ＤＡＰ、ＩＩＡＮ、　ＴＢ等）、セルパ
ラメーター（偏光子の光学軸方向、液晶層の複屈折の大
きさＡｎｄ等）、基板の種類などに依存しており、種々
のものがあり得るが、特にＤＡＰ、１（ＡＮ、傾斜配向
型等の液晶表示素子の視角補償に有効な、面内の屈折率
ｎ４．　ｎｙが面に垂直な方向の屈折率ｎｚよりも大き
いような視角補償用複屈折層は、以下の理由により良い
特性のものが得られなかった。In order to reduce the viewing angle dependence of display characteristics,
It has been proposed to provide a birefringent layer between the liquid crystal layer and the polarizer. D that modulates light by changing the magnitude of refraction
It has been disclosed that in an AP type ECB type liquid crystal display element, a polymer film made to have negative optical anisotropy is provided as a birefringent layer, and viewing angle compensation is performed by the birefringent layer. Generally, the characteristics required of such a birefringent layer for viewing angle compensation are the mode (STN,
It depends on IC [3, DAP, IIAN, TB, etc.), cell parameters (optical axis direction of polarizer, magnitude of birefringence of liquid crystal layer And, etc.), type of substrate, etc., and there are various possible ones. However, it is particularly effective for viewing angle compensation of liquid crystal display elements such as DAP, 1 (AN, tilt alignment type, etc.), where the in-plane refractive index n4.ny is larger than the refractive index nz in the direction perpendicular to the plane. A birefringent layer with good characteristics could not be obtained for the following reasons.

■　−軸延伸したポリマーでは、　ｎｘとｎｙが異なる
ために視角補償できる方向が狭い範囲に限定されてしま
う。(2) - In an axially stretched polymer, the directions in which viewing angle can be compensated are limited to a narrow range because nx and ny are different.

■　特開昭６２−２１０４２３公報に記載されている如
きポリマーでは非常に特殊な成形を行う必要があり、均
質なフィルムを作るのは困難で、しかも複屈折の大きさ
をコントロールするのも非常に困難である。■ Polymers such as those described in JP-A No. 62-210423 require very special molding, making it difficult to make a homogeneous film, and moreover, controlling the magnitude of birefringence is extremely difficult. Have difficulty.

■　棒状分子からなる一般の液晶を配向させたセルでは
、分子長軸方向と短軸方向の屈折率ｎ１ｇｎ工は一般に
ｎ、）ｎ工となっているため、ホモジニアス配向をさせ
て上記■と同様の特性を持ったセルを作ることはできる
が、既述のとおり視角補償できる範囲は限定される。■ In a cell in which a general liquid crystal consisting of rod-shaped molecules is oriented, the refractive index in the long axis direction and short axis direction of the molecules is generally n, )n, so homogeneous alignment is performed and the refractive index is the same as in the above (■). It is possible to create a cell with the following characteristics, but as mentioned above, the range in which viewing angle compensation can be made is limited.

本発明はこのような従来技術の実情に鑑みてなされたも
のであって、簡便な方法によって作製されたｎｘ”ｎｙ
＞ｎｚなる特性を有する均質な複屈折層を用い、表示特
性の視角依存性が著しく低減した高品位な液晶表示素子
を提供することを目的とする。The present invention has been made in view of the actual state of the prior art, and is based on the nx”ny fabricated by a simple method.
An object of the present invention is to provide a high-quality liquid crystal display element in which viewing angle dependence of display characteristics is significantly reduced by using a homogeneous birefringent layer having a characteristic of >nz.

〔課題を解決するための手段及び作目〕上記目的を達成
するため１本発明によれば、電極を有する一対の基板間
に挾持された液晶層と、複屈折層と、これら２つの層を
外側か、ら挾むように配置された一対の偏光子とから構
成され、該電極に電気信号を入力して光変調を行う液晶
表示素子において、該複屈折層が板状分子からなる液晶
からなり、該板状分子の平面方向が該複屈折層の平面方
向と略平行であることを特徴とする液晶表示素子が提供
される。[Means and works for solving the problems] In order to achieve the above object, the present invention provides a liquid crystal layer sandwiched between a pair of substrates having electrodes, a birefringent layer, and a birefringent layer. In a liquid crystal display element, which is composed of a pair of polarizers arranged to sandwich each other from the outside, and which modulates light by inputting an electric signal to the electrodes, the birefringent layer is made of a liquid crystal made of plate-like molecules, A liquid crystal display element is provided, wherein the plane direction of the plate-like molecules is substantially parallel to the plane direction of the birefringent layer.

本発明では、ｎｚ＝ｎｙ＞ｎｙ、ｃ平面内で等方向で、
厚み方向の屈折率ｎｚが平面内の屈折率ｎｘ、　ｎｙよ
り小さい）なる特性を持つ複屈折層を平板状液晶分子を
配向させることによって簡便に作製し、この複屈折層に
より表示特性の視覚依存性を著しく低減させるものであ
る。In the present invention, nz=ny>ny, isodirectional within the c plane,
A birefringent layer having the property that the refractive index nz in the thickness direction is smaller than the refractive index nx, ny in the plane is easily produced by orienting flat liquid crystal molecules, and this birefringent layer improves visual dependence of display characteristics. This significantly reduces the

次に本発明の液晶表示素子を図面を参照して更に詳述す
る。Next, the liquid crystal display element of the present invention will be explained in more detail with reference to the drawings.

第１図は本発明による液晶表示素子の具体的な構成例を
示す断面図であり１図中１，９は偏光子、２゜５．８は
基板、３，６は配向膜、４，７はシール材、ＩＯは第１
液晶層、１１は第２液晶層、１２は電極である。FIG. 1 is a cross-sectional view showing a specific configuration example of a liquid crystal display element according to the present invention. In the figure, 1 and 9 are polarizers, 2°5.8 is a substrate, 3 and 6 are alignment films, and 4 and 7 is the sealing material, IO is the first
A liquid crystal layer, 11 is a second liquid crystal layer, and 12 is an electrode.

下基板８と中間基板５に挾まれた部分は通常の液晶セル
（以下″駆動セル″′と記す、）を構成しており、配向
膜６によって配向した第２液晶層に電極１２を用いて電
圧を印加し、液晶の配向状態を変化させて光変調を行う
ようになっている。上基板２と中間基板５に挾まれた部
分は平板状分子からなる液晶を封入した液晶セル（以下
パ視角補償セル″と記す、）を構成しており、配向膜３
によって第１液晶層ｌＯの平板状分子の平面方向は配向
膜３に対して略平行になっている。平板状分子の多くは
、平面方向の屈折率ｎ−が、平面に垂直な方向の屈折率
ｎ′７より大きいために、上述のような配向をとらせた
場合、平面内では等方向で厚み方向の屈折率が平面内の
屈折率より小さいという特性を持つた複屈折Ｊｄとなる
。平板状分子は、ｎ’、／＞　ｎ′Ｌという特性を持っ
ていれば良いので、その形状は完全な平板状である必要
はなく、いわゆる”ｂｏｉｉｌ−１ｉｋｅ”分子でも良
い。The part sandwiched between the lower substrate 8 and the intermediate substrate 5 constitutes a normal liquid crystal cell (hereinafter referred to as "driving cell"). Light is modulated by applying a voltage and changing the alignment state of the liquid crystal. The portion sandwiched between the upper substrate 2 and the intermediate substrate 5 constitutes a liquid crystal cell (hereinafter referred to as "viewing angle compensation cell") in which liquid crystal made of plate-shaped molecules is sealed, and the alignment film 3
Therefore, the planar direction of the flat molecules of the first liquid crystal layer IO is approximately parallel to the alignment film 3. In many tabular molecules, the refractive index n- in the plane direction is larger than the refractive index n'7 in the direction perpendicular to the plane, so when the above-mentioned orientation is taken, the thickness is uniform in the plane. Birefringence Jd has the characteristic that the refractive index in the direction is smaller than the refractive index in the plane. Since the tabular molecule only needs to have the characteristics n', //n'L, its shape does not need to be completely tabular, and may be a so-called "boiil-1ike" molecule.

上記のような特性を満足する平板状分子としては以下の
構造のものが知られている。The following structure is known as a tabular molecule that satisfies the above characteristics.

（上記において、置換基Ｒ，Ｒ’は以下を意味する。(In the above, substituents R and R' mean the following.

−２１、（か。-21, (?

Ｑお、今。Q Oh, now.

ｒ’ｌＣｗＪ＋ｘｗｓｓｐ□−＊ ｎＣ，Ｈ，，，−Ｑ研 鴫２Ｈ２，十外（偽）、−１ ｒ１電：；、１Ｎ、、−ＣＨ−ＣＨ□−−ＣＯｆ）。r’lCwJ+xwssp□-* nC,H,,,-Q lab Shizu 2H2, Jugai (false), -1 r1 electron:;, 1N, -CH-CH□--COf).

へ 一〇、−ＰＬ−ｆｃｌＬφ０務 Ｉ３ ここで挙げた置換基を上記の構造式と組み合わせたもの
すべてが液晶相をとるわけではなく、また１本発明の’
ｆＭＡｎ折層に使用される液晶は上述の組み合わせに限
定されるものではないが、常温での液晶相がネマティッ
ク液晶に類似していれば、均一な配向が得られやすい。10, -PL-fclLφ0function I3 Not all of the combinations of the substituents listed here with the above structural formula take a liquid crystal phase, and one of the '
The liquid crystal used in the fMAN folding layer is not limited to the above-mentioned combinations, but if the liquid crystal phase at room temperature is similar to that of nematic liquid crystal, uniform alignment is likely to be obtained.

また、第１図の構成例では中間基板５が駆動セル部分と
視角補償セル部分に共有されるようになっているが、も
う１枚基板を用いて２つの液晶セルを全く別々に作った
後に貼り合せるようにしてもよい。In addition, in the configuration example shown in FIG. 1, the intermediate substrate 5 is shared by the drive cell portion and the viewing angle compensation cell portion, but after two liquid crystal cells are made completely separately using another substrate, They may be pasted together.

〔実施例〕〔Example〕

次に、本発明の詳細な説明する。 Next, the present invention will be explained in detail.

実施例１ 配向剤としてスリーエム社製の垂直配向剤ＦＣ−８０５
を用い、これを透明電極付きのガラス基板にスピンナー
塗布し、焼成した。垂直配向剤面を植毛布によりラビン
グし、ラビング方向が反平行となるように２枚の基板を
貼り合わせて駆動セルとした。駆動セルのセル厚はガラ
スファイバーの散布によって、１１．０μｍに制御した
。駆動セルには誘電異カ性が負のネマティック液晶であ
るＺＬＩ−４３１８（メルク社製）を封入した。Example 1 Vertical alignment agent FC-805 manufactured by 3M Co., Ltd. as an alignment agent
Using a spinner, this was coated on a glass substrate with a transparent electrode and fired. The vertical alignment agent surface was rubbed with a flocked cloth, and the two substrates were bonded together so that the rubbing directions were antiparallel to form a drive cell. The cell thickness of the drive cell was controlled to 11.0 μm by scattering glass fibers. ZLI-4318 (manufactured by Merck & Co., Ltd.), which is a nematic liquid crystal with negative dielectric anisotropy, was sealed in the drive cell.

一方、配向剤として日立化成製の水平配向剤ＨＬ−１１
１０を用い、電極の付いていないガラス基板にスピンナ
ー塗布し、焼成した。水平配向剤面を植毛布によってラ
ビングし、４０μＩ径のスペーサーを介して２枚の基板
を貼り合わせ、下記構造式で表わされる板状分子からな
る液晶の混合物を封入して視角補償セルを作った。On the other hand, the horizontal alignment agent HL-11 manufactured by Hitachi Chemical was used as an alignment agent.
No. 10 was used to coat a glass substrate with no electrodes using a spinner, and then baked. The surface of the horizontal alignment agent was rubbed with a flocked cloth, the two substrates were bonded together via a 40μI diameter spacer, and a liquid crystal mixture consisting of plate-shaped molecules represented by the following structural formula was sealed to create a viewing angle compensation cell. .

（Ｒ−＝ｎ−Ｃ，Ｈ，，−０−１ｎ−Ｃ，Ｈ，、−０−
である２種の化合物の混合物（モル比でｉ：ｔ）） 本実施例では、第１図の構造例とは異なり、駆動セルと
視角補償セルを別々に作り、視角補償セルがあるとない
ときの表示特性を比較しやすくした。クロスニコルにし
た２枚の偏光板の間に、偏光板の透過軸に対してラビン
グ方向が４５°になるように駆動セルを挾み、電極に交
流信号を入力したところ、交流信号の大きさに応じて各
種の色が観察された。この色は視角によって著しく変化
し、表示特性の視角依存性の大きいことがわかった。(R-=n-C,H,,-0-1n-C,H,,-0-
A mixture of two types of compounds (molar ratio i:t)) In this example, unlike the structural example shown in FIG. This makes it easier to compare the display characteristics at different times. When a drive cell is sandwiched between two crossed nicol polarizing plates so that the rubbing direction is 45 degrees with respect to the transmission axis of the polarizing plate, and an AC signal is input to the electrodes, the signal changes depending on the magnitude of the AC signal. Various colors were observed. This color changed significantly depending on the viewing angle, and it was found that the display characteristics were highly dependent on the viewing angle.

次に駆動セルと偏光板の間に上記で作成した視角補償セ
ルを挾んだところ、色変化の視角依存性は小さくなり、
視野角が広がることを確認した。Next, when the viewing angle compensation cell created above was sandwiched between the drive cell and the polarizing plate, the viewing angle dependence of color change became smaller.
We confirmed that the viewing angle was widened.

〔発明の効果〕〔Effect of the invention〕

本発明によれば、簡便な方法によって作製された良好な
特性を持つ複屈折層により、表示特性の視角依存性を著
しく改善することが可能となる。According to the present invention, the viewing angle dependence of display characteristics can be significantly improved by using a birefringent layer with good characteristics that is manufactured by a simple method.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明による液晶表示素子の一構成例を示す断
面図である。 １．９・・・偏光子 ２．５．８・・・基板 ３．６・・・配向膜 ４．７・・・シール材 １０・・・第１液晶層 １１・・・第２液晶層 １２・・・電極FIG. 1 is a sectional view showing an example of the structure of a liquid crystal display element according to the present invention. 1.9... Polarizer 2.5.8... Substrate 3.6... Alignment film 4.7... Seal material 10... First liquid crystal layer 11... Second liquid crystal layer 12 ···electrode

Claims (1)

【特許請求の範囲】[Claims] （１）電極を有する一対の基板間に挾持された液晶層と
、複屈折層と、これら２つの層を外側から挾むように配
置された一対の偏光子とから構成され、該電極に電気信
号を入力して光変調を行う液晶表示素子において、該複
屈折層が板状分子からなる液晶からなり、該板状分子の
平面方向が該複屈折層の平面方向と略平行であることを
特徴とする液晶表示素子。(1) Consists of a liquid crystal layer sandwiched between a pair of substrates having electrodes, a birefringent layer, and a pair of polarizers placed between these two layers from the outside, and transmits an electrical signal to the electrodes. A liquid crystal display element that modulates light by inputting light, characterized in that the birefringent layer is made of liquid crystal made of plate-like molecules, and the plane direction of the plate-like molecules is approximately parallel to the plane direction of the birefringence layer. LCD display element.