JPS61219931A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain a good display of the panel by disposing a smectic liquid crystal cell having a ferroelectricity between an upper substrate and a lower substrate, and by using an orientation films having different polarities with each other on the upper and lower substrates respectively, and by using a polyvinyl alcohol on one side of the orientation films. CONSTITUTION:The transparent electrode 2 is provided on a glass substrate 1 composed of the ferroelectricity liquid crystal panel. The orientation film 3 composed of polyvinyl alcohol is coated on the transparent electrode 2. The ferroelectricity liquid crystal 4 is disposed between the two sheets of the substrates 1. The liquid crystal 4 comprises for example, p-decyloxybenzylidene- p-amino-2-methylbutylcinnamate. If the electric field is impressed, the liquid crystal is orientated by C-director-5, and a dipole moment 6 of the liquid crystal molecule. As the polarities of the substrates make to the different one by using polyvinylalcohol to either of the upper and lower electrodes, when the electric field is not impressed, the liquid crystal does not have a twist structure resulting in orientating with an inclination of + or -theta against the normal line of the layer, thereby preventing the generation of a color shade and being obtained a good display characteristics.

Description

【発明の詳細な説明】 産業上の利用分野 本発明は液晶表示装置に係わり、特に強誘電性液晶を用
いた液晶セルに関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid crystal display device, and particularly to a liquid crystal cell using ferroelectric liquid crystal.

従来の技術 従来のネマチック液晶セルの配向制御はラビンＢｕ１１
．Ｓｏｃ　Ｆｒａｎｃ　Ｃｒ１ｓｔ、　６８１０５（１
９４３））（１９７２））。しかし、スメクチック液晶
の場合には粘性が高く流動性が小さいため、一旦スメク
チック層が形成され界面によって固定されると層全体が
動かすには大きな力を必要とする０現在公知であるスメ
クチック液晶の配向処理方法として、ラビングないし斜
方蒸着を施したセルを熱処理炉等で高温に保持し、液晶
を等方性液体で注入した後長時間かけて徐冷しつつスメ
クチックＡ相（ＳＡ相）をモノドメインとして結晶成長
させ、その後ゆっくり降温処理を行ない目的とする強誘
電性を持つカイラルスメクチックＣ相（Ｓｃ相）やカイ
ラルスメクチックＦ相（ＳＦ＊相）のモノドメイン相を
得ている〔竹添秀夫、福田敦夫、久世栄−；「工業材料
」、第３１巻、第１ｏ号、２２〕。Conventional technology The alignment control of conventional nematic liquid crystal cells is carried out using Rabin Bu11.
．． Soc Franc Cr1st, 68105(1
943)) (1972)). However, since smectic liquid crystals have high viscosity and low fluidity, once a smectic layer is formed and fixed at the interface, a large force is required to move the entire layer. As a processing method, a cell subjected to rubbing or oblique evaporation is held at high temperature in a heat treatment furnace, etc., and after injecting liquid crystal with an isotropic liquid, it is slowly cooled over a long period of time to monopolize the smectic A phase (SA phase). Crystals are grown as domains and then slowly cooled to obtain monodomain phases such as chiral smectic C phase (Sc phase) and chiral smectic F phase (SF* phase) that have the desired ferroelectricity [Hideo Takezoe, Atsuo Fukuda, Sakae Kuze; "Industrial Materials", Vol. 31, No. 1o, 22].

以下図面を用いて、従来の強誘電性液晶パネルの一例に
ついて説明する０第３図は従来のスメクチック液晶パネ
ルの構造を示すものである◇第３１　図において１４は
ガラス基板、１５はＳｎ　２０５（ＩＴＯ）より成る透
明電極、１６は強誘電性液晶層、１７は液晶分子のＣダ
イレクタ−１１８は双極子モーメントである。An example of a conventional ferroelectric liquid crystal panel will be explained below with reference to the drawings.0 Figure 3 shows the structure of a conventional smectic liquid crystal panel. 16 is a ferroelectric liquid crystal layer, 17 is a C director of liquid crystal molecules, and 118 is a dipole moment.

強誘電性液晶はＪ一般に分子長軸に垂直な方向に双極子
モーメントを持っており、薄膜化により自発分極を持つ
ようになる。強誘電性を示すスメクチックＣ＊相の例を
用いて強誘電性液晶の表記方法を第４図に示す。第４図
ａは層の法線に対し分子長軸が＋θ度傾いた状態、第４
図すは一〇度傾いた状態の強誘電体液晶の表記法である
。１９は層の法線、２ｏは分子の長軸方向ｎ１２１は双
極子した時のＣダイレクタＣ１２３は分子長軸の法線に
対する傾き角±θ度である。Ferroelectric liquid crystals generally have a dipole moment in the direction perpendicular to the long axis of the molecules, and as they become thinner, they come to have spontaneous polarization. FIG. 4 shows how to describe ferroelectric liquid crystal using an example of smectic C* phase exhibiting ferroelectricity. Figure 4a shows a state in which the long axis of the molecule is tilted by +θ degrees with respect to the normal to the layer.
The figure shows the notation for a ferroelectric liquid crystal tilted 10 degrees. 19 is the normal line of the layer, and 2o is the inclination angle ±θ degrees of the C director C123 when the long axis direction n121 of the molecule is a dipole with respect to the normal line of the long axis of the molecule.

以上のような構造を持つ強誘電性液晶パネルについて、
以下その動作原理について図を参照しながら説明する。Regarding the ferroelectric liquid crystal panel with the above structure,
The principle of operation will be explained below with reference to the drawings.

第６図に従来の強誘電性液晶パネルの表示方法の原理図
を示す。第５図ａは電圧無印加の状態、第５図すは紙面
方向に電圧を印加した場合、第５図Ｃは逆方向に電圧を
印加した場合の動作原理である◇２４は層法線に対して
分子長軸力料θ度傾いた液晶分子、２５は一θ度傾いた
液晶分子、２６は紙面表方向の双極子モーメント、２７
は紙面裏方向の双極子モーメント、２８は２枚の偏光板
の方向である。パネルの厚さを強誘電体液晶の螺旋ピッ
チ以下の薄さにすると第５図ａのように螺旋がほどけ層
に対して分子が＋θ度傾いた領域と一〇度傾いた領域に
分かれる。＋θ度傾いた領域で双極子モーメントが紙面
に対して上向きなら一θ度傾いた領域ではそれは下向き
である。従来の強誘電性液晶パネルのように上下基板に
同一の極性の大きな電極材料、例えばＩＴＯを使用する
と無電界時において第３図に示すように上下基板付近で
は双極子モーメントは下向きになシ、下基板付近では上
向きになり全体としてｔ：１を角の２倍のねじれ角を持
つツイスト構造になる。第３図に示した上下電極間１５
に電圧を印加することによシ第５図すのようにセル全体
が＋θ度傾いたモノドメインになる。又、逆電圧を印加
すると第５図Ｃのようにセル全体が一θ度傾いたモノド
メインになる。FIG. 6 shows a principle diagram of a conventional ferroelectric liquid crystal panel display method. Figure 5 a shows the operating principle when no voltage is applied, Figure 5 shows the operating principle when voltage is applied in the direction of the paper, and Figure 5 C shows the operating principle when voltage is applied in the opposite direction. 25 is a liquid crystal molecule tilted by 1 θ degree, 26 is a dipole moment in the direction of the surface of the paper, 27
is the dipole moment in the direction toward the back of the paper, and 28 is the direction of the two polarizing plates. When the thickness of the panel is made thinner than the helical pitch of the ferroelectric liquid crystal, the helix unravels as shown in Figure 5a, and the molecules are divided into a region where the molecules are tilted by +θ degrees and a region where the molecules are tilted by 10 degrees. If the dipole moment points upward with respect to the plane of the paper in a region tilted by +θ degrees, it points downward in a region tilted by 1θ degrees. If an electrode material with large polarity, such as ITO, is used for the upper and lower substrates as in a conventional ferroelectric liquid crystal panel, the dipole moment will not be directed downward near the upper and lower substrates in the absence of an electric field, as shown in Figure 3. In the vicinity of the lower substrate, it is directed upward, and the entire structure becomes a twisted structure with a twist angle of t:1 twice the angle. Between the upper and lower electrodes 15 shown in Figure 3
By applying a voltage to , the entire cell becomes a monodomain tilted by +θ degrees as shown in FIG. Furthermore, when a reverse voltage is applied, the entire cell becomes a monodomain tilted by 1θ degree as shown in FIG. 5C.

従がって、電気光学効果による複屈折または２色性を利
用すれば±θ度傾いた２つの状態により明暗を表わすこ
とができる。〔竹添秀夫、福田敦夫。Therefore, by using birefringence or dichroism due to the electro-optic effect, it is possible to represent brightness and darkness by two states tilted by ±θ degrees. [Hideo Takezoe, Atsuo Fukuda.

久世栄−：「工業材料」第３１巻、第１０号、２２〕発
明が解決しようとする問題点 しかしながら先程も述べたように上記のような構成では
、電圧無印加時において第６図ａのように分子が層の法
線より＋θ度傾いたドメインと一θ度傾いたドメインが
混在し、さらに、上下基板上に大きな極性を持つＩＴＯ
電極との相互作用により第３図のようなツイスト構造と
が共存するため色むらが生じるという問題点を有してい
た。Sakae Kuze: "Industrial Materials" Vol. 31, No. 10, 22] Problems to be Solved by the Invention However, as mentioned earlier, in the above configuration, when no voltage is applied, the problem shown in FIG. As shown in FIG.
Due to the interaction with the electrodes, a twisted structure as shown in FIG. 3 coexists, resulting in color unevenness.

本発明は、上記問題点に鑑み、上下基板で異なった極性
を有する配向膜、または電極材料を用い電圧無印加時に
於いても色むらの少ない表面を持つ表示特性の秀れた液
晶表示装置を提供するものである。In view of the above-mentioned problems, the present invention provides a liquid crystal display device that uses alignment films or electrode materials with different polarities on the upper and lower substrates, and has a surface with less color unevenness even when no voltage is applied, and has excellent display characteristics. This is what we provide.

問題点を解決するための手段 上記問題点を解決するために本発明の液晶表示装置は上
下基板で極性の異なる配向膜、または電極材料を用いる
ことを特徴としており、上記構成により電圧無印加時に
おいて色むらの少ない表面を持つ表示特性の秀れた強誘
電性液晶表示パネルとするものである。Means for Solving the Problems In order to solve the above problems, the liquid crystal display device of the present invention is characterized in that the upper and lower substrates use alignment films or electrode materials with different polarities. The present invention provides a ferroelectric liquid crystal display panel with excellent display characteristics and a surface with little color unevenness.

作　　用 本発明は極性の異なる配向膜、または電極材料を用いる
ことにより極性の小さな電極面と強誘電性液晶間の相互
作用が優勢になる。この結果、強誘電性液晶は第３図の
ようなツイスト構造はとらずに殆んど層法線に対し＋０
度か−θ度傾いたどちらか一方の平行配向するようにな
る。以上のような作用によりこの強誘電性液晶パネルは
電界無印加時において、従来のような色むらは現われに
くくなる。Function In the present invention, by using alignment films or electrode materials with different polarities, the interaction between the electrode surface with small polarity and the ferroelectric liquid crystal becomes dominant. As a result, the ferroelectric liquid crystal does not have a twisted structure as shown in Figure 3, but almost has a +0
The parallel orientation is either tilted by -θ degrees or -θ degrees. Due to the above-described effects, this ferroelectric liquid crystal panel is less likely to exhibit color unevenness as in conventional panels when no electric field is applied.

実施例 次に本発明の一実施例について図面を参照しながら説明
する〇 第１図は本発明の一実施例の強誘電性液晶パネルの概略
を示すものである。第１図において、１はガラス基板、
２は透明電極、３はＰＶＡ配向膜、４は強誘電性液晶層
、５は液晶分子のＣダイレクタ−１６は双極子モーメン
トである。Embodiment Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a ferroelectric liquid crystal panel according to an embodiment of the present invention. In FIG. 1, 1 is a glass substrate;
2 is a transparent electrode, 3 is a PVA alignment film, 4 is a ferroelectric liquid crystal layer, 5 is a C director of liquid crystal molecules, and 16 is a dipole moment.

透明な電圧印加用電極を付与した２枚の絶縁基板の一方
にＰＶＡの高分子膜を塗布した後高温で架橋し固化して
配向膜とする。このような構成の基板を４μｍのＰＥＴ
膜をスペーサとして所定の方法により貼り合わせて液晶
セルを作成し、その中に強誘電性液晶、例えば（＋）Ｐ
−デシルオキシベンジリデン−Ｐ−アミノ−２メチルプ
チルシンナメイ）　（＋ＤＯＢＡＭＢＣ）すなわち次の
構造式を有する液晶化合物を封入する。A PVA polymer film is coated on one of two insulating substrates provided with transparent voltage applying electrodes, and then crosslinked and solidified at high temperature to form an alignment film. A substrate with such a configuration is made of 4 μm PET.
A liquid crystal cell is created by bonding the film as a spacer using a predetermined method, and a ferroelectric liquid crystal, such as (+)P, is placed inside the cell.
-decyloxybenzylidene-P-amino-2methylbutylcinnamei) (+DOBAMBC), that is, a liquid crystal compound having the following structural formula is sealed.

（但しＣ＊は光学活性な炭素原子を示す。）相転移温度 ”　ｓｏ“　ＳＡ“ＳＣ＊□ＳＧ＊ １２０°　　９１°　　　６０゜ 但し、工ｓＯ：等方性液体 ＳＡ　：スメクチックＡ相 Ｓ＊：カイラルスチクチックＣ相 Ｓ＊：カイラルスメクチックＧ相 第２図は強誘電性スメクチック液晶の配向制御方法の概
略図であり、了は高温側電気炉（１３０℃）、８は低温
側電気炉（１００℃）、９はテフロン、１ｏは強誘電性
液晶パネル、１１．１２は４μｍのＰＥＴスペーサ、１
３は強誘電性液晶層である。(However, C* indicates an optically active carbon atom.) Phase transition temperature "so"SA"SC*□SG* 120° 91° 60° However, SO: Isotropic liquid SA: Smectic A phase S*: Chiral smectic C phase S*: Chiral smectic G phase Figure 2 is a schematic diagram of the method for controlling the orientation of ferroelectric smectic liquid crystals. 100℃), 9 is Teflon, 1o is a ferroelectric liquid crystal panel, 11.12 is a 4 μm PET spacer, 1
3 is a ferroelectric liquid crystal layer.

まず第２図７の高温側電気炉を１３０℃に、第２図８の
低温側電気炉を１００℃に保つ。この温度勾配（３０℃
）を有する電気炉上で上記液晶化合物を封入した液晶パ
ネルを高温側から低温側へゆっくり移動させるとスペー
サエツジを核として等方性液体からＳＡ相がモノドメイ
ンとして成長する。そして更にＳＡ相からＳｃ相への転
移温度である９１℃より数度低い温度まで徐冷する。こ
の様な方法でＳｃ＊相のモノドメインを作成した。First, the high-temperature electric furnace shown in FIG. 2 7 is maintained at 130° C., and the low-temperature electric furnace shown in FIG. 2 8 is maintained at 100° C. This temperature gradient (30℃
) When a liquid crystal panel filled with the above liquid crystal compound is slowly moved from a high temperature side to a low temperature side in an electric furnace having an electric furnace, an SA phase grows as a monodomain from an isotropic liquid using the spacer edges as nuclei. Then, it is slowly cooled to a temperature several degrees lower than 91° C., which is the transition temperature from the SA phase to the Sc phase. A Sc* phase monodomain was created in this manner.

発明の効果 以上のように本発明は、上下基板で極性の異なる配向膜
または電極材料を形成することにより強誘電性液晶は電
界無印加時においてツイスト構造はとらず層法線に対し
て十〇または一〇傾いた平行配向するようになシ、電界
無印加時における色むらを抑制することができる。この
ことから、表示特性の秀れた強誘電性液晶パネルが提供
可能となりその工業的価値は大なるものである。Effects of the Invention As described above, in the present invention, by forming alignment films or electrode materials with different polarities on the upper and lower substrates, the ferroelectric liquid crystal does not have a twisted structure when no electric field is applied, but has a 100° angle with respect to the layer normal. Alternatively, by arranging them in parallel at an angle of 10 degrees, it is possible to suppress color unevenness when no electric field is applied. This makes it possible to provide a ferroelectric liquid crystal panel with excellent display characteristics, which has great industrial value.

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

第１図は本発明の実施例における強誘電性液晶パネルの
パネル断面図、第２図は強誘電性スメクチック液晶の配
向制御方法を示す図、第３図は従来の強誘電性液晶パネ
ルのパネル断面図、第４図はスメクチックＣ＊液晶の表
記法を示す図、第５図は従来の強誘電性液晶パネルの表
示の原理を示す図である。 １・・・・・・ガラス基板、２・・・・・・透明電極、
３・・・・・・ＰＶＡ配向膜、４・・・・・・強誘電性
液晶層、５・・・・・・液晶分子のＣダイレクタ−１６
・・・・・・双極子モーメント、７・・・・・・高温側
電気炉、８・・・・・・低温側電気炉、９・・・・・・
テフロン、１ｏ・・・・・・強誘電性液晶パネル、１１
１２・・・・・・ＰＥＴスペーサ、１３・・・・・・強
誘電性液晶層、１４・・・・・・ガラス基板、１５・・
・・・・ＩＴＯの透明電極、１６・・・・・・強誘電性
液晶層、１７・・・・・・液晶分子のＣダイレクタ、１
８・・・・・・双極子モーメント、１９・・・・・・層
の法線、２０・・・・・・分子の長軸方向ｎ、２１・・
・・・・双極子モーメン）Ｐ　　１２２・・・・・・Ｃ
ダイレクタ、２３・・・・・・分子長軸の法線に対する
傾き角±θ度、２４・・・・・・層法線に対して分子の
長軸が＋θ度傾０た液晶分子、２５・・・・・・−θ度
傾いた液晶分子、２６・・・・・・紙面表方向の双極子
モーメント、２７・・・・・・紙面裏方向の双極子モー
メント、２８・・・・・・２枚の偏向板の方向。 代理人の氏名　弁理士　中　尾　敏　男　ほか１名第５
ｒＩＩＪ 第３図 第４図Fig. 1 is a cross-sectional view of a ferroelectric liquid crystal panel according to an embodiment of the present invention, Fig. 2 is a diagram showing a method for controlling the alignment of ferroelectric smectic liquid crystal, and Fig. 3 is a panel of a conventional ferroelectric liquid crystal panel. A cross-sectional view, FIG. 4 is a diagram showing the notation of smectic C* liquid crystal, and FIG. 5 is a diagram showing the principle of display of a conventional ferroelectric liquid crystal panel. 1...Glass substrate, 2...Transparent electrode,
3...PVA alignment film, 4...Ferroelectric liquid crystal layer, 5...C director of liquid crystal molecules-16
...Dipole moment, 7...High temperature side electric furnace, 8...Low temperature side electric furnace, 9...
Teflon, 1o... Ferroelectric liquid crystal panel, 11
12... PET spacer, 13... Ferroelectric liquid crystal layer, 14... Glass substrate, 15...
... ITO transparent electrode, 16 ... Ferroelectric liquid crystal layer, 17 ... C director of liquid crystal molecules, 1
8...Dipole moment, 19...Normal to layer, 20...Long axis direction of molecule n, 21...
...Dipole moment) P 122...C
Director, 23... Tilt angle of the long axis of the molecule ±θ degrees with respect to the normal line, 24... Liquid crystal molecule whose long axis of the molecule is tilted +θ degrees with respect to the layer normal, 25. ......Liquid crystal molecules tilted by -θ degrees, 26...Dipole moment towards the front of the paper, 27...Dipole moment towards the back of the paper, 28... Direction of two deflection plates. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 5
rIIJ Figure 3 Figure 4

Claims (2)

【特許請求の範囲】[Claims] （１）上基板と下基板の間に強誘電性を示すスメクチッ
ク液晶を配し、前記上基板と下基板が互いに極性の異な
る配向膜または電極材料を備えたことを特徴とする液晶
表示装置。(1) A liquid crystal display device characterized in that a smectic liquid crystal exhibiting ferroelectricity is arranged between an upper substrate and a lower substrate, and the upper substrate and the lower substrate are provided with alignment films or electrode materials having mutually different polarities. （２）配向膜の一方がポリビニルアルコールであること
を特徴とする特許請求の範囲第１項記載の液晶表示装置
。(2) The liquid crystal display device according to claim 1, wherein one of the alignment films is made of polyvinyl alcohol.