JP3463132B2 - Liquid crystal display device - Google Patents
Liquid crystal display deviceInfo
- Publication number
- JP3463132B2 JP3463132B2 JP33899795A JP33899795A JP3463132B2 JP 3463132 B2 JP3463132 B2 JP 3463132B2 JP 33899795 A JP33899795 A JP 33899795A JP 33899795 A JP33899795 A JP 33899795A JP 3463132 B2 JP3463132 B2 JP 3463132B2
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- Prior art keywords
- liquid crystal
- dyn
- crystal display
- alignment
- molecules
- Prior art date
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Description
【発明の詳細な説明】Detailed Description of the Invention
【０００１】[0001]
【発明の属する技術分野】この発明は、液晶分子のダイ
レクタを配向膜で規定せずに広い視野角を得るようにし
た液晶表示素子に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device capable of obtaining a wide viewing angle without defining a director of liquid crystal molecules with an alignment film.
【０００２】[0002]
【従来の技術】液晶表示素子としては、一般に、ＴＮ
（ツイステッドネマティック）型のものが利用されてい
る。このＴＮ型液晶表示素子は、液晶層をはさんで対向
する一対の透明基板の内面にそれぞれ透明電極と配向膜
とが設けられているとともに、前記液晶層の液晶の分子
が、一対の基板間においてツイスト配向しているもので
あり、液晶分子のツイスト角は、一般に、ほぼ９０°〜
２７０°の範囲に設定されている。2. Description of the Related Art Generally, TN is used as a liquid crystal display device.
(Twisted nematic) type is used. In this TN type liquid crystal display element, a transparent electrode and an alignment film are provided on the inner surfaces of a pair of transparent substrates that face each other across a liquid crystal layer, and the molecules of the liquid crystal in the liquid crystal layer are disposed between the pair of substrates. The twist angle of the liquid crystal molecules is generally 90 ° to 90 °.
It is set in the range of 270 °.
【０００３】ところで、従来のＴＮ型液晶表示素子は、
前記一対の基板の内面に設けた配向膜にそれぞれラビン
グ等による配向処理を施した構成となっており、液晶の
分子は、それぞれの基板の近傍における配向方向を前記
配向膜で規制されて、その間でツイスト配向している。By the way, the conventional TN type liquid crystal display device is
The alignment films provided on the inner surfaces of the pair of substrates are each subjected to an alignment treatment by rubbing or the like, and the molecules of the liquid crystal are controlled by the alignment films in the alignment direction in the vicinity of each substrate, It has a twist orientation.
【０００４】しかし、この液晶表示素子は、液晶分子の
ダイレクタが配向膜の配向処理方向によって規定される
ため、電圧−透過率特性に視角依存性があり、そのため
に、視野角が狭いという問題をもっている。However, in this liquid crystal display element, since the director of the liquid crystal molecule is defined by the alignment treatment direction of the alignment film, the voltage-transmittance characteristic has a viewing angle dependency, and therefore the viewing angle is narrow. There is.
【０００５】このため、従来から、ＴＮ型液晶表示素子
の視野角を改善することが研究されており、その手段の
１つとして、液晶分子のダイレクタを配向膜で規定せず
に広い視野角を得るようにした液晶表示素子が考えられ
ている。Therefore, research has been conventionally conducted to improve the viewing angle of a TN type liquid crystal display device, and as one of the means, a wide viewing angle is provided without defining the director of liquid crystal molecules with an alignment film. A liquid crystal display device to be obtained is considered.
【０００６】この液晶表示素子は、液晶層をはさんで対
向する一対の基板の内面にそれぞれ配向処理しない配向
膜が設けられており、液晶の分子が液晶材料のねじれ性
に応じたツイスト角でツイスト配向しているものであ
り、そのツイスト角は、一対の基板間の間隙に応じて液
晶材料のねじれ性を選択することにより所定の角度に設
定されている。In this liquid crystal display element, an alignment film that is not subjected to alignment treatment is provided on the inner surfaces of a pair of substrates that face each other across the liquid crystal layer, and the molecules of the liquid crystal have a twist angle according to the twistability of the liquid crystal material. The twist orientation is set, and the twist angle is set to a predetermined angle by selecting the twistability of the liquid crystal material according to the gap between the pair of substrates.
【０００７】すなわち、上記液晶材料は、ネマティック
液晶に、光学活性物質として用いられる、液晶分子を所
定のピッチでツイストさせるためのカイラル物質を添加
したものであり、そのねじれ性、つまり液晶材料の固有
のねじれピッチ（ナチュラルピッチ）は、前記光学活性
物質の添加量を調整することによって任意に選ぶことが
できるため、一対の基板間の間隙に合わせて、その間隙
において所定角度ねじれるような液晶材料を用いれば、
所望のツイスト角が得られる。That is, the above-mentioned liquid crystal material is a nematic liquid crystal to which a chiral substance used as an optically active substance for twisting liquid crystal molecules at a predetermined pitch is added. The twist pitch (natural pitch) can be arbitrarily selected by adjusting the addition amount of the optically active substance. Therefore, a liquid crystal material that twists at a predetermined angle in the gap according to the gap between the pair of substrates is selected. If used,
The desired twist angle is obtained.
【０００８】この液晶表示素子は、液晶分子のダイレク
タが配向膜によって規定されないため、基板間における
液晶分子分子のツイスト角は液晶層の全域において同じ
であっても、ミクロ的に見た各点でのダイレクタは様々
な向きにあるから、電圧−透過率特性の視角依存性がほ
とんどなく、したがって、広い視野角が得られる。In this liquid crystal display element, since the director of the liquid crystal molecules is not defined by the alignment film, even if the twist angles of the liquid crystal molecule molecules between the substrates are the same throughout the liquid crystal layer, they are microscopically different. Since the directors of (1) have various orientations, there is almost no dependence of the voltage-transmittance characteristic on the viewing angle, and therefore a wide viewing angle can be obtained.
【０００９】この液晶表示素子は、従来、電極を設ける
とともにその上に配向処理しない配向膜を設けた一対の
基板を枠状のシール材を介して接合して液晶セルを組立
て、その液晶セル内に、上記液晶材料を、アイソトロピ
ック相になる温度に加熱した状態で真空注入法により注
入し、その後、徐冷によりセル内の液晶材料をネマティ
ック相に戻す方法で製造されている。In this liquid crystal display element, conventionally, a pair of substrates provided with electrodes and an alignment film which is not subjected to alignment treatment are bonded to each other through a frame-shaped sealing material to assemble a liquid crystal cell, and the inside of the liquid crystal cell is assembled. In addition, the liquid crystal material is injected by a vacuum injection method while being heated to a temperature at which it becomes an isotropic phase, and then slowly cooled to return the liquid crystal material in the cell to the nematic phase.
【００１０】[0010]
【発明が解決しようとする課題】しかしながら、上記液
晶表示素子は、ランダムなツイスト配向状態を得るため
に液晶材料をアイソトロピック相になる温度に加熱した
状態で液晶セル内に注入し、その後、徐冷によりセル内
の液晶材料をネマティック相に戻す方法で製造されてい
るので、液晶表示素子の製造に時間がかかり、したがっ
て製造能率が悪いし、また、液晶材料の組成が加熱によ
って変化することがあるため、製造された液晶表示素子
の信頼性も低いという問題をもっている。However, in the above liquid crystal display device, in order to obtain a random twist alignment state, the liquid crystal material is injected into the liquid crystal cell while being heated to a temperature at which it is in an isotropic phase, and then slowly. Since it is manufactured by the method of returning the liquid crystal material in the cell to the nematic phase by cooling, it takes time to manufacture the liquid crystal display element, and therefore the manufacturing efficiency is poor, and the composition of the liquid crystal material may change due to heating. Therefore, there is a problem that the reliability of the manufactured liquid crystal display element is low.
【００１１】この発明は、液晶分子のダイレクタを配向
膜で規定せずに広い視野角を得るようにした液晶表示素
子として、短時間で能率良く製造することができるとと
もに、液晶材料の組成変化もなくして信頼性を向上させ
ることができるものを提供することを目的としたもので
ある。The present invention can be efficiently manufactured in a short time as a liquid crystal display device in which a director of liquid crystal molecules is not defined by an alignment film and a wide viewing angle is obtained, and a composition change of a liquid crystal material is also obtained. The purpose of the present invention is to provide a product that can improve reliability without it.
【００１２】[0012]
【課題を解決するための手段】この発明は、液晶分子を
所定のピッチでツイストさせるためのカイラル物質が添
加された液晶層を挟んで対向する一対の基板の内面にそ
れぞれ配向処理しない配向膜が設けられており、液晶の
分子が液晶材料のねじれ性に応じたツイスト角でツイス
ト配向している液晶表示素子において、前記配向膜の表
面エネルギーの極性力成分を１５ｄｙｎ／ｃｍ未満、４
ｄｙｎ／ｃｍ以上とし、前記液晶の分子をミクロ的に見
た各点でのダイレクタを様々な向に配向させたことを特
徴とするものである。The present invention provides liquid crystal molecules.
A chiral substance for twisting at a specified pitch is added.
A liquid crystal display in which alignment films that are not subjected to alignment treatment are provided on the inner surfaces of a pair of substrates that face each other across the applied liquid crystal layer, and the liquid crystal molecules are twist-aligned at a twist angle according to the twistability of the liquid crystal material. In the device, the polar force component of the surface energy of the alignment film is less than 15 dyn / cm, 4
dyn / cm or more to see the liquid crystal molecules microscopically
In addition, the director at each point is oriented in various directions .
【００１３】また、この発明は、前記液晶表示素子にお
いて、前記配向膜は、極性力成分が４ｄｙｎ／ｃｍ以
上、８ｄｙｎ／ｃｍ未満の表面エネルギーを有すること
を特徴とする。 Further, in the invention, in the liquid crystal display device, the orientation film has a polar component of 4 dyn / cm or less.
Top, having a surface energy of less than 8 dyn / cm
Is characterized by.
【００１４】このように、前記配向膜の表面エネルギー
の極性力成分を１５ｄｙｎ／ｃｍ未満、４ｄｙｎ／ｃｍ
以上とし、さらに好ましくは、４ｄｙｎ／ｃｍ以上、８
ｄｙｎ／ｃｍ未満することにより、液晶材料をネマティ
ック相の状態で注入しても、配向膜面に隣接する液晶分
子はランダムな方向に向いており、層厚方向方向の分子
が液晶材料のねじれ性に応じたツイスト角でツイスト配
向するので、ミクロ的に見た各点での液晶分子のダイレ
クタが様々な向きにある良好な配向状態が得られる。Thus, the surface energy of the alignment film is
Polarity component of less than 15 dyn / cm, 4 dyn / cm
And more preferably 4 dyn / cm or more and 8
By setting less than dyn / cm, even if the liquid crystal material is injected in a nematic phase, the liquid crystal molecules adjacent to the alignment film surface are oriented in random directions, and the molecules in the layer thickness direction are twisted in the liquid crystal material. Since the twist alignment is performed at a twist angle corresponding to, it is possible to obtain a good alignment state in which the directors of liquid crystal molecules at various points in a microscopic view are in various directions.
【００１５】このため、この発明によれば、液晶材料の
注入を室温で行なって、ミクロ的に見た各点での液晶分
子のダイレクタが様々な向きにある広視野角の液晶表示
素子を得ることができるから、液晶表示素子を短時間で
能率良く製造することができるし、また、従来のように
液晶材料をアイソトロピック相になる温度に加熱する必
要がないため、加熱による液晶材料の組成変化もなくし
て信頼性を向上させることができる。Therefore, according to the present invention, the liquid crystal material is injected at room temperature to obtain a liquid crystal display element having a wide viewing angle in which the directors of liquid crystal molecules at various points in a microscopic view are in various directions. Therefore, the liquid crystal display device can be manufactured efficiently in a short time, and since it is not necessary to heat the liquid crystal material to a temperature at which it becomes an isotropic phase as in the conventional case, the composition of the liquid crystal material by heating can be improved. The reliability can be improved without any change.
【００１６】[0016]
【発明の実施の形態】以下、この発明を、液晶分子のツ
イスト角をほぼ９０°とした液晶表示素子に適用したと
きの実施の形態を説明する。この実施の形態は、液晶層
をはさんで対向する一対の透明基板の内面にそれぞれ透
明電極と配向処理しない配向膜とが設けられており、液
晶の分子が液晶材料のねじれ性により一対の基板間でほ
ぼ９０°のツイスト角でツイスト配向している液晶表示
素子において、前記配向膜の表面エネルギーを５１ｄｙ
ｎ／ｃｍ未満とするか、あるいは前記配向膜の表面エネ
ルギーの極性力成分を１５ｄｙｎ／ｃｍ未満としたもの
である。BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a liquid crystal display device in which the twist angle of liquid crystal molecules is approximately 90 ° will be described below. In this embodiment, a transparent electrode and an alignment film that is not aligned are provided on the inner surfaces of a pair of transparent substrates that face each other across the liquid crystal layer, and the molecules of the liquid crystal are twisted by the liquid crystal material to form a pair of substrates. In the liquid crystal display element in which the twist alignment is carried out at a twist angle of about 90 ° between them, the surface energy of the alignment film is 51 dy.
It is less than n / cm, or the polar force component of the surface energy of the alignment film is less than 15 dyn / cm.
【００１７】なお、上記液晶表示素子は、その構成を示
す図は省略するが、電極と配向処理しない配向膜を設け
た一対の基板を枠状のシール材を介して接合して液晶セ
ルを組立て、その液晶セル内に、前記シール材の一部を
欠落させて形成しておいた液晶注入口から、真空注入法
によって上記液晶材料を注入し、その後前記液晶注入口
を封止する方法で製造されるものであり、両基板の外面
にはそれぞれ偏光板が配置される。Although the liquid crystal display element is not shown in the drawing, the liquid crystal cell is assembled by joining a pair of substrates provided with an alignment film which is not subjected to alignment treatment through a frame-shaped sealing material. Manufactured by a method of injecting the above liquid crystal material into the liquid crystal cell by a vacuum injection method from a liquid crystal injection port formed by removing a part of the sealing material, and then sealing the liquid crystal injection port. Polarizing plates are arranged on the outer surfaces of both substrates, respectively.
【００１８】上記液晶材料は、ネマティック液晶に、光
学活性物質として用いられる、液晶分子を所定のピッチ
でツイストさせるためのカイラル物質を添加したもので
あり、そのねじれ性、つまり液晶材料の固有のねじれピ
ッチ（以下、ナチュラルピッチという）Ｐは、前記光学
活性物質の添加量によって決まる。The above-mentioned liquid crystal material is a nematic liquid crystal to which a chiral substance used as an optically active substance for twisting liquid crystal molecules at a predetermined pitch is added, and its twisting property, that is, the inherent twisting of the liquid crystal material. The pitch (hereinafter referred to as natural pitch) P is determined by the amount of the optically active substance added.
【００１９】そして、この実施形態では、液晶分子が一
対の基板間で所定のツイスト角で配列するようにナチュ
ラルピッチＰが設定されている。例えば、上記液晶材料
として、ナチュラルピッチＰが２０μｍのものを用い、
前記一対の基板間の間隙（以下、セルギャップという）
ｄを５μｍに設定することにより、液晶分子のツイスト
角をほぼ９０°に設定している。In this embodiment, the natural pitch P is set so that the liquid crystal molecules are arranged between the pair of substrates at a predetermined twist angle. For example, a liquid crystal material having a natural pitch P of 20 μm is used,
Gap between the pair of substrates (hereinafter referred to as cell gap)
By setting d to 5 μm, the twist angle of the liquid crystal molecules is set to about 90 °.
【００２０】すなわち、一対の基板間における液晶分子
のツイスト角は、セルギャップｄと液晶材料のナチュラ
ルピッチＰとの比（ｄ／Ｐ）によって決まり、セルギャ
ップｄがｄ＝５μｍ、液晶材料のナチュラルピッチＰが
Ｐ＝２０μｍであれば、
ｄ／Ｐ＝５／２０＝０．２５
であるから、液晶分子のツイスト角は、
３６０°×０．２５＝９０°
となる。That is, the twist angle of the liquid crystal molecules between the pair of substrates is determined by the ratio (d / P) of the cell gap d and the natural pitch P of the liquid crystal material. The cell gap d is d = 5 μm and the natural pitch of the liquid crystal material is When the pitch P is P = 20 μm, since d / P = 5/20 = 0.25, the twist angle of the liquid crystal molecules is 360 ° × 0.25 = 90 °.
【００２１】上記液晶表示素子は、液晶分子のダイレク
タが配向膜によって規定されないため、基板間における
液晶分子分子のツイスト角は液晶層の全域において同じ
であっても、ミクロ的に見た各点でのダイレクタは様々
な向きにあるから、電圧−透過率特性の視角依存性がほ
とんどなく、したがって、広い視野角が得られる。In the above liquid crystal display device, since the director of the liquid crystal molecules is not defined by the alignment film, even if the twist angles of the liquid crystal molecule molecules between the substrates are the same throughout the liquid crystal layer, they are microscopically different. Since the directors of (1) have various orientations, there is almost no dependence of the voltage-transmittance characteristic on the viewing angle, and therefore a wide viewing angle can be obtained.
【００２２】そして、この実施形態の液晶表示素子のよ
うに、一対の基板の内面に設けた配向膜の表面エネルギ
ーを５１ｄｙｎ／ｃｍ未満とするか、あるいは前記配向
膜の表面エネルギーの極性力成分を１５ｄｙｎ／ｃｍ未
満と小さくしているので、配向膜と液晶分子との相互作
用が弱くなり、液晶の注入の際に生じる液晶の流れに沿
って配向した液晶分子が配向膜に吸着されることがなく
なる。Then, as in the liquid crystal display device of this embodiment, the surface energy of the alignment film provided on the inner surfaces of the pair of substrates is set to less than 51 dyn / cm, or the polar component of the surface energy of the alignment film is set. Since it is less than 15 dyn / cm, the interaction between the alignment film and the liquid crystal molecules is weakened, and the liquid crystal molecules aligned along the flow of the liquid crystal generated when the liquid crystal is injected may be adsorbed to the alignment film. Disappear.
【００２３】そのため、液晶材料をネマティック相の状
態で注入しても、層厚方向の分子が、液晶材料のねじれ
性に応じたツイスト角でツイスト配向する。したがっ
て、ミクロ的に見た各点での液晶分子のダイレクタが様
々な向きにある良好な配向状態が得られる。Therefore, even if the liquid crystal material is injected in the nematic phase, the molecules in the layer thickness direction are twist-aligned at a twist angle according to the twistability of the liquid crystal material. Therefore, it is possible to obtain a good alignment state in which the directors of liquid crystal molecules at various points in a microscopic view are in various directions.
【００２４】このため、この液晶表示素子によれば、液
晶材料の注入を室温で行なって、ミクロ的に見た各点で
の液晶分子のダイレクタが様々な向きにある広視野角の
液晶表示素子を得ることができるから、短時間で能率良
く製造することができるし、また、従来のように液晶材
料をアイソトロピック相になる温度に加熱する必要がな
いため、加熱による液晶材料の組成変化もなくして信頼
性を向上させることができる。Therefore, according to this liquid crystal display element, the liquid crystal material is injected at room temperature, and the directors of the liquid crystal molecules at various points in a microscopic view have a wide viewing angle. Therefore, it is possible to efficiently manufacture the liquid crystal material in a short time, and since it is not necessary to heat the liquid crystal material to a temperature at which the liquid crystal material is in the isotropic phase as in the conventional case, the composition change of the liquid crystal material due to the heating The reliability can be improved without it.
【００２５】[0025]
【実施例】この発明の具体的な実施例を説明すると、こ
の実施例では、一対の基板の内面に設けた配向膜をそれ
ぞれ、表面エネルギーが５１ｄｙｎ／ｃｍ未満のポリイ
ミド膜からなる、配向処理を施さない配向膜とするとと
もに、液晶材料として、
ナチュラルピッチＰが２０μｍ
誘電異方性Δｎが０．０９０
Ｎ−Ｉ点が８６．９℃
誘電異方性Δεが４．５
しきい値電圧Ｖthが２．３７Ｖ
である物性のものを用い、セルギャップｄを５μｍとし
て、液晶分子のツイスト角をほぼ９０°に設定した。EXAMPLE A specific example of the present invention will be described. In this example, an alignment treatment is performed in which the alignment films provided on the inner surfaces of a pair of substrates are each made of a polyimide film having a surface energy of less than 51 dyn / cm. The alignment film is not applied, and the liquid crystal material has a natural pitch P of 20 μm, a dielectric anisotropy Δn of 0.090, an NI point of 86.9 ° C., a dielectric anisotropy Δε of 4.5, and a threshold voltage Vth of With a physical property of 2.37 V, the cell gap d was set to 5 μm, and the twist angle of liquid crystal molecules was set to about 90 °.
【００２６】この実施例によれば、一対の基板の内面に
設けた配向膜の表面エネルギーを５１ｄｙｎ／ｃｍ未満
としているため、液晶表示素子の製造に際して、液晶材
料をネマティック相の状態で注入しても、配向膜面に隣
接する液晶分子はランダムな方向を向いて配向し、層厚
方向の分子が、液晶材料のねじれ性に応じたツイスト角
でツイスト配向するので、ミクロ的に見た各点での液晶
分子のダイレクタが様々な向きにある良好な配向状態が
得られる。According to this embodiment, since the surface energy of the alignment films provided on the inner surfaces of the pair of substrates is less than 51 dyn / cm, the liquid crystal material is injected in the nematic phase state during the manufacture of the liquid crystal display device. In addition, the liquid crystal molecules adjacent to the alignment film surface are oriented in random directions, and the molecules in the layer thickness direction are twisted at a twist angle according to the twistability of the liquid crystal material. A good alignment state in which the directors of liquid crystal molecules in various directions are obtained can be obtained.
【００２７】次の［表１］は、表面エネルギーの異なる
Ａ〜Ｅの配向膜を用いて５種類の液晶表示素子を試作
し、これらの液晶表示素子に上述した液晶材料を室温
（ネマティック相の状態）で注入して、その注入後の液
晶分子の配向状態と、ドメインの発生の有無とを調べた
結果を示している。In the following [Table 1], five kinds of liquid crystal display elements were prototyped by using the alignment films A to E having different surface energies, and the liquid crystal materials described above were applied to these liquid crystal display elements at room temperature (nematic phase). State), and the results of examining the alignment state of liquid crystal molecules after the injection and the presence or absence of domains are shown.
【００２８】[0028]
【表１】 [Table 1]
【００２９】この［表１］のように、表面エネルギーが
５１ｄｙｎ／ｃｍ以上であるＡ，Ｂ，Ｃの配向膜を用い
た液晶表示素子は、液晶物質を注入した後の液晶分子の
配向状態が、注入時の液晶物質の流れの跡が残ったむら
の有る状態が観察された。すなわち、配向膜面に隣接す
る液晶分子のダイレクタが前記流れ方向にそろって配向
する箇所が部分的に生じて、ドメインが発生する。As shown in [Table 1], a liquid crystal display device using an alignment film of A, B, and C having a surface energy of 51 dyn / cm or more has an alignment state of liquid crystal molecules after a liquid crystal substance is injected. , The uneven state in which the trace of the flow of the liquid crystal substance at the time of injection was left was observed. That is, the directors of the liquid crystal molecules adjacent to the surface of the alignment film are partially aligned in the flow direction, and domains are generated.
【００３０】これに対して、表面エネルギーが４５ｄｙ
ｎ／ｃｍまたは４１ｄｙｎ／ｃｍと小さいＤ，Ｅの配向
膜を用いた液晶表示素子は、液晶物質を注入した後の液
晶分子の配向状態が、注入時の液晶物質の流れの跡が全
く残らない良好な状態であり、また、ミクロ的に見た各
点での液晶分子のダイレクタが様々な向きにあるため、
ドメインの発生も無い。On the other hand, the surface energy is 45 dy.
In the liquid crystal display device using the D and E alignment films as small as n / cm or 41 dyn / cm, the alignment state of the liquid crystal molecules after the liquid crystal substance is injected does not leave any trace of the flow of the liquid crystal substance at the time of injection. It is in a good state, and because the directors of liquid crystal molecules at various points on a microscopic scale are in various directions,
There is no domain.
【００３１】なお、［表１］には、Ａ〜Ｅの配向膜を用
いた５種類の各液晶表示素子における液晶分子の配向状
態とドメインの発生の有無とを示したが、一対の基板の
内面に設けた配向膜の表面エネルギーがそれぞれ５１ｄ
ｙｎ／ｃｍ未満であれば、液晶物質を注入した後の液晶
分子の配向状態が良好な状態で、ドメインの発生も無
い。[Table 1] shows the alignment state of liquid crystal molecules and the presence or absence of domains in each of the five types of liquid crystal display elements using the alignment films A to E. The surface energy of the alignment film provided on the inner surface is 51d.
When it is less than yn / cm, the alignment state of liquid crystal molecules after the liquid crystal substance is injected is in a good state, and no domain is generated.
【００３２】すなわち、配向膜の表面エネルギーが５１
ｄｙｎ／ｃｍ未満、４１ｄｙｎ／ｃｍ以上であれば、液
晶材料をネマティック相の状態で注入しても、その分子
が、液晶材料のねじれ性に応じたツイスト角で、かつ、
ミクロ的に見た各点での液晶分子のダイレクタが様々な
向きにある良好な配向状態で配向する。That is, the surface energy of the alignment film is 51
When the liquid crystal material is less than dyn / cm and 41 dyn / cm or more , even if the liquid crystal material is injected in a nematic phase, the molecules have twist angles according to the twistability of the liquid crystal material, and
The directors of the liquid crystal molecules at each microscopic point are oriented in various orientations in good orientation.
【００３３】このため、この実施例によれば、液晶材料
の注入を室温で行なって、ミクロ的に見た各点での液晶
分子のダイレクタが様々な向きにある広視野角の液晶表
示素子を得ることができるから、液晶表示素子を短時間
で能率良く製造することができるし、また、従来のよう
に液晶材料をアイソトロピック相になる温度に加熱する
必要がないため、加熱による液晶材料の組成変化もなく
して信頼性を向上させることができる。Therefore, according to this embodiment, a liquid crystal display device having a wide viewing angle in which liquid crystal material is injected at room temperature and directors of liquid crystal molecules at various points viewed microscopically are in various directions. Since it is possible to obtain the liquid crystal display element, it is possible to efficiently manufacture the liquid crystal display element in a short time. Further, since it is not necessary to heat the liquid crystal material to a temperature at which the liquid crystal material is in an isotropic phase as in the conventional case, the liquid crystal material is The reliability can be improved without changing the composition.
【００３４】なお、この実施例において、より望ましい
配向膜の表面エネルギーは、４１ｄｙｎ／ｃｍ以上、４
５ｄｙｎ／ｃｍ未満（［表１］参照）の範囲であり、配
向膜の表面エネルギーがこの範囲であれば、より良好な
液晶分子の配向状態を得ることができる。In this embodiment, the more desirable surface energy of the alignment film is 41 dyn / cm or more, 4 or more.
It is less than 5 dyn / cm (see [Table 1]), and if the surface energy of the alignment film is in this range, a better alignment state of liquid crystal molecules can be obtained.
【００３５】次に、この発明の他の具体的な実施例を説
明すると、この実施例では、一対の基板の内面に設けた
配向膜をそれぞれ、表面エネルギーの極性力成分が１５
ｄｙｎ／ｃｍ未満のポリイミド膜からなる、配向処理を
施さない配向膜とするとともに、液晶材料として、上述
した物性（ナチュラルピッチＰが２０μｍ、誘電異方性
Δｎが０．０９０、Ｎ−Ｉ点が８６．９℃、誘電異方性
Δεが４．５、しきい値電圧Ｖthが２．３７Ｖ）のもの
を用い、セルギャップｄを５μｍとして、液晶分子のツ
イスト角をほぼ９０°に設定した。Next, another specific embodiment of the present invention will be described. In this embodiment, the alignment films provided on the inner surfaces of the pair of substrates have a polar force component of surface energy of 15 respectively.
In addition to an alignment film that is not subjected to an alignment treatment and is composed of a polyimide film of less than dyn / cm, the liquid crystal material has the above-mentioned physical properties (natural pitch P of 20 μm, dielectric anisotropy Δn of 0.090, and NI point. 86.9 ° C., a dielectric anisotropy Δε of 4.5, and a threshold voltage Vth of 2.37 V) were used, the cell gap d was set to 5 μm, and the twist angle of the liquid crystal molecules was set to about 90 °.
【００３６】この実施例によれば、一対の基板の内面に
設けた配向膜の表面エネルギーの極性力成分を１５ｄｙ
ｎ／ｃｍ未満としているため、液晶表示素子の製造に際
して、液晶材料をネマティック相の状態で注入しても、
配向膜面に隣接する液晶分子はランダムな方向を向いて
配向し、層厚方向の分子が、液晶材料のねじれ性に応じ
たツイスト角でツイスト配向するので、ミクロ的に見た
各点での液晶分子のダイレクタが様々な向きにある良好
な配向状態が得られる。According to this embodiment, the polar component of the surface energy of the alignment films provided on the inner surfaces of the pair of substrates is 15 dy.
Since it is less than n / cm, even if a liquid crystal material is injected in the state of a nematic phase when manufacturing a liquid crystal display element,
Liquid crystal molecules adjacent to the alignment film surface are oriented in random directions, and molecules in the layer thickness direction are twisted at a twist angle according to the twistability of the liquid crystal material. A good alignment state in which the directors of liquid crystal molecules are in various directions can be obtained.
【００３７】次の［表２］は、表面エネルギーの極性力
成分が異なるＦ〜Ｊの配向膜を用いて５種類の液晶表示
素子を試作し、これらの液晶表示素子に上述した液晶材
料を室温（ネマティック相の状態）で注入して、その注
入後の液晶分子の配向状態と、ドメインの発生の有無と
を調べた結果を示している。In the following [Table 2], five kinds of liquid crystal display elements were experimentally produced by using alignment films F to J having different polar force components of surface energy, and the above liquid crystal materials were applied to these liquid crystal display elements at room temperature. The results of examining the alignment state of liquid crystal molecules after injection and the presence or absence of domains are shown.
【００３８】[0038]
【表２】 [Table 2]
【００３９】この［表２］のように、表面エネルギーの
極性力成分が１５ｄｙｎ／ｃｍ以上であるＦ，Ｇ，Ｈの
配向膜を用いた液晶表示素子は、液晶物質を注入した後
の液晶分子の配向状態が、注入時の液晶物質の流れの跡
が残ったむらの有る状態が観察された。すなわち、配向
膜面に隣接する液晶分子のダイレクタが前記流れの方向
にそろって配向する箇所が部分的に生じて、ドメインが
発生する。As shown in [Table 2], the liquid crystal display element using the F, G, and H alignment films whose surface energy has a polar force component of 15 dyn / cm or more is used. It was observed that the alignment state of 1 was uneven with traces of the flow of the liquid crystal substance at the time of injection. That is, the directors of the liquid crystal molecules adjacent to the alignment film surface are partially aligned in the direction of the flow, and domains are generated.
【００４０】これに対して、表面エネルギーＮＯ極性力
成分が８ｄｙｎ／ｃｍまたは４ｄｙｎ／ｃｍと小さい
Ｉ，Ｊの配向膜を用いた液晶表示素子は、液晶物質を注
入した後の液晶分子の配向状態が、注入時の液晶物質の
流れの跡が全く残らない良好な状態であり、また、ミク
ロ的に見た各点での液晶分子のダイレクタが様々な向き
にあるため、ドメインの発生も無い。On the other hand, the liquid crystal display element using the I and J alignment films having a surface energy NO polar component of as small as 8 dyn / cm or 4 dyn / cm is the alignment state of the liquid crystal molecules after the liquid crystal substance is injected. However, it is in a good state in which no trace of the flow of the liquid crystal substance at the time of injection remains, and since the directors of liquid crystal molecules at various points in a microscopic view are in various directions, no domain is generated.
【００４１】なお、［表２］には、Ｆ〜Ｊの配向膜を用
いた５種類の各液晶表示素子における液晶分子の配向状
態とドメインの発生の有無とを示したが、一対の基板の
内面に設けた配向膜の表面エネルギーの極性力成分がそ
れぞれ１５ｄｙｎ／ｃｍ未満であれば、液晶物質を注入
した後の液晶分子の配向状態が良好な状態で、ドメイン
の発生も無い。[Table 2] shows the alignment state of liquid crystal molecules and the presence or absence of domains in each of the five types of liquid crystal display elements using the alignment films F to J. When the polar force components of the surface energy of the alignment film provided on the inner surface are each less than 15 dyn / cm, the alignment state of the liquid crystal molecules after injection of the liquid crystal substance is in a good state and no domain is generated.
【００４２】すなわち、配向膜の表面エネルギーの極性
力成分が１５ｄｙｎ／ｃｍ未満、４ｄｙｎ／ｃｍ以上で
あれば、液晶材料をネマティック相の状態で注入して
も、その分子が、液晶材料のねじれ性に応じたツイスト
角で、かつ、ミクロ的に見た各点での液晶分子のダイレ
クタが様々な向きにある良好な配向状態で配向する。That is, when the polar force component of the surface energy of the alignment film is less than 15 dyn / cm and 4 dyn / cm or more , even if the liquid crystal material is injected in a nematic phase, the molecules thereof have a twisting property of the liquid crystal material. The directors of the liquid crystal molecules are aligned in various orientations at various twist angles according to the above and at microscopically different points.
【００４３】このため、この実施例によれば、液晶材料
の注入を室温で行なって、ミクロ的に見た各点での液晶
分子のダイレクタが様々な向きにある広視野角の液晶表
示素子を得ることができるから、液晶表示素子を短時間
で能率良く製造することができるし、また、従来のよう
に液晶材料をアイソトロピック相になる温度に加熱する
必要がないため、加熱による液晶材料の組成変化もなく
して信頼性を向上させることができる。Therefore, according to this embodiment, the liquid crystal material is injected at room temperature, and the liquid crystal display element having a wide viewing angle in which the directors of the liquid crystal molecules at each microscopic point are in various directions. Since it is possible to obtain the liquid crystal display element, it is possible to efficiently manufacture the liquid crystal display element in a short time. Further, since it is not necessary to heat the liquid crystal material to a temperature at which the liquid crystal material is in an isotropic phase as in the conventional case, the liquid crystal material is The reliability can be improved without changing the composition.
【００４４】なお、この実施例において、より望ましい
配向膜の表面エネルギーの極性力成分は、４ｄｙｎ／ｃ
ｍ以上、８ｄｙｎ／ｃｍ未満（［表２］参照）の範囲で
あり、配向膜の表面エネルギーの極性力成分がこの範囲
であれば、より良好な液晶分子の配向状態を得ることが
できる。In this example, the polar force component of the surface energy of the alignment film is more preferably 4 dyn / c.
It is in the range of m or more and less than 8 dyn / cm (see [Table 2]), and if the polar force component of the surface energy of the alignment film is in this range, a better alignment state of liquid crystal molecules can be obtained.
【００４５】また、上記各実施例では、配向膜の表面エ
ネルギー、またはその極性力成分だけに着目したが、こ
の発明の最も好ましい実施の形態は、配向膜の表面エネ
ルギーを５１ｄｙｎ／ｃｍ未満（望ましくは４１ｄｙｎ
／ｃｍ以上、４５ｄｙｎ／ｃｍ未満）とし、さらに前記
極性力成分を１５ｄｙｎ／ｃｍ未満（望ましくは４ｄｙ
ｎ／ｃｍ以上、８ｄｙｎ／ｃｍ未満）とすることであ
り、このようにすれば、さらに良好な液晶分子の配向状
態を得ることができる。Further, in each of the above-mentioned examples, only the surface energy of the alignment film or its polar force component was focused, but in the most preferred embodiment of the present invention, the surface energy of the alignment film is less than 51 dyn / cm (desirably). Is 41 dyn
/ Cm or more and less than 45 dyn / cm), and the polar force component is less than 15 dyn / cm (desirably 4 dy).
n / cm or more and less than 8 dyn / cm). By doing so, a better alignment state of liquid crystal molecules can be obtained.
【００４６】また、この発明は、液晶分子のツイスト角
がほぼ９０°の液晶表示素子に限らず、液晶分子のツイ
スト角を任意に設定した液晶表示素子に広く適用するこ
とができる。Further, the present invention is not limited to the liquid crystal display device in which the twist angle of the liquid crystal molecules is about 90 °, but can be widely applied to the liquid crystal display device in which the twist angle of the liquid crystal molecules is arbitrarily set.
【００４７】[0047]
【発明の効果】この発明は、液晶層をはさんで対向する
一対の基板の内面にそれぞれ配向処理しない配向膜が設
けられており、液晶の分子が液晶材料のねじれ性に応じ
たツイスト角でツイスト配向している液晶表示素子にお
いて、前記配向膜の表面エネルギーの極性力成分を１５
ｄｙｎ／ｃｍ未満、４ｄｙｎ／ｃｍ以上とし、さらに好
ましくは、４ｄｙｎ／ｃｍ以上、８ｄｙｎ／ｃｍ未満と
したため、液晶材料をネマティック相の状態で注入して
も、配向膜面に隣接する液晶分子はランダムな方向を向
いており、層厚方向の分子が、液晶材料のねじれ性に応
じたツイスト角でツイスト配向するので、ミクロ的に見
た各点での液晶分子のダイレクタが様々な向きにある良
好な配向状態が得られる。According to the present invention, an alignment film that is not subjected to alignment treatment is provided on the inner surfaces of a pair of substrates that face each other across a liquid crystal layer, and the molecules of the liquid crystal have a twist angle according to the twistability of the liquid crystal material. in the liquid crystal display device are twisted, polar force component of the surface energy of the previous SL alignment film 15
Less than dyn / cm , 4 dyn / cm or more, more preferable
More preferably, 4 dyn / cm or more and less than 8 dyn / cm
Therefore , even if the liquid crystal material is injected in the nematic phase, the liquid crystal molecules adjacent to the alignment film surface are oriented randomly, and the molecules in the layer thickness direction have a twist angle according to the twistability of the liquid crystal material. Since the twist alignment is performed, it is possible to obtain a good alignment state in which the directors of liquid crystal molecules at various points in a microscopic view are in various directions.
【００４８】このため、この発明によれば、液晶分子の
ダイレクタを配向膜で規定せずに広い視野角を得るよう
にした液晶表示素子として、短時間で能率良く製造する
ことができるとともに、液晶材料の組成変化もなくして
信頼性を向上させることができるものを提供することが
できる。Therefore, according to the present invention, it is possible to efficiently manufacture the liquid crystal display element in a short time and to obtain a wide viewing angle without defining the director of the liquid crystal molecule by the alignment film, and at the same time, the liquid crystal can be manufactured. It is possible to provide a material that can improve reliability without changing the composition of the material.
Claims (2)
ためのカイラル物質が添加された液晶層を挟んで対向す
る一対の基板の内面にそれぞれ配向処理しない配向膜が
設けられており、液晶の分子が液晶材料のねじれ性に応
じたツイスト配向している液晶表示素子において、 前記配向膜の表面エネルギーの極性力成分を１５ｄｙｎ
／ｃｍ未満、４ｄｙｎ／ｃｍ以上とし、前記液晶の分子
をミクロ的に見た各点でのダイレクタを様々な向に配向
させたことを特徴とする液晶表示素子。1. Alignment films that are not subjected to alignment treatment are provided on the inner surfaces of a pair of substrates facing each other with a liquid crystal layer added with a chiral substance for twisting liquid crystal molecules at a predetermined pitch interposed therebetween. In a liquid crystal display element in which is twisted according to the twistability of the liquid crystal material, the polar force component of the surface energy of the alignment film is 15 dyn.
/ Cm or less and 4 dyn / cm or more, and the molecules of the liquid crystal
Orienting the director at various points from a micro perspective
A liquid crystal display device characterized by being made .
膜は、極性力成分が４ｄｙｎ／ｃｍ以上、８ｄｙｎ／ｃ
ｍ未満の表面エネルギーを有することを特徴とする請求
項１に記載の液晶表示素子。 2. An alignment provided on each of the inner surfaces between a pair of substrates.
The membrane has a polar component of 4 dyn / cm or more, 8 dyn / c
Claims characterized by having a surface energy of less than m
Item 2. The liquid crystal display device according to item 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33899795A JP3463132B2 (en) | 1995-12-26 | 1995-12-26 | Liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33899795A JP3463132B2 (en) | 1995-12-26 | 1995-12-26 | Liquid crystal display device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09179122A JPH09179122A (en) | 1997-07-11 |
| JP3463132B2 true JP3463132B2 (en) | 2003-11-05 |
Family
ID=18323300
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33899795A Expired - Lifetime JP3463132B2 (en) | 1995-12-26 | 1995-12-26 | Liquid crystal display device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3463132B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002090744A (en) * | 2000-09-12 | 2002-03-27 | Toshiba Corp | Liquid crystal display device |
-
1995
- 1995-12-26 JP JP33899795A patent/JP3463132B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09179122A (en) | 1997-07-11 |
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