【発明の詳細な説明】〔産業上の利用分野〕本発明は、ツイステッドネマテインク液晶、又はコレス
テリック液晶を使った液晶表示装置に関するものである
．〔従来の技術〕液晶表示装置は、低電圧、低消費電力でＩＣ回路への直
結が可能であること、表示機能が多樺であること、高生
産性軽量化が可能であること等多くの特長を有し、その
用途は拡大してきた。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device using twisted nematic ink liquid crystal or cholesteric liquid crystal. [Prior Art] Liquid crystal display devices have many advantages such as low voltage, low power consumption, direct connection to IC circuits, multi-layer display functions, high productivity and light weight. Due to its unique characteristics, its uses have expanded.
ワードプロセッサやパーソナルコンピュータ等のＯＡ関
連機器に用いるドットマトリクス形液晶表示装置には現
在、液晶分子のツイスト角が１６０゜以上のツイステッ
ドネマチック液晶表示装置（以後ＳＴＮ−ＬＣＤ）が実
用化され主流になっている。それはＳＴＮ−ＬＣＤが従
来のツイスト角が９０゜のツイステッドネマチック液晶
表示装ｆ（ＴＮ−ＬＣＤ）に比べ、高マルチプレックス
駆動時においても高コントラストが維持できることによ
っている。Twisted nematic liquid crystal display devices (hereinafter referred to as STN-LCDs), in which the twist angle of liquid crystal molecules is 160° or more, are currently in practical use as dot matrix liquid crystal display devices used in OA-related equipment such as word processors and personal computers, and have become mainstream. There is. This is because the STN-LCD can maintain high contrast even during high multiplex driving compared to the conventional twisted nematic liquid crystal display f (TN-LCD) with a twist angle of 90 degrees.
ＳＴＮは液晶表示装置の外観の色相を白くすることは不
可能であり、緑色から黄赤色の色味を呈し、表示装置と
して不適当であった。この問題を解決するために一対の
偏光板の間に一層又は複数３層の光学異方体を備える方
法が提案されている。STN cannot make the external appearance of a liquid crystal display device white, and exhibits a green to yellow-red hue, making it unsuitable for use as a display device. In order to solve this problem, a method has been proposed in which one or more three layers of optically anisotropic material are provided between a pair of polarizing plates.
この場合一対の偏光板の一方を通過した直線偏光が液晶
素子の液晶層と光学異方体を通過したとき約４００ｎｍ
から約７００ｎｍの波長域において長軸方向のほぼ揃っ
た楕円偏光が得られる．結果的には、もう一方の偏光板
を通過した時に特定の波長域が遮断されることはなく、
白色光となるものである。In this case, when the linearly polarized light that has passed through one of the pair of polarizing plates passes through the liquid crystal layer of the liquid crystal element and the optically anisotropic body, it has a wavelength of approximately 400 nm.
In the wavelength range of approximately 700 nm, elliptically polarized light with almost uniform major axes can be obtained. As a result, a specific wavelength range is not blocked when passing through the other polarizing plate.
It produces white light.
又、ＳＴＮ−ＬＣＤに着色除去用として利用される位相
差板単独の特許出願も見られる．例えば特開昭６３−１
８９８０４号は、偏光顕微鏡によるレターデーシッン（
？！［屈折値とフイルム厚みの積）の測定値が２００〜
３ ５ ０ ｎｍもしくは４７５〜６２５ｎｍになるよ
うに一軸方向に延伸したポリカーポネートフィルムに関
するものである。There are also patent applications for individual retardation plates used for color removal in STN-LCDs. For example, JP-A-63-1
No. 89804 is a letter delineation method using a polarizing microscope (
? ! The measured value of [product of refraction value and film thickness] is 200~
The present invention relates to a polycarbonate film uniaxially stretched to a thickness of 350 nm or 475 to 625 nm.
又、特開昭６３−１６７３０４号は、一軸方向に延伸処
理した複屈折性を有するフィルム又はシートを、その光
学的主軸が直交するように２枚又はそれ以上重ねたフィ
ルム積層体に関するものである。上記発明においては二
枚の複屈折フィルム（各々のレターデーション値がＲ＋
、Ｒｚ ）を直交して２枚重ね合わせると積層体のレ
ターデーションが Ｒ，−Ｒ． の位相差フィルムが
得られることを利用して、Ｒ１、Ｒ２が大きなレターデ
ション値を有していても Ｒ，−Ｒ． を９０〜１８
０ｎｍ，２００〜３５０ｎｍ、４７５〜６２５ｎｍ等の
範囲に調節できるという効果を狙ったものである。Furthermore, JP-A-63-167304 relates to a film laminate in which two or more uniaxially stretched birefringent films or sheets are stacked so that their optical principal axes are perpendicular to each other. . In the above invention, two birefringent films (each with a retardation value of R+
, Rz), the retardation of the laminate becomes R, -Rz. Even if R1 and R2 have large retardation values, R, -R. 90-18
This is aimed at the effect of being able to adjust the wavelength to a range such as 0 nm, 200 to 350 nm, or 475 to 625 nm.
上記発明は全てＳＴＮ−ＬＣＤの着色除去を目的とした
ものであり、その点に関して大幅に改善され、白／黒表
示に近いものが得られている。又、高分子の複屈折フィ
ルム（以後位相差フィルム）を使用する方法はコストメ
リットもあり需要が急速に拡大している。All of the above-mentioned inventions are aimed at removing coloring from STN-LCDs, and in this respect, they have been significantly improved and a display close to white/black has been obtained. In addition, a method using a polymeric birefringent film (hereinafter referred to as a retardation film) has cost advantages, and demand is rapidly increasing.
しかしながら、この位相差フィルムにおいては液晶ディ
スプレイを真正面から見たときには着色の除去がほぼ達
戒できるものの斜めからディスプレイを見た場合には、
わずかな角度変化による着色や画面の表示内容が消失す
るというＳＴＮ−ＬＣＤ全般に見られる視角特性の問題
点は解消されていないのが実状である。又この問題はＳ
ＴＮＬＣＤの重大な課題となっている。However, with this retardation film, when the liquid crystal display is viewed from the front, the coloring can be almost completely removed, but when the display is viewed from an angle,
The reality is that the problem of viewing angle characteristics found in STN-LCDs in general, such as coloring or disappearance of displayed contents on the screen due to slight changes in angle, has not been resolved. Also, this problem is S
This has become a serious issue for TNLCD.
本発明は上記ＳＴＮ−ＬＣＤの視角特性を大幅に改善し
、新規な液晶表示装置を提供するために研究を重ねた結
果完威されたものである。すなわち、本発明は下記の通
りである．（１）対向する２枚の電極基板間にねじれ配向したネマ
チック液晶を挟持してなる液晶素子と、少なくとも二枚
の複屈折フイルムと、それらを挾んで両側に配置された
一対の偏光板とを備えた液晶表示装置において、前記複
屈折フイルムが、正の固有複屈折値を有すると共に光透
過性を有するポリマーからなる少なくとも１枚の一軸延
伸フィルムと負の固有複屈折値を有すると共に光透過性
を有するポリマーからなる少なくともｌ枚の一軸延伸フ
ィルムからなることを特徴とする液晶表示装置。The present invention was achieved as a result of repeated research in order to significantly improve the viewing angle characteristics of the STN-LCD and provide a new liquid crystal display device. That is, the present invention is as follows. (1) A liquid crystal element consisting of a twisted oriented nematic liquid crystal sandwiched between two opposing electrode substrates, at least two birefringent films, and a pair of polarizing plates placed on both sides sandwiching them. In the liquid crystal display device, the birefringent film includes at least one uniaxially stretched film made of a polymer having a positive intrinsic birefringence value and optical transparency; and at least one uniaxially stretched film made of a polymer having a negative intrinsic birefringence value and optical transparency A liquid crystal display device comprising at least one uniaxially stretched film made of a polymer having the following properties.
（２）正の固有複屈折値を有すると共に光透過性を有す
るポリマーからなる一軸延伸フィルムと負の固有複屈折
値を有すると共に光透過性を有するポリマーからなる一
軸延伸フィルムとが各々の光軸が互いに直交積層してな
る前記（１）記載の液晶表示装置。(2) A uniaxially stretched film made of a polymer having a positive intrinsic birefringence value and optical transparency, and a uniaxially stretched film consisting of a polymer having a negative intrinsic birefringence value and optical transparency, each having their respective optical axes. The liquid crystal display device according to (1) above, wherein the liquid crystal display devices are stacked orthogonally to each other.
（３）負の固有複屈折値を有すると共に光透過性を有す
るポリマーがスチレン系ポリマーであることを特徴とす
る前記（１）、（２）記載の液晶表示装置。(3) The liquid crystal display device according to (1) or (2) above, wherein the polymer having a negative intrinsic birefringence value and light transmittance is a styrene polymer.
本発明は、ＳＴＮ−ＬＣＤの視野角の問題点を位相差フ
ィルムの三次元方向の屈折率を変化させることによって
改善できないかどうか検討したことによって達成された
ものである．具体的にはフィルムの複屈折値（Δｎ）と
厚み（ｄ）の積として定義されるレターデーション（Ｒ
ｅ）の視角依存性とＬＣＤの視野角が密接な関係にある
二とが判明し、レターデーションの視角依存性について
検討を重ねた結果、フィルムの法線方向に実質的に光軸
を有するフィルム、具体的には負の固有複屈折値を有す
る二軸延伸フィルムと正の固有複屈折値を有する一軸延
伸フィルムとの積層フィルムを液晶セルと偏光板の間に
挿入することによって視野角を大幅に改善できることを
突き止め特許出願（特願昭６３−２７８５９２）Ｌた。The present invention was achieved by investigating whether the viewing angle problem of STN-LCDs could be improved by changing the three-dimensional refractive index of the retardation film. Specifically, the retardation (R
It was found that the viewing angle dependence in e) and the viewing angle of the LCD are closely related, and as a result of repeated studies on the viewing angle dependence of retardation, it was found that a film having an optical axis substantially in the normal direction of the film was found. Specifically, the viewing angle is significantly improved by inserting a laminated film of a biaxially stretched film with a negative intrinsic birefringence value and a uniaxially stretched film with a positive intrinsic birefringence value between the liquid crystal cell and the polarizing plate. I discovered what I could do and filed a patent application (Japanese Patent Application No. 63-278592).
しかし鋭意研究を進めた結果、総合的に大幅な視野角改
善があったものの、特定の方向にまた視角不十分な部分
があることが判明し、更に研究を進めた結果、正の固有
複屈折値を有するポリマーの一軸延伸フィルムと負の固
有複屈折値を有するポリマーの一軸延伸フィルムの積層
体を液晶セルと偏光板の間に挿入することにより液晶表
示装置における視角特性を大幅に改善できることを突き
止め本発明の完戒に至ったものである。However, as a result of intensive research, it was discovered that although there was a significant overall improvement in the viewing angle, there were still areas where the viewing angle was insufficient in certain directions. This paper found that the viewing angle characteristics of a liquid crystal display device can be significantly improved by inserting a laminate of a uniaxially stretched polymer film with a high value and a uniaxially stretched polymer film with a negative intrinsic birefringence value between the liquid crystal cell and the polarizing plate. This led to the completion of invention.
現在、位相差フィルムとして利用されているフィルム素
材の固有複屈折値を全て正である．固有複屈折値が正の
ポリマーの縦一軸延伸フィルムの延伸軸方向の屈折率を
ｎ０、延伸軸と直交する方向の屈折率をｎｔｏ、フィル
ム面法線線方向の屈折率をｎ．ＮＤとすると、各々の屈
折率の大小関係はｎＭＤ＞ｎＴＤ≧ｎｓｏとなる。従っ
て入射光がフィルム面に垂直に入る場合、Ｒｅ＝ （ｎ
ｘＩｌ ｎｙｅ）ｄとなる。次に入射光が延伸方向に直
交する面を通る場合、複屈折値は入射角の変化に伴って
Δｎ＝ｎＮｏ ｎＴＤからΔｎ−ｎ，ｌ＋＋ ｎｕ
ｎの範囲で変化する．ここでｎＭＤ ｎｕｌｌ≦ｎＮ
Ｄ ｎｓｅであるため蔦Δｎは斜入射によって無変化
又は増大する．一方光路長は斜入射によって増大するた
め、Ｒｅ＝Δｎ・ｄは斜入射に伴って急激に増大するこ
とになる．又、入射光をフィルム法線方向から延伸軸方
向に傾けて入射した場合、Δｎはｎｕｌｌ ｎＮＤか
らｎ，ｌＩｌｎｔ＋＋まで急激な変化を伴うため、光路
長の増大によってもその減少を補償しきれず斜入射に伴
ってＲｅ＝Δｎ−ｄは急激に減少する。原理的にはレタ
ーデーションの変化率が最も小さい一軸延伸フィルムは
ｎｘｏ＞ｎ７ゎ＝ｌｌ，，の場合であるが、この場合に
おいてもＲｅは斜入射に伴う光路長の増大によって大き
く変化する．ところで、本発明における、正の固有複屈折値を有する
ポリマーから形成される一軸延伸フィルムと負の固有複
屈折値を有するポリマーから形威される一軸延伸フィル
ムとの積層体においてはフィルム法線方向のレターデー
シッンは互いに加算され消滅されることなしに全方位討
入射．に対してレターデーションの変化が極めて小さい
フィルムや適度なレターデーション変化を有するフィル
ムなど目的により自在にコントローノレできるという優
れた効果があることが判明した。特にこれらの効果が顕
著に現われるケースは、正の固有複屈折値を有するポリ
マーの一軸延伸フィルムと負の固有複屈折値を有するポ
リマーの一軸延伸フィルムがその延伸軸が互いに直交す
るように積層されたときであることが判明した．これと
同様の効果即ち全方位に対してレターデーション変化の
小さいフィルム積層体は、正の固有複屈折値を有するポ
リマーから形成される一軸延伸フィルムと正の固有複屈
折値を有するポリマーから形威される一軸延伸フィルム
との直交積層体や、負の固有複屈折値を有するポリマー
から形威される一軸延伸フィルムと負の固有複屈折値を
有するポリマーから形威される一軸延伸フィルムとの直
交積層体においては共に実現されないものであり、本発
明の構或によってのみ実現されるものである．さて、本発明における、正の固有複屈折直交を有するポ
リマーから形成される一軸延伸フィルムと負の固有複屈
折値を有するポリマーから形威される一軸延伸フィルム
との積層体においては、各々の一軸延伸フィルムの分子
の配向レベルを延伸等によって制御することによって、
積層体のレターデーションの視角依存性をほとんどなく
することも適度の変化をつけることも自在にコントロー
ルできるため、ＳＴＮ−ＬＣＤの光学特性に応じて、レ
ターデーシッンの視角特性を適合できるため、ＳＴＮ−
ＬＣＤにおける偏光板と液晶セルの間に位相差フィルム
として配設した場合にＳＴＮＬＣＤの視野角を大幅に拡
大できることが認められた．更に詳細に説明すると、本発明は９０”以上特に１８０
゜〜３３０゜のねしれ角を有するツイスティッドネマテ
インク液晶、又はコレステリック液晶を使った液晶表示
装置における液晶セルの複屈折性に起因する着色現象を
なくすると共に視野角、高コントラスト域の拡大を可能
とする液晶表示装置に関するものであり、フィルム法線
方向のレターデーシッンに関しては、正の固有複屈折値
を有するポリマーから形威されるフィルムの一軸延伸に
おけるレターデーションと負の固有複屈折値を有するポ
リマーから形威されるフィルムの一軸延伸におけるレタ
ーデーシジンの加算値が得られる。ただし、該正、負の
固有複屈折値を有するポリマーの一軸延伸フィルムの延
伸軸が一致した場合にはレターデーションは打ち消され
、好ましくはない．従って該フィルム積層体の延伸軸は
互いに略直交に配置されるのが好ましい。具体的には相
対角が７０゜乃至１１０゜が最も好ましい。The intrinsic birefringence values of film materials currently used as retardation films are all positive. The refractive index in the direction of the stretching axis of a longitudinally uniaxially stretched film of a polymer with a positive intrinsic birefringence value is n0, the refractive index in the direction perpendicular to the stretching axis is nto, and the refractive index in the direction normal to the film surface is n. When ND is used, the relationship in magnitude of each refractive index is nMD>nTD≧nso. Therefore, when the incident light enters the film plane perpendicularly, Re= (n
xIlnye)d. Next, when the incident light passes through a plane perpendicular to the stretching direction, the birefringence value changes from Δn=nNo nTD to Δn−n,l++ nu as the incident angle changes.
It changes within the range of n. Here nMD null≦nN
Since D nse, the ivy Δn remains unchanged or increases due to oblique incidence. On the other hand, since the optical path length increases with oblique incidence, Re=Δn·d increases rapidly with oblique incidence. Furthermore, when the incident light is incident at an angle from the normal direction of the film to the direction of the stretching axis, Δn undergoes a rapid change from null nND to n,lIlnt++, so even an increase in the optical path length cannot compensate for the decrease, resulting in oblique incidence. Accordingly, Re=Δn−d decreases rapidly. In principle, the uniaxially stretched film with the smallest rate of change in retardation is the case where nxo>n7ゎ=ll, but even in this case, Re changes significantly due to the increase in optical path length due to oblique incidence. By the way, in the present invention, in a laminate of a uniaxially stretched film formed from a polymer having a positive intrinsic birefringence value and a uniaxially stretched film formed from a polymer having a negative intrinsic birefringence value, the film normal direction Letters are added to each other and can be fired from all directions without being canceled. It has been found that this film has an excellent effect in that it can be freely controlled depending on the purpose, such as films with extremely small changes in retardation or films with moderate changes in retardation. In particular, these effects are particularly noticeable when a uniaxially stretched polymer film with a positive intrinsic birefringence value and a uniaxially stretched polymer film with a negative intrinsic birefringence value are laminated such that their stretching axes are orthogonal to each other. It turned out that it was time. A film laminate with a similar effect, that is, a small retardation change in all directions, can be produced by forming a uniaxially stretched film made of a polymer with a positive intrinsic birefringence value and a polymer with a positive intrinsic birefringence value. Orthogonal laminates of uniaxially oriented films made of a polymer with a negative intrinsic birefringence value and uniaxially oriented films made of a polymer with a negative intrinsic birefringence value. Both cannot be realized in a laminate, and can only be realized by the structure of the present invention. In the present invention, in a laminate of a uniaxially stretched film formed from a polymer having a positive intrinsic birefringence orthogonal to a uniaxially stretched film formed from a polymer having a negative intrinsic birefringence value, each uniaxially stretched film is formed from a polymer having a negative intrinsic birefringence value. By controlling the molecular orientation level of the stretched film through stretching, etc.
Since the viewing angle dependence of the retardation of the laminate can be controlled to be almost completely eliminated or to be moderately changed, the viewing angle characteristics of the retardation can be adapted to the optical characteristics of the STN-LCD.
It has been found that the viewing angle of STNLCD can be greatly expanded when it is placed as a retardation film between the polarizing plate and the liquid crystal cell in the LCD. More specifically, the present invention applies to 90" or more, especially 180"
Eliminates the coloring phenomenon caused by the birefringence of liquid crystal cells in liquid crystal display devices using twisted nematic ink liquid crystals or cholesteric liquid crystals with a helix angle of 330° to 330°, and also expands the viewing angle and high contrast area. Regarding the retardation in the normal direction of the film, the retardation in uniaxial stretching of a film formed from a polymer having a positive intrinsic birefringence value and the retardation in the film normal direction and having a negative intrinsic birefringence value The additive value of retardation in uniaxial stretching of films formed from polymers is obtained. However, if the stretching axes of the uniaxially stretched polymer films having positive and negative intrinsic birefringence values coincide, retardation is canceled out, which is not preferable. Therefore, it is preferable that the stretching axes of the film laminate are arranged substantially perpendicular to each other. Specifically, the relative angle is most preferably 70° to 110°.
ただし、該正、負の固有複屈折値を有するフィルムが液
晶セルを介して配置される場合はその限りでない。つま
り該フィルムは常に積層されて使われなくても、液晶セ
ルの両サイドに配置されてもよいし、偏光板の液晶セル
側の保護フィルムを兼用しても構わない。特に偏光板保
護フィルムとして使った場合は視野角拡大の機能と共に
低コスト化を実現できるメリットがある。又、本発明に
おけるフィルムとは、一般的に考えられているフィルム
だけでなく、ある基材に塗布された膜状物も含まれる。However, this is not the case when the films having positive and negative intrinsic birefringence values are arranged via a liquid crystal cell. That is, the films do not have to be always used in a laminated manner, but may be placed on both sides of the liquid crystal cell, or may also serve as a protective film on the liquid crystal cell side of the polarizing plate. In particular, when used as a polarizing plate protective film, it has the advantage of widening the viewing angle and reducing costs. Further, the film in the present invention includes not only a film as generally considered, but also a film-like material coated on a certain base material.
又、一軸延伸フィルムとは、純粋な一軸性フィルムだけ
でなく、若干二輪性が付与されていても本質的に一軸性
フィルムとして機能するものであれば本発明の対象とな
る。Moreover, the uniaxially stretched film is not only a pure uniaxial film, but also a film that essentially functions as a uniaxial film even if it has been given some biaxiality, and is the object of the present invention.
従って、テンター法による横一軸延伸、ロール間の周速
の差を利用した縦一軸延伸、この場合幅方向の延伸時の
自然収縮を行う場合も制限する場合も含まれる。Therefore, it includes horizontal uniaxial stretching using a tenter method, longitudinal uniaxial stretching using the difference in circumferential speed between rolls, and in this case, cases in which natural shrinkage during width direction stretching is performed or limited.
さて、本発明において光透過性を有し且つ正の固有複屈
折値を有するフィルムは、光の透過性が７０％以上で無
彩色であることが好ましく、更に好ましくは光の透過性
が９０％以上で無彩色である．ここで固有複屈折値（Δ
ｎ’）は分子が理想的に一方向に配向したときの複屈折
値を意味し、で表わされる．ここでπ：円周率 ｄ：密度 Ｎ：アボガドロ数ｎ：平
均屈折率 Δα＝α１．一α土ここでα．：高分子の分子鎖軸方向のモノマーあたりの
分極率α土：高分子の分子鎖軸と垂直な方向の分極率該、正の固有複屈折値を有するフイルムに用いるポリマ
ーとして制約はないが、具体的にはボリカーボネート、
ポリアリレート、ポリエチレンテレフタレート、ポリエ
ーテルスルホン、ポリフエニレンサルファイド、ポリフ
エニレンオキサイド、ポリアリルスルホン、ポリアミド
イミド、ポリイミド、ポリオレフイン、ポリ塩化ビニル
、セルロ−ス、ポリエステル系高分子等が好ましく、特
にポリカーボネート系高分子、ポリアリレート系高分子
、ポリエステル系高分子等、固有複屈折値が大きく溶液
製膜により面状の均質なフィルムを作りやすい高分子が
好ましい。Now, in the present invention, the film having light transmittance and a positive intrinsic birefringence value preferably has a light transmittance of 70% or more and is achromatic, and more preferably has a light transmittance of 90%. The above is an achromatic color. Here, the intrinsic birefringence value (Δ
n') means the birefringence value when molecules are ideally oriented in one direction, and is expressed as. Here, π: Pi d: Density N: Avogadro's number n: Average refractive index Δα=α1. α So here α. : Polarizability per monomer in the direction of the molecular chain axis of the polymer α: Polarizability in the direction perpendicular to the molecular chain axis of the polymer There are no restrictions on the polymer used for the film having a positive intrinsic birefringence value. Specifically, polycarbonate,
Polyarylate, polyethylene terephthalate, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyallyl sulfone, polyamideimide, polyimide, polyolefin, polyvinyl chloride, cellulose, polyester-based polymers, etc. are preferred, and polycarbonate-based polymers are particularly preferred. Polymers, such as polymers, polyarylate polymers, and polyester polymers, are preferred because they have a large intrinsic birefringence value and are easy to form into a homogeneous planar film by solution casting.
又、上記ポリマーは、単にホモポリマーだけでなく、コ
ポリマー、それらの誘導体、ブレンド物等であってもよ
い。Moreover, the above-mentioned polymer may be not only a homopolymer but also a copolymer, a derivative thereof, a blend thereof, and the like.
本発明における光透過性を有し、且つ負の固有複屈折値
を有するフィルムとは、光の透過性が７０％以上で無彩
色であることが好ましく、更に好ましくは光の透過性が
９０％以上で無彩色である．フィルムに用いるポリマー
として制約はないが、具体的にはスチレン系重合体、ア
クリル酸エステル系重合体、メタアクリル酸エステル系
重合体、アクリロニトリル系重合体及びメタアクリロニ
トリル系重合体が好ましく、ポリスチレン系重合体が３
つの観点即ち、固有複屈折値の絶対値が大きいこと、透
明性に優れ着色がないこと、溶液製膜が可能であること
から最も好ましい．ここでスチレン系重合体とは、スチレン及びスチレン誘
導体のホモポリマー、スチレン及ｐスチレン誘導体のコ
ポリマー、ブレンド物等である。In the present invention, the film having light transmittance and a negative intrinsic birefringence value preferably has a light transmittance of 70% or more and is achromatic, and more preferably has a light transmittance of 90%. The above is an achromatic color. There are no restrictions on the polymer used for the film, but specifically styrene polymers, acrylic ester polymers, methacrylic ester polymers, acrylonitrile polymers, and methacrylonitrile polymers are preferred, and polystyrene polymers are preferred. 3 combinations
It is most preferable from three points of view: it has a large absolute value of intrinsic birefringence, it has excellent transparency and is free from coloration, and it can be formed into a solution film. Here, the styrenic polymer includes a homopolymer of styrene and a styrene derivative, a copolymer of styrene and a p-styrene derivative, a blend, and the like.
スチレン誘導体とは例えば、α−メチルスチレン、０−
メチルスチレン、ｐ−メチルスチレン、ｐ−クロロスチ
レン、ｐ−ニトロスチレン、ｐ−アミノスチレン、ｐ一
カルボキシルスチレン、ｐフェニルスチレン、２．５−
ジクロロスチレン等が挙げられるが上記に制限されるも
のではない。Examples of styrene derivatives include α-methylstyrene, 0-
Methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxylstyrene, p-phenylstyrene, 2.5-
Examples include dichlorostyrene, but are not limited to the above.
スチレン及びスチレン誘導体（以下ＳＴと略す）とのコ
ポリマー、ブレンド物はＳＴと適度な戒膜性を有するも
のであれば特に限定されるものではなく、相分離構造を
有していても透明性等が損われなければ本発明の対象と
なるものであり、例えば、コポリマーとしてはＳＴ／ア
クリロニトリル、ＳＴ／メタアクリロニトリル、ＳＴ／
メタアクリル酸メチル、ＳＴ／メタアクリル酸エチル、
ＳＴ／α−クロロアクリロニトリル、ＳＴ／アクリル酸
メチル、ＳＴ／アクリル酸エチル、ＳＴ／アクリル酸プ
チル、ＳＴ／アクリル酸、ＳＴ／メタクリル酸、ＳＴ／
ブタジエン、ＳＴ／イソプレン、ＳＴ／無水マレイン酸
、ＳＴ／酢酸ビニルコポリマー、α−メチルスチレン／
アクリロニトリル、α−メチルスチレン／メタクリロニ
トリル、αメチルスチレン／メチルメタクリレート及び
スチレン／スチレン誘導体コポマリー等が挙げられる。Copolymers and blends with styrene and styrene derivatives (hereinafter abbreviated as ST) are not particularly limited as long as they have suitable film properties with ST, and even if they have a phase-separated structure, they have transparency etc. For example, as a copolymer, ST/acrylonitrile, ST/methacrylonitrile, ST/
Methyl methacrylate, ST/ethyl methacrylate,
ST/α-chloroacrylonitrile, ST/methyl acrylate, ST/ethyl acrylate, ST/butyl acrylate, ST/acrylic acid, ST/methacrylic acid, ST/
Butadiene, ST/Isoprene, ST/Maleic anhydride, ST/Vinyl acetate copolymer, α-methylstyrene/
Examples include acrylonitrile, α-methylstyrene/methacrylonitrile, α-methylstyrene/methyl methacrylate, and styrene/styrene derivative copolymer.
もちろん、以上に挙げた二元コポリマー以外にＳＴ／α
−メチルスチレン／アクリロニトリル、ＳＴ／α−メチ
ルスチレン／メチルメタクリレート等の三元以上のコポ
リマーも使用することが出来る。又、ブレンド物は上記
のスチレンホモポリマ、スチレン誘導体ホモポリマー及
び、スチレン及びスチレン誘導体コポリマー間のブレン
ドはもちろんとして、スチレン及びスチレン誘導体から
なるポリマー（以下ＰＳＴと略す）と、ＰＳＴを含まな
いポリマーとのブレンド物も使用できる。Of course, in addition to the binary copolymers listed above, ST/α
- Ternary or higher copolymers such as methylstyrene/acrylonitrile, ST/α-methylstyrene/methylmethacrylate, etc. can also be used. Blends include not only the above-mentioned styrene homopolymers, styrene derivative homopolymers, and styrene and styrene derivative copolymers, but also polymers consisting of styrene and styrene derivatives (hereinafter abbreviated as PST) and polymers not containing PST. Blends of can also be used.
これらのブレンドは一例としてＰＳＴ／ブチルセルロー
ス、ＰＳＴ／クマロン樹脂がある．ところで、固有複屈
折値の絶対値が小さくても厚みを大きくするか延伸倍率
を大きくすることによって十分に利用できるのであるが
それらの制約を受けないためには、固有複屈折値は好ま
しくは絶対値で０．０２以上、より好ましくは０．０４
以上である。又、一旦延伸によって配向した分子がＬＣ
Ｄの製造工程や表示中での昇温による配向緩和を防ぐた
めには素材のＴｇ（ガラス転移点）が１００度以上、よ
り好ましくは１１０度以上更に好ましくは１１５度以上
である．また、複屈折値を持つフィルムの厚みは特に制限がない
が、１０μ〜ｌｆｆｉＩ１の範囲が好ましい．〔実施例
〕以下実施例によって詳細に説明する。Examples of these blends include PST/butylcellulose and PST/coumaron resin. By the way, even if the absolute value of the intrinsic birefringence value is small, it can be fully utilized by increasing the thickness or increasing the stretching ratio, but in order to avoid these restrictions, the intrinsic birefringence value should preferably be an absolute value. Value of 0.02 or more, more preferably 0.04
That's all. In addition, molecules once oriented by stretching become LC
In order to prevent orientation relaxation due to temperature rise during the manufacturing process and display of D, the Tg (glass transition point) of the material is 100 degrees or higher, more preferably 110 degrees or higher, and even more preferably 115 degrees or higher. Further, the thickness of the film having a birefringence value is not particularly limited, but is preferably in the range of 10μ to lffiI1. [Example] The following will be described in detail with reference to Examples.
実施例 １分子量約１０万のポリカーボネートを二塩化メチレン溶
媒に溶解し２０％溶液とした。該溶液をスチールドラム
上に流延し、連続的に剥ぎとって厚さ９０ｕｍ幅５００
ＩＩＩａ＋の透明なＴｇｌ５５゜固有複屈折値（Δｎ’
）０．１０のボリカーボネートフィルム（ＰＣフィルム
）を得た。該フィルムを１７０℃の温度条件下で周速の
異なるロールによる縦一軸延伸によって１６％延伸し、
フィルム（ａ）を得た。Example 1 Polycarbonate having a molecular weight of about 100,000 was dissolved in methylene dichloride solvent to form a 20% solution. The solution was cast onto a steel drum and continuously stripped to a thickness of 90 um and a width of 500 um.
Transparent Tgl of IIIa+ 55° intrinsic birefringence value (Δn'
) 0.10 polycarbonate film (PC film) was obtained. The film was stretched by 16% by longitudinal uniaxial stretching using rolls with different circumferential speeds at a temperature of 170°C,
Film (a) was obtained.
次に、分子量約２０万、Ｔｇｌ０２＠、△ｎが一〇．１
０のボリスレチンを二塩化メチレンに溶解し、２５％溶
液とした。該溶液をスチールドラム上に流延し、連続的
に剥ぎとって厚さ９０ＩＩｍ、幅５００ｍｍのボリスレ
チンフィルム（ＰＳｔフィルム）を得た。該フィルムを
９０℃の温度条件下で周速の異なるロールによる縦一軸
延伸によって１７％１１１しフィルム（ｂ）を得た。フ
ィルム（ａ）及びフィルム（ｂ）を延伸軸が直交するよ
うにアクリル系粘着剤で積層し、フィルム（ａ）の延伸
軸方向をθ＝Ｏとし、フィルム（ｂ）の延伸軸方向をθ
＝９０゜として、該フィルム積層体の法線方向から第３
図のθ＝０、θ＝４５゜、θ＝９０゜の方向へ各々４０
”斜入射したときのレターデーシダンＲｅ（４０）と、
法線方向のレターデーションＲ （０）を測定し、レタ
ーデーシッンの変化率ｌＲｅ（ ０ ） −Ｒｅ （４
０）ｌ＋ｌＲｅ（ ０ ）１を計算した。ただしレタ
ーデーションの測定には島津製作所（製）エリプソメー
ターＡＲＰ−１００を使った。使用した光源は波長６３
２．Ｅｌｎｍであり、測定結果を表−１に示す．次に本実施例に使用した液晶表示装置を第１図及び第２
図に従って説明する。Next, the molecular weight is about 200,000, Tgl02@, △n is 10. 1
0 Borisretin was dissolved in methylene dichloride to make a 25% solution. The solution was cast onto a steel drum and continuously peeled off to obtain a Borisretin film (PSt film) with a thickness of 90 II m and a width of 500 mm. The film was subjected to longitudinal uniaxial stretching using rolls having different circumferential speeds at a temperature of 90° C. to obtain a film (b) of 17%. Film (a) and film (b) are laminated with an acrylic adhesive so that their stretching axes are perpendicular to each other, and the stretching axis direction of film (a) is set to θ=O, and the stretching axis direction of film (b) is set to θ.
= 90°, and the third direction from the normal direction of the film laminate.
40 degrees each in the directions of θ=0, θ=45°, and θ=90° in the figure.
``The letter radiance Re(40) at oblique incidence,
Measure the retardation R (0) in the normal direction, and calculate the rate of change in retardation lRe (0) −Re (4
0)l+lRe(0)1 was calculated. However, an ellipsometer ARP-100 manufactured by Shimadzu Corporation was used to measure retardation. The light source used has a wavelength of 63
2. Elnm, and the measurement results are shown in Table 1. Next, the liquid crystal display device used in this example is shown in Figures 1 and 2.
This will be explained according to the diagram.
第ｌ図は、液晶表示装置の斜視図であって、層構戒を示
したものである。つまり、対向する２枚の偏向板ｌ及び
９の間に２枚の基板２、６及び透明電極３、５に挟持さ
れた液晶層４から或る液晶セル１０と該液晶セルと観察
側の偏光板９の間に固有複屈折値が正及び負の一軸延伸
フィルム７、８が挟持された構造を有するものである。FIG. 1 is a perspective view of a liquid crystal display device, showing the layer structure. In other words, the polarized light from the liquid crystal layer 4 sandwiched between the two substrates 2, 6 and the transparent electrodes 3, 5 between the two opposing polarizing plates 1 and 9 is transmitted to a certain liquid crystal cell 10 and the polarized light from the liquid crystal cell to the observation side. It has a structure in which uniaxially stretched films 7 and 8 having positive and negative intrinsic birefringence values are sandwiched between plates 9.
第２図は液晶表示装置の各軸の関係を示したものであり
、水平軸２０と第一偏光板の偏光軸２１は９０”の相対
角を有し、水平軸と第２偏光板の偏光軸２２は４０゜の
相対角を有している。更に第１偏光板の偏光軸２１と透
明行電極基板のラビング方向２３は４５゜の相対角を有
する。透明行電極基板のラビング方向２３と透明列電極
基板のラビング方向２４によって液晶のねじれ角２５が
決まる。この場合２４０゜である。Figure 2 shows the relationship between each axis of the liquid crystal display device, where the horizontal axis 20 and the polarizing axis 21 of the first polarizing plate have a relative angle of 90'', and the horizontal axis and the polarizing axis of the second polarizing plate have a relative angle of 90''. The axis 22 has a relative angle of 40°. Furthermore, the polarization axis 21 of the first polarizer and the rubbing direction 23 of the transparent row electrode substrate have a relative angle of 45°. The rubbing direction 23 of the transparent row electrode substrate The rubbing direction 24 of the transparent column electrode substrate determines the twist angle 25 of the liquid crystal, which is 240° in this case.
さて、上記構戒でセルギャップ６μｍ１Δｎ×ｄ（複屈
折値×液晶の厚み）＝０．６８μｍとなるようなネマチ
ック液晶を第１図基板２、４の間に封入し、液晶セル１
０と偏光板９０間にフィルム（ａ）７及びフィルム（ｂ
）８をその延伸軸が直交するように積層し且つ最大コン
トラストが得られるように配設した。液晶表示装置とし
ての表示特性を大塚電子ＬＣ−５０００で１／２００デ
ューティの条件で調べたところ、白黒表示が得られたと
共に、全方位視野角が大幅に改善され、左右においては
合計１２０’以上、上下においては合計１００”以上の
広視野角が得られた。尚ここで視野角の範囲としてコン
トラスト５のところを境界線とした．比較例ｌ実施例１で得たフィルム（ａ）のみを実施例ｌと同様の
条件で特性を評価したところ、白黒表示は得られなっか
った。又、正面からのコントラストが５程度と低かった
。また、レターデーションの測定結果を表−１に示す。Now, according to the above structure, a nematic liquid crystal with a cell gap of 6 μm 1Δn×d (birefringence value×thickness of liquid crystal) = 0.68 μm is sealed between the substrates 2 and 4 in FIG. 1, and the liquid crystal cell 1
0 and the polarizing plate 90, the film (a) 7 and the film (b
) 8 were stacked so that their stretching axes were perpendicular to each other, and arranged so as to obtain maximum contrast. When we investigated the display characteristics of a liquid crystal display device using an Otsuka Electronics LC-5000 at 1/200 duty, we found that not only a black and white display was obtained, but the omnidirectional viewing angle was significantly improved, with a total viewing angle of more than 120' on the left and right sides. , a wide viewing angle of more than 100'' in total was obtained in the upper and lower directions.Here, the viewing angle range was defined as the boundary line at contrast 5. Comparative Example 1 Only the film (a) obtained in Example 1 was used. When the characteristics were evaluated under the same conditions as in Example 1, no black and white display was obtained.Furthermore, the contrast from the front was as low as about 5.Furthermore, the measurement results of retardation are shown in Table 1.
比較例２実施例１で得たフィルム（ｂ）のみを実施例１と同様の
条件で特性を評価したところ、白黒表示は得られなかっ
た。又、正面からのコントラストが５程度と低かった。Comparative Example 2 When the characteristics of only the film (b) obtained in Example 1 were evaluated under the same conditions as in Example 1, no black and white display was obtained. Also, the contrast from the front was low at about 5.
また、レターデーションの測定結果を表−１に示す。Furthermore, the measurement results of retardation are shown in Table 1.
比較例３実施例１で得たポリカーボネートフィルムを１７５゜Ｃ
の温度条件下で周速の異なるロールを利用する縦一軸延
伸装置で３３％延伸し、複屈折フィルムを得た。該フィ
ルムの光学的特性を表−１に示す。又、該フィルムを実
施例ｌの液晶セルと偏光板（観察側）の間に介挿し、液
晶セルの表示特性を調べたところ、真正面からの観察で
はほぼ白黒表示が達戒できたものの斜入射で着色し、視
野角が上下合計４０゜、左右合計５０’と狭視野であっ
た。Comparative Example 3 The polycarbonate film obtained in Example 1 was heated to 175°C.
A birefringent film was obtained by stretching the film by 33% using a longitudinal uniaxial stretching apparatus using rolls with different circumferential speeds under the temperature conditions of . The optical properties of the film are shown in Table 1. In addition, when the film was inserted between the liquid crystal cell of Example 1 and the polarizing plate (observation side) and the display characteristics of the liquid crystal cell were investigated, it was found that almost black and white display was achieved when observed from the front, but when viewed at an oblique angle. The viewing angle was narrow, with a total vertical viewing angle of 40° and a horizontal viewing angle of 50′.
比較例４実施例ｌで得た未延伸ＰＳｔフイルムを９０゜Ｃの温度
条件下で縦一軸延伸により３５％延伸を行ったところ、
フィルムの光学特性は表一■のようになった。該フィル
ムを実施例１と同様の方法で表示特性を調べたところ、
真正面からの観察ではほぼ白黒表示が達戒できたものの
斜入射で着色し、視野角も上下合計５０ｍ、左右合計４
０゜と狭視野であった。また、レターデーションの測定
結果を表−１に示す。Comparative Example 4 The unstretched PSt film obtained in Example 1 was stretched by 35% by longitudinal uniaxial stretching at a temperature of 90°C.
The optical properties of the film were as shown in Table 1. When the display characteristics of the film were examined in the same manner as in Example 1,
When observed directly from the front, the display was almost black and white, but it became colored under oblique incidence, and the viewing angle was 50 meters in total vertically and 4 meters in total left and right.
It had a narrow field of view of 0°. In addition, the measurement results of retardation are shown in Table 1.
比較例５特開昭６３−１６７３０４の実施例とほぼ同様の方法で
フィルム積層体を得た。即ち、高密度ポリエチレン（住
友化学製、ス藁カセンハード２７２３）からなる３００
μｍのフィルムをロール温度９０゜Ｃ、潤滑液に水を用
いて、縦一軸に約６倍〜約７倍延伸し偏光顕微鏡による
レターデーションの測定値が約１９６０ｎｍのフィルム
と約２５３０ｎｍのフィルムを得た．これらのフイルム
をその光学主軸が直交するように積層し、偏光顕微鏡に
よるレターデーシヲンの測定値が５７０ｎｍとなった。Comparative Example 5 A film laminate was obtained in substantially the same manner as in the example of JP-A-63-167304. That is, 300 ml of high-density polyethylene (Suwara Kasen Hard 2723, manufactured by Sumitomo Chemical)
A μm film was stretched uniaxially by about 6 to 7 times at a roll temperature of 90°C using water as a lubricant to obtain a film with a retardation value of about 1960 nm and a film with a retardation value of about 2530 nm using a polarizing microscope. Ta. These films were stacked so that their optical principal axes were perpendicular to each other, and the retardation value measured using a polarizing microscope was 570 nm.
更に該フィルム積層体を実施例−１と同様に波長６３２
．８ｎｍのエリプソメーターＡＲＰ−１ ００を使って
フィルムの光学特性を調べた．結果を表−１に示す．又
、該積層フィルムを実施例−１と同様に視野角を調査し
たところ、上下合計４０゜、左右合計４５゜と狭視野で
あった。Further, the film laminate was heated to a wavelength of 632 as in Example-1.
．． The optical properties of the film were investigated using an 8 nm ellipsometer ARP-100. The results are shown in Table 1. Furthermore, when the viewing angle of the laminated film was investigated in the same manner as in Example 1, it was found that the viewing angle was narrow, with a total of 40° vertically and a total of 45° horizontally.
実施例２分子量約２０万のポリアクリレートを二塩化メチレン溶
媒に溶解し２０％溶液とした。該溶液をスチールドラム
上に流延し、連続的に剥ぎとって厚さ９０μｍ幅５００
ａｏの透明なＴｇｌ８５゜Δｎ”０．１１のポリアクリ
レートフイルム（ＰＡｒフィルム）を得た．該フイルム
を１９０”Ｃの温度条件下で周速の異なるロールによる
縦一軸延伸によって１５％延伸し、フイルム（ａ）を得
た。Example 2 Polyacrylate having a molecular weight of about 200,000 was dissolved in methylene dichloride solvent to form a 20% solution. The solution was cast onto a steel drum and continuously peeled off to a thickness of 90 μm and a width of 500 μm.
A transparent polyacrylate film (PAr film) with a Tgl of 85°Δn”0.11 was obtained. (a) was obtained.
分子量約２０万のスチレン・アクリロニトリル共重合体
（アクリ口ニトリル比 ３５重量％）を二塩化メチレン
溶媒に溶解し２０％溶液とした。A styrene/acrylonitrile copolymer having a molecular weight of about 200,000 (acrylonitrile ratio: 35% by weight) was dissolved in methylene dichloride solvent to make a 20% solution.
該溶液をスチールドラム上に流延し、連続的に剥ぎとっ
て厚さ１１０μｍ幅５００ｍｍの透明な’ｒｇ１ｌ５＠
Δｎ −０．０５のＳＴ／ＡＮフィルムを得た。該フ
ィルムを９０″Ｃの温度条件下で３２％延伸し、フィル
ム（ｂ）を得た。The solution was cast onto a steel drum and continuously peeled off to form a transparent 'rg1l5@ with a thickness of 110 μm and a width of 500 mm.
An ST/AN film with Δn −0.05 was obtained. The film was stretched by 32% at a temperature of 90''C to obtain a film (b).
フィルム（ａ）及び（ｂ）を延伸軸が直交するように積
層し、実施例１と同様の方法でレターデーションを測定
した．結果を表−１に示す。Films (a) and (b) were laminated so that their stretching axes were perpendicular to each other, and the retardation was measured in the same manner as in Example 1. The results are shown in Table-1.
又、該フィルム積層体を実施例１と同様の液晶セルと偏
光板（観察側）の間にフィルム（ａ）が液晶セル側にな
るように、且つ最大コントラストが得られる角度にして
介挿し、液晶表示装置としての表示特性を調べたところ
、白黒表示が得られたと共に、全方位視野角が大幅に改
善され、左右においては合計１２０″′以上、上下にお
いては合８１１００゜以上の広視野角が得られた。In addition, the film laminate was inserted between the liquid crystal cell and the polarizing plate (observation side) as in Example 1, with the film (a) facing the liquid crystal cell side and at an angle that would provide the maximum contrast, When we investigated the display characteristics of the liquid crystal display device, we found that a black and white display was obtained, and the viewing angle in all directions was significantly improved, with a total viewing angle of more than 120'' on the left and right, and a total viewing angle of more than 81,100° on the top and bottom. was gotten.
比較例６実施例２で得たフィルム（ａ）のみを実施例１と同様の
条件で特性を評価したところ、白黒表示は得られなかっ
た。又、正面からのコントラストが５程度と低かった．
また、レターデーションの測定結果を表−１に示す．比較例７実施例２で得たフィルム（ｂ）のみを実施例１と同様の
条件で特性を評価したところ、白黒表示は得られなかっ
た。又、正面からのコントラストが５程度と低かった．
また、レターデーションの測定結果を表−１に示す。Comparative Example 6 When the characteristics of only the film (a) obtained in Example 2 were evaluated under the same conditions as in Example 1, no black and white display was obtained. Also, the contrast from the front was low at around 5.
Table 1 shows the retardation measurement results. Comparative Example 7 When the characteristics of only the film (b) obtained in Example 2 were evaluated under the same conditions as in Example 1, no black and white display was obtained. Also, the contrast from the front was low at around 5.
In addition, the measurement results of retardation are shown in Table 1.
実施例３実施例ｌで得たフィルム（ａ）及び（ｂ）の延伸軸の相
対角が７０゜になるように積層し以下実施例ｌと同様に
表示特性を調べたところ、白黒表示が得られたと共に、
全方位視野角が大幅に改善され、左右においては合計１
１０″′以上、上下においては合計１１０゜以上の広視
野角が得られた。Example 3 Films (a) and (b) obtained in Example 1 were laminated so that the relative angle of the stretching axes was 70°, and the display characteristics were examined in the same manner as in Example 1, and a black and white display was obtained. At the same time,
The omnidirectional viewing angle has been significantly improved, with a total of 1
A wide viewing angle of more than 10'' and a total of more than 110° in the upper and lower directions was obtained.
実施例４エプソン■製パーソナルワード・プロセッサーＰＷＰ−
ＬＱＸ （製造番号０２０００００５１５）の位相差フ
ィルムを取り除き、実施例１で得たフィルム積層体のＰ
Ｃフイルム延伸軸が上下になるように且つＰＣフィルム
が液晶セル側になるように、該フィルム積層体を液晶セ
ルと偏光板の間に配設し実施例１と同様の方法で表示特
性を調べたところ鮮明な白黒表示が得られると共に、上
下合計１１０゜以上、左右合計１００＠以上の広視野角
が得られた。Example 4 Epson personal word processor PWP-
The retardation film of LQX (manufacturing number 0200000515) was removed, and the P of the film laminate obtained in Example 1 was
The film laminate was placed between the liquid crystal cell and the polarizing plate so that the C film stretching axis was vertical and the PC film was on the liquid crystal cell side, and the display characteristics were examined in the same manner as in Example 1. A clear black-and-white display was obtained, as well as a wide viewing angle of more than 110° in the vertical direction and more than 100° in the left and right directions.
比較例８実施例４で使用したパーソナルワードプロセッサーＰＷ
Ｐ−ＬＱＸ （購入段階）の表示特性を調べたところ、
白黒表示は得られているが視野角が非常に狭く、上下合
計５０゜、左右合計４５゜であった。Comparative Example 8 Personal word processor PW used in Example 4
When we investigated the display characteristics of P-LQX (purchase stage), we found that
Although a black and white display was obtained, the viewing angle was very narrow, with a total of 50 degrees vertically and 45 degrees horizontally.
実施例５実施例１で得た未延伸ポリカーポネートフイルムを１７
０゜Ｃの温度条件下で、周速の異なるロールによる縦一
軸延伸によって１８％延伸、フイルム（ａ）を得た。Example 5 The unstretched polycarbonate film obtained in Example 1 was
Under a temperature condition of 0°C, film (a) was obtained by 18% stretching by longitudinal uniaxial stretching using rolls having different circumferential speeds.
次に、実施例ｌで得た未延伸ボリスチレンフイルムを９
０゜Ｃの温度条件下で周速の異なるロールによる縦一軸
延伸によって１６％延伸しフイルム（ｂ）を得た。フィ
ルム（ａ）及び（ｂ）を延伸軸が直交するように積層し
、フィルム（ａ）の延伸軸方向をθ＝０とし、フィルム
（ｂ）の砥伸軸方向をθ＝９０＠として、該フィルム積
層体の法線方向からθ＝０、θ＝４５゜、θ＝９０゜の
方向へ各々４０’斜入射したときのレターデーションＲ
ｅ （４０）と、法線方向のレターデーシッンＲ （０
）を測定し、レターデーシゴンの変化率Ｒｅ（ ０ ）
− Ｒｅ（ ４０ ）１＋ ｌＲｅ（ ０ ）ｌ
を計算した。ただしレターデーションの測定には島津製
作所（製）ＡＲＰ−１００を使った。使用した光源は波
長６３２．８ｎｍであり、測定結果を表１に示す。Next, the unstretched polystyrene film obtained in Example 1 was
The film (b) was stretched by 16% by longitudinal uniaxial stretching using rolls having different circumferential speeds at a temperature of 0°C. Films (a) and (b) are laminated so that their stretching axes are perpendicular to each other, and the stretching axis direction of film (a) is set to θ = 0, and the abrasive stretching axis direction of film (b) is set to θ = 90 @. Retardation R when incident at an angle of 40' in the directions of θ=0, θ=45°, and θ=90° from the normal direction of the film laminate
e (40) and the normal direction letter density R (0
), and the rate of change of the letter decigon Re(0) is measured.
−Re(40)1+lRe(0)l
was calculated. However, ARP-100 manufactured by Shimadzu Corporation was used to measure retardation. The light source used had a wavelength of 632.8 nm, and the measurement results are shown in Table 1.
又、該フィルム積層体を実施例４と同様の方法で表示特
性を評価したところ鮮明な白黒表示が得られると共に、
上下合計７５゜、左右合計８５゜の広視野角が得られた
．比較例９実施例５で得たフィルム（ａ）のみを実施例４と同様の
条件で特性を評価したところ、十分な白黒表示は得られ
なかった。又視野角は上下合計３０゜、左右合計４０’
と狭かった。また、レターデーションの測定結果を表−
１に示す。Furthermore, when the display characteristics of the film laminate were evaluated in the same manner as in Example 4, a clear black and white display was obtained, and
A wide viewing angle of 75° vertically and 85° horizontally was obtained. Comparative Example 9 When the characteristics of only the film (a) obtained in Example 5 were evaluated under the same conditions as in Example 4, sufficient black and white display was not obtained. The viewing angle is 30° vertically and 40' horizontally.
It was small. In addition, the retardation measurement results are shown.
Shown in 1.
比較例１０実施例５で得たフィルム（ｂ）のみをその延伸軸が水平
となるようにして、実施例４の液晶セルに配設し、実施
例４と同様の方法で表示特性を調べたところコントラス
ト５以下で白黒表示は得られなかった．また、レターデ
ーシッンの測定結果を表−１に示す。Comparative Example 10 Only the film (b) obtained in Example 5 was placed in the liquid crystal cell of Example 4 so that its stretching axis was horizontal, and the display characteristics were examined in the same manner as in Example 4. However, black and white display could not be obtained with a contrast of 5 or less. Table 1 also shows the measurement results for letter densities.
比較例１ｌ比較例３で得たボリカーボネートー軸延伸フィルムとポ
リスチレンニ軸延伸フィルム（三菱モンサント化成工業
■製 ＯＰＳ−００７）をフィルムの長手方向が一致す
るように積層し、光学特性を評価した．結果を表−１に
示す．又、実施例１と液晶表示装置としての表示特性を調べた
ところ白黒表示が得られたと共に、視野角が大幅に改善
され、左右合計１１０゜、上下合計１００”の広視野角
が得られたが液晶ディスプレイの上下、左右の中間の斜
めの方向において特に視野角が狭く、着色が目立った。Comparative Example 1l The polycarbonate axially stretched film obtained in Comparative Example 3 and the polystyrene biaxially stretched film (OPS-007 manufactured by Mitsubishi Monsanto Chemical Industries, Ltd.) were laminated so that the longitudinal direction of the films matched, and the optical properties were evaluated. ．． The results are shown in Table 1. Further, when the display characteristics of Example 1 and the liquid crystal display device were investigated, a black and white display was obtained, and the viewing angle was significantly improved, with a wide viewing angle of 110° in total on the left and right sides and 100'' in total on the top and bottom. However, the viewing angle was particularly narrow in diagonal directions between the top, bottom, left and right of the LCD display, and the coloring was noticeable.
表−１及び実施例からわかる通り、本発明による正の固
有複屈折値を有するポリマーから形威されるフィルムの
一軸延伸フィルムと、負の固有複屈折値を有するポリマ
ーから形威されるフィルムの一軸延伸フィルムの延伸軸
を互いに直交又は略直交させるように積層したフィルム
を液晶セルと偏光板の間に介挿させることにより、視野
角が広い高品位の白黒表示が得られる．As can be seen from Table 1 and Examples, the uniaxially stretched film of the present invention is made of a polymer having a positive intrinsic birefringence value, and the film is made of a polymer of a negative intrinsic birefringence value. A high-quality black and white display with a wide viewing angle can be obtained by inserting a stack of uniaxially stretched films with their stretching axes perpendicular or nearly perpendicular to each other and interposed between the liquid crystal cell and the polarizing plate.
第１図は本発明の実施例に使用した液晶表示装置の斜視
図である．第２図は本発明の液晶表示装置の各軸の関係を示した図
である．第３図はフィルム（ａ）とフィルム（ｂ）の積層体の光
学特性を測定するときの、６３２．８ｎｍのレーザー光
の入射する方向に関する図である。図中の数字は下記を意味する。１・・・第１偏光板２・・・第１基板３・・・透明行電極４・・・液晶層５・・・透明列電極６・・・第２基板７・・・固有複屈折値が正の一軸延伸フイルム８・・・
固有複屈折値が負の一軸延伸フイルム９・・・第２偏光
板１０・・・液晶セル（ＳＴＮ）１１・・・光源からの光の方向工２・・・観察者２０・・・水平軸２１・・・第１偏光板偏光軸２２・・・第２偏光板偏光軸２３・・・透明行電極基板ラビング方向２４・・・透明
列電極基板ラビング方向２５・・・液晶分子のねじれ角２６・・・固有複屈折値が正の一軸延伸フイルムの延伸
軸２７・・・固有複屈折値が負の一軸延伸フイルムの延伸
軸２８・・・水平軸と第１偏光板偏光軸との為す角度２９
・・・第１偏光板偏光軸と透明行電極ラビング方向との
為す角度３０・・・透明列電極基板ラビング方向と固有複屈折値
が正の一軸延伸フィルムの延伸軸との為す角度３１・・・固有複屈折値が正及び負の一軸延伸フィルム
の各々の延伸軸の為す角度３２・・・水平軸と第２偏光板の偏光軸との為す角度４
ｌ・・・フィルム（ａ）４２・・・フィルム（ｂ）４３・・・フィルム（ａ）の延伸軸４４・・・フィルム（ｂ）の延伸軸４５・・・θ−０゜の方向への斜入射方向４６・・・フ
ィルム法線方向FIG. 1 is a perspective view of a liquid crystal display device used in an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between each axis of the liquid crystal display device of the present invention. FIG. 3 is a diagram regarding the incident direction of a 632.8 nm laser beam when measuring the optical properties of a laminate of films (a) and (b). The numbers in the figure mean the following. 1... First polarizing plate 2... First substrate 3... Transparent row electrode 4... Liquid crystal layer 5... Transparent column electrode 6... Second substrate 7... Intrinsic birefringence value is a positive uniaxially stretched film 8...
Uniaxially stretched film 9 with a negative intrinsic birefringence value...Second polarizing plate 10...Liquid crystal cell (STN) 11...Direction of light from the light source 2...Observer 20...Horizontal axis 21... First polarizing plate polarizing axis 22... Second polarizing plate polarizing axis 23... Transparent row electrode substrate rubbing direction 24... Transparent column electrode substrate rubbing direction 25... Twisting angle of liquid crystal molecules 26 ...Stretching axis 27 of a uniaxially stretched film with a positive intrinsic birefringence value...Stretching axis 28 of a uniaxially stretched film with a negative intrinsic birefringence value...Angle formed between the horizontal axis and the polarizing axis of the first polarizing plate 29
...Angle 30 between the polarizing axis of the first polarizing plate and the rubbing direction of the transparent row electrode...Angle 31 between the rubbing direction of the transparent column electrode substrate and the stretching axis of the uniaxially stretched film with a positive intrinsic birefringence value...・Angle 32 formed by each stretching axis of the uniaxially stretched films with positive and negative intrinsic birefringence values...Angle 4 formed between the horizontal axis and the polarizing axis of the second polarizing plate
l... Film (a) 42... Film (b) 43... Stretching axis of film (a) 44... Stretching axis of film (b) 45... In the direction of θ-0° Oblique incidence direction 46...Film normal direction
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/603,483US5138474A (en) | 1989-10-27 | 1990-10-26 | Liquid crystal display with compensator having two films with positive and negative intrinsic birefringence, respectively |
| EP90120564AEP0424951B1 (en) | 1989-10-27 | 1990-10-26 | Liquid crystal display |
| DE69016349TDE69016349T2 (en) | 1989-10-27 | 1990-10-26 | Liquid crystal display. |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1-281247 | 1989-10-27 | ||
| JP28124789 | 1989-10-27 |
| Publication Number | Publication Date |
|---|---|
| JPH03206422Atrue JPH03206422A (en) | 1991-09-09 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2242982APendingJPH03206422A (en) | 1989-10-27 | 1990-09-13 | Liquid crystal display device |
| Country | Link |
|---|---|
| JP (1) | JPH03206422A (en) |
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