JP2550654B2 - Liquid crystal display element - Google Patents
Liquid crystal display elementInfo
- Publication number
- JP2550654B2 JP2550654B2 JP63101667A JP10166788A JP2550654B2 JP 2550654 B2 JP2550654 B2 JP 2550654B2 JP 63101667 A JP63101667 A JP 63101667A JP 10166788 A JP10166788 A JP 10166788A JP 2550654 B2 JP2550654 B2 JP 2550654B2
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- crystal display
- alignment film
- fading
- transparent pixel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Liquid Crystal (AREA)
Description
【発明の詳細な説明】 ［産業上の利用分野］ この発明は、液晶表示素子に関し、特に例えばゲスト
−ホスト液晶組成物のような色素添加型液晶組成物を用
いる液晶表示素子に関するものである。Description: TECHNICAL FIELD The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device using a dye-added liquid crystal composition such as a guest-host liquid crystal composition.
［従来の技術］ 液晶を用いた表示装置は時計や電卓などに広く使われ
ているが、その殆どが白黒表示の静止画像であった。最
近はテレビ画像など動画をフルカラーで表示することが
試みられている。しかしながらこのようなカラー表示を
従来のツイスト−ネマティック（TN）方式で行なうと、
視角方向やセル厚のむらによって色が変化するという現
象が起きる。このためTN方式は大画面表示や広視角を必
要とするような表示の場合には適切でない。[Prior Art] Display devices using liquid crystals are widely used for clocks, calculators, etc., but most of them are still images in black and white. Recently, it has been attempted to display moving images such as television images in full color. However, when such a color display is performed by the conventional twist-nematic (TN) system,
The phenomenon that the color changes depending on the viewing angle direction and the uneven cell thickness occurs. For this reason, the TN method is not suitable for a large screen display or a display that requires a wide viewing angle.
またフルカラーで動画を表示する場合、階調制御が問
題となっているが、TN方式では電圧とコントラスト特性
においてコントラストの電圧による変化が急で、階調を
制御する電圧の調整が非常に微妙になる。さらに、電圧
−コントラスト特性は、温度変化を受けやすく、このこ
とが適切な階調を得ることをさらに困難にさせている。In addition, when displaying a moving image in full color, gradation control is a problem, but in the TN method, the voltage and contrast characteristics change sharply due to the voltage of the contrast, and the adjustment of the voltage for controlling the gradation is extremely delicate. Become. Further, the voltage-contrast characteristic is susceptible to temperature changes, which makes it more difficult to obtain an appropriate gradation.
それに対し、ゲスト−ホスト（以下GHと略称）液晶組
成物を対向する透明電極上に配向膜を施したガラス基板
間に配向させ、ホスト液晶の電界によるフレデリクス転
移にともなってゲストである色素配向方向を電界により
制御し、光透過量を制御しコントラストを得るGH方式の
場合、ゲスト分子として色素分子の長軸と短軸とで吸光
度の異なる二色性色素を利用することにより、TN方式の
場合のように偏光板を二枚使用せずに表示が行なえるた
め、視角やセル圧による表示むらが小さくなる。また、
電圧−コントラスト特性は、液晶分子配列に従った配向
としている色素の吸収遷移モーメントと入射光との相対
的な方向に依存しているため、TN方式にくらべてなだら
かな特性を示す。なお、GH液晶表示素子については例え
ば文献（Phil.Trans.R.Society.Lond.A309,189〜201.19
83年）等に詳しく述べられている。On the other hand, a guest-host (hereinafter abbreviated as GH) liquid crystal composition is aligned between glass substrates each having an alignment film on a transparent electrode facing each other, and the orientation direction of a dye as a guest is accompanied by a Fredericks transition due to an electric field of a host liquid crystal. In the case of the TN method, in which the GH method obtains contrast by controlling the light transmission amount by controlling the electric field, the guest molecule uses a dichroic dye having different absorbances on the long axis and the short axis of the dye molecule. As described above, since display can be performed without using two polarizing plates, display unevenness due to viewing angle and cell pressure is reduced. Also,
Since the voltage-contrast characteristic depends on the relative direction between the absorption transition moment of the dye that is oriented according to the liquid crystal molecular alignment and the incident light, it exhibits a gentler characteristic than the TN method. Regarding the GH liquid crystal display element, for example, refer to (Phil.Trans.R.Society.Lond.A309,189-201.19).
1983) and so on.
［発明が解決しようとする課題］ このようにGH液晶表示素子はTN液晶表示素子にくらべ
て優れた特長を有するが、一方、外部光または背面光源
からの透過光により液晶中の色素が褪色し、色の変化を
起こして素子の寿命を短くしてしまうという問題点があ
る。これは例えば刊行物（第５回液晶討論会予稿集2R1
3）に示されている。さらに同一セル内の液晶組成物全
体が連続しているセルにおいては、同一セル内で上記の
褪色の速度が異なり、結果的に表示素子面内で色調が変
わり、観察者に色むらとして感知され、通常の色素の平
均的な褪色よりはるかに早い時間内で素子の劣化として
認識されるという問題点があった。ここでは便宜上、こ
の面内での不均一な褪色現象を褪色異方性と呼ぶことに
する。発明者らがこの褪色現象をさらに詳細に検討した
ところ、褪色の異方性が必ずラビング方向にそって出現
する、即ち、セル面内でラビング方向の先端に位置する
部位と、根本に位置する部位との褪色の程度および褪色
モードの差が最も著しいことが判明した。[Problems to be Solved by the Invention] As described above, the GH liquid crystal display device has excellent characteristics as compared with the TN liquid crystal display device, but on the other hand, the dye in the liquid crystal is faded by external light or transmitted light from the back light source. However, there is a problem that the life of the device is shortened by causing a color change. This is, for example, a publication (Proceedings of the 5th Liquid Crystal Symposium 2R1
3). Further, in a cell in which the entire liquid crystal composition in the same cell is continuous, the speed of fading described above is different in the same cell, and as a result, the color tone changes in the surface of the display element, which is perceived by the observer as uneven color. However, there is a problem that it is recognized as deterioration of the device within a time much earlier than the average fading of the usual dye. Here, for the sake of convenience, the non-uniform fading phenomenon in this plane is referred to as fading anisotropy. When the inventors examined this fading phenomenon in more detail, the anisotropy of fading always appeared along the rubbing direction, that is, the site located at the tip of the rubbing direction in the cell plane and the root position. It was found that the degree of fading from the site and the difference in fading mode were the most remarkable.
この発明は上記のような問題点を解消するためになさ
れたもので、セル内での褪色異方性を極力抑制し、耐光
性に優れ、信頼性の高い液晶表示素子を得ることを目的
とする。The present invention has been made to solve the above problems, and an object of the present invention is to suppress the fading anisotropy in the cell as much as possible, excellent in light resistance, and to obtain a highly reliable liquid crystal display element. To do.
［課題を解決するための手段］ この発明に係る液晶表示素子は、配向膜が透明画素電
極間でラビング方向に互いに離隔した複数の単位配向膜
から成るものである。[Means for Solving the Problems] In the liquid crystal display element according to the present invention, the alignment film is composed of a plurality of unit alignment films separated from each other in the rubbing direction between the transparent pixel electrodes.
［作用］ この発明における配向膜は、透明画素電極間でラビン
グ方向に分断されているので、褪色の異方性が分断され
た配向膜単位で起こるため、液晶表示素子（セル）全体
としての褪色異方性を小さくすることができる。[Function] Since the alignment film in the present invention is divided in the rubbing direction between the transparent pixel electrodes, anisotropy of fading occurs in the divided alignment film units, and thus the fading of the liquid crystal display element (cell) as a whole. Anisotropy can be reduced.
［実施例］ 以下、この発明の一実施例を図について説明する。本
発明における透明基板、配向膜、透明画素電極の形状、
大きさには特に限定はない。また配向膜の種類について
も特に限定はなく、例えば、ポリイミド、ポリビニルア
ルコール、ポリオキシエチレン、カーボン、バーサミド
125、レシチン、ステアリン酸、ヘキサデシルトリメチ
ルアンモニウムブロマイド（CTAB）、オクタデシルアミ
ンハイドロクロライドなどを用いることができる。さら
に、配向膜の膜厚は50〜5000Åが適当であり、特に500
〜1000Åが望ましい。即ち、50Å以下だと安定な配向が
得られず、5000Å以上だと電気特性に悪影響を与える。[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. The transparent substrate in the present invention, the alignment film, the shape of the transparent pixel electrode,
There is no particular limitation on the size. The type of alignment film is not particularly limited, and examples thereof include polyimide, polyvinyl alcohol, polyoxyethylene, carbon, and versamide.
125, lecithin, stearic acid, hexadecyltrimethylammonium bromide (CTAB), octadecylamine hydrochloride and the like can be used. Furthermore, it is appropriate that the thickness of the alignment film is 50 to 5000Å, especially 500
~ 1000Å is desirable. That is, if it is less than 50Å, stable orientation cannot be obtained, and if it is more than 5000Å, the electrical characteristics are adversely affected.
実施例１ 第１図Ａ、Ｂにそれぞれ上面図および断面図で示すよ
うに、全面に透明画素電極（３）を有し、一定の方向に
ラビングされ配向膜（１）が施されている２枚の50×31
0mmの透明基板、例えばガラス基板（２）間にGH液晶組
成物を注入して液晶表示素子を構成している。配向膜
（１）は透明画素電極（３）間で、ラビング方向（４）
に分断されて、互いに離隔した複数（図では３つ）の単
位配向膜から成っている。この液晶表示素子を試料Ｉと
した。Example 1 As shown in FIGS. 1A and 1B in a top view and a sectional view, respectively, a transparent pixel electrode (3) is provided on the entire surface, and an alignment film (1) is rubbed in a certain direction to form a transparent pixel electrode (2). 50 x 31 pieces
A GH liquid crystal composition is injected between 0 mm transparent substrates such as a glass substrate (2) to form a liquid crystal display element. The alignment film (1) is disposed between the transparent pixel electrodes (3) in the rubbing direction (4).
It is composed of a plurality of (three in the figure) unit alignment films which are separated from each other and separated from each other. This liquid crystal display device was designated as Sample I.
比較例 第２図Ａ、Ｂにそれぞれ上面図および断面図で示すよ
うに、試料Ｉと同様の透明画素電極（３）を有し、全面
に配向膜（１）を施した２枚の50×310mmのガラス基板
（２）間にGH液晶組成物を注入した従来と同様の液晶表
示素子を試料IIとした。Comparative Example As shown in FIGS. 2A and 2B in a top view and a cross-sectional view, respectively, two 50 × 50 × substrates each having a transparent pixel electrode (3) similar to that of Sample I and having an alignment film (1) applied on the entire surface. A liquid crystal display device similar to the conventional one in which a GH liquid crystal composition was injected between 310 mm glass substrates (2) was designated as Sample II.
試料Ｉ、IIをそれぞれ０〜1000時間露光試験を行な
い、セルの図面に向かって右端と左端の可視吸収スペク
トルを測定した。測定データを測色学の色表現Ｌ＊、ｕ
＊,v＊に変換し、露光時間に対するセル内の褪色異方性
による色差△Eu＊ｖ＊を求めた。この結果を第３図に示
す。○は実施例、△は比較例を示す。ラビング方向に対
し配向膜（１）を分断した試料Ｉの褪色異方性は比較例
である試料IIに比べて大幅に抑制された。Samples I and II were each subjected to an exposure test for 0 to 1000 hours, and visible absorption spectra at the right end and the left end were measured toward the drawing of the cell. Colorimetric representation of measurement data in colorimetry L * , u
The color difference ΔEu * v * due to the anisotropy of fading in the cell with respect to the exposure time was determined by converting into * , v * . The results are shown in FIG. ◯ indicates an example, and Δ indicates a comparative example. The fading anisotropy of the sample I in which the alignment film (1) was divided in the rubbing direction was significantly suppressed as compared with the comparative sample II.
実施例２ 第４図に示すように、10mm×20mmの透明画素電極
（３）を50個有すると共にラビング方向（４）に対して
５段に分断し離隔された配向膜（１）を有する160mm×1
65mmの２枚のガラス基板（２）間にGH液晶組成物を注入
した液晶表示素子を試料IIIとした。Example 2 As shown in FIG. 4, 160 mm having 50 transparent pixel electrodes (3) of 10 mm × 20 mm and having an alignment film (1) divided into 5 steps in the rubbing direction (4). × 1
A liquid crystal display device in which a GH liquid crystal composition was injected between two 65 mm glass substrates (2) was designated as Sample III.
比較例２ 第５図に示すように、試料IIIと同様に10mm×20mmの
透明画素電極（３）を50個有すると共に、全面に配向膜
（１）を施した160mm×165mmの２枚のガラス基板（２）
間にGH液晶組成物を注入した従来と同様の液晶表示素子
を試料IVとした。Comparative Example 2 As shown in FIG. 5, two glass plates of 160 mm × 165 mm each having 50 transparent pixel electrodes (3) of 10 mm × 20 mm and having an alignment film (1) on the entire surface, as in Sample III. Board (2)
A liquid crystal display device similar to the conventional one in which a GH liquid crystal composition was injected was used as Sample IV.
これらの試料III、IVを実施例１と同様の露光試験を
行ない、試料面内の上下の色差を比較したところ、実施
例１と同様に実施例２（試料III）においても比較例２
（試料IV）に比べて褪色異方性が大幅に抑制された。The samples III and IV were subjected to the same exposure test as in Example 1 and the upper and lower color differences in the sample plane were compared. As with Example 1, in Example 2 (Sample III) as well, Comparative Example 2 was obtained.
The fading anisotropy was significantly suppressed compared to (Sample IV).
実施例３ 第６図に示すように、実施例２と同様の透明画素電極
（３）をパターニングし、それぞれの透明画素電極
（３）を個々に分断し離隔した配向膜（１）を覆った16
0mm×165mmの２枚のガラス基板（２）間にGH液晶組成物
を注入した液晶表示素子を試料Ｖとした。Example 3 As shown in FIG. 6, a transparent pixel electrode (3) similar to that of Example 2 was patterned to individually divide each transparent pixel electrode (3) to cover the separated alignment film (1). 16
Sample V was a liquid crystal display device in which the GH liquid crystal composition was injected between two glass substrates (2) of 0 mm × 165 mm.
この試料Ｖについて実施例１と同様の露光試験を行な
い、比較例である試料IVと試料面内の上下の色差を比較
したところ、実施例２と同様に褪色異方性が大幅に抑制
された。This sample V was subjected to the same exposure test as in Example 1, and the color difference between the upper and lower sides of the sample IV as a comparative example was compared with each other. As a result, similar to Example 2, fading anisotropy was significantly suppressed. .
なお、上記実施例ではいずれも配向膜（１）が１画素
単位でラビング方向に分断されている場合を示したが、
一般にはラビング方向に数十個、数百個という画素が配
置されていることが多く、例えば第７図に示すように２
画素単位など複数画素単位で分断し離隔してもよく上記
実施例と同様の効果を奏する。In each of the above examples, the alignment film (1) is divided in the rubbing direction on a pixel-by-pixel basis.
Generally, tens or hundreds of pixels are arranged in the rubbing direction in many cases. For example, as shown in FIG.
It may be divided into a plurality of pixel units such as a pixel unit and may be separated from each other, and the same effect as that of the above-described embodiment is obtained.
［発明の効果］ 以上のように、この発明によれば、配向膜が透明画素
電極間でラビング方向に分断し離隔されているので、液
晶組成物中の色素の外部光または背面光源からの透過光
による褪色がセル面内で異方的に起こる現象を抑制し、
耐光性に優れ、安定で信頼性の高い液晶表示素子が得ら
れる効果がある。[Effects of the Invention] As described above, according to the present invention, since the alignment film is divided and separated in the rubbing direction between the transparent pixel electrodes, the dye in the liquid crystal composition is transmitted through the external light or the back light source. Suppresses the phenomenon that fading due to light occurs anisotropically in the cell plane,
A liquid crystal display element having excellent light resistance, stability and high reliability can be obtained.
第１図（Ａ）、（Ｂ）はこの発明の一実施例による液晶
表示素子を示すそれぞれ上面図および断面図、第２図
（Ａ）、（Ｂ）は比較例による従来の液晶表示素子を示
すそれぞれ上面図および断面図、第３図は第１図の実施
例および第２図の比較例の露光時間に対する褪色異方性
による色差を示す特性図、第４図はこの発明の他の実施
例による液晶表示素子を示す上面図、第５図は他の比較
例による従来の液晶表示素子を示す上面図、第６図、第
７図はそれぞれこの発明の他の実施例による液晶表示素
子を示す上面図である。 図において、（１）は配向膜、（２）はガラス基板、
（３）は透明画素電極、（４）はラビング方向である。 なお、各図中同一符号は同一または相当部分を示す。1 (A) and 1 (B) are top views and cross-sectional views showing a liquid crystal display element according to an embodiment of the present invention, and FIGS. 2 (A) and 2 (B) are conventional liquid crystal display elements according to a comparative example. FIG. 4 is a top view and a cross-sectional view, respectively, FIG. 3 is a characteristic diagram showing the color difference due to fading anisotropy with respect to the exposure time of the embodiment of FIG. 1 and the comparative example of FIG. 2, and FIG. FIG. 5 is a top view showing a liquid crystal display device according to an example, FIG. 5 is a top view showing a conventional liquid crystal display device according to another comparative example, and FIGS. 6 and 7 are liquid crystal display devices according to other embodiments of the present invention. It is a top view shown. In the figure, (1) is an alignment film, (2) is a glass substrate,
(3) is a transparent pixel electrode, and (4) is a rubbing direction. In the drawings, the same reference numerals indicate the same or corresponding parts.
Claims (1)
２枚の透明基板間に色素添加型液晶組成物を挟持し、上
記配向膜を一定方向にラビングすることにより上記液晶
を上記ラビングの方向に配向させ、上記各透明画素電極
に電圧を印加して画素表示を行うように構成する液晶表
示素子において、上記配向膜は、上記透明画素電極間で
上記ラビングの方向に互いに離隔した複数の単位配向膜
から成ることを特徴とする液晶表示素子。1. A liquid crystal composition containing a dye is sandwiched between two transparent substrates each having an alignment film and a plurality of transparent pixel electrodes, and the alignment film is rubbed in a certain direction so that the liquid crystal is rubbed in the rubbing direction. In a liquid crystal display device configured to perform pixel display by applying a voltage to each of the transparent pixel electrodes, and the alignment film includes a plurality of units separated from each other in the rubbing direction between the transparent pixel electrodes. A liquid crystal display device comprising an alignment film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63101667A JP2550654B2 (en) | 1988-04-25 | 1988-04-25 | Liquid crystal display element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63101667A JP2550654B2 (en) | 1988-04-25 | 1988-04-25 | Liquid crystal display element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01271724A JPH01271724A (en) | 1989-10-30 |
| JP2550654B2 true JP2550654B2 (en) | 1996-11-06 |
Family
ID=14306723
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63101667A Expired - Lifetime JP2550654B2 (en) | 1988-04-25 | 1988-04-25 | Liquid crystal display element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2550654B2 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57108827A (en) * | 1980-12-25 | 1982-07-07 | Fujitsu Kiden Ltd | Liquid crystal display device |
| JP2529184B2 (en) * | 1985-04-08 | 1996-08-28 | 松下電器産業株式会社 | Transmissive liquid crystal display device |
| JPH0616140B2 (en) * | 1986-08-04 | 1994-03-02 | キヤノン株式会社 | Liquid crystal light modulator |
-
1988
- 1988-04-25 JP JP63101667A patent/JP2550654B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01271724A (en) | 1989-10-30 |
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