JP2004061690A - Liquid crystal display device and method of manufacturing the same - Google Patents

Abstract

An object of the present invention is to provide a liquid crystal display device used as a display unit of an information device or the like and a method of manufacturing the same, and to provide a liquid crystal display device capable of shortening a liquid crystal injection time and a method of manufacturing the same.
Kind Code: A1 A plurality of types of liquid crystals having different surface tensions are injected into a bonding substrate in order from a liquid crystal having a large surface tension. The injected plural types of liquid crystals A to C are mixed in the bonded substrate 20.
[Selection diagram] Fig. 4

Description

【００１１】
表１は、複数種類の液晶Ａ〜Ｄの表面張力γ（ｄｙｎ／ｃｍ（１ｄｙｎ／ｃｍ＝１０^−３Ｎ／ｍ））と、貼合せ基板２０の対向面に塗布形成された配向膜表面（臨界表面張力約２５〜４５ｄｙｎ／ｃｍ）に対する液晶Ａ〜Ｄの接触角Θ（ｄｅｇ．）とを示している。表１に示すように、液晶Ａの表面張力γは３０．３ｄｙｎ／ｃｍであり、接触角Θは２４．３°である。液晶Ｂの表面張力γは２８．３ｄｙｎ／ｃｍであり、接触角Θは１５．９°である。液晶Ｃの表面張力γは２７．２ｄｙｎ／ｃｍであり、接触角Θは２３．８°である。液晶Ｄの表面張力γは２５．３ｄｙｎ／ｃｍであり、接触角Θは１５．３°である。本実施の形態では、例えば３種類の液晶Ａ〜Ｃを用いる。以下、液晶Ａ〜Ｃの表面張力をそれぞれγＡ〜γＣと表す。
【００１２】
まず、真空チャンバ１０内に、複数の貼合せ基板２０を保持したカセット１８を取り付ける。また、液晶Ａ〜Ｃをそれぞれ満たした３つの液晶皿２６を移動装置２４上に載置する。次に、排気用バルブ３０、３１を開き、真空ポンプ３２を用いて排気して、真空チャンバ１０内を減圧する。これにより貼合せ基板２０内が脱気される。真空チャンバ１０内が所定の気圧（真空度）になったら移動装置２４を上方に移動させ、各貼合せ基板２０の液晶注入口を液晶皿２６内の液晶Ａに接触させる。
【００１３】
図２乃至図４は、貼合せ基板２０内に液晶Ａ〜Ｃを注入する際の状態を模式的に示している。図２に示すように、貼合せ基板２０のシール剤４８の切れ目である液晶注入口４０には、「く」の字形状の液晶注入管４２が取り付けられている。液晶注入管４２の途中には、液晶注入弁４６が取り付けられている。液晶皿２６ａ内の液晶Ａに液晶注入管４２の先端部を接触させた後、加圧部４４を用いて液晶Ａを加圧するとともに液晶注入弁４６を開くことによって、貼合せ基板２０内に液晶Ａが注入されるようになっている。本例では加圧部４４に代えて、貼合せ基板２０内外の気圧差を用いている。
【００１４】
液晶注入弁４６を開くと、液晶Ａは、まず毛細管現象により貼合せ基板２０内に浸透する。次に、各貼合せ基板２０の液晶注入口４０を液晶Ａに接触させた状態で、ガス導入用バルブ３４を開き、空気又は不活性ガスを導入する。これにより、ほぼ真空状態の貼合せ基板２０内と大気圧に戻った真空チャンバ１０内との気圧差により、貼合せ基板２０内に液晶Ａが注入される。所定量の液晶Ａが注入されたら、液晶注入弁４６を閉じる。液晶Ａの注入量は、例えば貼合せ基板２０内に注入される液晶の総注入量の１／３程度とする。
【００１５】
次に、図３に示すように、移動装置２４を鉛直方向及び水平方向に移動させ、液晶注入管４２の先端部を液晶皿２６ａ内の液晶Ａから離し、液晶皿２６ｂ内の液晶Ｂ（γＢ＜γＡ）に接触させる。その後液晶注入弁４６を開き、液晶Ａと同様に液晶Ｂを貼合せ基板２０内に注入する。所定量の液晶Ｂが注入されたら、液晶注入弁４６を閉じる。液晶Ｂの注入量は、例えば液晶Ａと同程度とする。
【００１６】
次に、図４に示すように、移動装置２４を鉛直方向及び水平方向に移動させ、液晶注入管４２の先端部を液晶皿２６ｂ内の液晶Ｂから離し、液晶皿２６ｃ内の液晶Ｃ（γＣ＜γＢ）に接触させる。その後液晶注入弁４６を開き、液晶Ａ、Ｂと同様に所定量の液晶Ｃを貼合せ基板２０内に注入し、液晶注入弁４６を閉じる。液晶Ｃの注入量は、例えば液晶Ａ、Ｂと同程度とする。
【００１７】
次に、貼合せ基板２０内に注入された３種類の液晶Ａ〜Ｃを貼合せ基板２０内で混合させる。例えば、貼合せ基板２０及び貼合せ基板２０内の液晶Ａ〜Ｃを７０〜１００℃程度に加熱することにより混合が促進される。液晶Ａ〜Ｃは、混合された後に所望の電気的及び光学的特性が得られるように選択される。以上の工程を経て、液晶表示装置が完成する。
【００１８】
本実施の形態では、互いに異なる表面張力を有する３種類の液晶Ａ〜Ｃを表面張力の大きい方から順に貼合せ基板２０内に注入している。互いに異なる表面張力を有する液晶間の界面では、相対的に表面張力の小さい液晶が表面張力の大きい液晶に引き寄せられて流れが発生する現象（マランゴニ効果又はマランゴニ対流）が生じる。すなわち、液晶Ａ、Ｂ間及び液晶Ｂ、Ｃ間の界面では、液晶の注入を促進する方向への流れが生じる。このため、本実施の形態によれば、液晶の注入時間を短縮できる。なお、液晶の注入時間は、液晶間の表面張力の差や、液晶を加圧する圧力（すなわち減圧時の貼合せ基板２０内の気圧）、貼合せ基板２０の対角サイズ及びセルギャップ等によって異なる。
【００１９】
本実施の形態では、互いに異なる表面張力を有する３種類の液晶Ａ〜Ｃを用いているが、用いる液晶は２種類又は４種類以上であっても構わない。
また本実施の形態では、移動装置２４を移動させることにより、各貼合せ基板２０と複数の液晶皿２６ａ〜２６ｃとの間を相対的に移動させているが、各貼合せ基板２０側を移動させるようにしてもよい。
【００２０】
本実施の形態では、比較的表面張力の大きい液晶Ａを最初に貼合せ基板２０に注入している。液晶Ａを迅速に貼合せ基板２０に注入するために、注入前の液晶Ａを７０〜１００℃程度に予備加熱してもよい。予備加熱することによって、液晶Ａの表面張力及び粘性係数が低下し、注入時間がさらに短縮される。
【００２１】
〔第２の実施の形態〕
次に、本発明の第２の実施の形態による液晶表示装置及びその製造方法について図５を用いて説明する。本実施の形態は、領域毎に異なる臨界表面張力を有する配向膜を用いることを特徴としている。図５は、本実施の形態による液晶表示装置の貼合せ基板２０の構成を示している。図５に示すように、貼合せ基板２０を構成する一対の基板の各対向面には、領域毎に異なる臨界表面張力を有する配向膜が形成されている。図５では、配向膜は５つの領域ａ〜ｅに分割されている。液晶注入口４０側の端部は領域ａになっている。領域ａに隣接して領域ｂ、ｃが配置されている。液晶注入口４０の反対側の端部には、領域ｂ、ｃに隣接する領域ｄと、領域ｂのみに隣接する領域ｅとが配置されている。液晶注入口４０から注入された液晶は、図中の矢印方向に進行して充填される。
【００２２】
配向膜の各領域ａ〜ｅでの臨界表面張力をそれぞれγｃａ〜γｃｅとすると、臨界表面張力γｃａ〜γｃｅは、γｃａ＜γｃｂ、γｃａ＜γｃｃ、γｃｂ＜γｃｄ、γｃｂ＜γｃｅ、及びγｃｃ＜γｃｄの関係を満たしている。特に、γｃａ＜γｃｂ＜γｃｃ＜γｃｄ＜γｃｅの関係が満たされるのが望ましい。例えば、臨界表面張力γｃａは１５ｄｙｎ／ｃｍであり、臨界表面張力γｃｂは２０ｄｙｎ／ｃｍ、臨界表面張力γｃｃは３０ｄｙｎ／ｃｍである。また、臨界表面張力γｃｄは４０ｄｙｎ／ｃｍであり、臨界表面張力γｃｅは５０ｄｙｎ／ｃｍである。また、注入される液晶の表面張力は、例えば臨界表面張力γｃａより小さくなっている。
【００２３】
本実施の形態では、領域毎に異なる臨界表面張力を有する配向膜が、液晶注入口側の領域に相対的に小さい臨界表面張力を有するように形成されている。互いに異なる臨界表面張力を有する領域間の境界部上の液晶には、マランゴニ効果により、相対的に臨界表面張力の大きい領域に向かう流れが生じる。すなわち液晶には、液晶の注入を促進する方向への流れが生じる。このため、本実施の形態によれば、液晶の注入時間を短縮できる。また、本実施の形態による貼合せ基板２０に、第１の実施の形態による液晶注入方法を用いて液晶を注入すると、さらに液晶の注入時間が短縮する。
【００２４】
次に、本実施の形態による液晶表示装置の製造方法について説明する。まず、薄膜トランジスタ（ＴＦＴ；Ｔｈｉｎ　Ｆｉｌｍ　Ｔｒａｎｓｉｓｔｏｒ）等がガラス基板上に形成されたＴＦＴ基板上、及びカラーフィルタ等がガラス基板上に形成された対向基板上に、固形分濃度６ｗｔ％の低臨界表面張力のポリイミドワニスを印刷形成する。その後、ポリイミドワニスを焼成硬化させて、例えば膜厚６０〜７０ｎｍの配向膜を形成する。低臨界表面張力ポリイミドからなる配向膜の臨界表面張力は、約１５ｄｙｎ／ｃｍである。次に、臨界表面張力を変化させる領域が開口されたフォトマスクを介して、超高圧水銀ランプにより所定の照射強度のＵＶ光を照射する。ＵＶ光を例えば１０分間程度照射することにより、配向膜の臨界表面張力が約４０ｄｙｎ／ｃｍに増加する。このように、領域毎に異なる照射量のＵＶ光を配向膜に照射することにより、図５に示すような貼合せ基板２０が得られる。
【００２５】
領域毎に異なる臨界表面張力を有する配向膜は、領域毎に異なる配向膜形成材料を塗布することにより形成してもよい。
【００２６】
【表２】

【００２７】
表２は、複数種類の配向膜形成材料Ｅ〜Ｈの臨界表面張力γｃ（ｄｙｎ／ｃｍ）の値の一例を示している。表２に示すように、配向膜形成材料Ｅの臨界表面張力γｃは２５ｄｙｎ／ｃｍであり、配向膜形成材料Ｆの臨界表面張力γｃは３５ｄｙｎ／ｃｍである。配向膜形成材料Ｇの臨界表面張力γｃは４０ｄｙｎ／ｃｍであり、配向膜形成材料Ｈの臨界表面張力γｃは５０ｄｙｎ／ｃｍである。このように、液晶注入口側の領域が相対的に小さい臨界表面張力γｃを有するように、互いに異なる臨界表面張力γｃの得られる配向膜形成材料を塗布形成することにより、図５に示すような貼合せ基板２０が得られる。
【００２８】
また、本実施の形態では、真空注入法を用いて液晶を注入しているが、滴下注入法を用いた液晶注入にも適用できる。滴下注入法を用いた液晶注入に本発明を適用した場合の効果としては、領域毎に異なる臨界表面張力γｃを有する２種類以上の配向膜を基板上に形成することにより、滴下後の液晶が均一かつ迅速に基板面内に広がること等がある。
【００２９】
〔第３の実施の形態〕
次に、本発明の第３の実施の形態による液晶表示装置の製造方法について図６を用いて説明する。本実施の形態は、液晶の温度を変化させることにより、液晶の表面張力を異ならせていることを特徴としている。図６に示すように、液晶Ａの満たされた液晶皿２６ａは、液晶ヒータ５０上に配置されている。液晶ヒータ５０は、少なくとも２段階の温度レベルに調整可能になっている。また、貼合せ基板２０の外側の表面には、蛇腹状のヒータ５２が取り付けられている。ヒータ５２は、貼合せ基板２０及び貼合せ基板２０内に注入された液晶の温度を一定（例えば１０〜２０℃）に維持するために設けられている。
【００３０】
まず、液晶ヒータ５０により相対的に低い温度に調整された液晶Ａを所定量だけ貼合せ基板２０内に注入する。相対的に低い温度の液晶Ａの注入量は、液晶の総注入量の１／２程度とする。注入後の液晶Ａの温度は、ヒータ５２により相対的に低い温度のままでほぼ一定に維持される。
【００３１】
続いて、液晶ヒータ５０の温度設定を変更し、液晶Ａの温度を相対的に高い温度に調整する。相対的に高い温度に調整された液晶Ａを所定量だけ貼合せ基板２０内に注入する。注入が終了したら液晶注入弁４６を閉じる。
【００３２】
本実施の形態では、相対的に低い温度に調整された液晶Ａを先に注入し、その後に相対的に高い温度に調整された液晶Ａを注入している。液晶の表面張力γは温度に依存して変化する。表面張力γは、高温では小さくなり、低温では大きくなる。このため、第１の実施の形態と同様に、互いに異なる表面張力γを有する液晶間の界面ではマランゴニ効果が生じ、液晶の注入を促進する方向への流れが生じる。このため、本実施の形態によれば、液晶の注入時間を短縮できる。
【００３３】
本実施の形態では、液晶Ａの温度レベルを２段階としているが、温度レベルは３段階以上であっても構わない。
また、貼合せ基板２０の外側の表面に取り付けられたヒータ５２等を用いて、貼合せ基板２０内の温度を領域によって異ならせるようにしてもよい。液晶注入口４０側の領域を相対的に高い温度に調整し、液晶注入口４０から離れた領域を相対的に低い温度に調整することにより、本実施の形態と同様の効果が得られる。
【００３４】
本発明は、上記実施の形態に限らず種々の変形が可能である。
例えば、上記第２の実施の形態では、アクティブマトリクス型の液晶表示装置を例に挙げたが、本発明はこれに限らず、単純マトリクス型の液晶表示装置にも適用できる。
【００３５】
以上説明した実施の形態による液晶表示装置及びその製造方法は、以下のようにまとめられる。
（付記１）
一対の基板を貼り合わせて貼合せ基板を作製し、
互いに異なる表面張力を有する複数種類の液晶を前記表面張力の大きい方から順に前記貼合せ基板内に注入し、
注入された前記複数種類の液晶を前記貼合せ基板内で混合すること
を特徴とする液晶表示装置の製造方法。
【００３６】
（付記２）
配向膜形成材料を基板上に塗布し、
領域毎に異なる照射量の紫外光を前記配向膜形成材料に照射し、
前記領域毎に異なる臨界表面張力を有する配向膜を形成すること
を特徴とする液晶表示装置の製造方法。
【００３７】
（付記３）
領域毎に異なる配向膜形成材料を基板上に塗布し、
前記領域毎に異なる臨界表面張力を有する配向膜を形成すること
を特徴とする液晶表示装置の製造方法。
【００３８】
（付記４）
付記３記載の液晶表示装置の製造方法において、
前記配向膜は、液晶が注入される液晶注入口側の領域に相対的に小さい臨界表面張力を有するように形成されること
を特徴とする液晶表示装置の製造方法。
【００３９】
（付記５）
対向配置された一対の基板と、
前記一対の基板の対向面に形成され、領域毎に異なる臨界表面張力を有する配向膜と、
前記一対の基板間に封止された液晶と
を有することを特徴とする液晶表示装置。
【００４０】
【発明の効果】
以上の通り、本発明によれば、液晶の注入時間を短縮できる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態による液晶表示装置の製造方法に用いる液晶注入装置の構成を示す図である。
【図２】本発明の第１の実施の形態による液晶表示装置の製造方法を示す図である。
【図３】本発明の第１の実施の形態による液晶表示装置の製造方法を示す図である。
【図４】本発明の第１の実施の形態による液晶表示装置の製造方法を示す図である。
【図５】本発明の第２の実施の形態による液晶表示装置の貼合せ基板の構成を示す図である。
【図６】本発明の第３の実施の形態による液晶表示装置の製造方法を示す図である。
【符号の説明】
１　液晶注入装置
１０　真空チャンバ
１２　ヒーティングユニット
１４　クーリングユニット
１６　液晶注入室
１８　カセット
２０　貼合せ基板
２２　ゲート弁
２４　移動装置
２６、２６ａ、２６ｂ、２６ｃ　液晶皿
３０、３１　排気用バルブ
３２　真空ポンプ
３４　ガス導入用バルブ
４０　液晶注入口
４２　液晶注入管
４４　加圧部
４６　液晶注入弁
４８　シール剤
５０　液晶ヒータ
５２　ヒータ
Ａ、Ｂ、Ｃ　液晶
Ｅ、Ｆ、Ｇ、Ｈ　配向膜形成材料
ａ、ｂ、ｃ、ｄ、ｅ　領域[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device used as a display unit of an information device or the like and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a vacuum injection method has been used as a method for injecting liquid crystal into a bonded substrate in which a pair of substrates arranged opposite to each other are bonded via a sealant. Of the various liquid crystal injection steps using the vacuum injection method, methods generally used, which are excellent in terms of productivity, manufacturing cost, and the like, will be described below.
[0003]
First, a bonded substrate and a liquid crystal dish filled with liquid crystal are arranged in a vacuum chamber for liquid crystal injection. An exhaust system and a pressurizing system for controlling the atmospheric pressure in the vacuum chamber are connected to the vacuum chamber. After the inside of the vacuum chamber is depressurized by the exhaust system to eliminate the remaining air in the bonded substrate, the liquid crystal injection port of the bonded substrate is immersed in the liquid crystal of the liquid crystal dish.
Next, air or an inert gas is introduced into the vacuum chamber by a pressurizing system. As a result, the liquid crystal is filled in the bonded substrate by utilizing a pressure difference between the bonded substrate in a substantially vacuum state and the vacuum chamber returned to the atmospheric pressure and a capillary phenomenon due to the surface tension of the bonded substrate inner surface. You. The liquid crystal injection step using this vacuum injection method is generally performed at room temperature.
[0004]
[Problems to be solved by the invention]
However, in the above-described liquid crystal injection step, the injection time increases almost in proportion to the square of the diagonal size. Therefore, with the recent increase in the size of the liquid crystal display device, it takes a long time to inject the liquid crystal. Has occurred. As a solution to this problem, it is conceivable that the liquid crystal before injection is heated to lower the viscosity coefficient, and the resistance at the time of liquid crystal injection is reduced, thereby shortening the injection time. However, heating the liquid crystal causes a problem that the liquid crystal evaporates. In addition, there is a problem that it is difficult to install various equipment such as a heater necessary for heating the liquid crystal in the vacuum chamber.
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device capable of reducing a liquid crystal injection time and a method of manufacturing the same.
[0006]
[Means for Solving the Problems]
The above object is to produce a laminated substrate by laminating a pair of substrates, injecting a plurality of types of liquid crystals having different surface tensions into the laminated substrate in order from the larger surface tension, the injected This is achieved by a method for manufacturing a liquid crystal display device, wherein a plurality of types of liquid crystals are mixed in the bonding substrate.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
[First Embodiment]
A method for manufacturing the liquid crystal display device according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the configuration of a liquid crystal injection device used in the method for manufacturing a liquid crystal display device according to the present embodiment. The liquid crystal injection device 1 has a vacuum chamber 10, and an exhaust system (main exhaust line) and a pressurizing system (slow vent line) connected to the vacuum chamber 10, respectively. A heating unit 12 for heating the inside of the vacuum chamber 10 and a cooling unit 14 for cooling the inside of the vacuum chamber 10 are installed above the inside of the vacuum chamber 10 in order to control the temperature inside the vacuum chamber 10. . Below the heating unit 12 and the cooling unit 14, a liquid crystal injection chamber 16 is arranged. A cassette 18 holding a plurality of bonded substrates 20 is attached to the liquid crystal injection chamber 16. Below the inside of the vacuum chamber 10, a moving device 24 that can move in a vertical direction and a horizontal direction, for example, is installed. On the moving device 24, a plurality of liquid crystal dishes 26 (only one is shown in FIG. 1) are placed. The inside of the vacuum chamber 10 can be separated into two parts by a gate valve 22 provided between the liquid crystal injection chamber 16 and the moving device 24.
[0008]
The exhaust system includes an exhaust valve 30 connected above the vacuum chamber 10, an exhaust valve 31 connected below the vacuum chamber 10, and a vacuum pump 32 such as a rotary pump. The pressurizing system has a gas introduction valve 34 and a gas source (not shown).
[0009]
Next, a method for manufacturing the liquid crystal display device according to the present embodiment will be described. In this embodiment mode, a plurality of types of liquid crystals having different surface tensions are used.
[0010]
[Table 1]

[0011]
Table 1 shows the surface tension γ (dyn / cm (1 dyn / cm = 10 ⁻³ N / m)) of the plurality of types of liquid crystals A to D, and the surface of the alignment film applied to the facing surface of the bonded substrate 20 ( 3 shows the contact angles Θ (deg.) Of the liquid crystals A to D with respect to the critical surface tension (about 25 to 45 dyn / cm). As shown in Table 1, the surface tension γ of the liquid crystal A is 30.3 dyn / cm, and the contact angle Θ is 24.3 °. The surface tension γ of the liquid crystal B is 28.3 dyn / cm, and the contact angle Θ is 15.9 °. The surface tension γ of the liquid crystal C is 27.2 dyn / cm, and the contact angle Θ is 23.8 °. The surface tension γ of the liquid crystal D is 25.3 dyn / cm, and the contact angle Θ is 15.3 °. In the present embodiment, for example, three types of liquid crystals A to C are used. Hereinafter, the surface tensions of the liquid crystals A to C are represented by γA to γC, respectively.
[0012]
First, a cassette 18 holding a plurality of bonded substrates 20 is mounted in the vacuum chamber 10. Further, three liquid crystal dishes 26 respectively filled with liquid crystals A to C are placed on the moving device 24. Next, the exhaust valves 30 and 31 are opened, and the interior of the vacuum chamber 10 is evacuated using the vacuum pump 32 to reduce the pressure. Thereby, the inside of the bonded substrate 20 is degassed. When the inside of the vacuum chamber 10 reaches a predetermined atmospheric pressure (degree of vacuum), the moving device 24 is moved upward to bring the liquid crystal injection port of each bonded substrate 20 into contact with the liquid crystal A in the liquid crystal dish 26.
[0013]
FIG. 2 to FIG. 4 schematically show states when liquid crystals A to C are injected into the bonding substrate 20. As shown in FIG. 2, a liquid crystal injection pipe 42 having a “<” shape is attached to a liquid crystal injection port 40 which is a cut of the sealant 48 of the bonded substrate 20. In the middle of the liquid crystal injection tube 42, a liquid crystal injection valve 46 is attached. After the tip of the liquid crystal injection tube 42 is brought into contact with the liquid crystal A in the liquid crystal dish 26a, the liquid crystal A is pressurized using the pressurizing section 44 and the liquid crystal injection valve 46 is opened, so that the liquid crystal A is to be injected. In this example, a pressure difference between the inside and outside of the bonded substrate 20 is used instead of the pressurizing unit 44.
[0014]
When the liquid crystal injection valve 46 is opened, the liquid crystal A first penetrates into the bonded substrate 20 by capillary action. Next, with the liquid crystal injection port 40 of each bonded substrate 20 in contact with the liquid crystal A, the gas introduction valve 34 is opened, and air or an inert gas is introduced. Thereby, the liquid crystal A is injected into the bonding substrate 20 due to the pressure difference between the inside of the bonding substrate 20 in a substantially vacuum state and the inside of the vacuum chamber 10 returning to the atmospheric pressure. When a predetermined amount of liquid crystal A is injected, the liquid crystal injection valve 46 is closed. The injection amount of the liquid crystal A is, for example, about 程度 of the total injection amount of the liquid crystal injected into the bonding substrate 20.
[0015]
Next, as shown in FIG. 3, the moving device 24 is moved in the vertical direction and the horizontal direction, the tip of the liquid crystal injection tube 42 is separated from the liquid crystal A in the liquid crystal dish 26a, and the liquid crystal B (γB <ΓA). Thereafter, the liquid crystal injection valve 46 is opened, and the liquid crystal B is injected into the bonding substrate 20 in the same manner as the liquid crystal A. When a predetermined amount of liquid crystal B is injected, the liquid crystal injection valve 46 is closed. The injection amount of the liquid crystal B is, for example, approximately the same as that of the liquid crystal A.
[0016]
Next, as shown in FIG. 4, the moving device 24 is moved in the vertical direction and the horizontal direction, the tip of the liquid crystal injection tube 42 is separated from the liquid crystal B in the liquid crystal dish 26b, and the liquid crystal C (γC <ΓB). Thereafter, the liquid crystal injection valve 46 is opened, a predetermined amount of the liquid crystal C is injected into the bonding substrate 20 in the same manner as the liquid crystals A and B, and the liquid crystal injection valve 46 is closed. The injection amount of the liquid crystal C is, for example, approximately equal to that of the liquid crystals A and B.
[0017]
Next, the three types of liquid crystals A to C injected into the bonding substrate 20 are mixed in the bonding substrate 20. For example, the mixing is promoted by heating the bonded substrate 20 and the liquid crystals A to C in the bonded substrate 20 to about 70 to 100 ° C. The liquid crystals A to C are selected so as to obtain desired electrical and optical properties after being mixed. Through the above steps, a liquid crystal display device is completed.
[0018]
In the present embodiment, three types of liquid crystals A to C having different surface tensions are injected into the bonding substrate 20 in order from the one having the largest surface tension. At an interface between liquid crystals having different surface tensions, a liquid crystal having a relatively low surface tension is attracted to a liquid crystal having a high surface tension to generate a flow (Marangoni effect or Marangoni convection). That is, at the interface between the liquid crystals A and B and between the liquid crystals B and C, a flow is generated in a direction to promote the injection of the liquid crystal. Therefore, according to the present embodiment, the time for injecting liquid crystal can be reduced. Note that the injection time of the liquid crystal depends on the difference in surface tension between the liquid crystals, the pressure for pressurizing the liquid crystal (that is, the air pressure in the bonded substrate 20 when depressurizing), the diagonal size of the bonded substrate 20, the cell gap, and the like. .
[0019]
In the present embodiment, three types of liquid crystals A to C having different surface tensions are used, but two or more types of liquid crystals may be used.
Also, in the present embodiment, the moving device 24 is moved to relatively move each of the bonded substrates 20 and the plurality of liquid crystal dishes 26a to 26c. You may make it do.
[0020]
In the present embodiment, liquid crystal A having a relatively large surface tension is first injected into bonded substrate 20. In order to quickly inject the liquid crystal A into the bonding substrate 20, the liquid crystal A before the injection may be preheated to about 70 to 100 ° C. By preheating, the surface tension and the viscosity coefficient of the liquid crystal A are reduced, and the injection time is further reduced.
[0021]
[Second embodiment]
Next, a liquid crystal display according to a second embodiment of the present invention and a method for manufacturing the same will be described with reference to FIG. This embodiment is characterized in that an alignment film having a different critical surface tension for each region is used. FIG. 5 shows a configuration of the bonding substrate 20 of the liquid crystal display device according to the present embodiment. As shown in FIG. 5, an alignment film having a different critical surface tension for each region is formed on each of the opposing surfaces of the pair of substrates constituting the bonded substrate 20. In FIG. 5, the alignment film is divided into five regions a to e. The end on the liquid crystal injection port 40 side is a region a. Regions b and c are arranged adjacent to the region a. At the opposite end of the liquid crystal injection port 40, a region d adjacent to the regions b and c and a region e adjacent only to the region b are arranged. The liquid crystal injected from the liquid crystal injection port 40 is filled in the direction of the arrow in the figure.
[0022]
Assuming that the critical surface tensions in the respective regions a to e of the alignment film are γca to γce, the critical surface tensions γca to γce are γca <γcb, γca <γcc, γcb <γcd, γcb <γce, and γcc <γcd. Meet the relationship. In particular, it is desirable that the relationship of γca <γcb <γcc <γcd <γce is satisfied. For example, the critical surface tension γca is 15 dyn / cm, the critical surface tension γcb is 20 dyn / cm, and the critical surface tension γcc is 30 dyn / cm. The critical surface tension γcd is 40 dyn / cm, and the critical surface tension γce is 50 dyn / cm. The surface tension of the injected liquid crystal is smaller than, for example, the critical surface tension γca.
[0023]
In the present embodiment, the alignment film having a different critical surface tension for each region is formed so as to have a relatively small critical surface tension in the region on the liquid crystal injection port side. Due to the Marangoni effect, a liquid flows toward a region having a relatively high critical surface tension in the liquid crystal on the boundary between regions having different critical surface tensions. That is, the liquid crystal flows in a direction that promotes the injection of the liquid crystal. Therefore, according to the present embodiment, the time for injecting liquid crystal can be reduced. Further, when the liquid crystal is injected into the bonded substrate 20 according to the present embodiment using the liquid crystal injection method according to the first embodiment, the injection time of the liquid crystal is further reduced.
[0024]
Next, a method for manufacturing the liquid crystal display device according to the present embodiment will be described. First, a low critical surface tension having a solid concentration of 6 wt% is formed on a TFT substrate on which a thin film transistor (TFT) is formed on a glass substrate and on an opposite substrate on which a color filter and the like are formed on a glass substrate. Is formed by printing. Thereafter, the polyimide varnish is baked and cured to form an alignment film having a thickness of, for example, 60 to 70 nm. The critical surface tension of the alignment film made of low critical surface tension polyimide is about 15 dyn / cm. Next, UV light having a predetermined irradiation intensity is irradiated by an ultra-high pressure mercury lamp through a photomask in which a region for changing the critical surface tension is opened. By irradiating with UV light, for example, for about 10 minutes, the critical surface tension of the alignment film increases to about 40 dyn / cm. In this manner, by irradiating the alignment film with a different amount of UV light for each region, a bonded substrate 20 as shown in FIG. 5 is obtained.
[0025]
The alignment film having a different critical surface tension for each region may be formed by applying a different alignment film forming material for each region.
[0026]
[Table 2]

[0027]
Table 2 shows an example of the value of the critical surface tension γc (dyn / cm) of a plurality of types of alignment film forming materials E to H. As shown in Table 2, the critical surface tension γc of the alignment film forming material E is 25 dyn / cm, and the critical surface tension γc of the alignment film forming material F is 35 dyn / cm. The critical surface tension γc of the alignment film forming material G is 40 dyn / cm, and the critical surface tension γc of the alignment film forming material H is 50 dyn / cm. As described above, by applying and forming the alignment film forming materials having different critical surface tensions γc so that the region on the liquid crystal injection port side has a relatively small critical surface tension γc, as shown in FIG. The bonded substrate 20 is obtained.
[0028]
In this embodiment mode, liquid crystal is injected by using a vacuum injection method, but the present invention can be applied to liquid crystal injection by using a drop injection method. The effect of applying the present invention to liquid crystal injection using the drop injection method is that two or more types of alignment films having a different critical surface tension γc for each region are formed on the substrate, so that the liquid crystal after the drop is reduced. It may spread uniformly and quickly within the substrate surface.
[0029]
[Third Embodiment]
Next, a method for manufacturing a liquid crystal display device according to a third embodiment of the present invention will be described with reference to FIG. This embodiment is characterized in that the surface tension of the liquid crystal is changed by changing the temperature of the liquid crystal. As shown in FIG. 6, the liquid crystal dish 26a filled with the liquid crystal A is disposed on the liquid crystal heater 50. The liquid crystal heater 50 can be adjusted to at least two temperature levels. A bellows-shaped heater 52 is attached to the outer surface of the bonded substrate 20. The heater 52 is provided for maintaining the temperature of the bonded substrate 20 and the liquid crystal injected into the bonded substrate 20 at a constant temperature (for example, 10 to 20 ° C.).
[0030]
First, a predetermined amount of the liquid crystal A adjusted to a relatively low temperature by the liquid crystal heater 50 is injected into the bonding substrate 20. The injection amount of the liquid crystal A at a relatively low temperature is about の of the total injection amount of the liquid crystal. The temperature of the liquid crystal A after the injection is maintained by the heater 52 at a relatively low temperature and substantially constant.
[0031]
Subsequently, the temperature setting of the liquid crystal heater 50 is changed to adjust the temperature of the liquid crystal A to a relatively high temperature. A predetermined amount of the liquid crystal A adjusted to a relatively high temperature is injected into the bonding substrate 20. When the injection is completed, the liquid crystal injection valve 46 is closed.
[0032]
In the present embodiment, the liquid crystal A adjusted to a relatively low temperature is injected first, and then the liquid crystal A adjusted to a relatively high temperature is injected. The surface tension γ of the liquid crystal changes depending on the temperature. The surface tension γ decreases at high temperatures and increases at low temperatures. Therefore, as in the first embodiment, the Marangoni effect occurs at the interface between liquid crystals having different surface tensions γ, and a flow is generated in a direction to promote the injection of the liquid crystal. Therefore, according to the present embodiment, the time for injecting liquid crystal can be reduced.
[0033]
In the present embodiment, the liquid crystal A has two temperature levels, but the temperature level may be three or more.
Further, the temperature in the bonded substrate 20 may be varied depending on the region by using a heater 52 or the like attached to the outer surface of the bonded substrate 20. By adjusting the region on the liquid crystal injection port 40 side to a relatively high temperature and adjusting the region far from the liquid crystal injection port 40 to a relatively low temperature, the same effect as in the present embodiment can be obtained.
[0034]
The present invention is not limited to the above embodiment, and various modifications are possible.
For example, in the second embodiment, an active matrix type liquid crystal display device has been described as an example, but the present invention is not limited to this, and can be applied to a simple matrix type liquid crystal display device.
[0035]
The liquid crystal display device and the method of manufacturing the same according to the above-described embodiments are summarized as follows.
(Appendix 1)
Laminate a pair of substrates to produce a laminated substrate,
Injecting a plurality of types of liquid crystals having different surface tensions into the bonding substrate in order from the one with the larger surface tension,
A method of manufacturing a liquid crystal display device, wherein the plurality of types of injected liquid crystals are mixed in the bonded substrate.
[0036]
(Appendix 2)
Apply the alignment film forming material on the substrate,
Irradiating the alignment film forming material with ultraviolet light having a different irradiation amount for each region,
A method for manufacturing a liquid crystal display device, comprising forming an alignment film having a different critical surface tension for each of the regions.
[0037]
(Appendix 3)
Apply a different alignment film forming material to the substrate for each area,
A method for manufacturing a liquid crystal display device, comprising forming an alignment film having a different critical surface tension for each of the regions.
[0038]
(Appendix 4)
The method for manufacturing a liquid crystal display device according to claim 3, wherein
The method according to claim 1, wherein the alignment layer is formed to have a relatively small critical surface tension in a region near a liquid crystal injection port into which liquid crystal is injected.
[0039]
(Appendix 5)
A pair of substrates arranged opposite to each other,
An alignment film formed on the opposing surfaces of the pair of substrates and having a different critical surface tension for each region,
And a liquid crystal sealed between the pair of substrates.
[0040]
【The invention's effect】
As described above, according to the present invention, the injection time of liquid crystal can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a liquid crystal injection device used in a method for manufacturing a liquid crystal display device according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a method for manufacturing the liquid crystal display device according to the first embodiment of the present invention.
FIG. 3 is a diagram illustrating a method for manufacturing the liquid crystal display device according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating a method of manufacturing the liquid crystal display device according to the first embodiment of the present invention.
FIG. 5 is a diagram showing a configuration of a bonded substrate of a liquid crystal display according to a second embodiment of the present invention.
FIG. 6 is a view illustrating a method of manufacturing a liquid crystal display according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid crystal injection device 10 Vacuum chamber 12 Heating unit 14 Cooling unit 16 Liquid crystal injection chamber 18 Cassette 20 Laminated substrate 22 Gate valve 24 Moving device 26, 26a, 26b, 26c Liquid crystal plate 30, 31 Exhaust valve 32 Vacuum pump 34 Gas Introduction valve 40 Liquid crystal injection port 42 Liquid crystal injection pipe 44 Pressurizing section 46 Liquid crystal injection valve 48 Sealant 50 Liquid crystal heater 52 Heaters A, B, C Liquid crystals E, F, G, H Alignment film forming materials a, b, c, d, e area

Claims (4)

Laminate a pair of substrates to produce a laminated substrate,
Injecting a plurality of types of liquid crystals having different surface tensions into the bonding substrate in order from the one with the larger surface tension,
A method of manufacturing a liquid crystal display device, wherein the plurality of types of injected liquid crystals are mixed in the bonded substrate. Apply the alignment film forming material on the substrate,
Irradiating the alignment film forming material with ultraviolet light having a different irradiation amount for each region,
A method for manufacturing a liquid crystal display device, comprising forming an alignment film having a different critical surface tension for each of the regions. Apply a different alignment film forming material to the substrate for each area,
A method for manufacturing a liquid crystal display device, comprising forming an alignment film having a different critical surface tension for each of the regions. A pair of substrates arranged opposite to each other,
An alignment film formed on the opposing surfaces of the pair of substrates and having a different critical surface tension for each region,
And a liquid crystal sealed between the pair of substrates.

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