JP4126241B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

【００２１】
未乾燥の配向膜材料塗膜（膜厚１．５μｍ）が形成されたガラス基板（１００ｍｍ×１００ｍｍ×１．１ｍｍ）を複数準備し、図３に示すように各ガラス基板１をそれぞれ未乾燥の配向膜材料塗膜３０を上側に向けていずれかの材料のブロック材ＢＬ上に配置した。ただし、各材料のブロック材ＢＬには、各ガラス基板１の配向膜材料塗膜３０の形成領域の反対側の領域の一部３０Ａを接触させた。
【００２２】
この状態で各ガラス基板１の配向膜材料塗膜３０に約１００℃の温風を吹き付けたところ、熱拡散率０．４７ｍｍ²／ｓ以下の材料で形成されたブロック材ＢＬに乗せたガラス基板１の配向膜材料塗膜３０には乾燥むらが生じなかった。そこで本実施の形態では、各基板支持ピン１４の少なくとも先端部を熱拡散率０．５ｍｍ²／ｓ以下の材料で形成することとした。
【００２３】
また、１６ａ，１６ｂはノズル１１よりブローされた熱風をガラス基板１の四隅へ誘導させるとともにガラス基板１に当って跳ね返る熱風の淀みを吸引する側面側排気溝、１７はチャンバ２内の熱風の淀み及びガラス基板１を載置するベースプレート１２の下部周辺部に滞留する熱風の淀みなどを吸引してチャンバ２の内部全体の気流の流れを制御する下面側排気溝である。
【００２４】
また、１８は下面側排気溝１７の背面側に配設され、ベースプレート１２に連結された揺動装置であり、この揺動装置１８は、揺動体本体１８ａがモータ１８ｂに連結されたボールネジ１８ｃに結合されて構成されており、揺動体本体１８ａがモータ１８ｂの回転によりボールネジ１８ｃが矢印Ａ−Ａ´方向に往復移動し、これによってベースプレート１２に連結されている揺動体本体１８ａが矢印Ａ−Ａ´方向に揺動される。したがって、ベースプレート１２上に載置されるガラス基板１が面内方向に矢印で示すＡ−Ａ´方向に揺動される。
【００２５】
また、１９はチャンバ２の底部に配設されたチャンバ側排気装置であり、この排気装置１９は揺動装置１８による矢印Ａ−Ａ´方向の揺動動作により発塵した異物等を吸引し、チャンバ２の内部への流れ込み等を防止させる。
【００２６】
なお、これらの上面側排気溝１３ａ，１３ｂ、側面側排気溝１５ａ，１５ｂ，下面側排気溝１６及びチャンバ側排気装置１９は、それぞれ対応するダンパ２０ａ，２０ｂ、ダンパ２１ａ，２１ｂ、ダンパ２２ａ，２２ｂ、ダンパ２３を介して三方弁２４の一方の弁に結合され、さらにこの三方弁２４の他方の弁には前述した三方弁６の他方の弁が結合され、チャンバ２内で気化した溶媒を含む不要な熱風及びガラス基板１の投入出時の熱風とともに集結されて排気ブロア２５によりクリーンルームの外部に強制的に排気させ、溶媒の再付着を防止させている。
【００２７】
図４は、熱風乾燥装置を収容するレベリング装置の概略構成を説明する図であり、図４（ａ）は上方から見た平面図、図４（ｂ）は側面から見た平面図である。図４（ａ），（ｂ）において、１００は図１で説明した熱風乾燥装置内のチャンバ２が２段２列（４ポジション）にわたって設置された熱風乾燥装置部であり、この熱風乾燥装置部１００の前後には、処理前のガラス基板１をチャンバ２の内部に搬入させる搬送アーム１５を有する搬入用ロボット２００及び処理後のガラス基板１をチャンバ２から搬出させる搬送アーム１５´を有する搬出用ロボット３００が配設されている。
【００２８】
これらの搬入用ロボット２００及び搬出用ロボット３００は、図４（ａ）に示すように各搬送アーム１５，１５´が矢印Ｂ−Ｂ´方向に並行移動し、さらに、図４（ｂ）に示すように矢印Ｃ−Ｃ´方向に上下移動する機能を有しており、熱風乾燥装置部１００の２段２列（４ポジション）に設置されている各チャンバ２に対して各搬送アーム１５，１５´が交互に移動動作を繰り返すことによりガラス基板１の搬入出の並行処理が可能となる。
【００２９】
また、この搬入用ロボット２００の前段側には、当該ガラス基板１の清浄処理等の前処理工程を行う上流側装置４００が設置され、さらに搬出用ロボット３００の後段側には、配向膜を成膜した当該ガラス基板１の焼成処理等の後処理工程を行う下流側装置５００が設置されている。したがって、清浄処理された当該ガラス基板１は搬入用ロボット２００の搬送アーム１５に載置されてチャンバ２内に搬入され、配向膜を成膜したガラス基板１はチャンバ２内から搬出用ロボット３００の搬送アーム１５´に載置されて焼成処理を行う下流側装置５００へ搬送されることになる。
【００３０】
また、６００は図１に示したチャンバ２を２段２列の４ポジションで設置した熱風乾燥装置部１００，搬入用ロボット２００及び搬出用ロボット３００をそれぞれ個別に分割させて格納するロボットフレーム、７００はそのロボットカバーフレーム、８００は温調ユニットである。なお、図１で説明したチャンバ２の外部に配設される例えば給気ブロワ３，ヒータ４，へパフィルタ５，三方弁６，分岐弁７，ダンパ２０ａ，２０ｂ〜２３，三方弁２４及び排気ブロワ２５等は、床下に収容される構造となっている。
【００３１】
また、９００は熱風乾燥装置部１００，搬入用ロボット２００及び搬出用ロボット３００の背面側に配設されて温調ユニット８００内の各種装置，搬入用ロボット２００及び搬出用ロボット３００等を駆動させる駆動回路及びそれらの制御回路が収納されている制御装置部である。なお、この制御装置部９００を装置背面側に背負う構造で設置するとするとともに、熱風乾燥装置部１００，ロボットフレーム６００，ロボットカバーフレーム７００などを分割式構造で構成するすることにより、移設，再組立て時の作業効率を向上させることができる。
【００３２】
なお、図中、矢印Ａ−Ａ´方向は図１に示す揺動装置１８の往復移動によるベースプレート１２の揺動方向を示しており、ベースプレート１２の矢印Ａ−Ａ´方向のストロークは約２００ｍｍ程度であり、搬送アーム１５の矢印Ｃ−Ｃ´方向のストロークは約７５０ｍｍ程度である。また、このレベリング装置は、その幅が約３５００ｍｍ，長さが約４５００ｍｍ，高さが約２７５０ｍｍの寸法を有して形成されている。
【００３３】
このよう構成されるレベリング装置を用いることにより、寸法の異なる大型ガラス基板の処理時には、基板サイズによる段取り換え作業が不要となるとともに、定常の交換作業に要する時間，安全性及び作業性が極めて高くなる。
【００３４】
次に、このように構成される熱風乾燥装置を用いて液晶表示装置の製造プロセスの配向膜形成処理について説明する。
【００３５】
液晶表示装置の製造プロセスには、配向膜形成プロセス，ラビングプロセス，シール材印刷プロセス，スペーサ散布プロセス，基板貼り合わせプロセス，シール材焼成プロセス，液晶注入プロセス，液晶注入口封止プロセス及び偏光板貼り付けプロセス等が含まれているが、ここでは、図１で説明した熱風乾燥装置を用いる配向膜形成プロセスに重点をおいて説明する。
【００３６】
一方の面（以下、電極形成面を呼ぶ）にＴＦＴ（表示領域対角１７インチ）またはカラーフィルタパターンが６面にわたって形成配置された洗浄後のガラス基板が上流装置４００から搬入用ロボット２００により配向膜形成プロセスに搬送されと、以下に示すようにガラス基板１上に形成されている配向膜材料塗膜に対する乾燥処理が実行される。なお、ここでは、可溶性ポリイミドまたはポリアミック酸を１−メチル−２−ピロリドン（ＮＭＰ）またはγ−ブチロラクトン（ＢＬ）に溶解させることによって得られた約５ｗｔ％の配向膜材料溶液を用いることとする。
【００３７】
まず、給気ブロワ３が回転を開始させることにより、クリーンルーム内の大気を取り込み、加熱中のヒータ４に送り込む。これによって加熱された空気がヘパフィルタ５，三方弁６，分岐弁７，６分岐管８及びダンパ９ａ，９ｂをそれぞれ通過して均熱容器１０に一旦蓄えられた後、ノズル１１の各スリットノズルの先端から一様な温度（例えば約６０℃程度）で放出される。これと同時に上面排気溝１３ａ，１３ｂ、側面排気溝１６ａ，１６ｂ、下面排気溝１７及びチャンバ内排気装置１９を駆動させてチャンバ２内の大気を適宜排気させる。
【００３８】
その間に上流装置４００にて洗浄後のガラス基板（６５０ｍｍ×８３０ｍｍ×０．５〜０．７ｍｍまたは７３０ｍｍ×９２０ｍｍ×０．５〜０．７ｍｍ）の電極形成面にフレキソ印刷法によって配向膜材料塗膜を形成しておく。そして、チャンバ２の内部温度が適当な温度（例えば約５５℃程度）に安定したら、チャンバ２の搬入口を開け、上流装置４００より搬入用ロボット２００が上流装置４００よりガラス基板を配向膜材料塗膜が上面となるように搬送アーム１５の先端部に掬い上げ、チャンバ２の搬入口を開け、熱風乾燥装置部１００内のチャンバ５内のベースプレート１２上まで搬送する。
【００３９】
その後、搬送アーム１５の先端部がベースプレート１２上のピン列の間に収容されるように搬送アーム１５をＺ軸方向に移動させる。これにより搬送アーム１５の先端部からピン群に先端にガラス基板１が乗り換えられたら、搬送アーム１５をＸＹＺ軸によるＸ方向に移動させることによって搬送アーム１５の先端部をピン列の間から引き抜く。そして、チャンバ２の搬入口のシャッタを閉じる。
【００４０】
その後、揺動装置１８のモータ1８ａの回転を開始することによってベースプレート１２を適当な速度（例えば約１００ｍｍ／ｓ）でＡ−Ａ´方向に約２００ｍｍのストロークで往復移動させる。このときのベースプレート１２のストロークは、ノズル１１の各スリットノズルの配置間隔とほぼ等しい距離である。これにより、配向膜材料塗膜の全面から溶剤を均一かつ効率的に蒸発させることができる。
【００４１】
図５は、ガラス基板１上に形成された配向膜材料塗膜の溶剤が均一かつ効率的に蒸発するメカニズムについて説明する模式図である。まず、図５（ａ）に示すようにノズル１１の各スリットノズル１１ａからガラス基板１に向けてブローした熱風ＨＡは、ガラス基板１の上面に当った後、ガラス基板１上で淀み、その淀み部ＨＡ´からなる熱風層ＨＬＡを形成し、これによって次に引続き放出される熱風ＨＡがガラス基板１の上面に当らなくなってしまう。
【００４２】
そして、図５（ｂ）に示すように各スリットノズル１１ａの間隔Ｄを広げ、各スリットノズル１１ａ相互間に熱風ＨＡが排気する道筋ＥＸを形成することで次ぎの新しい熱風ＨＡをガラス基板１上に当てることができるが、ガラス基板１の上面において、各スリットノズル１１ａの直下の加熱エリアＨＡＲと排気されて加熱されないエリアＣＡＲとで温度差が生じる。
【００４３】
そこで、図５（ｃ）に示すようにガラス基板１を矢印Ａ−Ａ´方向に往復運動させることで加熱エリアＨＡＲ，加熱されないエリアＣＡＲ毎の温度差がなくなり、温度分布が均一化されるので、部分的な乾燥を防止させ、均一加熱による乾燥が得られる。すなわち、ガラス基板１が中央部及び四隅を含む全面に均等に熱風ＨＡが供給されることで均一な温度分布による乾燥が得られる。なお、このガラス基板１を矢印Ａ−Ａ´方向に往復運動させる揺動手段は、図１及び図２に示す揺動装置１８のモータ１８ｂの駆動により矢印Ａ−Ａ´方向の往復運動に連動して行われる。
【００４４】
なお、ここでガラス基板の寸法及びその種類により放出する熱風に角度が必要になる場合には、ノズル１１の取付け用のアルミクランプ部で角度をもたせ、これによって熱風放出角度を調節することができる。また、ガラス基板の寸法及びノズル１１からの距離が変化した場合にノズル１１の前段にあるダンパ９ａ，９ｂ（図１参照）の調整でガラス基板の端部及び中央部などのガラス基板内の各場所毎に放出する熱風量を変更することができる。
【００４５】
このため、焼成前の段階で配向膜材料塗膜の膜厚及び膜物性にばらつきの発生を防止することができる。なお、このとき、ガラス基板１の表面付近における熱風の速度が０．５ｍ／ｓ以上となるように各スリットノズル１１ａから熱風を放出させれば、気化した溶剤を含む熱風がガラス基板１に表面付近で滞留させずに図１に示す上面排気溝１３ａ，１３ｂ、側面排気溝１６ａ，１６ｂ、下面側排気溝１７及びチャンバ内排気装置１９の駆動によりダンパ２０ａ，２０ｂ〜２３及び三方弁２４を介して排気ブロワ２５により吸引され、外部にスムーズに放出されるので、乾燥時間を大幅に短縮させることができる。
【００４６】
このようにして配向膜材料塗膜の含有溶剤の約８０％程度が蒸発し、配向膜材料塗膜の流動性が失われた後に搬送用ロボット３００の搬送アーム１５´の先端部がガラス基板１とベースプレート１２との間の隙間Ｇに挿入されるように搬送アーム１５´をＸ方向に移動させ、さらに支持ピン１４の先端から搬送アーム１５´の先端部にガラス基板１が乗り換わるように搬送アーム１５´をＺ方向に移動させる。これにより、支持ピン１４の先端からガラス基板１をスムーズに掬い上げることができる。
【００４７】
このようにガラス基板１に過度の力を付与することなく、支持ピン１４の先端からからガラス基板１を掬い上げることができるのは、ガラス基板１との接触面積が狭い各支持ピン１４は、ホットプレートのプレートとは異なり、ガラス基板１との間に静電気（剥離帯電）を殆ど発生させないことに起因している。このため、ガラス基板１の割れ等の発生を防止することができる。
【００４８】
なお、ベースプレート１２の支持ピン１４の先端からガラス基板１を掬い上げたら、次のガラス基板１に配向膜材料塗膜に対する乾燥処理が開始するまで、給気ブロワ３からの吸気を停止させて支持ピン１４の熱風による加熱を防止することが望ましい。
【００４９】
次に、この熱風乾燥装置部１００での乾燥処理が終了したら、ガラス基板１は、その状態で搬出用ロボット３００の搬送アーム１５´で次工程の赤外線乾燥を行う下流装置５００へと搬送される。そして、ガラス基板１の配向膜材料塗膜に対する焼成処理が実行される。すなわち、赤外線加熱炉の内部でガラス基板１を適当な温度（例えば、約２３０℃）で適当な時間（例えば、約２０分）にわたって加熱することによってガラス基板１上の配向膜材料塗膜を焼成する。これにより、ガラス基板１上に均一な膜厚及び膜物性の配向膜が形成される。
【００５０】
その後、ガラス基板１は、配向膜形成プロセスから、順次、ラビングプロセス，シール材印刷プロセス，スペーサ散布プロセス，基板貼り合わせプロセス，シール材焼成プロセス，液晶注入プロセス，液晶注入口封止プロセス及び偏光板貼り付けプロセス等へと搬送される。これにより、そのガラス基板１を含む液晶表示装置が完成する。
【００５１】
以上の液晶表示装置製造プロセスによれば、配向膜形成工程において、一様な膜物性の配向膜を一様な膜厚で形成することができるので、液晶表示装置における液晶分子配列の乱れの発生を確実に防止することができる。このために良好な表示特性の液晶表示装置を得ることができる。また、ホットプレートを用いた配向膜形成工程において発生し易かった基板割れの発生を確実に防止することができるので、液晶表示装置製造プロセスの歩留まりを向上させることができる。さらに、ホットプレートを用いた場合よりも、突上げピンによる基板突上げ処理が必要ない分だけ効率化を図ることができる。
【００５２】
これらの効果についてホットプレートを用いた工程と比較して下記表２に示す。
【００５３】
【表２】

【００５４】
（１）本実施例による係わる熱風乾燥装置を用いた場合には、ホットプレーを用いた場合に生じる剥離帯電が全く生じない。このためにホットプレートを用いた場合と異なり、ガラス基板１の割れの発生が皆無となる。
【００５５】
（２）ホットプレートを用いた場合、ガラス基板１の割れの発生を防止するために突上げピン１４によってガラス基板１をゆっくり持ち上げる必要がある。これに対して本実施例に係わる熱風乾燥装置を用いた場合には、このようなガラス基板１の突き上げ処理が必要ない。このためにその分だけ配向膜の形成プロセスを効率化することができる。例えば、ホットプレートによれば、７２０ｍｍ×９３０ｍｍのガラス基板の乾燥処理（搬入から搬出まで）に約１００秒以上の時間を要するのに対して本実施例に係わる熱風乾燥装置によれば、７２０ｍｍ×９３０ｍｍのガラス基板１の乾燥処理に要する時間を約６０秒以下に短縮することができる。
【００５６】
（３）ホットプレートを用いた場合には、ガラス基板１の温度に±２℃程度のばらつきが生じるのに対して本実施例に係わる熱風乾燥装置を用いた場合には、ガラス基板１の温度のばらつきが±１℃程度に抑制される。このために配向膜材料塗膜を一様に乾燥させることができる。この効果は、以下の実験により確認される。
【００５７】
熱拡散率が約０．１ｍｍ²／ｓのベスペル（登録商標）で形成された支持ピン１４と約２００ｍｍの間隔で並べられたスリットノズル１１とを有する乾燥装置を用いて以下の実験を行った。内部温度が約５５℃に安定化させたチャンバ２において、各スリットノズル１１から約６０℃に温風を速度０．５ｍ／ｓ〜２ｍ／ｓで放出させながら、スリットノズル１１の先端から約２００ｍｍ離れた位置で配向膜材料溶液塗布済みのガラス基板１を１００ｍｍ／ｓで往復させた。このときのガラス基板１のストロークは、約２００ｍｍである。
【００５８】
この結果、チャンバ２にガラス基板１を投入してから約２５秒で配向膜材料塗膜の仮乾燥が完了したので、チャンバ２にガラス基板１を投入してから約４０秒後に熱風の放出とガラス基板１の往復移動とを停止し、ガラス基板１の外観及び面内温度分布を観察した。この結果、ガラス基板１には割れ等の欠陥が生じていないことが確認された。また、ガラス基板１の温度のばらつきは、±１℃程度に抑制されていることが判った。
【００５９】
ただし、図６に示すようにガラス基板１の一部の領域を除けば、ガラス基板１の温度のばらつきは、±０．５℃程度に抑制されることが判った。すなわち、配向膜材料塗膜に乾燥むらの要因となるガラス基板１の温度むらが抑制されていることが確認された。
【００６０】
また、前述したようにプロセス時間が約４０秒，搬送時間は合計で約３０秒であり、一部動作を並行化により短縮し約２０秒として約６０秒以下に短縮することができることから、チャンバ２を４ポジション設けているので、合計約６０秒／４ポジションで約１５秒／枚の目標タクトを達成できた。
【００６１】
その後、赤外線加熱炉で約２３０℃で約２０分間ガラス基板を加熱することによってガラス基板上の配向膜材料を硬化させた。このようにして配向膜が形成されたガラス基板を用いてＬＣＤパネルを作製し、そのプレチルト角を測定した。この結果、ホットプレートＨＰで配向膜を形成したガラス基板を用いたＬＣＤパネルと同程度のプレチルト角（約６°）を示すことが確認された。
【００６２】
次に、本実施例に係わる熱風乾燥装置を用いた乾燥処理の最適条件について説明する。ここでは、乾燥処理の最適条件を得るために以下の実験を行った。
【００６３】
（１）実験１
乾燥時間を最適化するために図７に示すようにホットプレートＨＰからの伝熱及びドライヤーＤＲからの温風によってそれぞれ１００ｍｍ×１００ｍｍ×１．１ｍｍのガラス基板１上の配向膜材料塗膜を乾燥させた。なお、ここではドライヤーＤＲをガラス基板１上に温風が垂直に吹き付けられるような姿勢で水平方向に往復移動させた。
【００６４】
ここで用いた配向膜材料は、ポリイミド骨格に主鎖と長鎖アルキル基の側鎖とからなり、長鎖アルキル基が配向膜表面に存在することでプレチルト角を発現する材料を用いた。配向膜材料を希釈した溶剤は、１−メチル−２−ピロリドン（ＮＭＰ）、γ−ブチロラクトン（ＢＬ）である。
【００６５】
溶剤乾燥後、同条件で液晶セルを作製し、プレチルト角を測定したところ、図８に示すようになった。ここで、乾燥時間は以下のように定義した。基板上に塗布された溶液が乾燥して溶剤が蒸発するときには、膜厚減少が起こり、膜面に干渉縞を生じる。溶剤が蒸発して膜厚が均一になると、干渉縞が消え、膜面は一様に干渉色を示す。基板加熱開始から一様の干渉色となるまでの時間を乾燥時間として測定した。
【００６６】
ホットプレート乾燥では乾燥時間によらず、ほぼ一定のプレチルト角を示すのに対して熱風乾燥では乾燥時間によって大きくプレチルト角が変わり、乾燥時間が短いと、プレチルト角が小さい。
【００６７】
ここで、溶剤組成が配向膜高分子に与える影響を調べた。ＮＭＰ，ＢＬに配向膜高分子をそれぞれ溶解し、分子サイズを光散乱強度の散乱角度依存性から求めた。この結果を図９に示す。ＮＭＰ溶液中では、高分子が収縮していることが判った。高分子が収縮すると、プレチルト角の発現に寄与する側鎖が主鎖の中に丸め込まれると考えられる。さらに、ＮＭＰ比率が高い溶液から成膜した配向膜ではプレチルト角が低下することが判った。配向膜高分子が伸長しているときには、熱風と親和性の高い側鎖は膜表面に偏在するが、配向膜高分子が収縮するとき、プレチルト角に寄与する側鎖は主鎖に丸め込まれて膜表面に存在する量が減り、その結果、プレチルト角が低下すると考えている。
【００６８】
溶剤乾燥工程では、混合溶剤が均一に蒸発せず、蒸発速度はＮＭＰよりもＢＬの方が速い。このために塗膜中では配向膜高分子の濃縮と同時に混合溶剤組成変化が起きる。溶剤乾燥時の塗膜中の溶剤組成は以下のように変化すると考えられる。加熱により配向膜表面からはＢＬが蒸発する。膜内では深さ方向に溶剤の濃度勾配を生じ、基板側より表面に向かってＢＬが拡散するが、乾燥時間が短いと、表面の蒸発に対して膜内の拡散が追いつかず、表面は蒸発し難いＮＭＰの組成比が増加する。また、熱風乾燥では、溶剤の滞留を防ぐために積極的に溶剤を除去しているので、ＢＬとＮＭＰとの蒸発速度差を増大させ、表面のＮＭＰ濃度が進む。したがって、ＮＭＰが濃縮され易い乾燥速度の速い条件では、表面の高分子が収縮し、プレチルト角が低下する。
【００６９】
以上の結果から、プレチルト角が従来方法のホットプレート乾燥と同等以上となる約２０秒以上の乾燥時間となる温度及び風速をこの配向膜材料の最適熱風乾燥条件とした。その温度は熱風の吹出し口温度が７０℃〜９０℃、ガラス基板上の風速が１．５〜２．０ｍ／ｓであることが判った。
【００７０】
（２）実験２
本実施例に係わる熱風乾燥装置により、各温度の熱風をガラス基板１に吹付け、配向膜材料塗膜の外観を観察した。この結果、約３０℃以下の熱風を吹付けた場合には、配向膜材料塗膜の平坦性が低下することが判った。また、約３０℃以上の熱風を吹付けた配向膜材料塗膜の平坦性は、図１０に示すように熱風の温度に対応して変化することが判った。すなわち、熱風温度が高いほど、配向膜材料溶液の流動性が高くなるため、平坦性が向上することが判った。
【００７１】
配向膜溶液の溶剤は一般的に混合溶剤であり、乾燥時には溶剤成分比が変化する。このとき、時間とともに配向膜高分子と溶剤との親和性の変化及び配向膜の濃度の増加による流動性の低下が起き、最表面の配向膜高分子構造が決定される。例えば、配向膜との親和性が若干劣る溶剤が濃縮されて分子が収縮し、この結果、プレチルト角を発現する要素である高分子側鎖の表面濃度が低下してプレチルト角が低下する。そこで、各温度の熱風による乾燥処理を経たガラス基板でそれぞれ液晶セルを作製し、そのプレチルト角を測定した。この結果、図１１に示すように熱風温度が高くなるほどプレチルト角が低下することが確認された。そして、約１００℃以上の熱風による乾燥では、適切なプレチルト角を得ることが困難であることが確認された。
【００７２】
以上の結果より、本実施例では、ノズルから供給する熱風の最適温度の範囲として約３０℃〜１００℃を採用することとした。
【００７３】
（３）実験３
ホットプレートによる乾燥課程について詳細に説明すると、図１２（ａ）に断面図で示すようにガラス基板１上に塗布した溶液ＳＯが乾燥により膜厚が減少する。このとき、ガラス基板１の端部については溶液ＳＯの乾燥速度が大きいので、液膜の流れがガラス基板１の中央部から端部に向かうことにより、突起部ＰＲが発生する。なお、塗布された当初の配向膜材料塗膜の膜厚は１０００ｎｍ〜１５００ｎｍである。
【００７４】
その後、乾燥が進行し、図１２（ｂ）に示すように溶液ＳＯはガラス基板１の端部に膜厚が薄い部分が生じ、その中央部の膜厚が厚い部分との間に傾斜が生じる。さらに乾燥が進行し、図１２（ｃ）に示すように溶液ＳＯは膜厚が薄い部分が端部から中央部分に移動する。乾燥後は、図１２（ｄ）に示すように端部から中央部まで均一の膜厚となる。ただし、端部については上述の理由により突起部ＰＲが発生している。この場合、乾燥した配向膜材料塗膜は、均一な中央部では約６０ｎｍとなり、突起部ＰＲでは約１００ｎｍとなる。
【００７５】
この配向膜材料塗膜は、乾燥後に焼成されて配向膜が形成されるが、配向膜の膜厚も同様に中央部で約６０ｎｍであり、突起部ＰＲでは約１００ｎｍである。このようにホットプレートによる乾燥では、乾燥を開始する位置がガラス基板１の端部に固定されており、乾燥開始位置を自由に変更できるものではない。
【００７６】
なお、上述したホットプレートによる乾燥の場合、ガラス基板１上に塗布した溶液ＳＯが乾燥により膜厚が減少するメカニズムは、図１３（ａ）に拡大断面図で示すようにガラス基板１上に溶液ＳＯが塗布された膜表面は飽和蒸気圧にあり、中央部では気流が弱いので、実線の矢印で示す方向でその大きさを示すように蒸発速度が中央部では端部よりも小さい。このために端部の蒸発を補うために太線の矢印で示す方向に液膜が中央部から端部へ向かって移動する。この結果、図１３（ｂ）に示すように端部（特に辺部より角部）は表面積が大となり、中央部における溶液ＳＯの蒸発速度が大となる。この結果、図１３（ｃ）に示すように端部に突起部ＰＲを有し、中央部で膜厚がほぼ均一な配向膜ＯＲが形成されると考えられている。
【００７７】
これに対して本実施例に係わる熱風乾燥装置を用いた熱風乾燥処理の場合では、図１４（ａ）に断面図で示すようにガラス基板１上に塗布した溶液ＳＯは、均等に蒸発し、端部には突起部が生じ難い。ただし、図１４（ｂ）に示すようにノズルとの位置により乾燥速度が大となる部分があり、その部分に突起部ＰＲが生じるが、ガラス基板１が移動しているので、突起部ＰＲもこれに伴なって移動する。このために干渉縞が発生する位置もランダムになる。このように熱風乾燥の場合では、溶液ＳＯの乾燥速度が大の部分をランダムに発生させることで、突起部ＰＲの発生を減少させている。これによって図１４（ｃ）に示すように溶液ＳＯの膜厚は均等に減少し、乾燥後は、図１４（ｄ）に示すように端部から中央部まで全体がほぼ均一の膜厚となり、乾燥が完了する。
【００７８】
なお、上述した熱風乾燥の場合、ガラス基板１上に塗布した溶液ＳＯが乾燥により膜厚が減少するメカニズムは、図１５（ａ）に拡大断面図で示すようにガラス基板１上に溶液ＳＯが塗布された膜表面は常に換気され、実線の矢印で示す方向でその大きさを示すように溶液ＳＯの蒸発速度が端部と中央部とで一定であるので、蒸発速度は面内で略均一となる。このために液膜が中央部から端部に移動する量が減少し、溶液ＳＯが均等に蒸発し、図１５（ｂ）に示すように端部には突起部が生じ難くなり、端部及び中央部で膜厚がほぼ均一な配向膜ＯＲが形成されると考えられている。
【００７９】
以上の説明から、ホットプレート乾燥と熱風乾燥とによる端部の形状を対比すると、図１６に示すように本実施例に係わる熱風乾燥装置による熱風乾燥ＨＡでは、配向膜の端部に形成される突起部の高さ方向の寸法がホットプレート乾燥ＨＰのそれの約１／３程度となり、配向膜の中央部と略均一な膜厚が得られることが判った。
【００８０】
図１７は、ガラス基板１上に形成された配向膜ＯＲの形状を説明する図であり、図１７（ａ）は平面図である。図１７（ａ）において、ＯＲは配向膜を、ＣＥは配向膜ＯＲの中心部を、ＥＤは配向膜ＯＲの端部を、ＣＯは配向膜ＯＲの角部をそれぞれ示している。また、図１７（ｂ）は図１７（ａ）の端部ＥＤの拡大断面図を、図１７（ｃ）は図１７（ａ）の角部ＣＯの拡大断面図をそれぞれ示している。
【００８１】
図１７において、配向膜ＯＲを形成する溶液の粘度（粘性率）が低い場合及び溶媒の割合が多い場合には、特に端部ＥＤへの液膜の移動量が大となり、端部ＥＤの突起部が大となる問題点が見出された。このために本実施例に係わる熱風乾燥では、図１７（ｂ），（ｃ）に示すように端部ＥＤ及び角部ＣＯに形成される突起部ＰＲの発生を防止またはその形状を小さくすることができ、溶液の粘度が低い場合及び溶媒の割合が多い場合には、特に有効である。
【００８２】
また、図１７（ａ）に示す角部ＣＯは、端部ＥＤに比べて蒸発速度が大となるため、図１７（ｃ）に示すように端部ＥＤよりも突起部ＰＲが大きくなる。このため、熱風乾燥を用いた場合でも角部ＣＯには突起部ＰＲが残る場合もある。さらに、溶液の粘度が低い場合では、特に角部ＣＯに塗布された溶液は中心部ＣＥに向かい後退（縮退）することが見出された。このため、図１８（ａ），（ｂ）に示すように角部ＣＯには、所謂丸み（面取り）が生じる場合がある。ここで、溶液の粘性率が約２５ｃｐ以下の場合、特に８〜１２ｃｐの場合には、角部ＣＯに生じる丸みの半径ｒは、０．１ｍｍ〜１ｍｍの間となる。
【００８３】
配向膜ＯＲの形成後には、この配向膜ＯＲ上にはシール材ＳＥが塗布形成されるが、この場合、配向膜ＯＲの角部ＣＯには、図１８（ｂ）に示すように配向膜ＯＲの端部ＥＤの丸みに沿うようにシール材ＳＥを塗布し、配向膜ＯＲと一部重なるようにシール材ＳＥが塗布される。このとき、シール材ＳＥの内側（液晶組成物側）の丸み半径を配向膜ＯＲの角部ＣＯの半径ｒよりも小さくして液晶組成物が形成される領域の丸みを小さくすることができる。
【００８４】
図１９は、（ａ），（ｂ）は、図１８に示す角部ＣＯに配向膜ＯＲが形成されているガラス基板１上にカラーフィルタ基板ＣＦＰを重ね合わせた状態を示す平面図である。図１９において、カラーフィルタＣＦＲには、遮光膜としてブラックマトリクス（ブラックマスクとも言う）ＢＭが設けられている。また、このブラックマトリクスＢＭには開口ＯＰが設けられており、一般にこの開口ＯＰにはＲ（赤），Ｇ（緑），Ｂ（青）各色を透過するカラーフィルタが設けられている。このＲ（赤），Ｇ（緑），Ｂ（青）の３ドットで１画素が構成されているとすると、開口ＯＰは１ドットを構成することになる。
【００８５】
シール材ＳＥが設けられている部分には、液晶組成物が存在しないので、表示に寄与することがなく、一般に図１９（ａ）に示すようにシール材ＳＥにかからないように開口ＯＰが設けられる。しかし、この場合、ブラックマトリクスＢＭの枠の幅Ｗ１が広くなるという問題が生じる。このため、図１９（ｂ）に示すように丸みが生じた角部ＣＯに開口ＯＰが一部重なるようにブラックマトリクスＢＭを設け、幅Ｗ２が狭くなるようにする。この場合、角部ＣＯに丸みによる影ＳＨが生じ、表示品質が損なわれることになる。
【００８６】
ここで、図１８（ｂ）に示したようにシール材ＳＥで配向膜ＯＲの角部ＣＯを覆うことで図１９（ｂ）に示すように開口ＯＰと重なる丸みをシール材ＳＥにより形成される丸みとすることにより、角部ＣＯの丸みの半径を小さくすることができ、これによって開口ＯＰに生じる影ＳＨを減少させることが可能となる。
【００８７】
さらに、同様に図２０（ａ），（ｂ）に示すように配向膜ＯＲの角部ＣＯには、中心部ＣＥから外部に向かい、平面的な突出部ＰＲ１を形成する。または、配向膜材料塗膜を平面的な突出部ＰＲ１を形成するように塗布し、その後、乾燥，焼成により角部ＣＯがほぼ直角に近くなるような突出部ＰＲ１を形成しても良い。このとき、本実施例に係わる熱風乾燥処理を用いることにより、蒸発速度を局所的に変化させることができるので、角部ＣＯの蒸発速度を他の部分と異ならせ、丸みを減少させることができる。このため、前述したノズルは角部ＣＯに吹付けられる熱風量及びその温度を制御可能に形成される。なお、丸みを減少させるように熱風量及びその温度を制御すると、断面方向の突起部が増加することになる。
【００８８】
また、図２０（ｂ）に示すように配向膜ＯＲと一部重なるようにシール材ＳＥを塗布して液晶組成物が存在する領域の丸みが減少するようにしている。なお、図２０（ｂ）では配向膜ＯＲの端部ＥＤを点線で示している。また、図が複雑になることを避け、開口ＯＰが形成される位置についても点線で示した。このようにシール材ＳＥにより配向膜ＯＲの角部ＣＯの形状と、この角部ＣＯに隣接するブラックマトリクスＢＭの開口ＯＰの角部の形状とを近づけることが可能となる。
【００８９】
本実施例に係わる熱風乾燥処理では、配向膜材料塗膜が均一な膜厚に形成されるので、この配向膜材料塗膜の表面には転写ローラの凹凸部が残る場合がある。図２１（ａ）に概略斜視図で示すように転写ローラＲＯの表面には突起ＲＯ１が設けられており、この突起ＲＯ１は配向膜材料溶液が転写ローラＲＯに保持され易くするために設けられている。このために図２１（ｂ）に示すように配向膜材料塗膜を焼成した配向膜ＯＲにも同様の凹凸ＯＲ１が形成されることになる。
【００９０】
なお、前述した実施例においては、基板支持ピンによりガラス基板をベースプレートから浮かす構成とした場合について説明したが、基板支持ピン以外の支持部材でガラス基板をベースプレートから浮かせるように構成しても良い。例えば、ガラス基板に線接触する凸部をベースプレートに形成してガラス基板を浮かすように構成にしても良い。
【００９１】
また、前述した熱風乾燥装置においては、熱風流形成手段（ノズル）に対してべースプレートを往復移動させるように構成した場合について説明したが、ベースプレートに対してノズルに揺動装置を連結させ、このノズルを往復移動させるように構成しても良い。さらにはノズル及びベースプレートの双方を相対的に往復移動させるように構成しても良い。
【００９２】
また、前述した熱風乾燥装置においては、チャンバ２の内部に大気を供給する給気ブロワ３及びチャンバ２の内部の不要熱風を排気する排気ブロワ２５を設けた場合について説明したが、給気ブロワ３及び排気ブロワ２５にそれぞれインバータを設け、大気の供給量と排気量とのバランスを取ることでチャンバ２内から熱風漏れによる周囲の影響及びチャンバ２内への外気の流入による乾燥不良を防止することができる。
【００９３】
また、ガラス基板１をチャンバ２内に搬入する際に熱風を乾燥処理中と同量に供給されると、ノズル１１の直下の部分のみが先に乾燥が進行してしまう。これを防止するためにガラス基板１の搬入時には上述したインバータによる給気ブロワ３及び排気ブロワ２５のモータ回転数の制御及び三方弁６の切り換えによる熱風の供給量を低下（停止）させることにより、ノズル１１の直下の先行乾燥を防止することができる。また、待機時の基板支持ピン１４の温度上昇による乾燥むらの発生を防止できる。
【００９４】
また、前述した熱風乾燥装置においては、チャンバ２の内部に熱風の舞い上がりを吸引する上面排気溝１３ａ，１３ｂ及びガラス基板１に当った熱風を吸引する側面排気溝１６ａ，１６ｂ並びにチャンバ２内部の全体に淀む不要熱風を吸引する下面排気溝１７の３種類の排気システムを設けた場合について説明したが、これらの溝１３ａ，１３ｂ，１６ａ，１６ｂ，１７にそれぞれスリットまたはパンチングを設け、その開口面積を調節することにより、流量及び流速を調整することでチャンバ２内の気流を制御し、効率的な乾燥及び異物の低減を図ることができる。
【００９５】
また、前述した熱風乾燥装置においては、ベースプレート１２に立設される複数の基板支持ピン１４は、ベースプレート１２上に固定されている場合について説明したが、このベースプレート１２にガラス基板１の搬入出時及び乾燥処理時に基板支持ピン１４の高さを変更可能なアクチュエータを設け、ガラス基板１の搬入出時の許容範囲大，品種及び寸法等によりノズル１１からの距離の変更が必要な場合にその対応が可能となる。
【００９６】
以上、説明したように本発明による液晶表示装置の製造方法によれば、ガラス基板上に形成した配向膜材料塗膜の乾燥むら及び配向膜の膜厚のばらつきの発生などがなくなるので、配向膜表面における液晶分子の配列に悪影響を及ぼすことが皆無となるので、良好な表示特性を有する液晶表示装置が得られるという極めて優れた効果を有する。
【００９７】
また、本発明による液晶表示装置の製造方法によれば、ガラス基板内の温度分布のばらつき及び静電気帯電による撓みの発生によるガラス基板の割れなどの発生が皆無となるので、液晶表示装置の歩留まりの向上させ、延いては生産性を大幅に向上させることができるなどの極めて優れた効果を有する。
【００９８】
また、本発明による液晶表示装置の製造方法によれば、ガラス基板上に形成された配向膜の角部と重なってシール材を形成することによってシール材の内側（液晶組成物側）の丸みの半径を配向膜角部の丸みの半径よりも小さくして液晶組成物が形成される領域の丸みを小さくすることができるという極めて優れた効果が得られる。
【図面の簡単な説明】
【図１】 本発明による液晶表示装置の製造方法の一実施例による構成を説明する前提手段として用いられる熱風乾燥装置の構成を示すシステム図である。
【図２】 図１に示すチャンバ内に収容されている熱風供給手段周辺部の構成を示す斜視図である。
【図３】 ガラス基板の支持材料が基板温度分布に与える影響を調べるための実験設備の概略斜視図である。
【図４】 本発明に係わる熱風乾燥装置が搭載されるレベリング装置の構成を示す図である。
【図５】 本発明に係わる熱風乾燥装置による熱風乾燥のメカニズムを説明する模式図である。
【図６】 本発明に係わる熱風乾燥装置により熱風乾燥処理されたガラス基板の面内温度分布を説明する図である。
【図７】 熱風乾燥処理を最適化するための実験設備の概略斜視図である。
【図８】 乾燥方式ごとに乾燥時間とプレチルト角との関係を示す図である。
【図９】 配向膜形成材料溶液中における高分子の広がりを概念的に示す図である。
【図１０】 本発明に係わる熱風乾燥装置のチャンバ内の温度と仮乾燥後の塗膜の表面粗さとの関係を示す図である。
【図１１】 熱風の温度とプレチルト角度との関係を示す図である。
【図１２】 ホットプレートによる配向膜形成材料溶液の乾燥課程を説明する断面図である。
【図１３】 図１２に示す配向膜形成材料溶液の乾燥のメカニズムを説明する塗布膜の端部の拡大断面図である。
【図１４】 本発明による液晶表示装置の製造方法の一実施例による構成を説明するための熱風乾燥装置により形成された配向膜形成材料溶液の乾燥課程を説明する断面図である。
【図１５】 図１４に示す配向膜形成材料溶液の乾燥のメカニズムを説明する塗布膜の端部の拡大断面図である。
【図１６】 ホットプレート乾燥と本発明に係わる熱風乾燥装置の熱風乾燥とによる塗膜端部の形状を比較する図である。
【図１７】 ガラス基板上に形成された配向膜の形状を示す図である。
【図１８】 ガラス基板に形成された配向膜上にシール材が塗布された状態を示す平面図である。
【図１９】 図１８に示すシール材上にカラーフィルタ基板が重ね合わせた状態を示す平面図である。
【図２０】 ガラス基板の角部における配向膜の退縮防止構造を説明する平面図である。
【図２１】 配向膜材料を塗布する転写ローラ及びこの転写ローラにより塗布された塗膜の熱風乾燥により形成された配向膜の形状を示す斜視図である。
【図２２】 従来のホットプレートによる乾燥装置の構成を示す概略断面図である。
【図２３】 従来のホットプレートによる乾燥装置の構成を示す概略断面図である。
【符号の説明】
１ ガラス基板
２ 背面パネル
３ 給気ブロア
４ ヒータ
５ ヘパフィルタ
６ 三方弁
７ 分岐弁
８ ６分岐管
９ａ ダンパ
９ｂ ダンパ
１０ 均熱容器
１１ ノズル
１１ａ スリットノズル
１２ ベースプレート
１３ａ 上面排気溝
１３ｂ 上面排気溝
１４ 支持ピン
１５ 搬送アーム
１６ａ 側面排気溝
１６ｂ 側面排気溝
１７ 下面排気溝
１８ 揺動装置
１８ａ 揺動体本体
１８ｂ モータ
１８ｃ ボールネジ
１９ 排気装置
２０ａ ダンパ
２０ｂ ダンパ
２１ａ ダンパ
２１ｂ ダンパ
２２ａ ダンパ
２２ｂ ダンパ
２３ ダンパ
２４ 三方弁
２５ 排気ブロワ
３０ 配向膜材料塗膜
３０Ａ 形成領域の反対側の領域の一部３０Ａ
ＳＯ 溶液
ＰＲ 突起部
ＯＲ 配向膜
ＥＤ 配向膜端部
ＣＯ 配向膜角部
ＣＥ 配向膜中心部
ＳＥ シール材
ＯＰ 開口
ＰＲ１ 突出部。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a liquid crystal display device, and in particular, a liquid crystal display device having an alignment film formed by applying an alignment film material solution to an inner wall surface of a glass substrate constituting the liquid crystal display device and drying it.Manufacturing methodIt is about.
[0002]
[Prior art]
In general, a liquid crystal alignment film is formed on the inner wall surface of a liquid crystal display device to make the molecular alignment state of the liquid crystal material uniform. The alignment film forming process includes a printing process in which a coating film of an alignment film material diluted with a solvent (hereinafter referred to as an alignment film material coating film) is formed on one surface of the substrate, A heating step of heat-curing the formed alignment film material coating film.
[0003]
In this heating step, a drying treatment step in which the solvent contained in the alignment film material coating film is temporarily dried at a temperature of about 100 ° C., and a baking in which the alignment film material coating film after temporary drying is baked at a temperature of about 180 ° C. or more. And processing steps. In these stepwise processing steps, a hot plate as shown in FIG. 22 is used. This hot plate has a through-hole H that passes from a plurality of positions to an exhaust port in a region (hereinafter referred to as a substrate contact region) where the other surface of the glass substrate 1 (the side opposite to the surface on which the alignment film material coating film is formed) is in contact. Formed on the hot plate HP, a heater 4 embedded in the hot plate HP, a push-up pin 14 for pushing the glass substrate 1 upward, and a vacuum pump (not shown) connected to the exhaust port of the hot plate HP And is configured.
[0004]
According to such a configuration, the glass substrate 1 can be brought into close contact with the hot plate HP by the vacuum suction of the vacuum pump, so that the heat of the heater 4 is efficiently conducted to the glass substrate 1 through the hot plate HP. be able to. Thus, the coating film formed on the glass substrate 1 is temporarily dried or baked by the heat.
[0005]
By the way, after the heat treatment, it is necessary to transfer the glass substrate 1 in close contact with the hot plate HP from the hot plate HP to the transfer arm. Therefore, a plurality of push-up pins 14 that push up the glass substrate 1 from the substrate contact surface are accommodated inside the hot plate HP. As shown in FIG. 23, since the glass substrate 1 is lifted from the hot plate HP by the push-up of these push-up pins 14, a space for inserting the transfer arm 15 is secured between the glass substrate 1 and the hot plate HP. Has been.
[0006]
[Problems to be solved by the invention]
However, since the end portion of the through hole H and the end portion of the receiving hole of the push-up pin 14 are formed in the substrate contact area of the hot plate HP, the hot plate is partially formed on the back surface of the glass substrate 1. An area that does not come into contact with HP is generated. As a result, drying unevenness occurs in the alignment film material coating, and the film thickness of the alignment film varies, affecting the alignment of liquid crystal molecules on the alignment film surface, and as a result, the display characteristics of the liquid crystal display device are degraded.
[0007]
In the hot plate adsorption method, the glass substrate 1 is cracked due to variations in the temperature distribution in the substrate during the drying process. Further, when the glass substrate 1 after the drying process is peeled off, bending due to static electricity is generated, which causes the glass substrate 1 to crack.
[0008]
Accordingly, the present invention has been made to solve the above-described conventional problems, and the object of the present invention is to form the alignment film by using a drying means for supplying hot air, thereby solving the above-described problems. It is an object of the present invention to provide a liquid crystal display device that can solve all of the problems, obtain good display characteristics, improve production yield, and improve productivity.
[0009]
[Means for Solving the Problems]
  In order to achieve such an object, the liquid crystal display device according to the present inventionManufacturing methodApplies an alignment film material solution to one surface of the glass substrate, applies a flow of hot air to the alignment film material solution applied on the glass substrate, and exhausts the remaining hot air remaining in the periphery of the glass substrate And drying by reciprocally moving the plane intersecting the flow of the hot air and the glass substrate in the plane direction.An alignment film is formed and driedThe alignment filmInFilm thickness at the corner of the alignment film than at the end of the alignment filmTo be thickerThe protrusionIt is characterized by forming.
[0010]
The present invention is not limited to the above-described configuration and the configuration of each embodiment described later, and it goes without saying that various modifications can be made without departing from the technical idea of the present invention.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described below in detail with reference to the drawings of the embodiments.
  FIG. 1 shows a liquid crystal display device according to the present invention.Manufacturing methodIt is a system diagram explaining the structure of the hot air drying apparatus used as a premise means explaining the structure by one Example, The same code | symbol is attached | subjected to the same part as the figure mentioned above, and the description is abbreviate | omitted. Hereinafter, for convenience of explanation, an orthogonal coordinate system including the installation surface of the hot air drying device on the X-axis and Y-axis surfaces is defined. Further, the arrow direction indicated by a solid line indicates the direction in which hot air flows during heating and drying, and the arrow direction indicated by a dotted line indicates the direction in which hot air flows during loading and unloading of the glass substrate.
[0012]
In FIG. 1, 1 is a glass substrate coated with an alignment film material solution on one surface, 2 contains a glass substrate 1 inside, and the alignment film material solution applied on one surface of the glass substrate 1 is heated with hot air. A chamber for forming an alignment film by drying, 3 for example, an air supply blower for sucking and feeding air in a clean room, 4 for a heater for heating the air fed from the air supply blower 3, and 5 for heating A hepafilter 6 that removes foreign substances in the air and cleans them, and a three-way valve 6 that divides the heated air sent from the hepafilter 5 into a bypass pipe while stopping the flow of hot air during the loading of the glass substrate 1.
[0013]
Reference numeral 7 is a branch valve for branching the heated air sent from one of the three-way valves 6 in two directions and introducing it into the chamber 2. Reference numeral 8 is provided in the chamber 2 and introduced via the branch valve 7. 6 branch pipes, 9a, 9b for branching while keeping the temperature and flow rate of the hot air uniformly maintained, are dampers for adjusting the flow rate of the heated air sent from the six branch pipes 8 for each nozzle, and 10 is a damper 9a, It is a soaking vessel that temporarily stores the heated air that has passed through 9b. Sanitary piping is used as piping for hot air supplied from the hepa filter 5 into the chamber 2 to prevent the generation and adhesion of foreign matter.
[0014]
Reference numeral 11 denotes a nozzle that blows heated air accumulated in the soaking vessel 10 toward the upper surface of the base plate 12 on which the glass substrate 1 is placed. As shown in the perspective view of FIG. 2, the nozzle 11 has a plurality of slit nozzles 11a accommodated therein, each having a slit-like nozzle hole facing the upper surface of the base plate 12, and these slit nozzles. 11a is arranged in a line in the Y direction at substantially equal intervals so that the long holes of the respective nozzle holes are along the X direction in the XYZ axes, and uniformly blows hot air HA on the base plate 12.
[0015]
Here, even if the temperature and flow rate of hot air blown from each slit nozzle 11a in the nozzle 11 are uniform, there is no meaning if there is variation among the slit nozzles 11a. A branch pipe having an equal dividing function is adopted in the inside thereof, and hot air is supplied to each slit nozzle 11a equally in both temperature and air volume. The number of slit nozzles 11 a is determined in accordance with the surface area of the glass substrate 1 placed on the base plate 12.
[0016]
Reference numerals 13a and 13b denote exhaust grooves on the upper surface side for sucking hot air from the heated air blown from the nozzle 11 on the upper surface of the glass substrate 1. A plurality of substrate support pins 14 are provided on the upper surface of the base plate 12 to support the other surface (back surface) of the glass substrate 1. These substrate support pins 14 are arranged so as to maintain a state in which a gap G into which the tip of the transfer arm 15 can be inserted is formed between the glass substrate 1 and the base plate 12.
[0017]
Therefore, it is only necessary that three or more substrate support pins 14 including three pins that are not arranged in a row are provided on the upper surface of the base plate 12 other than the insertion path of the transfer arm 15. For example, when the tip of the transfer arm 15 has a bifurcated shape, a plurality of substrate support pins can be arranged in a matrix of two rows having a row interval equal to or greater than the width of the tip leg portion of the transfer arm 15. .
[0018]
These substrate support pins 14 point-support the glass substrate 1 as described above, but actually have a small area at the contact interface with the glass substrate 1. Therefore, when the substrate support pins 14 are heated by the hot air discharged from the slit nozzle 11a during the drying process, the glass substrate 1 is partially heated by the heat from the contact interface with each substrate support pin 14. . In order to reduce the temperature unevenness of the glass substrate 1 by this, it is preferable to make the contact area between the tip of each substrate support pin 14 and the glass substrate 1 narrower.
[0019]
Therefore, it is more preferable to adopt a spherical shape with a radius of curvature of 5 mm or less as the tip shape of each substrate support pin 14 and further to form the tip of each substrate support pin 14 with a material having a low thermal diffusivity. Therefore, in order to determine an appropriate material as a material for forming the tip of each substrate support pin 14, the thermal diffusivity shown in Table 1 below is 30 mm.²/S~0.1mm²The following experiment was conducted using a block material formed of / s material (aluminum, glass, Teflon (registered trademark), Vespel (registered trademark)).
[0020]
[Table 1]

[0021]
A plurality of glass substrates (100 mm × 100 mm × 1.1 mm) on which an undried alignment film material coating film (film thickness of 1.5 μm) is formed are prepared, and each glass substrate 1 is undried as shown in FIG. The alignment film material coating film 30 was placed on the block material BL of any material facing upward. However, the block material BL of each material was brought into contact with a part 30 </ b> A of a region on the opposite side of the formation region of the alignment film material coating film 30 of each glass substrate 1.
[0022]
In this state, when hot air of about 100 ° C. was blown onto the alignment film material coating film 30 of each glass substrate 1, the thermal diffusivity was 0.47 mm.²The alignment film material coating film 30 of the glass substrate 1 placed on the block material BL formed of a material of / s or less did not cause drying unevenness. Therefore, in the present embodiment, at least the tip of each substrate support pin 14 has a thermal diffusivity of 0.5 mm.²/ S or less.
[0023]
Further, 16a and 16b guide the hot air blown from the nozzle 11 to the four corners of the glass substrate 1 and suck the stagnation of the hot air that bounces off the glass substrate 1, and 17 indicates the stagnation of the hot air in the chamber 2. And a lower-side exhaust groove that sucks hot air stagnation and the like remaining in the lower peripheral portion of the base plate 12 on which the glass substrate 1 is placed, and controls the flow of air in the entire chamber 2.
[0024]
Reference numeral 18 denotes a swinging device disposed on the back side of the lower surface side exhaust groove 17 and connected to the base plate 12. The swinging device 18 is connected to a ball screw 18c having a swinging body main body 18a connected to a motor 18b. The oscillating body 18a is reciprocated in the direction of the arrow AA 'by the rotation of the motor 18b, and the oscillating body 18a connected to the base plate 12 is thereby moved by the arrow AA. It is swung in the ′ direction. Therefore, the glass substrate 1 placed on the base plate 12 is swung in the AA ′ direction indicated by the arrow in the in-plane direction.
[0025]
Reference numeral 19 denotes a chamber-side exhaust device disposed at the bottom of the chamber 2, and the exhaust device 19 sucks in foreign matter generated by the swinging operation in the direction of the arrow AA ′ by the swinging device 18, The flow into the chamber 2 is prevented.
[0026]
The upper surface side exhaust grooves 13a and 13b, the side surface side exhaust grooves 15a and 15b, the lower surface side exhaust groove 16 and the chamber side exhaust device 19 are respectively provided with corresponding dampers 20a and 20b, dampers 21a and 21b, dampers 22a and 22b. The other valve of the three-way valve 24 is connected to the other valve of the three-way valve 24 via the damper 23 and contains the solvent evaporated in the chamber 2. Unnecessary hot air and hot air at the time of loading and unloading of the glass substrate 1 are gathered and forced out to the outside of the clean room by the exhaust blower 25 to prevent the solvent from reattaching.
[0027]
4A and 4B are diagrams for explaining a schematic configuration of a leveling device that accommodates a hot air drying device. FIG. 4A is a plan view seen from above, and FIG. 4B is a plan view seen from the side. 4A and 4B, reference numeral 100 denotes a hot air dryer unit in which the chamber 2 in the hot air dryer described in FIG. 1 is installed in two stages and two rows (four positions). Before and after 100, an unloading robot 200 having a transport arm 15 for transporting the glass substrate 1 before processing into the chamber 2 and a transport arm 15 'for transporting the processed glass substrate 1 from the chamber 2 are used. A robot 300 is provided.
[0028]
In the loading robot 200 and the unloading robot 300, as shown in FIG. 4A, the transfer arms 15 and 15 ′ move in parallel in the direction of the arrow BB ′, and further, as shown in FIG. Thus, the transfer arms 15 and 15 have the function of moving up and down in the direction of the arrow C-C ′ and with respect to the chambers 2 installed in two stages and two rows (four positions) of the hot air drying device section 100. By repeating the moving operation of ′ alternately, parallel processing for loading and unloading the glass substrate 1 becomes possible.
[0029]
In addition, an upstream device 400 that performs a pretreatment process such as a cleaning process for the glass substrate 1 is installed on the front stage side of the loading robot 200, and an alignment film is formed on the rear stage side of the unloading robot 300. A downstream apparatus 500 that performs a post-processing step such as a baking process of the glass substrate 1 that has been formed is installed. Therefore, the cleaned glass substrate 1 is placed on the transfer arm 15 of the loading robot 200 and loaded into the chamber 2, and the glass substrate 1 on which the alignment film is formed is removed from the chamber 2 by the unloading robot 300. It is transported to the downstream apparatus 500 that is placed on the transport arm 15 ′ and performs the firing process.
[0030]
Reference numeral 600 denotes a robot frame for storing the chamber 2 shown in FIG. 1 in a two-stage, two-row, four-position four-position, 100, carrying robot 200, and carrying robot 300 separately. Is the robot cover frame, and 800 is the temperature control unit. For example, an air supply blower 3, a heater 4, a hepar filter 5, a three-way valve 6, a branch valve 7, dampers 20a, 20b to 23, a three-way valve 24, and an exhaust blower disposed outside the chamber 2 described in FIG. 25 etc. have a structure accommodated under the floor.
[0031]
Reference numeral 900 denotes a hot air drying apparatus 100, a loading robot 200, and a driving robot 300 disposed on the back side of the carrying robot 300 to drive various devices in the temperature control unit 800, the loading robot 200, the carrying robot 300, and the like. It is a control device section in which circuits and their control circuits are housed. It is assumed that the control unit 900 is installed on the back side of the device, and the hot air drying unit 100, the robot frame 600, the robot cover frame 700, etc. are configured in a split type structure so that they can be transferred and reassembled. The working efficiency at the time can be improved.
[0032]
In the figure, the arrow AA ′ direction indicates the swinging direction of the base plate 12 due to the reciprocating movement of the swinging device 18 shown in FIG. 1, and the stroke of the base plate 12 in the arrow AA ′ direction is about 200 mm. The stroke of the transfer arm 15 in the direction of the arrow CC ′ is about 750 mm. The leveling device is formed to have dimensions of about 3500 mm in width, about 4500 mm in length, and about 2750 mm in height.
[0033]
By using the leveling device configured as described above, when a large glass substrate having different dimensions is processed, it is not necessary to change the setup depending on the size of the substrate, and the time, safety and workability required for regular replacement are extremely high. Become.
[0034]
Next, the alignment film forming process of the manufacturing process of the liquid crystal display device will be described using the hot air drying apparatus configured as described above.
[0035]
The liquid crystal display manufacturing process includes alignment film formation process, rubbing process, sealing material printing process, spacer spraying process, substrate bonding process, sealing material firing process, liquid crystal injection process, liquid crystal inlet sealing process, and polarizing plate application. However, here, the description will focus on the alignment film forming process using the hot air drying apparatus described in FIG.
[0036]
A glass substrate after cleaning in which TFT (display area diagonal 17 inches) or a color filter pattern is formed and arranged on one surface (hereinafter referred to as an electrode formation surface) over 6 surfaces is oriented by the carrying robot 200 from the upstream device 400. When transported to the film forming process, a drying process is performed on the alignment film material coating film formed on the glass substrate 1 as shown below. Here, about 5 wt% alignment film material solution obtained by dissolving soluble polyimide or polyamic acid in 1-methyl-2-pyrrolidone (NMP) or γ-butyrolactone (BL) is used.
[0037]
First, the air supply blower 3 starts rotating to take in the air in the clean room and send it to the heater 4 being heated. After the heated air passes through the hepa filter 5, the three-way valve 6, the branch valve 7, the branch pipe 8, and the dampers 9a and 9b and is temporarily stored in the soaking vessel 10, the air of each slit nozzle of the nozzle 11 is stored. It is discharged from the tip at a uniform temperature (for example, about 60 ° C.). At the same time, the upper surface exhaust grooves 13a and 13b, the side surface exhaust grooves 16a and 16b, the lower surface exhaust groove 17 and the in-chamber exhaust device 19 are driven to appropriately exhaust the atmosphere in the chamber 2.
[0038]
In the meantime, the alignment film material is applied to the electrode forming surface of the glass substrate (650 mm × 830 mm × 0.5 to 0.7 mm or 730 mm × 920 mm × 0.5 to 0.7 mm) after being cleaned by the upstream apparatus 400 by flexographic printing. A film is formed. When the internal temperature of the chamber 2 is stabilized at an appropriate temperature (for example, about 55 ° C.), the inlet of the chamber 2 is opened, and the loading robot 200 applies the glass substrate from the upstream device 400 to the alignment film material. The film is lifted up to the tip of the transfer arm 15 so that the film is on the upper surface, the entrance of the chamber 2 is opened, and the film is transferred onto the base plate 12 in the chamber 5 in the hot air drying unit 100.
[0039]
Thereafter, the transfer arm 15 is moved in the Z-axis direction so that the tip of the transfer arm 15 is accommodated between the pin rows on the base plate 12. As a result, when the glass substrate 1 is transferred from the front end portion of the transport arm 15 to the pin group, the front end portion of the transport arm 15 is pulled out from between the pin rows by moving the transport arm 15 in the X direction along the XYZ axes. Then, the shutter at the carry-in port of the chamber 2 is closed.
[0040]
Thereafter, by starting the rotation of the motor 18a of the swinging device 18, the base plate 12 is reciprocated at a suitable speed (for example, about 100 mm / s) in the AA ′ direction with a stroke of about 200 mm. The stroke of the base plate 12 at this time is a distance substantially equal to the arrangement interval of the slit nozzles of the nozzle 11. Thereby, the solvent can be uniformly and efficiently evaporated from the entire surface of the alignment film material coating film.
[0041]
FIG. 5 is a schematic diagram for explaining a mechanism for uniformly and efficiently evaporating the solvent of the alignment film material coating film formed on the glass substrate 1. First, as shown in FIG. 5A, hot air HA blown from the slit nozzles 11a of the nozzle 11 toward the glass substrate 1 hits the upper surface of the glass substrate 1 and then stagnates on the glass substrate 1 and the stagnation. The hot air layer HLA composed of the portion HA ′ is formed so that the hot air HA that is subsequently released does not hit the upper surface of the glass substrate 1.
[0042]
Then, as shown in FIG. 5 (b), the interval D between the slit nozzles 11a is increased, and a path EX through which the hot air HA exhausts is formed between the slit nozzles 11a, whereby the next new hot air HA is applied to the glass substrate 1. However, on the upper surface of the glass substrate 1, there is a temperature difference between the heating area HAR directly below each slit nozzle 11a and the area CAR that is exhausted and not heated.
[0043]
Therefore, as shown in FIG. 5C, by reciprocating the glass substrate 1 in the direction of the arrow AA ′, the temperature difference between the heating area HAR and the non-heated area CAR is eliminated, and the temperature distribution is made uniform. , Preventing partial drying and obtaining drying by uniform heating. That is, drying with a uniform temperature distribution is obtained by supplying the hot air HA uniformly over the entire surface of the glass substrate 1 including the center and the four corners. The swinging means for reciprocating the glass substrate 1 in the direction of the arrow AA ′ is interlocked with the reciprocating motion in the direction of the arrow AA ′ by driving the motor 18b of the swinging device 18 shown in FIGS. Done.
[0044]
In addition, when an angle is needed for the hot air discharge | released by the dimension of the glass substrate and the kind here, an angle is given by the aluminum clamp part for attachment of the nozzle 11, and a hot air discharge | release angle can be adjusted by this. . Further, when the dimensions of the glass substrate and the distance from the nozzle 11 change, each of the glass substrates such as the end and the center of the glass substrate can be adjusted by adjusting the dampers 9a and 9b (see FIG. 1) in the previous stage of the nozzle 11. The amount of hot air discharged for each place can be changed.
[0045]
For this reason, it is possible to prevent variations in the film thickness and film physical properties of the alignment film material coating film before firing. At this time, if hot air is discharged from each slit nozzle 11a so that the speed of the hot air near the surface of the glass substrate 1 is 0.5 m / s or more, the hot air containing the vaporized solvent is applied to the glass substrate 1 on the surface. The upper surface exhaust grooves 13a and 13b, the side surface exhaust grooves 16a and 16b, the lower surface side exhaust groove 17 and the in-chamber exhaust device 19 shown in FIG. 1 are driven through the dampers 20a and 20b to 23 and the three-way valve 24 without being retained in the vicinity. Since the air is sucked by the exhaust blower 25 and discharged smoothly to the outside, the drying time can be greatly shortened.
[0046]
In this way, about 80% of the solvent contained in the alignment film material coating film evaporates, and after the fluidity of the alignment film material coating film is lost, the tip of the transfer arm 15 ′ of the transfer robot 300 becomes the glass substrate 1. The transfer arm 15 ′ is moved in the X direction so as to be inserted into the gap G between the support plate 14 and the base plate 12, and the glass substrate 1 is transferred from the tip of the support pin 14 to the tip of the transfer arm 15 ′. The arm 15 'is moved in the Z direction. Thereby, the glass substrate 1 can be smoothly scooped up from the tip of the support pin 14.
[0047]
Thus, without giving excessive force to the glass substrate 1, the glass substrate 1 can be scooped up from the tip of the support pin 14 because each support pin 14 with a small contact area with the glass substrate 1 is This is because, unlike the plate of the hot plate, almost no static electricity (peeling charge) is generated between the glass plate 1 and the glass plate 1. For this reason, generation | occurrence | production of the crack of the glass substrate 1, etc. can be prevented.
[0048]
When the glass substrate 1 is scooped up from the tip of the support pin 14 of the base plate 12, the suction from the air supply blower 3 is stopped and supported until the next glass substrate 1 starts the drying process on the alignment film material coating film. It is desirable to prevent the pins 14 from being heated by hot air.
[0049]
Next, when the drying process in the hot air drying apparatus unit 100 is completed, the glass substrate 1 is transferred to the downstream apparatus 500 that performs infrared drying in the next process by the transfer arm 15 ′ of the unloading robot 300 in that state. . And the baking process with respect to the alignment film material coating film of the glass substrate 1 is performed. That is, the alignment film material coating film on the glass substrate 1 is baked by heating the glass substrate 1 at an appropriate temperature (for example, about 230 ° C.) for an appropriate time (for example, about 20 minutes) inside the infrared heating furnace. To do. Thereby, an alignment film having a uniform film thickness and film properties is formed on the glass substrate 1.
[0050]
Thereafter, the glass substrate 1 is subjected to an alignment film forming process, a rubbing process, a sealing material printing process, a spacer spraying process, a substrate bonding process, a sealing material baking process, a liquid crystal injection process, a liquid crystal inlet sealing process, and a polarizing plate. It is conveyed to the pasting process. Thereby, the liquid crystal display device including the glass substrate 1 is completed.
[0051]
According to the above liquid crystal display device manufacturing process, an alignment film having a uniform film property can be formed with a uniform film thickness in the alignment film forming step. Can be reliably prevented. Therefore, a liquid crystal display device with good display characteristics can be obtained. In addition, since it is possible to surely prevent the occurrence of substrate cracking that is likely to occur in the alignment film forming process using a hot plate, the yield of the liquid crystal display device manufacturing process can be improved. Furthermore, the efficiency can be increased by the amount that the substrate push-up process using the push-up pins is not necessary, compared to the case where a hot plate is used.
[0052]
These effects are shown in Table 2 below in comparison with a process using a hot plate.
[0053]
[Table 2]

[0054]
(1) When the hot air drying apparatus according to the present embodiment is used, no peeling electrification that occurs when hot play is used does not occur at all. For this reason, unlike the case where a hot plate is used, the glass substrate 1 is not cracked at all.
[0055]
(2) When a hot plate is used, the glass substrate 1 needs to be slowly lifted by the push-up pins 14 in order to prevent the glass substrate 1 from cracking. On the other hand, when the hot air drying apparatus according to the present embodiment is used, the glass substrate 1 need not be pushed up. Therefore, the alignment film forming process can be made more efficient accordingly. For example, according to the hot plate, it takes about 100 seconds or more to dry the glass substrate of 720 mm × 930 mm (from carrying in to carrying out), whereas according to the hot air drying apparatus according to the present embodiment, 720 mm × The time required for the drying process of the 930 mm glass substrate 1 can be shortened to about 60 seconds or less.
[0056]
(3) When a hot plate is used, the temperature of the glass substrate 1 varies about ± 2 ° C., whereas when the hot air drying apparatus according to this embodiment is used, the temperature of the glass substrate 1 Variation is suppressed to about ± 1 ° C. For this reason, the alignment film material coating film can be uniformly dried. This effect is confirmed by the following experiment.
[0057]
Thermal diffusivity is about 0.1mm²The following experiment was conducted using a drying apparatus having support pins 14 formed of / s Vespel (registered trademark) and slit nozzles 11 arranged at intervals of about 200 mm. In the chamber 2 in which the internal temperature is stabilized at about 55 ° C., about 200 mm from the tip of the slit nozzle 11 while discharging warm air from each slit nozzle 11 to about 60 ° C. at a speed of 0.5 m / s to 2 m / s. The glass substrate 1 coated with the alignment film material solution was reciprocated at a distance of 100 mm / s. The stroke of the glass substrate 1 at this time is about 200 mm.
[0058]
As a result, since the temporary drying of the alignment film material coating film was completed about 25 seconds after the glass substrate 1 was put into the chamber 2, the hot air was released about 40 seconds after the glass substrate 1 was put into the chamber 2. The reciprocation of the glass substrate 1 was stopped, and the appearance and in-plane temperature distribution of the glass substrate 1 were observed. As a result, it was confirmed that the glass substrate 1 had no defects such as cracks. Moreover, it turned out that the dispersion | variation in the temperature of the glass substrate 1 is suppressed to about +/- 1 degreeC.
[0059]
However, as shown in FIG. 6, it was found that the temperature variation of the glass substrate 1 is suppressed to about ± 0.5 ° C. except for a part of the region of the glass substrate 1. That is, it was confirmed that the temperature unevenness of the glass substrate 1 that causes drying unevenness in the alignment film material coating film is suppressed.
[0060]
In addition, as described above, the process time is about 40 seconds and the transfer time is about 30 seconds in total, and a part of the operation can be shortened by parallelization and can be shortened to about 60 seconds or less as about 20 seconds. Since 2 positions are provided in 4 positions, the target tact of about 15 seconds / sheet was achieved with a total of about 60 seconds / 4 positions.
[0061]
Thereafter, the alignment film material on the glass substrate was cured by heating the glass substrate at about 230 ° C. for about 20 minutes in an infrared heating furnace. An LCD panel was produced using the glass substrate on which the alignment film was formed in this manner, and the pretilt angle was measured. As a result, it was confirmed that the same pretilt angle (about 6 °) as that of the LCD panel using the glass substrate on which the alignment film was formed by the hot plate HP was shown.
[0062]
Next, the optimum conditions for the drying process using the hot air drying apparatus according to this embodiment will be described. Here, the following experiment was performed in order to obtain the optimum conditions for the drying treatment.
[0063]
(1) Experiment 1
In order to optimize the drying time, as shown in FIG. 7, the alignment film material coating on the glass substrate 1 of 100 mm × 100 mm × 1.1 mm is dried by heat transfer from the hot plate HP and warm air from the dryer DR, respectively. I let you. Here, the dryer DR was reciprocated in the horizontal direction in such a posture that hot air was blown vertically onto the glass substrate 1.
[0064]
As the alignment film material used here, a material that has a main chain and a side chain of a long-chain alkyl group in a polyimide skeleton, and exhibits a pretilt angle by the presence of the long-chain alkyl group on the surface of the alignment film. The solvent in which the alignment film material is diluted is 1-methyl-2-pyrrolidone (NMP) or γ-butyrolactone (BL).
[0065]
After drying the solvent, a liquid crystal cell was produced under the same conditions and the pretilt angle was measured. As a result, it was as shown in FIG. Here, the drying time was defined as follows. When the solution applied on the substrate dries and the solvent evaporates, the film thickness decreases and interference fringes occur on the film surface. When the solvent evaporates and the film thickness becomes uniform, the interference fringes disappear and the film surface shows an interference color uniformly. The time from the start of substrate heating to the uniform interference color was measured as the drying time.
[0066]
Hot plate drying shows a substantially constant pretilt angle regardless of the drying time, while hot air drying greatly changes the pretilt angle depending on the drying time, and when the drying time is short, the pretilt angle is small.
[0067]
Here, the influence of the solvent composition on the alignment film polymer was examined. The alignment film polymer was dissolved in NMP and BL, respectively, and the molecular size was determined from the scattering angle dependence of the light scattering intensity. The result is shown in FIG. It was found that the polymer contracted in the NMP solution. When the polymer contracts, it is considered that the side chain contributing to the expression of the pretilt angle is rounded into the main chain. Furthermore, it has been found that the pretilt angle decreases in an alignment film formed from a solution having a high NMP ratio. When the alignment film polymer is stretched, side chains with high affinity to hot air are unevenly distributed on the film surface, but when the alignment film polymer contracts, the side chains that contribute to the pretilt angle are rounded into the main chain. It is believed that the amount present on the film surface decreases, and as a result, the pretilt angle decreases.
[0068]
In the solvent drying step, the mixed solvent does not evaporate uniformly, and the evaporation rate of BL is faster than that of NMP. For this reason, the composition of the mixed solvent changes simultaneously with the concentration of the alignment film polymer in the coating film. It is considered that the solvent composition in the coating film at the time of solvent drying changes as follows. BL evaporates from the surface of the alignment film by heating. In the film, a solvent concentration gradient occurs in the depth direction, and BL diffuses from the substrate side toward the surface. However, if the drying time is short, the diffusion in the film cannot catch up with the surface evaporation, and the surface evaporates. The composition ratio of NMP which is difficult to increase increases. In hot air drying, the solvent is positively removed to prevent the solvent from staying, so that the evaporation rate difference between BL and NMP is increased, and the NMP concentration on the surface advances. Therefore, under conditions where the NMP is easily concentrated and the drying speed is fast, the polymer on the surface contracts and the pretilt angle decreases.
[0069]
Based on the above results, the temperature and wind speed at which the pretilt angle is equal to or greater than that of the conventional hot plate drying and a drying time of about 20 seconds or more were determined as the optimum hot air drying conditions for this alignment film material. As for the temperature, it turned out that the blower outlet temperature of a hot air is 70 to 90 degreeC, and the wind speed on a glass substrate is 1.5 to 2.0 m / s.
[0070]
(2) Experiment 2
With the hot air drying apparatus according to this example, hot air at each temperature was sprayed onto the glass substrate 1 to observe the appearance of the alignment film material coating film. As a result, it was found that when hot air of about 30 ° C. or less was blown, the flatness of the alignment film material coating film was lowered. In addition, it was found that the flatness of the alignment film material coating film to which hot air of about 30 ° C. or higher was blown changed corresponding to the temperature of the hot air as shown in FIG. That is, it was found that the higher the hot air temperature is, the higher the fluidity of the alignment film material solution is, so that the flatness is improved.
[0071]
The solvent of the alignment film solution is generally a mixed solvent, and the solvent component ratio changes during drying. At this time, a change in the affinity between the alignment film polymer and the solvent with time and a decrease in fluidity due to an increase in the concentration of the alignment film occur, and the alignment film polymer structure on the outermost surface is determined. For example, a solvent having a slightly inferior affinity with the alignment film is concentrated and molecules are contracted. As a result, the surface concentration of the polymer side chain, which is an element that develops the pretilt angle, is lowered, and the pretilt angle is lowered. Therefore, a liquid crystal cell was produced on each glass substrate that had been subjected to a drying treatment with hot air at each temperature, and its pretilt angle was measured. As a result, as shown in FIG. 11, it was confirmed that the pretilt angle decreases as the hot air temperature increases. It was confirmed that it was difficult to obtain an appropriate pretilt angle by drying with hot air of about 100 ° C. or higher.
[0072]
From the above results, in this embodiment, about 30 ° C. to 100 ° C. was adopted as the optimum temperature range of the hot air supplied from the nozzle.
[0073]
(3) Experiment 3
The drying process using the hot plate will be described in detail. As shown in the sectional view of FIG. 12A, the film thickness of the solution SO applied on the glass substrate 1 is reduced by drying. At this time, since the drying speed of the solution SO is high at the end portion of the glass substrate 1, the projection PR is generated when the flow of the liquid film moves from the central portion to the end portion of the glass substrate 1. In addition, the film thickness of the initial alignment film material coating film applied is 1000 nm to 1500 nm.
[0074]
Thereafter, drying proceeds, and as shown in FIG. 12B, the solution SO has a thin portion at the end of the glass substrate 1, and an inclination occurs between the central portion and the thick portion. . The drying further proceeds, and as shown in FIG. 12C, the thin portion of the solution SO moves from the end portion to the central portion. After drying, the film thickness is uniform from the end to the center as shown in FIG. However, the protrusion PR is generated at the end for the above-described reason. In this case, the dried alignment film material coating film has a uniform central portion of approximately 60 nm, and the protrusion PR has a thickness of approximately 100 nm.
[0075]
This alignment film material coating film is baked after drying to form an alignment film, and the film thickness of the alignment film is also about 60 nm at the center and about 100 nm at the protrusion PR. Thus, in the drying by the hot plate, the position where the drying is started is fixed to the end of the glass substrate 1, and the drying start position cannot be freely changed.
[0076]
In the case of drying by the hot plate described above, the mechanism by which the film thickness of the solution SO applied on the glass substrate 1 is reduced by drying is that the solution SO is applied on the glass substrate 1 as shown in an enlarged sectional view in FIG. The surface of the film coated with SO is at a saturated vapor pressure, and since the airflow is weak in the central part, the evaporation rate is smaller in the central part than in the end part as shown in the direction indicated by the solid arrow. For this reason, in order to compensate for evaporation at the end, the liquid film moves from the center toward the end in the direction indicated by the thick arrow. As a result, as shown in FIG. 13B, the end portion (especially the corner portion from the side portion) has a large surface area, and the evaporation rate of the solution SO in the central portion becomes large. As a result, as shown in FIG. 13C, it is considered that an alignment film OR having a projection PR at the end and having a substantially uniform thickness at the center is formed.
[0077]
On the other hand, in the case of the hot air drying process using the hot air drying apparatus according to the present embodiment, the solution SO applied on the glass substrate 1 as shown in a cross-sectional view in FIG. Protrusions are unlikely to occur at the ends. However, as shown in FIG. 14B, there is a portion where the drying speed increases depending on the position with the nozzle, and the projection PR is generated in that portion, but since the glass substrate 1 is moved, the projection PR is also Move with this. For this reason, the position where the interference fringes are generated is also random. As described above, in the case of hot air drying, the generation of the protrusions PR is reduced by randomly generating a portion where the drying speed of the solution SO is large. As a result, the film thickness of the solution SO is uniformly reduced as shown in FIG. 14 (c), and after drying, the entire film has a substantially uniform film thickness from the end to the center as shown in FIG. 14 (d). Drying is complete.
[0078]
In the case of the hot air drying described above, the mechanism by which the film thickness of the solution SO applied on the glass substrate 1 is reduced by drying is such that the solution SO is formed on the glass substrate 1 as shown in an enlarged cross-sectional view in FIG. The applied film surface is always ventilated, and the evaporation rate of the solution SO is constant at the end and the center as shown by the size indicated by the solid arrow, so the evaporation rate is substantially uniform in the plane. It becomes. For this reason, the amount of movement of the liquid film from the central portion to the end portion decreases, the solution SO evaporates uniformly, and as shown in FIG. It is considered that an alignment film OR having a substantially uniform film thickness is formed at the center.
[0079]
From the above description, when comparing the shape of the end by hot plate drying and hot air drying, as shown in FIG. 16, in the hot air drying HA by the hot air drying apparatus according to the present embodiment, it is formed at the end of the alignment film. It was found that the dimension in the height direction of the protrusion is about 1/3 that of the hot plate drying HP, and a film thickness substantially uniform with the central part of the alignment film can be obtained.
[0080]
FIG. 17 is a view for explaining the shape of the alignment film OR formed on the glass substrate 1, and FIG. 17A is a plan view. In FIG. 17A, OR indicates the alignment film, CE indicates the center of the alignment film OR, ED indicates the end of the alignment film OR, and CO indicates the corner of the alignment film OR. FIG. 17B is an enlarged cross-sectional view of the end portion ED of FIG. 17A, and FIG. 17C is an enlarged cross-sectional view of the corner portion CO of FIG.
[0081]
In FIG. 17, when the viscosity (viscosity) of the solution forming the alignment film OR is low and the ratio of the solvent is large, the amount of movement of the liquid film to the end ED is particularly large, and the protrusion of the end ED The problem that the department becomes large was found. Therefore, in the hot air drying according to the present embodiment, as shown in FIGS. 17B and 17C, the generation of the protrusions PR formed at the end ED and the corner CO should be prevented or the shape thereof can be reduced. It is particularly effective when the viscosity of the solution is low and the ratio of the solvent is large.
[0082]
Further, since the corner portion CO shown in FIG. 17A has a higher evaporation rate than the end portion ED, the protrusion PR is larger than the end portion ED as shown in FIG. 17C. For this reason, even when hot air drying is used, the protrusion PR may remain in the corner portion CO. Furthermore, it has been found that when the viscosity of the solution is low, the solution applied particularly to the corners CO recedes (degenerates) toward the center CE. For this reason, as shown in FIGS. 18A and 18B, a so-called roundness (chamfering) may occur in the corner portion CO. Here, when the viscosity of the solution is about 25 cp or less, particularly when the viscosity is 8 to 12 cp, the radius r of the roundness generated in the corner portion CO is between 0.1 mm and 1 mm.
[0083]
After the formation of the alignment film OR, the sealing material SE is applied and formed on the alignment film OR. In this case, the alignment film OR is formed at the corner portion CO of the alignment film OR as shown in FIG. The sealing material SE is applied so as to follow the roundness of the end portion ED, and the sealing material SE is applied so as to partially overlap the alignment film OR. At this time, the radius of the inner side (liquid crystal composition side) of the sealing material SE can be made smaller than the radius r of the corner portion CO of the alignment film OR to reduce the roundness of the region where the liquid crystal composition is formed.
[0084]
FIGS. 19A and 19B are plan views showing a state in which the color filter substrate CFP is overlaid on the glass substrate 1 in which the alignment film OR is formed at the corner portion CO shown in FIG. In FIG. 19, the color filter CFR is provided with a black matrix (also referred to as a black mask) BM as a light shielding film. The black matrix BM is provided with an opening OP. Generally, the opening OP is provided with a color filter that transmits R (red), G (green), and B (blue) colors. If one pixel is constituted by three dots of R (red), G (green), and B (blue), the opening OP constitutes one dot.
[0085]
Since the liquid crystal composition is not present in the portion where the seal material SE is provided, it does not contribute to display, and generally an opening OP is provided so as not to cover the seal material SE as shown in FIG. . However, in this case, there arises a problem that the width W1 of the black matrix BM frame becomes wide. For this reason, as shown in FIG. 19B, the black matrix BM is provided so that the opening OP partially overlaps the rounded corner portion CO so that the width W2 becomes narrow. In this case, a shadow SH due to roundness occurs in the corner portion CO, and the display quality is impaired.
[0086]
Here, as shown in FIG. 18B, the corner portion CO of the alignment film OR is covered with the sealing material SE, thereby forming a round shape overlapping the opening OP as shown in FIG. 19B with the sealing material SE. By making it round, it is possible to reduce the radius of roundness of the corner portion CO, thereby reducing the shadow SH generated in the opening OP.
[0087]
Further, similarly, as shown in FIGS. 20A and 20B, a planar protrusion PR1 is formed at the corner portion CO of the alignment film OR from the center portion CE to the outside. Alternatively, the alignment film material coating film may be applied so as to form a planar protrusion PR1, and then the protrusion PR1 with the corner CO close to substantially a right angle may be formed by drying and baking. At this time, since the evaporation rate can be locally changed by using the hot air drying process according to the present embodiment, the evaporation rate of the corner portion CO can be made different from that of other portions, and the roundness can be reduced. . For this reason, the nozzle mentioned above is formed so that control of the amount of hot air sprayed on the corner | angular part CO and its temperature is possible. Note that when the amount of hot air and its temperature are controlled so as to reduce roundness, the number of protrusions in the cross-sectional direction increases.
[0088]
Further, as shown in FIG. 20B, the sealing material SE is applied so as to partially overlap the alignment film OR so that the roundness of the region where the liquid crystal composition exists is reduced. In FIG. 20B, the end ED of the alignment film OR is indicated by a dotted line. Further, the position where the opening OP is formed is also indicated by a dotted line in order to avoid complication of the drawing. As described above, the shape of the corner portion CO of the alignment film OR and the shape of the corner portion of the opening OP of the black matrix BM adjacent to the corner portion CO can be made closer to each other by the sealing material SE.
[0089]
In the hot air drying process according to the present embodiment, the alignment film material coating film is formed to have a uniform film thickness, and thus the uneven portion of the transfer roller may remain on the surface of the alignment film material coating film. As shown in a schematic perspective view in FIG. 21A, a protrusion RO1 is provided on the surface of the transfer roller RO. The protrusion RO1 is provided to facilitate the holding of the alignment film material solution on the transfer roller RO. Yes. For this reason, as shown in FIG. 21B, the same unevenness OR1 is also formed in the alignment film OR obtained by baking the alignment film material coating film.
[0090]
In the embodiment described above, the case where the glass substrate is floated from the base plate by the substrate support pins has been described. However, the glass substrate may be floated from the base plate by a support member other than the substrate support pins. For example, you may make it the structure which forms the convex part which carries out a line contact with a glass substrate in a baseplate, and floats a glass substrate.
[0091]
In the hot air drying device described above, the case where the base plate is reciprocated with respect to the hot air flow forming means (nozzle) has been described. The nozzle may be configured to reciprocate. Furthermore, you may comprise so that both a nozzle and a baseplate may reciprocate relatively.
[0092]
In the above-described hot air drying apparatus, the case where the air supply blower 3 for supplying air to the inside of the chamber 2 and the exhaust blower 25 for exhausting unnecessary hot air inside the chamber 2 has been described. In addition, an inverter is provided in each of the exhaust blower 25 to balance the air supply amount and the exhaust amount, thereby preventing the influence of the surroundings due to the leakage of hot air from the chamber 2 and the poor drying due to the inflow of outside air into the chamber 2. Can do.
[0093]
Further, when hot air is supplied in the same amount as during the drying process when the glass substrate 1 is carried into the chamber 2, only the portion immediately below the nozzle 11 is first dried. In order to prevent this, when the glass substrate 1 is carried in, by controlling the motor rotation speed of the air supply blower 3 and the exhaust blower 25 by the inverter described above and reducing (stopping) the hot air supply amount by switching the three-way valve 6, Advance drying immediately below the nozzle 11 can be prevented. Further, it is possible to prevent the occurrence of uneven drying due to the temperature rise of the substrate support pins 14 during standby.
[0094]
Further, in the hot air drying apparatus described above, the upper surface exhaust grooves 13a and 13b for sucking up the rising of hot air into the chamber 2, the side surface exhaust grooves 16a and 16b for sucking hot air hitting the glass substrate 1, and the inside of the chamber 2 as a whole. In the above description, the three types of exhaust systems for the lower surface exhaust groove 17 for sucking unnecessary hot air are provided. However, the grooves 13a, 13b, 16a, 16b, and 17 are provided with slits or punchings, respectively, and the opening area thereof is reduced. By adjusting, the air flow in the chamber 2 can be controlled by adjusting the flow rate and flow velocity, and efficient drying and reduction of foreign matters can be achieved.
[0095]
In the hot air drying apparatus described above, the case where the plurality of substrate support pins 14 standing on the base plate 12 is fixed on the base plate 12 has been described. However, when the glass substrate 1 is carried into and out of the base plate 12. In addition, an actuator capable of changing the height of the substrate support pins 14 during the drying process is provided, and when the distance from the nozzle 11 needs to be changed due to the large allowable range, type, size, etc. when the glass substrate 1 is carried in / out Is possible.
[0096]
  As described above, the liquid crystal display device according to the present invention.Manufacturing methodAccording to the above, since there is no occurrence of uneven drying of the alignment film material coating film formed on the glass substrate and variation in the film thickness of the alignment film, there is no adverse effect on the alignment of the liquid crystal molecules on the alignment film surface. Therefore, it has an extremely excellent effect that a liquid crystal display device having good display characteristics can be obtained.
[0097]
  Also, the liquid crystal display device according to the present inventionManufacturing methodAccording to the above, since there is no occurrence of cracks in the glass substrate due to variations in temperature distribution in the glass substrate and bending due to electrostatic charging, the yield of the liquid crystal display device is improved, and thus productivity is greatly improved. It has extremely excellent effects such as being able to improve.
[0098]
  Also, the liquid crystal display device according to the present inventionManufacturing methodAccording to the present invention, the radius of the roundness inside the sealing material (liquid crystal composition side) is made larger than the radius of the roundness of the orientation film corner by forming a sealing material overlapping the corner of the orientation film formed on the glass substrate. In this case, it is possible to reduce the roundness of the region where the liquid crystal composition is formed.
[Brief description of the drawings]
FIG. 1 is a liquid crystal display device according to the present invention.Manufacturing methodIt is a system diagram which shows the structure of the hot air drying apparatus used as a premise means explaining the structure by one Example.
2 is a perspective view showing a configuration of a peripheral portion of hot air supply means housed in the chamber shown in FIG. 1. FIG.
FIG. 3 is a schematic perspective view of an experimental facility for examining the influence of a glass substrate support material on a substrate temperature distribution.
FIG. 4 is a diagram showing a configuration of a leveling device on which a hot air drying device according to the present invention is mounted.
FIG. 5 is a schematic diagram for explaining the mechanism of hot air drying by the hot air drying apparatus according to the present invention.
FIG. 6 is a view for explaining an in-plane temperature distribution of a glass substrate that has been subjected to hot air drying treatment by a hot air drying apparatus according to the present invention.
FIG. 7 is a schematic perspective view of an experimental facility for optimizing the hot air drying process.
FIG. 8 is a diagram illustrating a relationship between a drying time and a pretilt angle for each drying method.
FIG. 9 is a diagram conceptually showing the spread of a polymer in an alignment film forming material solution.
FIG. 10 is a diagram showing the relationship between the temperature in the chamber of the hot air drying apparatus according to the present invention and the surface roughness of the coating film after temporary drying.
FIG. 11 is a diagram showing the relationship between the temperature of hot air and the pretilt angle.
FIG. 12 is a cross-sectional view illustrating a drying process of an alignment film forming material solution using a hot plate.
13 is an enlarged cross-sectional view of an end portion of a coating film for explaining a mechanism for drying the alignment film forming material solution shown in FIG.
FIG. 14 is a liquid crystal display device according to the present invention.Manufacturing methodIt is sectional drawing explaining the drying process of the alignment film forming material solution formed with the hot air drying apparatus for demonstrating the structure by one Example.
15 is an enlarged cross-sectional view of an end portion of a coating film for explaining a mechanism for drying the alignment film forming material solution shown in FIG.
FIG. 16 is a diagram comparing the shapes of coating film end portions by hot plate drying and hot air drying of the hot air drying apparatus according to the present invention.
FIG. 17 is a diagram showing the shape of an alignment film formed on a glass substrate.
FIG. 18 is a plan view showing a state in which a sealing material is applied on an alignment film formed on a glass substrate.
19 is a plan view showing a state in which a color filter substrate is superimposed on the sealing material shown in FIG.
FIG. 20 is a plan view for explaining a structure for preventing a retraction of an alignment film at a corner of a glass substrate.
FIG. 21 is a perspective view showing a shape of an alignment film formed by hot-air drying of a transfer roller for applying an alignment film material and a coating film applied by the transfer roller.
FIG. 22 is a schematic cross-sectional view showing the configuration of a conventional drying apparatus using a hot plate.
FIG. 23 is a schematic cross-sectional view showing the configuration of a conventional drying apparatus using a hot plate.
[Explanation of symbols]
  1 Glass substrate
  2 Rear panel
  3 Air supply blower
  4 Heater
  5 Hepa filter
  6 Three-way valve
  7 Branch valve
  8 6 branch pipe
  9a Damper
  9b damper
  10 Soaking container
  11 nozzles
  11a Slit nozzle
  12 Base plate
  13a Top exhaust groove
  13b Top surface exhaust groove
  14 Support pin
  15 Transfer arm
  16a Side exhaust groove
  16b Side exhaust groove
  17 Bottom exhaust groove
  18 Oscillator
  18a Oscillator body
  18b motor
  18c ball screw
  19 Exhaust device
  20a damper
  20b damper
  21a damper
  21b damper
  22a damper
  22b damper
  23 Damper
  24 3-way valve
  25 Exhaust blower
  30 Alignment film material coating film
  30A A part 30A of the region opposite to the formation region
  SO solution
  PR protrusion
  OR alignment film
  ED alignment film edge
  CO alignment film corner
  CE alignment film center
  SE sealing material
  OP opening
  PR1 protrusion.

Claims (3)

Applying an alignment film material solution on one surface of the glass substrate, applying a flow of hot air to the alignment film material solution applied on the glass substrate, exhausting the remaining hot air remaining in the periphery of the glass substrate, and a plane with the glass substrate that intersects the flow of the hot air dried by relatively reciprocated in the plane direction to form an alignment film, the corner portion of the alignment film on the alignment layer by the drying A method of manufacturing a liquid crystal display device , wherein the protrusion is formed so that the film thickness is larger than the end of the alignment film. Wherein the alignment layer of the glass substrate having a sealing material on the formed face, the liquid crystal according to claim 1, characterized that you form a corner and weight so as to the sealing material of the alignment layer Manufacturing method of display device. The method according to claim 2, the corner portion of the alignment layer, and forming a protrusion protruding in the surface direction in the corners of the sealing material.

Images