JP3574451B2 - Liquid crystal display panel manufacturing method - Google Patents

Description

【００２９】
表１は、シール材の粘度と封止不良率との関係を示した表である。この表から分かるとおり、シール材の粘度が２０，０００ｃｐ以下のときは封止不良率が極めて高く、その粘度が５０，０００ｃｐ以上ではシール材不良の発生率は極めて低い。従って、シール材２として粘度が５０，０００ｃｐ以上の材料を使用することが好ましい。
【００３０】
（スペーサについて）
第二の基板４側の配向膜（不図示）の上にはスペーサ５が均一に散布、付着されている。スペーサ５は均一の大きさの微粒子であり、ほぼ球状のプラスチック等からなる。スペーサ５の径は、第一及び第二の基板１，４をシール材２で接着した際に基板間の液晶層の厚さを全体に渡って均一にするように決められる。また、スペーサ５の径は、後の工程で行われる第一及び第二の基板１、４の再位置合わせの際の基板移動を妨げないことも考慮しなければならない。
【００３１】
【表２】

【００３２】
表２は、基板間の液晶厚とスペーサ径との差が、基板の移動および液晶厚ムラとどのように関係するかを示した表である。液晶厚ムラは、基板間で実際に形成される液晶層の厚さの誤差を示している。ここでは、直径が５μｍ（早川ゴム製）のスペーサ５を用い、かつ、第一及び第二の基板１、４の液晶層の厚さを異ならせた場合に、基板再合わせによる基板移動の状態とパネル全体における液晶厚ムラについて示してある。ここで基板の移動の試験は、一方の基板を真空チャックで固定し、他方の基板を別の真空チャックで固定して横方向に５０Ｋｇの力を加えることにより行った。
【００３３】
表２から明らかなように、基板の移動に関しては液晶厚が５．０μｍ以下のとき、つまりスペーサ径と同じかそれよりも小さいときに基板の移動が不可能であった。これに対し、液晶厚さが５．２μｍ以上では移動可能であった。液晶厚ムラに関しては、液晶厚が５．８μｍで大きくなり、５．６μｍ以下では変化がないことがわかった。
【００３４】
これらを考慮すると、直径が５μｍのスペーサを使用する場合には液晶厚さを５．２〜５．６μｍとするのが好ましい。即ち、スペーサの最大の直径を基板間の液晶層の厚さより０．２〜０．６μｍ小さくするのが好ましいことがわかる。即ち、基板間の液晶層の厚さ、スペーサの径の４〜１２％程度大きいことが好ましい。 そこで本実施例では、スペーサ５を直径５μｍのものを使用し、第一及び第二の基板１、４の間の液晶厚を５．２μｍとした。
【００３５】
ところで、スペーサ５を第二の基板４の表面に付着させるためには、例えばスペーサ５を溶剤などに混ぜて８０〜９０℃の雰囲気中で第二の基板４の表面に吹き付ける方法が採用される。この方法によれば、スペーサ５が第二の基板４に到達する前に溶剤は蒸発し、第二の基板４の表面にはスペーサ５だけが粒の状態で付着する。このときスペーサ５は、第二の基板４の表面に静電気的または化学的な吸着により付着される。他のスペーサ付着法として、ドライ噴霧法などでもよい。
【００３６】
またスペーサとしては、例えば表面に接着剤の被膜が形成されたスペーサを使用することが好ましい。これにより、スペーサ５が第二の基板４に確実に付着され、液晶流れなどによりスペーサ５が流されてスペーサ５の分布が不均一になるのを防ぐことができる。従って、液晶パネル全体の液晶層の厚さの均一性が向上する。
【００３７】
このような効果は、スペーサが液晶の流れに抵抗できる程度の強さ又はそれ以上で固定されることで生ずるものであることはいうまでもなく、必ずしも表面が接着剤で皮膜処理されていることが必要というわけではない。例えば、スペーサ径と同じ段差を有する土手等を加工して形成したスペーサにおいても当然効果は生じるものである。
【００３８】
本実施例では、接着剤に被覆されたスペーサ（早川ゴム製）を第二の基板４の表面に付着させるために、従来のスペーサの付着処理に１５０℃で３０分の熱処理を施した。このようにシール材を形成し、スペーサを付着し、第一及び第二の基板１、４を張り合わせた後に、図１（ｂ） に示すように、第一及び第二の基板１、４の間のセル６に液晶３を充填する。
【００３９】
その液晶を充填する場合には、それらの基板１、４を真空中において、液晶３が滴下された第一の基板１の上に第二の基板４を載せて押さえ、シール材２が第二の基板４の表面と密着したところで、雰囲気を真空から大気圧に戻す。このとき、シール材２によって封止されたセル６の内部は真空であり、セル６の外側は大気圧になるので、その圧力差によって第二の基板４は第一の基板１の方に引き寄せられ、結果的に液晶３は第一及び第二の基板１，４の面に沿って拡がる。
【００４０】
この場合、周囲の雰囲気を大気圧に戻す時点で液晶３が急激にセル内部に広がるため、液晶３に急激な流れが生じるが、本実施例では接着剤付きのスペーサを使用しているため、スペーサ５が液晶３の流れに押し流されてスペーサ分布が偏ることはなく、スペーサ５を均一に分布した状態で維持することができる。また、このときキャップ６の内側と外側には大きな気圧差があり、シール材２は大きな圧力を受けるが、シール材２はまだ未硬化なため封止不良が生じやすい。しかし、本実施例ではシール材２として粘度が５０，０００ｃｐの材料を使用しているので、その圧力によって損傷を受け難くなり、封止不良の発生を大幅に低減することができる。
【００４１】
第一及び第二の基板１、４の間のギャップ６に液晶３が完全に充填された状態を示すと図１（ｃ） のようになり、その液晶厚は所定値ｄになる。ここで液晶厚ｄは５．２μｍである。図には詳しく示していないが、実際にはスペーサ５は第一の基板１の表面と均一に接してはいない。第一及び第二の基板１、４のそれぞれの電極形成側には樹脂製の配向膜などが形成されているため平坦ではなく凹凸があり、さらにガラス基板自体にも湾曲があるため、液晶厚ｄはスペーサ５の直径よりも大きな値となる。
【００４２】
この時点では、シール材２は硬化していないので、第一の基板１又は第二の基板４の位置をずらして再位置合わせを行う。この工程は大気圧下で行われる。このとき、スペーサ５の径が第一及び第二の基板１、４の間の液晶層の厚さよりも０．２μｍ小さいため、第一及び第二の基板１、４の相互の移動が妨げられることがなく再位置合わせを容易且つ確実に行うことができる。
【００４３】
再位置合わせ後、図１（ｄ） に示すように、高圧水銀灯により紫外線７をシール材２に照射して硬化させ、第一及び第二の基板１、４を固定する。次に図１（ｅ） では、第二の基板４のシール材７よりも外側の部分を切断し、シール材２の外部にある第一及び第二の基板１、４の間の不要なスペーサ５、液晶３とともに除去する。したがって液晶表示パネルが簡素化され扱いやすくなる。
【００４４】
以上のように、本実施例では、接着剤付きのスペーサを利用することによって、パネル全体に渡ってスペーサの均一分布を維持することができ、従来１０インチクラスで１時間以上かかった作業が数分で完了する。また、基板間の液晶層の厚さより０．２μｍ小さい直径のスペーサを使用することで、基板の再位置合わせのための基板移動を確実に行えるようになる。さらに、シール材として、粘度が５０，０００ｃｐ以上のシール材料を使用しているので、封止不良の発生を低減でき液晶パネルの歩留まりを向上できる。
【００４５】
以上のような条件を満たすように、液晶パネルを作成することは必ずしも容易ではない。スペーサ径については、各種径のものが市販されており、容易に入手可能であるが、液晶を移管に一定量、高精度でかつ再現性良く滴下して供給するかが本技術のポイントとなる。本発明者は、種々のディスペンサを用いて調査検討した結果、電磁開閉式先端ニードル型のものが最良で且つ唯一適用可能であることを見いだした。
【００４６】
表３は、各種ディスペンサについて精度を調べた結果である。
【００４７】
【表３】

【００４８】
電磁開閉先端ニードル式のディスペンサは、例えば図２（ａ） に示すような構造を有している。図２（ａ） において、液晶３を収納する液晶収納器１１の下端には先が尖ったキャップ１２が取付けられ、そのキャップ１２の中央には通液孔１３が１つ形成されている。また、キャップ１２の通液孔１３の上には、電磁式で上下に移動可能なニードル１４が配置され、その上下動によってニードル１４の下端が通液孔１３の上部孔を閉じたり開いたりするように構成されている。また、液晶収納器１１の内部は常に一定圧力となるように調整されている。
【００４９】
次に、電磁開閉先端ニードル式のディスペンサを用いて液晶滴下供給性能を図に示す。例えばノードン製アキュラジェッタを用いた。また、液晶はＺＬＩ−４７９２（メルク製）を用いた。液晶収納器１１の内部圧力は例えば４ｋｇｆ／ｃｍ^２ 、ニードル１４の太さは例えば２６Ｇである。
【００５０】
ディスペンス時間（ニードルバルブの開時間）と液晶滴下量との関係と、ディスペンス時間の各時点における単位時間当たりの液晶滴下量の実験結果を図２（ｂ） に示す。この実験によれば、ディスペンス時間と液晶滴下量の間には良好な線形関係があり、また、単位時間あたりの液晶滴下量は高い精度で一定となっている。
【００５１】
次に、電磁開閉先端ニードル式のディスペンサによる液晶のショット数の増加に伴う液晶滴下量の精度と再現性を試験したところ、図３に示すような結果が得られた。これによれば、液晶を連続して２日間で１００回ショットしたところ、ディスペンサ量の誤差は±１％以内であり、高精度、高再現性が得られた。なお、１日目と２日目のショットの条件は同じに設定した。
【００５２】
電磁開閉先端ニードル式のディスペンサは、真空中で使用することも構造上可能であるので、真空雰囲気で液晶を滴下する滴下注入法にも適していることがわかる。なお、一般的に液晶は大気圧中で滴下される。
【００５３】
（第２実施例）
本実施例では、紫外線７によるシール材２と液晶３との反応を防ぎその反応によって生じる液晶３の汚染を防止するために、シール材２に内側近傍に沿った第二の基板４の下面に遮光膜を設けらている。その詳細を以下に述べる。
【００５４】
図４（ａ） は、第二の基板４に形成された遮光膜８の平面図、図４（ｂ） はその断面図である。図４（ａ） では、透明な第二の基板４を通してその裏側に形成された遮光膜８が示されている。遮光膜８は、枠状のシール材２の内側に沿った領域であって、表示領域９の外側に形成され、シール材２および表示領域９には重ならないように決められる。遮光膜８の形成領域がシール材２と重なったり近過ぎれば、シール材２に硬化されない部分が生じるので、遮光膜８とシール材２との間にはわずかな隙間を設けることが好ましい。また遮光膜８は、第二の基板４の上側に形成してもよいが、遮光精度の点からは第二の基板４の下側の方が好ましい。
【００５５】
遮光膜８は、表示品質を高めるために第二の基板４に形成されるブラックマトリクス膜を構成する膜（例えばクロム膜）をパターニングして形成すると、製造工程を複雑化させることはない。シール材２を硬化させるために紫外線を照射する際には、第一及び第二の基板１．４の外部に図４（ｂ） のような遮光マスク１０を置いて表示領域９の紫外線照射を防止する。遮光膜８による遮光領域は表示領域９とシール材２の形成領域との間に限られているからである。
【００５６】
また、紫外線を第一の基板１の側から照射してシール材７を硬化させる場合は、遮光膜を第一の基板１側に設けてもよいが、第一の基板１にはバスラインなどの配線がＡｌなどの金属で形成されており、そのため遮光膜は絶縁性材料で形成することが好ましい。このように、遮光膜８を設けることによって、シール材２近傍の液晶３に照射される紫外線量を大幅に少くすることができるので、紫外線照射によるシール材２と液晶３との反応を低減し、液晶７の汚染を極めて少くすることができる。しかも外部の遮光マスク１０によって表示領域での液晶とシール材２の微量な分子との反応を防止して液晶７の汚染の発生を抑制している。
【００５７】
以上のように、本実施例では、シール材近傍にある液晶の紫外線照射を防止するようにしているので、紫外線照射によるシール材硬化の際に、シール材２と液晶４の反応による液晶の汚染を回避できる。シール材としてＴ−４７０（カチオン重合型、長瀬チバ製、１０万ｃｐ）を用い、上記したように遮光して液晶電気抵抗の低下を電圧保持率の評価により行ったところ、液晶保持率の低下は殆ど見られなかった。なお、液晶３として、ＺＬＩ−４７９２（メルク製）を用い、シール材２の紫外線の照射条件は５０００ｍＪ／ ｃｍ^２ とした。
【００５８】
なお、紫外線をビーム状にして枠状のシール材２のみに照射してもよく、この場合には、遮光膜を用いる必要はなくなる。
【００５９】
（第３の実施例）
本発明の第３実施例に係る液晶表示パネルの製造方法は、第１の実施例で説明したものと全体的な流れは同じであるが、対向する２枚の基板を封止するためのシール材の形成方法が異なる。
【００６０】
図５（ａ），（ｂ） は、液晶が封入された状態にある液晶表示パネルの平面図及び断面図である。図５（ａ） において、パネル内のシール材２ａの外側にシール材２ｂが形成されており、シール材２ａの内側には液晶３が封入されている。シール材２ａと２ｂの間の空間は真空であり、シール材２ｂの外側は大気である。このような２重のシール材２ａと２ｂを形成するためには、第一及び第二の基板１、４を重ねる前に、真空中で第一の基板１にシール材２ａ、２ｂを付着させる。そして、第一及び第二の基板１、４を重ね合わせて接着し雰囲気を大気圧にすると、第一及び第二の基板１、４が引き寄せられて液晶３がシール材２ａの内部に充填される。このとき、シール材２ｂの外側は大気圧になるが、シール材２ａとシール材２ｂとの間は真空のままである。
【００６１】
周囲の雰囲気を大気圧にして液晶３を基板間に封入する際、液晶３がシール材２ａの内側に完全に充填されるまではシール材２ａの内側はほぼ真空である。しかし、このようにシール材を２重に設けることによって、シール材２ａの外側も真空にした状態にすることができる。したがって、シール材２ａの内外に急激な圧力差が生じるのを防ぐことができ、シール材２ａの封止不良の発生を回避することができる。
【００６２】
また、液晶３の封入が完了し少なくともシール材２ａを硬化させた後で、第二の基板４のシール材２ａよりも外側は切断して取り除かれる。そのため、シール材２ｂの材料はあまり限定されず様々な材料を使用することができる。このように、シール材の枠を２重に設けることによって、封止不良を低減でき液晶パネルの歩留まりを向上することができる。
【００６３】
以上述べたように本発明によれば、透明電極等を有する基板に、シール材の枠を形成してその枠内に液晶を滴下し、スペーサを付着させた別の基板を真空中で重ね合わせて周囲を大気圧に戻すことによって基板間に液晶を封入し、そしてシール材を硬化させる液晶表示パネルおよびその製造方法において、スペーサとして直径が基板間の液晶層の厚さよりも少くとも０．２μｍ小さいものを使用することにより、基板間の液晶層の厚さの均一性を維持しつつ再位置合わせの際の基板の移動を確実に行うことができる。
【００６４】
また、スペーサとして接着剤付きのスペーサを使用することにより、液晶流れによりスペーサが流されてスペーサの分布が偏るのを防ぐことができる。これにより、パネル全体に渡る基板間の液晶層の厚さの均一性が向上する。また、シール材として粘度が５００００ｃｐ以上のものを使用することにより、シール材が外力に対して強くなるので封止不良を低減することができる。さらに、シール材の枠を２重に設けることによって、液晶を封止する枠の内外の圧力差を緩和できるので、封止不良を低減することができる。これにより、液晶表示パネルの歩留まりを向上させることができる。
【００６５】
また、シール材として紫外線硬化型の材料を使用し硬化させる際に紫外線を照射する場合でも、基板のシール材近傍に遮光膜を設けることによって、紫外線により液晶とシール材が反応して生じる液晶の汚染を防ぐことができるので、液晶表示パネルの表示性能を高め安定化させることができる。本発明での液晶材料の滴下は、ニードルによって開閉するディスペンサを使用しているので、滴下量を高精度で均一化でき、しかも再現性を良くできる。
【図面の簡単な説明】
【図１】図１（ａ） 〜（ｅ） は、本発明の第１の実施例に係る液晶表示パネルの製造方法を概略的に示す断面図である。
【図２】図２（ａ） は本発明の第１実施例に使用する電磁開閉先端ニードル式の液晶ディスペンサの概略を示す断面図、図２（ｂ） はティスペンス時間とディスペンス量の関係を示すグラフとディスペンス時間の経過に沿った単位時間当たりのディスペンス量の変化を示すグラフである。
【図３】図３は、電磁開閉先端ニードル式の液晶ディスペンサによるショット回数とディスペンス量の関係を示すグラフである。
【図４】図１に示した液晶表示パネルの製造方法の一工程を詳細に示し、図４（ａ） は平面図、図４（ｂ） は断面図である。
【図５】本発明の第２の実施例に係る液晶表示パネルの製造方法の一工程を示し、図５（ａ） は平面図、図５（ｂ） は断面図である。
【図６】液晶表示パネルの製造方法を概略的に示し、図６（ａ） 〜（ｃ） はそれぞれ各工程を示す斜視図である。
【図７】従来の液晶表示パネルの製造方法により生じたシール材の封止不良を示す平面図である。
【図８】従来の液晶表示パネルの製造方法において、パネル内の異なる位置の液晶の電圧保持率の変化を示すグラフである。
【符号の説明】
１、４、２１、２４ 基板
２、２ａ、２ｂ、２２ シール材
３、２３ 液晶
５ スペーサ
６ セル
７ 紫外線
８ 遮光膜
９ 表示領域
１０ 遮光部材
１１ 液晶収納器
１２ キャップ
１３ 通液孔
１４ ニードル[0001]
[Industrial applications]
The present invention relates to a method for manufacturing a liquid crystal display panel, and more particularly, to a method for manufacturing a liquid crystal display panel formed by dropping a liquid crystal material on a substrate and sealing the liquid crystal material between opposing substrates.
[0002]
[Prior art]
2. Description of the Related Art Liquid crystal display devices are widely used as display devices because of their small thickness, light weight, and low power consumption. A liquid crystal panel for displaying characters and images, which is a main part of a liquid crystal display device, has a first substrate on which a transparent electrode is formed and a second substrate on which a driving circuit such as a TFT is formed. A liquid crystal material is sealed between the substrates.
[0003]
As a method of sealing liquid crystal between a pair of substrates, for example, there is a vacuum injection method or a vacuum drop injection method. In the vacuum injection method, an empty cell is formed by stacking two substrates at a predetermined interval with a frame-shaped sealing member partially having an opening therebetween, and the empty cell is put into a chamber to depressurize the inside. Then, the opening of the empty cell is immersed in the liquid crystal material, and then the pressure inside the chamber is increased by introducing nitrogen or the like into the chamber. Is sucked into the empty cell and filled. For example, it is proposed in Japanese Patent Application Laid-Open No. 62-89025.
[0004]
However, according to this method, when producing a large-sized liquid crystal panel, it takes a long time to evacuate the chamber. Further, a large amount of liquid crystal material is required to immerse the empty cell, so that the cost increases. Further, it takes time and effort to seal the opening after the liquid crystal is sealed and to wash the liquid crystal attached around the opening. On the other hand, the vacuum drop injection method has many advantages. FIG. 6 is a perspective view schematically showing a liquid crystal sealing step in the vacuum drop injection method, and FIGS. 6 (a) to 6 (c) show respective steps.
[0005]
In FIG. 6A, a sealing material 22 made of a photocurable resin is attached in a frame shape on a first substrate 21 on which a pixel electrode, a TFT element, an alignment film and the like are formed. Liquid crystal 23 is dropped inside the frame of the sealing material 22. Further, a transparent electrode and an alignment film are also formed on the second substrate 24, and the surface on the transparent electrode forming side faces the pixel electrode forming surface of the first substrate 21. Spacers (not shown) are uniformly dispersed on the alignment film of the second substrate 24. The spacers are substantially spherical fine particles having a diameter of several μm made of resin or the like. When the first and second substrates 21 and 24 are bonded together, a gap between the substrates 21 and 24 is formed over the entire panel. Used for uniformity across.
[0006]
Next, as shown in FIG. 6B, a second substrate 24 to which a spacer is attached is superposed in vacuum on the first substrate 21 on which the liquid crystal 23 has been dropped. When the sealing material 22 comes into contact with the second substrate 24 and a closed space is formed between the first and second substrates 21 and 24 by the frame of the sealing material 22, when the surroundings are changed from vacuum to atmospheric pressure, the cell The first and second substrates 21 and 24 are drawn by the pressure difference between the inside and outside. At this time, as the distance between the first and second electrode substrates 21 and 24 is reduced, the liquid crystal 23 is radially spread between the first and second substrates 21 and 24 in the horizontal direction.
[0007]
As a result, as shown in FIG. 6C, the liquid crystal 23 is completely filled in the frame of the sealing material 22 between the first and second substrates 21 and 24. Here, the gap between the first and second substrates 21 and 24 is made uniform over the entire panel by the spacer. At this time, repositioning is performed to precisely align the mutual positions of the first and second substrates 21 and 24 at the pixel level. This is performed by moving the first substrate 21 or the second substrate 24 in the lateral direction. When the repositioning is completed, the sealing material 22 is cured by irradiating ultraviolet rays, and the sealing of the liquid crystal is completed.
[0008]
[Problems to be solved by the invention]
However, such a method of manufacturing a liquid crystal display panel has the following problems. First, when a liquid crystal is dropped on one substrate and two substrates are bonded to each other, a sharp flow of the liquid crystal occurs between the two substrates. For this reason, the spacer, which has been uniformly attached in advance, may move due to the rapid flow of the liquid crystal, spread radially from the center of the panel, and may be biased annularly or may be biased toward the sealing material at the end of the panel. When the spacer distribution is uneven, the gap between the substrates on the panel surface becomes non-uniform, and the performance of the liquid crystal panel may be reduced.
[0009]
Further, depending on the relationship between the spacer diameter and the gap thickness between the substrates, the spacers and the substrate surface sometimes come into contact with each other more strongly than necessary. For this reason, when the substrate is moved for repositioning, the spacer may come into strong contact with the substrate surface, damaging the alignment film or the electrode film, or hindering the movement of the substrate. When filling the cells between the substrates with the liquid crystal, the pressure difference between the inside and the outside of the frame of the sealing member is used, but at the time of filling, the sealing member is still in an uncured and soft state. Therefore, the pressure may crack the sealing member and cause poor sealing.
[0010]
FIG. 7 shows a liquid crystal display panel in which such a sealing failure has occurred, in which two types of cracks 22a and 22b are formed in a sealing member 22 sandwiched between first and second substrates 21 and 24. One of the cracks 22a is generated by the pressure of the atmosphere acting from the outside to the inside of the frame of the sealing member 22 when the inside of the frame of the sealing member 22 is in a vacuum. The other crack 22b often occurs due to the pressure of the liquid crystal material 23 acting from the inside to the outside of the frame 22 and the compatibility between the liquid crystal and the sealing material. When such cracks 22a and 22b occur in the sealing member 22, the liquid crystal material leaks from the cell or air enters the cell, thereby deteriorating the display characteristics of the liquid crystal display panel.
[0011]
One of the factors related to the display performance of the liquid crystal display panel is contamination of liquid crystal. The contamination of the liquid crystal can be determined by measuring the voltage holding ratio between the opposed electrodes sandwiching the liquid crystal. The higher the voltage holding ratio, the higher the ability to maintain the potential difference between the opposing electrodes and the higher the ability to drive the liquid crystal. FIG. 8 is a graph in which the change in the voltage holding ratio depending on the irradiation time of the ultraviolet rays for curing the sealing member is measured at the center and the end of the liquid crystal display panel. In this graph, the horizontal axis indicates the ultraviolet irradiation time, the vertical axis indicates the voltage holding ratio of the liquid crystal, and the lines of the graph indicate A in the center of the display panel and B in the vicinity of the sealing member of the display panel. As can be seen from this graph, the voltage holding ratio of the liquid crystal in the central part of the liquid crystal display panel hardly changes even when the ultraviolet ray is irradiated for a long time. The longer the is, the lower it is. The ultraviolet irradiation conditions were within the range recommended by the manufacturer.
[0012]
This is because, when the liquid crystal in the vicinity of the sealing member is irradiated with ultraviolet rays, the liquid crystal reacts with the sealing member, and the reaction product dissolves in the liquid crystal to contaminate the liquid crystal. Although the contamination of the liquid crystal occurs near the sealing member, it spreads over time and deteriorates the performance of the entire liquid crystal display panel. The present invention has been made in view of such a conventional problem, and when a liquid crystal is sealed between substrates by a vacuum dropping method, spacers are uniformly distributed over the entire liquid crystal panel. It is an object of the present invention to provide a method of manufacturing a liquid crystal display panel that makes the gap between them uniform to enhance the display performance of the liquid crystal display panel, prevents damage to the substrate surface by spacers, and facilitates movement of the substrate for repositioning. Aim.
[0013]
Further, the present invention provides a liquid crystal display panel that can prevent a defective sealing due to cracking of a sealing member when sealing a liquid crystal between substrates by a vacuum drop injection method, and can improve the yield of the liquid crystal display panel. It is an object of the present invention to provide a method for producing the same. Still another object of the present invention is to provide a method of manufacturing a liquid crystal display panel capable of reducing contamination of liquid crystal caused by irradiation of ultraviolet rays for curing a sealing member and improving display performance of the liquid crystal display panel.
[0014]
[Means for Solving the Problems]
The above-described problem is solved by a sealing material applying step of forming a closed frame made of a sealing material on at least one inner surface of a pair of substrates along the surface, and a liquid crystal supply for dropping a liquid crystal material onto the one inner surface. And a step of forming a liquid crystal layer between the pair of substrates by superimposing the inner surfaces of the pair of substrates facing each other under reduced pressure, returning to atmospheric pressure, spreading the liquid crystal material, and forming the liquid crystal layer between the pair of substrates. And a sealing material curing step of irradiating the sealing material with light to cure the sealing material, wherein the pressure inside and outside the sealing material is outside the sealing material under the atmospheric pressure. The problem is solved by a method of manufacturing a liquid crystal display panel having a pressure difference relaxation region for reducing a difference.
[0015]
In the sealing material applying step, the closed frame is applied at least twice.
[0017]
The sealing material curing step is characterized in that the sealing material is cured by irradiating only the sealing material with a beam of light.
[0018]
In the liquid crystal supply step, a drop amount of the liquid crystal material is within 1% of a desired drop amount. In the liquid crystal supply step, a liquid crystal material container having a liquid crystal supply hole on the lower side and an internal pressure kept constant, and a dispenser having a needle disposed in the liquid crystal material container and opening and closing the liquid crystal supply hole is used. In this case, the amount of the liquid crystal material dropped is adjusted. Before the sealing material curing step, the pair of substrates is re-aligned. 2. The method according to claim 1, further comprising a spacer fixing step of fixing a spacer to the one inner surface, wherein the spacer is smaller by 0.2 to 0.6 [mu] m or 4 to 12% than the thickness of the liquid crystal layer. 4. The method for manufacturing a liquid crystal display panel according to any one of the above items. After the sealing material curing step, at least the innermost closed frame is cut off and cut off.
[0019]
[Operation]
According to the present invention, fine particles having a maximum diameter of at least 0.2 to 0.6 μm or 4 to 12% smaller than a liquid crystal layer formed in a pair of substrates constituting a liquid crystal display panel and covered with an adhesive material By adhering and fixing to one substrate, the substrate can be reliably moved for repositioning without damaging the inner surface of the substrate. This has been confirmed experimentally.
[0020]
In addition, a frame of a sealing material is formed on the electrode forming side of the substrate, fine particles with an adhesive are attached to the inside of the opposing substrate, liquid crystal is dropped into the frame of the sealing material, and the liquid crystal is sealed under reduced pressure. Thereby, the fine particles can be securely attached to the substrate. Therefore, it is possible to prevent the fine particles from flowing due to a sudden liquid crystal flow when the liquid crystal is filled between the substrates and the particles are unevenly distributed on the substrate, and the uniformity of the liquid crystal thickness between the substrates on the panel surface is reduced. Can be enhanced. In particular, since the fine particles having the above-mentioned diameter are easy to flow, it is necessary to cover the fine particles with an adhesive.
[0021]
Also, at least a double frame of sealing material is provided on the electrode forming side of the substrate along the plane of the substrate, and the liquid crystal is sealed by dropping liquid crystal inside the frame and sealing it under reduced pressure. The pressure difference between the inside and outside of the sealing material at the time of sealing is reduced, and the occurrence of sealing failure can be reduced. Further, by removing the substrate while leaving at least the innermost part of the frame of the sealing material, an unnecessary sealing frame is finally removed and the liquid crystal display panel is simplified.
[0022]
Further, a light-shielding means is provided near the inside of the frame of the photocurable sealing material attached to the electrode forming side of the substrate, the liquid crystal material is dropped and sealed in the frame of the sealing material, and the sealing material is irradiated with ultraviolet rays to seal the sealing material. By curing, contamination of the liquid crystal caused by the reaction between the liquid crystal and the sealing material due to irradiation with ultraviolet light can be prevented. Thereby, the display performance of the liquid crystal display panel can be improved.
[0023]
In the present invention, a liquid crystal material is dropped using a dispenser which is opened and closed by a needle. According to this, it was experimentally confirmed that the drop amount can be made uniform with high precision and reproducibility is good.
[0024]
【Example】
Therefore, embodiments of the present invention will be described below with reference to the drawings.
[0025]
(First embodiment)
1A to 1E are cross-sectional views schematically showing a method for manufacturing a liquid crystal display panel according to a first embodiment of the present invention.
[0026]
In these figures, the first substrate 1 is made of, for example, glass, etc., and in practice, a transparent electrode such as ITO and an alignment film are formed on one surface thereof, and circuits such as TFT elements and bus lines are patterned. Liquid crystal is supplied on the TFT elements and the like, but transparent electrodes, TFTs and the like are omitted in the figure for clarity of explanation. First, as shown in FIG. 1A, a sealing material 2 made of an ultraviolet curable resin or the like is formed in a frame shape on the surface of the first substrate 1 on the electrode forming side. A predetermined amount of liquid crystal 3 is dropped by a known method. The surface of the first substrate 1 on which the liquid crystal 3 has been dropped is disposed to face the surface of the second substrate 4 to which the spacer 5 is attached.
[0027]
The second substrate 4 is made of a transparent material such as glass and quartz. Further, a black matrix, a color filter, a common transparent electrode, and an alignment film are sequentially formed on a side of the second substrate 4 facing the first substrate 1, but these are omitted for simplicity of description. ing. Next, the sealing material and the spacer employed in this embodiment will be described.
(About sealing material)
The sealing material 2 is, for example, a UV-curing type, and serves as an adhesive for the first and second substrates 1 and 4 in a later step, and is used for defining a space for enclosing the liquid crystal 3 between the substrates. It is important to select a sealing material having an appropriate viscosity so that the sealing material 2 does not cause sealing failure due to a pressure difference between the inside and outside of the cell when filling 3.
[0028]
[Table 1]

[0029]
Table 1 is a table showing the relationship between the viscosity of the sealing material and the sealing failure rate. As can be seen from the table, when the viscosity of the sealing material is 20,000 cp or less, the sealing failure rate is extremely high, and when the viscosity is 50,000 cp or more, the rate of occurrence of the sealing material failure is extremely low. Therefore, it is preferable to use a material having a viscosity of 50,000 cp or more as the sealing material 2.
[0030]
(About spacer)
Spacers 5 are uniformly scattered and adhered on the alignment film (not shown) on the second substrate 4 side. The spacers 5 are fine particles of a uniform size, and are made of substantially spherical plastic or the like. The diameter of the spacer 5 is determined so that when the first and second substrates 1 and 4 are bonded with the sealing material 2, the thickness of the liquid crystal layer between the substrates is made uniform over the whole. It is also necessary to consider that the diameter of the spacer 5 does not hinder the movement of the substrate when repositioning the first and second substrates 1 and 4 performed in a later step.
[0031]
[Table 2]

[0032]
Table 2 is a table showing how the difference between the liquid crystal thickness and the spacer diameter between the substrates is related to the movement of the substrates and the liquid crystal thickness unevenness. The liquid crystal thickness unevenness indicates an error in the thickness of the liquid crystal layer actually formed between the substrates. Here, when the spacer 5 having a diameter of 5 μm (made by Hayakawa Rubber) is used and the thicknesses of the liquid crystal layers of the first and second substrates 1 and 4 are varied, the state of the substrate movement by the substrate realignment is described. And the liquid crystal thickness unevenness in the entire panel. Here, the test of the movement of the substrate was performed by fixing one substrate with a vacuum chuck and fixing the other substrate with another vacuum chuck and applying a force of 50 kg in the lateral direction.
[0033]
As is clear from Table 2, with respect to the movement of the substrate, when the liquid crystal thickness was 5.0 μm or less, that is, when the spacer diameter was equal to or smaller than the spacer diameter, the movement of the substrate was impossible. On the other hand, when the thickness of the liquid crystal was 5.2 μm or more, it was movable. Regarding the liquid crystal thickness unevenness, it was found that the liquid crystal thickness was increased at 5.8 μm, and did not change at 5.6 μm or less.
[0034]
In consideration of these, when a spacer having a diameter of 5 μm is used, the thickness of the liquid crystal is preferably set to 5.2 to 5.6 μm. That is, it is understood that it is preferable that the maximum diameter of the spacer be smaller by 0.2 to 0.6 μm than the thickness of the liquid crystal layer between the substrates. That is, the thickness of the liquid crystal layer between the substrates and the diameter of the spacer are preferably about 4 to 12% larger. Therefore, in this embodiment, the spacer 5 having a diameter of 5 μm is used, and the liquid crystal thickness between the first and second substrates 1 and 4 is set to 5.2 μm.
[0035]
Incidentally, in order to attach the spacer 5 to the surface of the second substrate 4, for example, a method is employed in which the spacer 5 is mixed with a solvent or the like and sprayed onto the surface of the second substrate 4 in an atmosphere at 80 to 90 ° C. . According to this method, the solvent evaporates before the spacer 5 reaches the second substrate 4, and only the spacer 5 adheres to the surface of the second substrate 4 in the form of particles. At this time, the spacer 5 is attached to the surface of the second substrate 4 by electrostatic or chemical adsorption. As another spacer attachment method, a dry spray method or the like may be used.
[0036]
As the spacer, it is preferable to use, for example, a spacer having a surface coated with an adhesive. Thereby, the spacers 5 are securely attached to the second substrate 4, and it is possible to prevent the spacers 5 from flowing due to the liquid crystal flow or the like, thereby preventing the spacers 5 from being unevenly distributed. Therefore, the uniformity of the thickness of the liquid crystal layer of the entire liquid crystal panel is improved.
[0037]
Needless to say, such an effect is caused by the spacer being fixed at a strength or higher enough to resist the flow of the liquid crystal, and that the surface is not necessarily coated with an adhesive. Is not necessary. For example, the effect can be naturally obtained in a spacer formed by processing a bank or the like having the same step as the spacer diameter.
[0038]
In this embodiment, in order to attach the spacer (made by Hayakawa Rubber) coated with the adhesive to the surface of the second substrate 4, a conventional heat treatment for attaching the spacer was performed at 150 ° C. for 30 minutes. After the sealing material is formed, the spacer is attached, and the first and second substrates 1 and 4 are bonded to each other, as shown in FIG. The liquid crystal 3 is filled in the inter-cell 6.
[0039]
When the liquid crystal is filled, the substrates 1 and 4 are placed in a vacuum, and the second substrate 4 is placed on the first substrate 1 on which the liquid crystal 3 is dropped, and is pressed. When it comes into close contact with the surface of the substrate 4, the atmosphere is returned from vacuum to atmospheric pressure. At this time, the inside of the cell 6 sealed by the sealing material 2 is in a vacuum, and the outside of the cell 6 is at atmospheric pressure, so that the second substrate 4 is drawn toward the first substrate 1 by the pressure difference. As a result, the liquid crystal 3 spreads along the surfaces of the first and second substrates 1 and 4.
[0040]
In this case, when the surrounding atmosphere is returned to the atmospheric pressure, the liquid crystal 3 rapidly expands inside the cell, so that a rapid flow occurs in the liquid crystal 3. However, in this embodiment, since the spacer with the adhesive is used, The spacers 5 are not pushed by the flow of the liquid crystal 3 and the spacer distribution is not biased, and the spacers 5 can be maintained in a uniformly distributed state. At this time, there is a large pressure difference between the inside and the outside of the cap 6, and the sealing member 2 receives a large pressure. However, since the sealing member 2 is not yet cured, sealing failure easily occurs. However, in this embodiment, since a material having a viscosity of 50,000 cp is used as the sealing material 2, it is hardly damaged by the pressure, and the occurrence of poor sealing can be greatly reduced.
[0041]
FIG. 1C shows a state where the liquid crystal 3 is completely filled in the gap 6 between the first and second substrates 1 and 4, and the liquid crystal thickness becomes a predetermined value d. Here, the liquid crystal thickness d is 5.2 μm. Although not shown in detail in the drawing, the spacer 5 is not actually in uniform contact with the surface of the first substrate 1. Since an alignment film made of resin is formed on each of the first and second substrates 1 and 4 on which the electrodes are formed, the substrate is not flat, but has irregularities. d is a value larger than the diameter of the spacer 5.
[0042]
At this point, since the sealing material 2 has not been cured, the position of the first substrate 1 or the second substrate 4 is shifted and repositioning is performed. This step is performed under atmospheric pressure. At this time, since the diameter of the spacer 5 is smaller than the thickness of the liquid crystal layer between the first and second substrates 1 and 4 by 0.2 μm, mutual movement of the first and second substrates 1 and 4 is prevented. Thus, repositioning can be performed easily and reliably.
[0043]
After the repositioning, as shown in FIG. 1D, the sealing material 2 is irradiated with ultraviolet rays 7 by a high-pressure mercury lamp to be cured, and the first and second substrates 1 and 4 are fixed. Next, in FIG. 1E, a portion of the second substrate 4 outside the sealing material 7 is cut, and unnecessary spacers between the first and second substrates 1 and 4 outside the sealing material 2 are cut. 5. Remove with the liquid crystal 3. Therefore, the liquid crystal display panel is simplified and easily handled.
[0044]
As described above, in the present embodiment, by using the spacer with the adhesive, it is possible to maintain the uniform distribution of the spacer over the entire panel, and it takes several hours or more for the conventional 10-inch class. Complete in minutes. Further, by using a spacer having a diameter of 0.2 μm smaller than the thickness of the liquid crystal layer between the substrates, the substrate can be reliably moved for repositioning the substrates. Furthermore, since a sealing material having a viscosity of 50,000 cp or more is used as the sealing material, occurrence of defective sealing can be reduced, and the yield of the liquid crystal panel can be improved.
[0045]
It is not always easy to create a liquid crystal panel so as to satisfy the above conditions. Regarding the spacer diameter, various diameters are commercially available and easily available, but the point of this technology is to supply a fixed amount of liquid crystal to the transfer tube with high precision and reproducibility. . The present inventor has conducted investigations using various dispensers, and as a result, has found that an electromagnetic opening / closing tip needle type is the best and only applicable.
[0046]
Table 3 shows the results of examining the accuracy of various dispensers.
[0047]
[Table 3]

[0048]
The electromagnetic opening / closing tip needle type dispenser has, for example, a structure as shown in FIG. In FIG. 2A, a sharp cap 12 is attached to the lower end of a liquid crystal container 11 for storing the liquid crystal 3, and one liquid passage hole 13 is formed in the center of the cap 12. An electromagnetically movable needle 14 is disposed above the liquid passage hole 13 of the cap 12, and the lower end of the needle 14 closes or opens the upper hole of the liquid passage hole 13 by the vertical movement. It is configured as follows. Further, the inside of the liquid crystal container 11 is adjusted so as to always have a constant pressure.
[0049]
Next, the liquid crystal drop supply performance is shown in the figure using an electromagnetic opening / closing tip needle type dispenser. For example, an Acura Jetta made by Nordon was used. The liquid crystal used was ZLI-4792 (manufactured by Merck). The internal pressure of the liquid crystal container 11 is, for example, 4 kgf / cm ² The thickness of the needle 14 is, for example, 26G.
[0050]
FIG. 2B shows the relationship between the dispense time (opening time of the needle valve) and the amount of liquid crystal dropped, and the experimental results of the amount of liquid crystal dropped per unit time at each point in the dispense time. According to this experiment, there is a good linear relationship between the dispensing time and the amount of liquid crystal dropped, and the amount of liquid crystal dropped per unit time is constant with high accuracy.
[0051]
Next, when the accuracy and reproducibility of the liquid crystal drop amount with the increase in the number of shots of the liquid crystal by the electromagnetic opening and closing needle type dispenser were tested, the results shown in FIG. 3 were obtained. According to this, when the liquid crystal was shot 100 times in two consecutive days, the error of the dispenser amount was within ± 1%, and high accuracy and high reproducibility were obtained. The conditions for the shots on the first day and the second day were set to be the same.
[0052]
Since the electromagnetic opening / closing tip needle type dispenser can be used in a vacuum in terms of structure, it can be seen that it is also suitable for the drop injection method of dropping liquid crystal in a vacuum atmosphere. Generally, the liquid crystal is dropped at atmospheric pressure.
[0053]
(Second embodiment)
In the present embodiment, in order to prevent the reaction between the sealing material 2 and the liquid crystal 3 due to the ultraviolet rays 7 and to prevent the contamination of the liquid crystal 3 caused by the reaction, the lower surface of the second substrate 4 along the vicinity of the inside of the sealing material 2 is provided. A light shielding film is provided. The details are described below.
[0054]
FIG. 4A is a plan view of the light shielding film 8 formed on the second substrate 4, and FIG. 4B is a sectional view thereof. FIG. 4A shows a light shielding film 8 formed on the back side through the transparent second substrate 4. The light-shielding film 8 is a region along the inside of the frame-shaped sealing material 2 and formed outside the display region 9, and is determined so as not to overlap the sealing material 2 and the display region 9. If the region where the light-shielding film 8 is formed overlaps or is too close to the sealing material 2, a portion that is not cured is generated in the sealing material 2. Therefore, it is preferable to provide a slight gap between the light-shielding film 8 and the sealing material 2. The light-shielding film 8 may be formed on the upper side of the second substrate 4, but is preferably on the lower side of the second substrate 4 from the viewpoint of light-shielding accuracy.
[0055]
If the light-shielding film 8 is formed by patterning a film (for example, a chromium film) constituting a black matrix film formed on the second substrate 4 in order to improve display quality, the manufacturing process will not be complicated. When irradiating ultraviolet rays to cure the sealing material 2, a light-shielding mask 10 as shown in FIG. 4B is placed outside the first and second substrates 1.4 to irradiate the display area 9 with ultraviolet rays. To prevent. This is because the light-shielding region by the light-shielding film 8 is limited between the display region 9 and the region where the sealing material 2 is formed.
[0056]
When the sealing material 7 is cured by irradiating ultraviolet rays from the first substrate 1 side, a light-shielding film may be provided on the first substrate 1 side. Is formed of a metal such as Al, and therefore, the light-shielding film is preferably formed of an insulating material. By providing the light-shielding film 8 in this manner, the amount of ultraviolet light applied to the liquid crystal 3 in the vicinity of the seal material 2 can be significantly reduced, so that the reaction between the seal material 2 and the liquid crystal 3 due to ultraviolet light irradiation can be reduced. In addition, the contamination of the liquid crystal 7 can be extremely reduced. In addition, the external light-shielding mask 10 prevents the liquid crystal in the display area from reacting with a small amount of molecules of the sealing material 2, thereby suppressing the contamination of the liquid crystal 7.
[0057]
As described above, in the present embodiment, the UV irradiation of the liquid crystal in the vicinity of the sealing material is prevented, so that the liquid crystal is contaminated by the reaction between the sealing material 2 and the liquid crystal 4 when the sealing material is cured by the UV irradiation. Can be avoided. T-470 (cationic polymerization type, manufactured by Chise Nagase, 100,000 cp) was used as a sealing material, and light was shielded as described above. Was rarely seen. Note that ZLI-4792 (manufactured by Merck) was used as the liquid crystal 3, and the irradiation condition of the sealing member 2 with ultraviolet light was 5000 mJ / cm. ² And
[0058]
It is to be noted that the beam may be irradiated with ultraviolet rays to be applied only to the frame-shaped sealing material 2, and in this case, it is not necessary to use a light-shielding film.
[0059]
(Third embodiment)
The method of manufacturing a liquid crystal display panel according to the third embodiment of the present invention has the same general flow as that described in the first embodiment, but a seal for sealing two opposing substrates. The method of forming the material is different.
[0060]
5A and 5B are a plan view and a cross-sectional view of a liquid crystal display panel in a state where liquid crystal is sealed. In FIG. 5A, a sealing material 2b is formed outside the sealing material 2a in the panel, and a liquid crystal 3 is sealed inside the sealing material 2a. The space between the sealing materials 2a and 2b is a vacuum, and the outside of the sealing material 2b is the atmosphere. In order to form such double sealing materials 2a and 2b, the sealing materials 2a and 2b are attached to the first substrate 1 in a vacuum before the first and second substrates 1 and 4 are stacked. . When the first and second substrates 1 and 4 are overlaid and bonded to each other to make the atmosphere atmospheric pressure, the first and second substrates 1 and 4 are drawn and the liquid crystal 3 is filled in the sealing material 2a. You. At this time, the outside of the sealing material 2b is at atmospheric pressure, but the space between the sealing material 2a and the sealing material 2b is still vacuum.
[0061]
When the liquid crystal 3 is sealed between the substrates by setting the surrounding atmosphere to the atmospheric pressure, the inside of the sealing material 2a is almost vacuum until the liquid crystal 3 is completely filled inside the sealing material 2a. However, by providing the sealing material twice in this manner, the outside of the sealing material 2a can be kept in a vacuum state. Therefore, it is possible to prevent a sudden pressure difference between the inside and the outside of the sealing material 2a, and to avoid the occurrence of poor sealing of the sealing material 2a.
[0062]
After the sealing of the liquid crystal 3 is completed and at least the sealing material 2a is cured, the outside of the second substrate 4 beyond the sealing material 2a is cut and removed. Therefore, the material of the sealing material 2b is not so limited, and various materials can be used. Thus, by providing the frame of the sealing material twice, the sealing failure can be reduced and the yield of the liquid crystal panel can be improved.
[0063]
As described above, according to the present invention, a frame of a sealing material is formed on a substrate having a transparent electrode or the like, liquid crystal is dropped in the frame, and another substrate with a spacer attached thereto is superposed in a vacuum. In a liquid crystal display panel and a method of manufacturing a liquid crystal display panel in which liquid crystal is sealed between substrates by returning the surroundings to atmospheric pressure and the sealing material is cured, the diameter of the spacer is at least 0.2 μm less than the thickness of the liquid crystal layer between the substrates. By using a small one, it is possible to reliably move the substrate at the time of repositioning while maintaining the uniformity of the thickness of the liquid crystal layer between the substrates.
[0064]
In addition, by using a spacer with an adhesive as the spacer, it is possible to prevent the spacer from flowing due to the liquid crystal flow and uneven distribution of the spacer. This improves the uniformity of the thickness of the liquid crystal layer between the substrates over the entire panel. In addition, by using a material having a viscosity of 50,000 cp or more as the sealing material, the sealing material becomes strong against external force, so that poor sealing can be reduced. Further, by providing a double frame of the sealing material, a pressure difference between the inside and the outside of the frame for sealing the liquid crystal can be reduced, so that poor sealing can be reduced. Thereby, the yield of the liquid crystal display panel can be improved.
[0065]
In addition, even when using an ultraviolet-curable material as a sealing material and irradiating ultraviolet rays during curing, by providing a light-shielding film in the vicinity of the sealing material on the substrate, the liquid crystal and the sealing material generated by the reaction between the liquid crystal and the sealing material by the ultraviolet rays can be formed. Since contamination can be prevented, the display performance of the liquid crystal display panel can be enhanced and stabilized. Since the dispenser that opens and closes with a needle is used for dropping the liquid crystal material in the present invention, the drop amount can be made uniform with high precision and reproducibility can be improved.
[Brief description of the drawings]
FIGS. 1A to 1E are cross-sectional views schematically showing a method for manufacturing a liquid crystal display panel according to a first embodiment of the present invention.
FIG. 2 (a) is a cross-sectional view schematically showing a liquid crystal dispenser of an electromagnetic opening / closing tip needle type used in a first embodiment of the present invention, and FIG. 2 (b) shows a relationship between a dispensing time and a dispensing amount. 7 is a graph illustrating a change in the dispensing amount per unit time along with the lapse of the dispensing time.
FIG. 3 is a graph showing the relationship between the number of shots and the amount of dispense by a liquid crystal dispenser of an electromagnetic opening / closing tip needle type.
4A and 4B show one step of the method for manufacturing the liquid crystal display panel shown in FIG. 1 in detail. FIG. 4A is a plan view, and FIG.
5A and 5B show one step of a method for manufacturing a liquid crystal display panel according to a second embodiment of the present invention, wherein FIG. 5A is a plan view and FIG. 5B is a cross-sectional view.
FIGS. 6A to 6C schematically show a method of manufacturing a liquid crystal display panel, and FIGS. 6A to 6C are perspective views showing respective steps.
FIG. 7 is a plan view showing sealing failure of a sealing material caused by a conventional method of manufacturing a liquid crystal display panel.
FIG. 8 is a graph showing a change in the voltage holding ratio of liquid crystal at different positions in the panel in a conventional method of manufacturing a liquid crystal display panel.
[Explanation of symbols]
1, 4, 21, 24 substrates
2, 2a, 2b, 22 Sealing material
3,23 liquid crystal
5 Spacer
6 cells
7 UV
8 Light shielding film
9 Display area
10 Light blocking member
11 LCD storage
12 caps
13 Liquid passage hole
14 Needle

Claims (8)

A sealing material applying step of forming a closed frame made of a sealing material on at least one inner surface of the pair of substrates along the surface,
A liquid crystal supply step of dropping a liquid crystal material on the one inner surface side,
A liquid crystal layer forming step of forming the liquid crystal layer between the pair of substrates by overlapping the inner surfaces of the pair of substrates under reduced pressure and returning to atmospheric pressure to spread the liquid crystal material,
A sealing material curing step of irradiating the sealing material with light to cure the sealing material,
A method for manufacturing a liquid crystal display panel, comprising: a pressure relaxation region for reducing a pressure difference between the inside and outside of the sealing material outside the sealing material under the atmospheric pressure. 2. The method according to claim 1, wherein in the sealing material applying step, the closed frame is applied at least two times. 3. 2. The method according to claim 1, wherein in the sealing material curing step, the sealing material is cured by irradiating only the sealing material with a beam of light. 3. 2. The method according to claim 1, wherein, in the liquid crystal supply step, a drop amount of the liquid crystal material is within 1% of a desired drop amount. 3. In the liquid crystal supply step, a liquid crystal material container having a liquid crystal supply hole on the lower side and an internal pressure maintained constant, and a dispenser having a needle disposed in the liquid crystal material container and opening and closing the liquid crystal supply hole is used. The method for manufacturing a liquid crystal display panel according to claim 1, wherein the amount of the liquid crystal material dropped is adjusted by adjusting the amount. 2. The method according to claim 1, wherein the pair of substrates are re-aligned before the sealing material curing step. 3. A spacer fixing step of fixing a spacer on the one inner surface or a step of forming a fixing spacer, wherein the spacer is 0.2 to 0.6 μm or 4 to 12% smaller than a thickness of the liquid crystal layer. The method for manufacturing a liquid crystal display panel according to claim 1, wherein: 3. The method according to claim 2, wherein the cutting is performed while leaving at least the innermost closed frame after the sealing material curing step.

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