JP3547591B2

JP3547591B2 - Reflector and reflective liquid crystal display

Info

Publication number: JP3547591B2
Application number: JP20363797A
Authority: JP
Inventors: 智正高塚; 幸一馬上; 正夫大北
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1997-07-29
Filing date: 1997-07-29
Publication date: 2004-07-28
Anticipated expiration: 2017-07-29
Also published as: JPH1152110A

Description

【０００１】
【発明の属する技術分野】
本発明は、広範囲にわたって均一な明るさと白さを有する反射体、およびその反射体を用いた反射型液晶表示装置に関するものである。
【０００２】
【従来の技術】
近年、ハンディタイプのコンピュータなどの表示部として、特に消費電力が小さいことから反射型液晶表示装置が広く利用されている。この反射型液晶表示装置には、表示面側から入射した光を反射させて表示を行うための反射板が備えられている。そして、従来の反射板には、表面が鏡面状態とされた反射板や表面にランダムな凹凸が形成された反射板が用いられていた。
このうち、図９に示すように、ランダムな凹凸面を備えた従来の反射板６０は、例えば厚さ３００ないし５００μｍのポリエステルフィルム６１を加熱することによってその表面に高さが数μｍの凹凸からなる凹凸面６１ａを形成し、さらに凹凸面６１ａ上に蒸着等の方法を用いてアルミニウムや銀等からなる反射膜６２を成膜することにより形成したものである。
【０００３】
この種の反射板６０を用いた従来の反射型液晶表示装置は、図１０に示すように、一対のガラス基板５１、５２の各々の対向面側に透明電極層５３、５４を設け、さらにこれら透明電極層５３、５４の各々の上に液晶の配向膜５５、５６を設け、これら配向膜５５、５６間に液晶層５７を配設した構成となっている。そして、ガラス基板５１、５２の外側にそれぞれ第１、第２の偏光板５８、５９を設け、第２の偏光板５９の外側には反射板６０を反射膜６２側の面を第２の偏光板５９側に向けて取り付けている。
【０００４】
上記構成の反射型液晶表示装置５０において、第１の偏光板５８に入射した光はこの偏光板５８によって直線偏光され、偏光された光が液晶層５７を透過することによって楕円偏光される。そして、楕円偏光された光は第２の偏光板５９によって再び直線偏光され、この直線偏光された光が反射板６０にて反射されて、再び第２の偏光板５９、液晶層５７を透過して第１の偏光板５８から出射する。
【０００５】
この反射板と反射型液晶表示装置は次のような反射特性を有している。
例えば図９に示すように、反射膜６２上に配置した点光源からの入射光Ｊの入射角度を反射膜６２表面に対する法線に対して入射角度３０度に一定にし、反射光Ｋの反射角度θを０度から６０度に変化させた場合の反射率を測定すると、反射角度３０度での反射率をピークとして左右の反射角度２０度以下および４０度以上では反射率がほぼ最低となることがわかった。そして、反射板単独での測定のみならず、この反射板を備えた液晶表示装置全体として測定してもこの傾向は同様であって、反射角度３０度での反射率をピークとして反射角度２３度以下ないし３７度以上の範囲でほぼ０％に低下することが判明した。
【０００６】
なお、表面を鏡面とした反射板の反射特性に関しては、一般に、表面にランダムな凹凸を持つ反射板と比較して、入射角度に対する特定の反射角度において非常に高い反射率を示す。しかしながら、反射率の高い反射角度の範囲が極めて狭い、すなわち視野角が狭いという特性を持っている。
【０００７】
【発明が解決しようとする課題】
上述したように、ランダムな凹凸反射面を持つ従来の反射板は、反射効率が悪いために全体的に反射率が低く、入射光をより広範囲の反射角度で効率良く反射させるという反射板のニーズに充分に応えることができなかった。したがって、この種の反射板を用いた反射型液晶表示装置は、視野角が約２５ないし３５度の範囲と狭く、しかも表示面の明るさも充分とはいえないという問題があった。また、反射板の特性には明るさと同時に白さも求められるが、この種の従来の反射板では種々の波長を持つ光が均一にバランス良く反射しないため、反射面の白さという点でも不充分であった。さらに、この種の反射板における反射角度や反射光強度等の反射特性は、ランダムに形成される凹凸によって自ずと決まってしまうものであり、光学的な設計により制御されたものではなかった。
【０００８】
そこで、これらの問題を解決するために、表面に直線状に延びる多数のストライプ溝を形成した反射板が提案されている。しかしながら、この反射板の場合、ストライプ溝に垂直な方向に関しては、ある範囲の反射角度で所望の明るさが得られるものの反射角度範囲が狭く、さらに、ストライプ溝に垂直な方向以外の方向に関しては、反射率がそもそも低い上に反射角度も極めて狭いものであった。したがって、この種の反射板を液晶表示装置に適用したところで、特にストライプ溝に平行な方向において、視野角が狭い、表示面の明るさや白さが不充分である、といった上記の問題が解決できなかった。
【０００９】
本発明は、上記の課題を解決するためになされたものであって、広い角度にわたって高い反射効率を得ることができる反射体、並びにそのような反射体を用いることでいずれの方向においても広い視野角とより明るい表示面を有する反射型液晶表示装置を提供することを目的とする。
【００１０】
【課題を解決するための手段】
上記の目的を達成するために、本発明の反射体は、反射体表面にその内面が球面状の一部をなし、先端球面形状の圧子をランダムなピッチ、ランダムな深さで押圧することにより個々に形成され、前記圧子の形状にて定められた多数の凹部が、連続して相互に隣接する凹部の端部どうしを重なり合うようにして形成され、前記凹部の深さが０．１ないし３μｍの範囲でランダムに形成され、隣接する凹部のピッチがランダムに配置され、前記凹部内面の傾斜角が−１０度ないし＋１０度の範囲において一定の分布を示すことを特徴とする。
更に本発明の反射体は、反射体表面にその内面が球面状の一部をなし、個々に先端球面形状の圧子をランダムなピッチ、ランダムな深さで押圧することにより個々に形成され、前記圧子の形状にて定められた多数の凹部が、連続して相互に隣接する凹部の端部どうしを重なり合うようにして形成され、前記凹部の深さが０．１ないし３μｍの範囲でランダムに形成され、隣接する凹部のピッチがランダムに配置されたパターンが繰り返し配置されて反射体表面が構成され、前記凹部内面の傾斜角が−１０度ないし＋１０度の範囲において一定の分布を示し、かつ、反射体表面の全体で反射光の拡散角を所定角度内にするように設定されるとともに、複数の深さと複数の異なるピッチと複数の異なる半径の凹部を個々に縦横の列で規定される領域に形成したパターンが繰り返し連続形成されたものであることを特徴とする。
【００１１】
本発明の反射体においては、内面を球面の一部をなす形状とした多数の凹部を表面に形成し、しかも凹部の深さ、隣接する凹部のピッチ等のパラメータを上記のような範囲に設定することにより、反射光の反射角を支配すると考えられる凹部内面の傾斜角（微小な単位面積内での傾斜角）がある角度範囲内で一定の分布を示すようになる。そして、凹部内面が球面状であることから、その一定の傾斜角分布が、反射体におけるある特定の方向だけでなく、全方向にわたって実現される。したがって、本発明の反射体によれば、全方向にわたって一様に高い反射効率が得られ、種々の波長を持つ光をバランス良く反射することができる。すなわち、従来の反射体に比べて、どの方向から見てもより明るく白い反射板を実現することができる。
【００１２】
なお、上記の「凹部の深さ」とは反射体表面から凹部の底部までの距離、「隣接する凹部のピッチ」とは平面視したときに円形となる凹部の中心間の距離のことである。また、「凹部内面の傾斜角」とは、図８に示すように、凹部４の内面の任意の箇所において０．５μｍ幅の微小な範囲をとったときに、その微小範囲内における斜面の水平面に対する角度θのことである。角度θの正負は、反射体表面に立てた法線に対して例えば図８における右側の斜面を正、左側の斜面を負と定義する。
【００１３】
上述したように、、これら凹部の深さ、隣接する凹部のピッチ、凹部内の傾斜角に関しては、凹部の深さを０．１ないし３μｍ、隣接する凹部のピッチをランダムに、凹部内面の傾斜角を−１０ないし＋１０度の範囲で一定の分布を示す設定にすることが好ましい。
特に、傾斜角分布を−１０ないし＋１０度の範囲で一定の分布を示す設定する点、隣接する凹部のピッチを平面全方向に対してランダムに配置する点が重要である。なぜならば、仮に隣接する凹部のピッチに規則性があると、光の干渉色が出て反射光が色付いてしまうという不具合があるからである。
また、凹部の深さが３μｍを超えると、後工程で凹部を平坦化する場合に凸部の頂上が平坦化膜で埋めきれず、所望の平坦性が得られなくなる。
また、実用上、反射体形成用母型の製作に使用し得る３０〜１００μｍ径のダイヤモンド圧子を用いる場合、隣接する凹部のピッチを５ないし５０μｍとすることが望ましい。
【００１４】
本発明の反射体は、先端球面形状の圧子を母型基材表面に押し付けて形成された多数の凹部を有する母型基材であって、前記多数の凹部の深さが前記圧子の押し付け深さにより設定されて母型基材表面上でランダムに設定され、前記凹部のピッチが前記圧子の押し付け位置のピッチにより母型基材表面上でランダムに設定され、前記多数の凹部が相互に隣接する凹部の端部どうしを重なり合うようにして形成された母型基材から、転写により転写型が形成され、該転写型から樹脂による転写により形成されてなる反射体であって、前記反射体表面にその内面が前記圧子の球面状の一部をなし、１つ１つが個々に圧子の形状で定められた多数の凹部が連続して形成され、前記凹部の深さが０．１ないし３μｍの範囲でランダムに形成されるとともに、複数の深さと複数の異なるピッチと複数の異なる半径の凹部を個々に縦横の列で規定された領域に形成したパターンを繰り返し連続形成させることにより表面全体が構成されたものである。
本発明の反射体は、前記圧子が前記領域に同じ深さで飛び飛びに押圧されて同じ深さの凹部が複数形成され、次いで前記領域に前記圧子が押圧深さを変えて同様の操作を繰り返し行って形成されたランダムな深さでランダムなピッチで複数の異なる半径の凹部が前記縦横の列で規定された領域に形成されたパターンが繰り返し連続形成されてなるものでも良い。
また、本発明の反射型液晶表示装置は、上記のような反射体、すなわち、反射体表面にその内面が球面状の一部をなし、圧子の形状にて定められた多数の凹部が連続して相互に隣接する凹部どうしを重なり合うようにして形成され、前記凹部の深さが０．１ないし３μｍの範囲でランダムに形成され、隣接する凹部のピッチがランダムに配置され、前記凹部内面の傾斜角が−１０度ないし＋１０度の範囲で一定の分布を示すことを特徴とするものである。
なお、反射体の設置形態としては、液晶セルの外側に設置する外付け型、あるいは液晶セルを構成する基板の内面に設置する内蔵型のいずれのタイプとしてもよい。
即ち、本発明では、対になる表示側基板と背面側基板間に液晶層が設けられ、前記表示側基板の上面側に偏光板と位相差板が設けられ、前記背面側基板の下面側に偏光板と請求項１〜５のいずれかに記載の反射体が備えられたことを特徴とする反射型液晶表示装置でも良い。
また、本発明では、対になる表示側基板と背面側基板間に液晶層が設けられ、前記表示側基板の上面側に偏光板と位相差板が設けられ、前記背面側基板の対向面側に請求項１〜５のいずれかに記載の反射体が配設されたことを特徴とする反射型液晶表示装置でも良い。
【００１５】
本発明の反射型液晶表示装置によれば、反射体自体が全方向にわたって反射効率が高く、種々の波長を持つ光をバランス良く反射するという特性を持っているため、従来の反射型液晶表示装置に比べて視角が広がり、表示面をより明るくすることができる。
【００１６】
【発明の実施の形態】
以下、本発明の一実施の形態を図１ないし図７を参照して説明する。
図１は本実施の形態の反射体を示す図である。この図に示すように、本実施の形態の反射体１は、例えばガラス等からなる基板２上に設けられた感光性樹脂層等からなる平板状の樹脂基材３（反射体用基材）の表面に、その内面が球面の一部をなす多数の凹部４が重なり合うように連続して形成され、その上に例えばアルミニウムや銀等の薄膜からなる反射膜５が蒸着または印刷等により形成されたものである。
【００１７】
上記凹部４の深さを０．１ないし３μｍの範囲でランダムに形成し、隣接する凹部４のピッチを５ないし５０μｍの範囲でランダムに配置し、上記凹部４内面の傾斜角を−１８ないし＋１８度の範囲に設定することが望ましい。
特に、凹部４内面の傾斜角分布を−１８ないし＋１８度の範囲に設定する点、隣接する凹部４のピッチを平面全方向に対してランダムに配置する点が重要である。なぜならば、仮に隣接する凹部４のピッチに規則性があると、光の干渉色が出て反射光が色付いてしまうという不具合があるからである。また、凹部４内面の傾斜角分布が−１８ないし＋１８度の範囲を超えると、反射光の拡散角が広がりすぎて反射強度が低下し、明るい反射板が得られない（反射光の拡散角がエアー中で３６度以上になり、液晶表示装置内部の反射強度ピークが低下し、全反射ロスが大きくなる）からである。
また、凹部４の深さが３μｍを超えると、後工程で凹部４を平坦化する場合に凸部の頂上が平坦化膜で埋めきれず、所望の平坦性が得られなくなる。
隣接する凹部４のピッチが５μｍ未満の場合、反射体形成用母型の製作上の制約があり、加工時間が極めて長くなる、所望の反射特性が得られるだけの形状が形成できない、干渉光が発生する等の問題が生じる。また、実用上、反射体形成用母型の製作に使用し得る３０〜１００μｍ径のダイヤモンド圧子を用いる場合、隣接する凹部４のピッチを５ないし５０μｍとすることが望ましい。
【００１８】
次に、上記構成の反射体の製造方法を図２ないし図５を用いて説明する。
まず、図２（ａ）に示すように、例えば黄銅、ステンレス、工具鋼等からなる表面が平坦な平板状の母型基材７を転造装置のテーブル上に固定する。そして、先端が所定の径Ｒを持つ球面形状のダイヤモンド圧子８で母型基材７の表面を押圧し、母型基材７を水平方向に移動させてはダイヤモンド圧子８を上下動させて押圧するという操作を多数回繰り返すことにより、深さや配列ピッチが異なる多数の凹部７ａを母型基材７の表面に転造し、図２（ｂ）に示すような反射体形成用母型９とする。図３に示すように、ここで用いる転造装置は、母型基材７を固定するテーブルが０．１μｍの分解能で水平面内のＸ方向、Ｙ方向に移動し、ダイヤモンド圧子８が１μｍの分解能で鉛直方向（Ｚ方向）に移動する機能を持つものである。なお、ダイヤモンド圧子８の先端の径Ｒは、２０ないし１００μｍ程度であることが望ましい。例えば、凹部７ａの深さを２μｍ程度とする場合、径Ｒが３０ないし５０μｍのもの、凹部７ａの深さを１μｍ程度とする場合、径Ｒが５０ないし１００μｍのものを用いるとよい。
【００１９】
また、ダイヤモンド圧子による転造の手順は次の通りである。
図４は転造のパターンを示す平面図であるが、この図に示すように、横一列において隣接する凹部のピッチは、左から順にｔ１（＝１７μｍ）、ｔ３（＝１５μｍ）、ｔ２（＝１６μｍ）、ｔ３、ｔ４（＝１４μｍ）、ｔ４、ｔ５（＝１３μｍ）、ｔ２、ｔ３、ｔ３となっている。また、縦一列において隣接する凹部のピッチも上から順に同様のパターンとなっている。そして、深さを１．１ないし２．１μｍの範囲で４種類設定して（図中ｄ１、ｄ２、ｄ３、ｄ４と示す）押圧することにより、押圧後の圧痕である円形の凹部の半径もｒ１（＝１１μｍ）、ｒ２（＝１０μｍ）、ｒ３（＝９μｍ）、ｒ４（＝８μｍ）の４種類となる。例えば縦一列における凹部の半径は、上から順にｒ１、ｒ２、ｒ３、ｒ１、ｒ４、ｒ２、ｒ４、ｒ３、ｒ１、ｒ４、ｒ１となる。
【００２０】
また、実際の転造の順番としては、例えば、最上段の横の列において深さｄ１の凹部を飛び飛びに全て形成した後、次に深さｄ２の凹部、深さｄ３の凹部、深さｄ４の凹部を形成するというように、４パターンの深さの転造操作を繰り返し、まず、最上段の横一列の凹部を全て形成する。その後、上から２番目の横の列に移動し、同様の操作を繰り返す。このようにして、パターン内の全ての凹部を形成していく。なお、図４はｔ＝１５０μｍ四方の転造のパターンを示すものであり、このパターンの繰り返しにより反射体全体が構成されている。図４に示したように、隣接する凹部の圧痕は一部重なるため、転造作業が全て終わった後の凹部全体の平面形状は図５に示すようになる。
【００２１】
その後、図２（ｃ）に示すように、母型９を箱形容器１０に収納、配置し、容器１０に例えばシリコーンなどの樹脂材料１１を流し込んで、常温にて放置、硬化させ、この硬化した樹脂製品を容器１０から取り出して不要な部分を切除し、図２（ｄ）に示すように、母型９の型面をなす多数の凹部と逆の凹凸形状である多数の凸部を持つ型面１２ａを有する転写型１２を作成する。
【００２２】
次に、ガラス基板の上面に、アクリル系レジスト、ポリスチレン系レジスト、アジドゴム系レジスト、イミド系レジスト等の感光性樹脂液をスピンコート法、スクリーン印刷法、吹き付け法等の塗布法により塗布する。そして、塗布終了後、加熱炉またはホットプレート等の加熱装置を用いて基板上の感光性樹脂液を例えば８０〜１００℃の温度範囲で１分以上加熱するプリベークを行って基板上に感光性樹脂層を形成する。ただし、用いる感光性樹脂の種類によってプリベーク条件は異なるため、上記範囲外の温度と時間で処理してもよいことは勿論である。なお、ここで形成する感光性樹脂層の膜厚は２〜５μｍの範囲とすることが好ましい。
【００２３】
その後、図２（ｅ）に示すように、図２（ｄ）に示した転写型１２を用い、この転写型１２の型面１２ａをガラス基板上の感光性樹脂層３に一定時間押し付けた後、転写型１２を感光性樹脂層３から外す。このようにして、図２（ｆ）に示すように、感光性樹脂層３の表面に転写型型面１２ａの凸部を転写して多数の凹部４を形成する。また、型押し時のプレス圧は用いる感光性樹脂の種類にあった値を選択することが好ましく、例えば３０〜５０ｋｇ／ｃｍ^２程度の圧力とするのがよい。プレス時間についても用いる感光性樹脂の種類にあった値を選択することが好ましく、例えば３０秒〜１０分程度の時間とする。
【００２４】
その後、透明なガラス基板の裏面側から感光性樹脂層３を硬化させるための紫外線（ｇ、ｈ、ｉ線）等の光線を照射し、感光性樹脂層３を硬化させる。ここで照射する紫外線等の光線は、上記種類の感光性樹脂層の場合、５０ｍＪ／ｃｍ^２以上の強度であれば感光性樹脂層を硬化させるのに充分であるが、感光性樹脂層の種類によってはこれ以外の強度で照射してもよいことは勿論である。そして、プリベークで用いたのと同様の加熱炉、ホットプレート等の加熱装置を用いてガラス基板上の感光性樹脂層３を例えば２４０℃程度で１分以上加熱するポストベークを行ってガラス基板上の感光性樹脂層３を焼成する。
【００２５】
最後に、感光性樹脂層３の表面に例えばアルミニウムをエレクトロンビーム蒸着等によって成膜して凹部の表面に沿って反射膜１を形成することにより、本実施の形態の反射体１が完成する。
【００２６】
本実施の形態の反射体１においては、内面を球面の一部をなす形状とした多数の凹部４を表面に形成し、しかも凹部４の深さ、隣接する凹部４のピッチ等の値を上記の範囲に設定したことにより、凹部内面の傾斜角がある角度範囲で一定の分布を示すようになる。一例として、図６は本実施の形態の反射体１における凹部内面の傾斜角の分布を示すものであり、横軸は傾斜角、縦軸はその傾斜角が存在する頻度を示している。この図に示すように、傾斜角は−１８ないし＋１８度の範囲、特に−１０ないし＋１０度の範囲においてほぼ一定の分布を示している。また、凹部４の内面は球面であり、全方向に対して対称形であるから、この一定の傾斜角分布は、反射体におけるある特定の方向だけでなく、全方向にわたって実現される。
凹部内面の傾斜角はその凹部内面における反射光の反射角を支配すると考えられ、本実施の形態の場合、反射体の全方向に対して傾斜角分布が一定であることから、全方向に対して一様な反射角および反射効率が得られることになり、種々の波長を持つ光をバランス良く反射することができる。すなわち、従来の反射体に比べて、どの方向から見てもより明るく白い反射板を実現することができる。
【００２７】
また、反射体形成用の母型９を製造する際には、ダイヤモンド圧子８を上下動させて母型基材７の表面を押圧するだけであるから、ダイヤモンド圧子８と母型基材７が擦れ合うようなことがない。その結果、ダイヤモンド圧子８先端の表面状態が母型９側に確実に転写され、圧子８の先端を鏡面状態としておけば母型９の凹部内面、ひいては反射体の凹部内面も容易に鏡面状態とすることができる。さらに、ポリエステル等の樹脂フィルムを加熱することで凹凸面を形成していた従来の反射体と異なり、本実施の形態の反射体１における凹部の深さ、径、ピッチ等の寸法、凹部内面の表面状態等は全て制御されたものであり、高精度の転造装置の使用により反射板の凹部形状をほぼ設計通りに作成することができる。したがって、本方法によれば、作成する反射板の反射角度、反射効率等の反射特性が従来に比べてより制御しやすいものとなり、所望の反射体を得ることができる。
【００２８】
なお、本実施の形態における反射体１の凹部４の深さ、径、ピッチ等の具体的な数値や図４に示した凹部の転造パターンはほんの一例に過ぎず、適宜設計変更が可能なことは勿論である。また、反射体用基材、母型用基材等の各種基材の材料、転写型の構成材料等に関しても適宜変更が可能である。
【００２９】
次に、上記の反射体を備えたＳＴＮ（ＳｕｐｅｒＴｗｉｓｔｅｄＮｅｍａｔｉｃ）方式の反射型液晶表示装置について説明する。
図７に示すように、この反射型液晶表示装置は、例えば厚さ０．７ｍｍの一対の表示側ガラス基板１３と背面側ガラス基板１４との間に液晶層１５を設け、表示側ガラス基板１３の上面側にポリカーボネート樹脂やポリアリレート樹脂等からなる１枚の位相差板１６を設け、さらに位相差板１６の上面側に第１の偏光板１７を配設している。また、背面側ガラス基板１４の下面側には、第２の偏光板１８、図１に示した本実施の形態の反射体１を順次設けている。
【００３０】
反射体１は、第２の偏光板１８の下面側に凹部４を形成した面が対向するように取り付けられ、第２の偏光板１８と反射体１との間には、グリセリン等の光の屈折率に悪影響を与えることのない材料からなる粘着体１９が充填されている。両ガラス基板１３、１４の対向面側にはＩＴＯ（インジウムスズ酸化物）等からなる透明電極層２０、２１がそれぞれ形成され、透明電極層２０、２１上にポリイミド樹脂等からなる配向膜２２、２３がそれぞれ設けられている。これら配向膜２２、２３等の関係により液晶層１５中の液晶は２４０度捻れた配置となっている。
【００３１】
また、前記背面側ガラス基板１４と透明電極層２１との間に、図示していないカラーフィルタを印刷等で形成することにより、この液晶表示装置をカラー表示できるようにしてもよい。
【００３２】
本実施の形態の液晶表示装置においては、上述したように、反射体１自体が全方向にわたって入射光の反射角度が広く、反射効率が高いという特性を持っているため、使用者が表示面をいずれの方向から見た場合においても、従来の液晶表示装置に比べて視野角が広がり、明るい表示面とすることができる。
【００３３】
なお、本実施の形態の反射型液晶表示装置では、反射板を第２の偏光板の外側に配設する、いわゆる外付けの反射板とする例を説明したが、背面側ガラス基板の対向面側に配設して内蔵型としてもよい。また、液晶表示装置の例としてＳＴＮ方式のもので説明したが、液晶層の液晶分子の捻れ角を９０度に設定したＴＮ（ＴｗｉｓｔｅｄＮｅｍａｔｉｃ）方式の液晶表示装置にも本発明の反射体を適用し得ることは勿論である。
【００３４】
【発明の効果】
以上、詳細に説明したように、本発明の反射体においては、内面を球面の一部をなす形状で、先端球面形状の圧子をランダムなピッチ、ランダムな深さで押圧することにより個々に形成され、前記圧子の形状にて定められた多数の凹部を表面に端部どうしを重なるように形成し、しかも凹部の深さを規定し、隣接する凹部のピッチをランダムにし、反射体の全方向に対して凹部内面の傾斜角分布がある角度範囲においてほぼ一定を示すようにしたため、全方向に対して一様な反射効率が得られ、種々の波長を持つ光をバランス良く反射することができる。すなわち、従来の反射体に比べて、どの方向から見てもより明るく白い反射板を実現することができる。そして、本発明の反射型液晶表示装置によれば、上記のような優れた特性を持つ反射体を備えたことにより、広い視野角と明るい表示面を有する液晶表示装置を実現することができる。
本発明では、内面を球面の一部をなす形状とした多数の凹部を表面に端部どうしを重なるように形成し、しかも凹部の深さを規定し、隣接する凹部のピッチをランダムにし、複数の深さと複数の異なるピッチと複数の異なる半径の凹部を個々に縦横の列で規定された領域に形成したパターンを繰り返し連続形成させることにより表面全体が構成されたものであるので、反射体の全方向に対して凹部内面の傾斜角分布がある角度範囲でほぼ一定としたパターンを繰り返し配置することにより反射体表面の全体を構成できる。
更に本発明では、１つ１つが圧子の形状により定められて、内面を球面の一部をなす形状とした多数の凹部を表面に端部どうしを重ねるように形成し、しかも凹部の深さを規定し、隣接する凹部のピッチをランダムにし、反射体の全方向に対して凹部内面の傾斜角分布がある角度範囲でほぼ一定とした母型基材から転写型を経て樹脂転写による反射体を得ることができ、前記圧子が前記領域に同じ深さで飛び飛びに押圧されて同じ深さの凹部が複数形成され、次いで前記領域に前記圧子が押圧深さを変えて同様の操作を繰り返し行って形成されたランダムな深さでランダムなピッチで複数の異なる半径の凹部が前記縦横の列で規定される領域に形成されたパターンが繰り返し連続形成されてなるので、全方向に対して一様な反射効率が得られ、種々の波長を持つ光をバランス良く反射することがで、従来の反射体に比べて、どの方向から見てもより明るく白い反射板を実現できる効果がある。
また、本発明では、反射膜と平坦化膜を設けることで表面を平坦化した反射体を得ることができる。その場合に凹部の深さを０．１ないし３μｍの範囲としておくことで、平坦化膜で埋めて平坦化することができ、所望の平坦性を得ることができる。
更に、本発明では、上述の優れた効果を有する反射体を外付けであるいは内蔵型で備えた反射型液晶表示装置を得ることができる。
【図面の簡単な説明】
【図１】本発明の一実施の形態である反射体を示す斜視図である。
【図２】同、反射体の製造過程を順を追って示したプロセスフロー図である。
【図３】同、反射体の形成に用いる母型の製造過程を示す図であって、ダイヤモンド圧子で母型基材を押圧している状態を示す図である。
【図４】同、母型の製造過程においてダイヤモンド圧子による転造のパターンを示す平面図である。
【図５】同、転造後の凹部全体の形状を示す平面図である。
【図６】同、反射体における凹部内面の傾斜角の分布を示す図である。
【図７】本発明の一実施の形態である反射型液晶表示装置を示す断面図である。
【図８】本発明に係る反射体の凹部内面の傾斜角を説明するための図である。
【図９】従来の反射体の一例を示す斜視図である。
【図１０】従来の反射型液晶表示装置の一例を示す断面図である。
【符号の説明】
１反射体
２基板
３樹脂基材（反射体用基材）
４凹部
５反射膜
７母型基材
８ダイヤモンド圧子
９反射体形成用母型
１２転写型[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reflector having uniform brightness and whiteness over a wide range, and a reflective liquid crystal display device using the reflector.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a reflection type liquid crystal display device has been widely used as a display unit of a handy type computer or the like because of particularly low power consumption. This reflective liquid crystal display device includes a reflector for reflecting light incident from the display surface side to perform display. As a conventional reflector, a reflector having a mirror-finished surface or a reflector having random irregularities formed on the surface has been used.
Among them, as shown in FIG. 9, a conventional reflector 60 having a random uneven surface is formed by heating a polyester film 61 having a thickness of 300 to 500 μm, for example, so that the surface thereof has a height of several μm. An irregular surface 61a is formed, and a reflective film 62 made of aluminum, silver, or the like is formed on the irregular surface 61a by using a method such as vapor deposition.
[0003]
As shown in FIG. 10, a conventional reflection type liquid crystal display device using a reflection plate 60 of this type is provided with transparent electrode layers 53 and 54 on opposite sides of a pair of glass substrates 51 and 52, respectively. Liquid crystal alignment films 55 and 56 are provided on each of the transparent electrode layers 53 and 54, and a liquid crystal layer 57 is provided between the alignment films 55 and 56. Then, first and second polarizing plates 58 and 59 are provided outside the glass substrates 51 and 52, respectively. A reflecting plate 60 is provided outside the second polarizing plate 59 and the surface on the side of the reflecting film 62 is second polarized light. It is attached to the plate 59 side.
[0004]
In the reflection type liquid crystal display device 50 having the above-described configuration, the light incident on the first polarizing plate 58 is linearly polarized by the polarizing plate 58, and the polarized light is elliptically polarized by transmitting through the liquid crystal layer 57. Then, the elliptically polarized light is linearly polarized again by the second polarizing plate 59, and the linearly polarized light is reflected by the reflecting plate 60, and again passes through the second polarizing plate 59 and the liquid crystal layer 57. Out of the first polarizing plate 58.
[0005]
The reflection plate and the reflection type liquid crystal display device have the following reflection characteristics.
For example, as shown in FIG. 9, the incident angle of the incident light J from the point light source disposed on the reflective film 62 is fixed at an incident angle of 30 degrees with respect to the normal to the surface of the reflective film 62, and the reflection angle of the reflected light K is When the reflectance is measured when θ is changed from 0 ° to 60 °, the reflectance at the reflection angle of 30 ° is a peak, and the reflectance is almost the lowest when the left and right reflection angles are 20 ° or less and 40 ° or more. I understood. This tendency is the same not only when measuring the reflection plate alone but also when measuring the entire liquid crystal display device including the reflection plate. The reflection angle at a reflection angle of 30 degrees is a peak and the reflection angle is 23 degrees. It has been found that the temperature drops to almost 0% in the range from below to 37 degrees or more.
[0006]
In addition, as for the reflection characteristics of a reflector having a mirror-finished surface, the reflectance generally shows a very high reflectance at a specific reflection angle with respect to the incident angle, as compared with a reflection plate having random irregularities on the surface. However, it has the characteristic that the range of the reflection angle with high reflectance is extremely narrow, that is, the viewing angle is narrow.
[0007]
[Problems to be solved by the invention]
As described above, the conventional reflector having a random uneven reflection surface has a low reflectance as a whole due to poor reflection efficiency, and the need for a reflector that efficiently reflects incident light at a wider range of reflection angles is needed. Couldn't respond enough. Therefore, the reflection type liquid crystal display device using this type of reflection plate has a problem that the viewing angle is narrow in the range of about 25 to 35 degrees and the brightness of the display surface is not sufficient. The characteristics of the reflector require whiteness as well as brightness.However, this type of conventional reflector does not uniformly reflect light of various wavelengths in a well-balanced manner. Met. Furthermore, the reflection characteristics such as the reflection angle and the reflected light intensity of this type of reflection plate are determined automatically by irregularities formed at random, and are not controlled by optical design.
[0008]
Therefore, in order to solve these problems, a reflector having a large number of stripe grooves extending linearly on the surface has been proposed. However, in the case of this reflector, in the direction perpendicular to the stripe groove, although a desired brightness can be obtained at a certain range of reflection angle, the reflection angle range is narrow, and further in the direction other than the direction perpendicular to the stripe groove. In addition, the reflectance was originally low and the reflection angle was extremely narrow. Therefore, when this type of reflector is applied to a liquid crystal display device, the above-mentioned problems, such as a narrow viewing angle and insufficient brightness and whiteness of the display surface, particularly in a direction parallel to the stripe groove, can be solved. Did not.
[0009]
The present invention has been made in order to solve the above problems, and a reflector capable of obtaining high reflection efficiency over a wide angle, and a wide field of view in any direction by using such a reflector. It is an object of the present invention to provide a reflective liquid crystal display device having corners and a brighter display surface.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the reflector of the present invention has a spherical surface part on the reflector surface,The indenter having a spherical tip is formed individually by pressing at a random pitch and a random depth.Numerous recesses determined by the shape of the indenter,The end portions of the concave portions which are successively adjacent to each other are formed so as to overlap each other, the depth of the concave portions is formed at random in the range of 0.1 to 3 μm, and the pitch of the adjacent concave portions is randomly arranged; The inclination angle of the inner surface of the recess has a constant distribution in a range of -10 degrees to +10 degrees.
Furthermore, the reflector of the present inventionThe inner surface forms a spherical part on the reflector surface,Individually formed by pressing the indenter of the tip spherical shape at random pitch, random depth, individuallyNumerous recesses determined by the shape of the indenter,The ends of the recesses which are continuously adjacent to each other are formed so as to overlap with each other, the depths of the recesses are formed at random in the range of 0.1 to 3 μm, and the pitch of the adjacent recesses is randomly arranged. The pattern is repeatedly arranged to form the reflector surface,The inclination angle of the inner surface of the concave portion shows a constant distribution in a range of -10 degrees to +10 degrees, andIt is set so that the diffusion angle of the reflected light is within a predetermined angle on the entire reflector surface.In addition, a pattern in which recesses having a plurality of depths, a plurality of different pitches, and a plurality of different radii are individually formed in regions defined by vertical and horizontal rows is repeatedly and continuously formed.It is characterized by the following.
[0011]
In the reflector of the present invention, a large number of concave portions having an inner surface that forms a part of a spherical surface are formed on the surface, and parameters such as the depth of the concave portions and the pitch between adjacent concave portions are set in the above ranges. By doing so, the inclination angle of the inner surface of the concave portion (inclination angle in a minute unit area), which is considered to dominate the reflection angle of the reflected light, shows a constant distribution within a certain angle range. Since the inner surface of the concave portion has a spherical shape, the constant inclination angle distribution is realized not only in a specific direction but also in all directions in the reflector. Therefore, according to the reflector of the present invention, high reflection efficiency can be obtained uniformly in all directions, and light having various wavelengths can be reflected with good balance. That is, it is possible to realize a brighter and whiter reflector when viewed from any direction as compared with a conventional reflector.
[0012]
Note that the “depth of the recess” is the distance from the reflector surface to the bottom of the recess, and the “pitch between adjacent recesses” is the distance between the centers of the recesses that is circular when viewed in plan. . Further, as shown in FIG. 8, the “inclination angle of the inner surface of the concave portion” refers to a horizontal plane of the inclined surface within the minute range when a minute range of 0.5 μm width is taken at an arbitrary position on the inner surface of the concave portion 4. Angle θ with respect to The positive and negative of the angle θ are defined, for example, that the right slope in FIG. 8 is positive and the left slope in FIG.
[0013]
As described above, regarding the depth of these recesses, the pitch of the adjacent recesses, and the inclination angle in the recesses, the depth of the recesses is 0.1 to 3 μm, the pitch of the adjacent recesses is random, and the inclination of the inner surface of the recesses is varied. It is preferable that the angle is set to show a constant distribution in the range of -10 to +10 degrees.
In particular, it is important to set the inclination angle distribution so as to show a constant distribution in the range of -10 to +10 degrees, and to arrange the pitches of adjacent concave portions at random in all directions in the plane. This is because if there is regularity in the pitch between adjacent concave portions, there is a problem that interference colors of light appear and reflected light is colored..
If the depth of the concave portion exceeds 3 μm, the top of the convex portion cannot be filled with the flattening film when the concave portion is flattened in a later step, and desired flatness cannot be obtained.
MaWhen a diamond indenter having a diameter of 30 to 100 μm, which can be used practically for manufacturing a reflector forming matrix, it is desirable that the pitch between adjacent concave portions is 5 to 50 μm.
[0014]
The reflector of the present invention,A matrix substrate having a number of recesses formed by pressing an indenter having a spherical tip at the surface of the matrix substrate, wherein the depth of the plurality of recesses is set by the pressing depth of the indenter. Randomly set on the surface of the base material, the pitch of the recesses is randomly set on the surface of the matrix base material by the pitch of the pressing position of the indenter, and the large number of recesses are formed between the ends of the recesses adjacent to each other. A transfer mold is formed by transfer from a matrix base material formed so as to be overlapped, and a reflector formed by transfer with a resin from the transfer mold, wherein an inner surface of the reflector surface is formed of the indenter. Part of a spherical shape,Each one individuallyA large number of recesses defined by the shape of the indenter are continuously formed, and the recesses are formed at random in a depth of 0.1 to 3 μm.In addition, the entire surface is formed by repeatedly and continuously forming a pattern in which recesses having a plurality of depths, a plurality of different pitches, and a plurality of different radii are individually formed in regions defined by vertical and horizontal rows.
In the reflector of the present invention, the indenter is repeatedly pressed at the same depth in the region to form a plurality of concave portions having the same depth, and then the same operation is repeated by changing the pressing depth of the indenter in the region. A pattern may be formed by repeatedly forming a pattern in which a plurality of concave portions having a different depth and a random pitch and formed in a region defined by the vertical and horizontal rows are formed repeatedly.
Further, in the reflection type liquid crystal display device of the present invention, the reflector as described above, that is, the inner surface of the reflector forms a part of a spherical surface, and a large number of concave portions defined by the shape of the indenter are continuous. The recesses adjacent to each other are formed so as to overlap each other, the depth of the recesses is formed at random in the range of 0.1 to 3 μm, the pitch of the adjacent recesses is randomly arranged, and the slope of the inner surface of the recesses is formed. It is characterized in that the angle shows a constant distribution in the range of -10 degrees to +10 degrees.
The reflector may be installed in either an external type installed outside the liquid crystal cell or a built-in type installed inside the substrate of the liquid crystal cell.
That is, in the present invention, a liquid crystal layer is provided between the display-side substrate and the back-side substrate that form a pair, a polarizing plate and a retardation plate are provided on the upper surface of the display-side substrate, and on the lower surface of the back-side substrate. A reflective liquid crystal display device comprising a polarizing plate and the reflector according to any one of claims 1 to 5 may be provided.
Further, in the present invention, a liquid crystal layer is provided between the display-side substrate and the rear-side substrate that form a pair, a polarizing plate and a retardation plate are provided on the upper surface side of the display-side substrate, and the opposing surface side of the rear-side substrate is provided. A reflection type liquid crystal display device, wherein the reflector according to any one of claims 1 to 5 is provided.
[0015]
According to the reflective liquid crystal display device of the present invention, the reflector itself has high reflection efficiency in all directions and has characteristics of reflecting light having various wavelengths in a well-balanced manner. The viewing angle is widened as compared with, and the display surface can be made brighter.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing a reflector according to the present embodiment. As shown in this figure, a reflector 1 of the present embodiment has a flat resin substrate 3 (a substrate for a reflector) made of a photosensitive resin layer or the like provided on a substrate 2 made of, for example, glass. A large number of concave portions 4 whose inner surfaces form a part of a spherical surface are continuously formed so as to overlap each other, and a reflective film 5 made of a thin film of, for example, aluminum or silver is formed thereon by vapor deposition or printing. It is a thing.
[0017]
The depth of the recesses 4 is randomly formed in the range of 0.1 to 3 μm, the pitch of the adjacent recesses 4 is randomly arranged in the range of 5 to 50 μm, and the inclination angle of the inner surface of the recess 4 is −18 to +18. It is desirable to set in the range of degrees.
In particular, it is important that the inclination angle distribution of the inner surface of the recess 4 is set in the range of −18 to +18 degrees, and that the pitch of the adjacent recesses 4 is randomly arranged in all directions in the plane. This is because if the pitch of the adjacent concave portions 4 is regular, there is a problem that interference colors of light appear and reflected light is colored. On the other hand, if the inclination angle distribution of the inner surface of the concave portion 4 exceeds the range of −18 to +18 degrees, the diffusion angle of the reflected light becomes too wide, the reflection intensity decreases, and a bright reflector cannot be obtained. This is because the temperature becomes 36 degrees or more in air, the reflection intensity peak inside the liquid crystal display device decreases, and the total reflection loss increases.)
If the depth of the concave portion 4 exceeds 3 μm, the top of the convex portion cannot be filled with the flattening film when the concave portion 4 is flattened in a later step, and desired flatness cannot be obtained.
When the pitch of the adjacent concave portions 4 is less than 5 μm, there is a restriction in the production of the reflector forming matrix, the processing time becomes extremely long, a shape that can obtain the desired reflection characteristics cannot be formed, and interference light is generated. And other problems arise. Further, in practice, when a diamond indenter having a diameter of 30 to 100 μm that can be used for manufacturing a reflector forming base is used, it is desirable that the pitch between adjacent concave portions 4 is 5 to 50 μm.
[0018]
Next, a method of manufacturing the reflector having the above configuration will be described with reference to FIGS.
First, as shown in FIG. 2A, a flat plate-shaped base material 7 made of, for example, brass, stainless steel, tool steel, or the like is fixed on a table of a rolling device. Then, the surface of the matrix base material 7 is pressed with a spherical diamond indenter 8 having a predetermined diameter R at the tip, and the base material 7 is moved in the horizontal direction, and the diamond indenter 8 is moved up and down to press. By repeating this operation many times, a large number of recesses 7a having different depths and arrangement pitches are rolled on the surface of the matrix base material 7, and are formed with the reflector forming matrix 9 as shown in FIG. I do. As shown in FIG. 3, in the rolling device used here, the table for fixing the matrix substrate 7 moves in the X and Y directions in the horizontal plane with a resolution of 0.1 μm, and the diamond indenter 8 has a resolution of 1 μm. Has a function of moving in the vertical direction (Z direction). The diameter R of the tip of the diamond indenter 8 is desirably about 20 to 100 μm. For example, when the depth of the recess 7a is about 2 μm, the diameter R is preferably 30 to 50 μm, and when the depth of the recess 7a is about 1 μm, the diameter R is preferably 50 to 100 μm.
[0019]
The procedure of rolling with a diamond indenter is as follows.
FIG. 4 is a plan view showing a rolling pattern. As shown in FIG. 4, pitches of adjacent recesses in one horizontal row are t1 (= 17 μm), t3 (= 15 μm), and t2 (= 16 μm), t3, t4 (= 14 μm), t4, t5 (= 13 μm), t2, t3, and t3. In addition, the pitches of the concave portions adjacent to each other in one vertical line have the same pattern in order from the top. By pressing four different depths in the range of 1.1 to 2.1 μm (shown as d1, d2, d3, and d4 in the drawing), the radius of the circular concave portion as an indentation after the pressing is also reduced. r1 (= 11 μm), r2 (= 10 μm), r3 (= 9 μm), and r4 (= 8 μm). For example, the radii of the concave portions in one vertical line are r1, r2, r3, r1, r4, r2, r4, r3, r1, r4, r1 in order from the top.
[0020]
In addition, as the actual order of the rolling, for example, in the uppermost horizontal row, after all of the recesses having the depth d1 are formed at intervals, then the recesses having the depth d2, the recesses having the depth d3, and the depth d4 are formed. The rolling operation with a depth of four patterns is repeated so as to form the recesses of the first pattern, and first, all the recesses in the uppermost row in a horizontal row are formed. After that, it moves to the second horizontal row from the top and repeats the same operation. Thus, all the concave portions in the pattern are formed. FIG. 4 shows a rolling pattern of t = 150 μm square, and the entire reflector is formed by repeating this pattern. As shown in FIG. 4, since the impressions of the adjacent concave portions partially overlap, the planar shape of the entire concave portion after all the rolling operations are completed is as shown in FIG.
[0021]
Thereafter, as shown in FIG. 2 (c), the matrix 9 is housed and placed in a box-shaped container 10, a resin material 11 such as silicone is poured into the container 10, and left and cured at room temperature. The removed resin product is taken out of the container 10 and unnecessary portions are cut off, and as shown in FIG. 2D, the resin product has a large number of concave portions forming the mold surface of the matrix 9 and a large number of convex portions having the opposite concave and convex shape. The transfer mold 12 having the mold surface 12a is created.
[0022]
Next, a photosensitive resin liquid such as an acrylic resist, a polystyrene resist, an azide rubber resist, or an imide resist is applied to the upper surface of the glass substrate by a coating method such as a spin coating method, a screen printing method, and a spraying method. After the application, the photosensitive resin liquid on the substrate is pre-baked by using a heating device such as a heating furnace or a hot plate in a temperature range of, for example, 80 to 100 ° C. for 1 minute or more, and the photosensitive resin is applied on the substrate. Form a layer. However, since the prebaking conditions vary depending on the type of the photosensitive resin used, it is needless to say that the treatment may be performed at a temperature and time outside the above range. The thickness of the photosensitive resin layer formed here is preferably in the range of 2 to 5 μm.
[0023]
Thereafter, as shown in FIG. 2E, the transfer mold 12 shown in FIG. 2D is used, and the mold surface 12a of the transfer mold 12 is pressed against the photosensitive resin layer 3 on the glass substrate for a predetermined time. Then, the transfer mold 12 is removed from the photosensitive resin layer 3. In this way, as shown in FIG. 2F, the convex portions of the transfer mold surface 12a are transferred to the surface of the photosensitive resin layer 3 to form a large number of concave portions 4. Further, it is preferable to select a value corresponding to the type of the photosensitive resin to be used for the pressing pressure at the time of embossing, for example, 30 to 50 kg / cm.²The pressure should be of the order of magnitude. As for the pressing time, it is preferable to select a value suitable for the type of the photosensitive resin to be used, for example, about 30 seconds to 10 minutes.
[0024]
Thereafter, a light beam such as an ultraviolet ray (g, h, i-line) for curing the photosensitive resin layer 3 is irradiated from the rear surface side of the transparent glass substrate to cure the photosensitive resin layer 3. In the case of a photosensitive resin layer of the type described above, a light beam such as an ultraviolet ray irradiated here is 50 mJ / cm.²The above intensity is sufficient to cure the photosensitive resin layer, but it is a matter of course that irradiation may be performed at other intensity depending on the type of the photosensitive resin layer. Then, the photosensitive resin layer 3 on the glass substrate is post-baked by heating the photosensitive resin layer 3 on the glass substrate at, for example, about 240 ° C. for 1 minute or more by using a heating device such as a heating furnace or a hot plate similar to that used in pre-baking. Is baked.
[0025]
Finally, for example, aluminum is formed on the surface of the photosensitive resin layer 3 by electron beam evaporation or the like, and the reflection film 1 is formed along the surface of the concave portion, thereby completing the reflector 1 of the present embodiment.
[0026]
In the reflector 1 of the present embodiment, a large number of recesses 4 whose inner surfaces are part of a spherical surface are formed on the surface, and the values of the depth of the recesses 4, the pitch of the adjacent recesses 4, and the like are set as described above. Is set, the inclination distribution of the inner surface of the concave portion shows a constant distribution in a certain angle range. As an example, FIG. 6 shows the distribution of the inclination angle of the inner surface of the concave portion in the reflector 1 of the present embodiment. The horizontal axis indicates the inclination angle, and the vertical axis indicates the frequency at which the inclination angle exists. As shown in this figure, the inclination angle shows a substantially constant distribution in the range of -18 to +18 degrees, particularly in the range of -10 to +10 degrees. Further, since the inner surface of the concave portion 4 is spherical and symmetrical with respect to all directions, this constant inclination angle distribution is realized not only in a specific direction but also in all directions in the reflector.
It is considered that the inclination angle of the inner surface of the concave portion governs the reflection angle of the reflected light on the inner surface of the concave portion, and in the case of the present embodiment, since the inclination angle distribution is constant in all directions of the reflector, As a result, uniform reflection angles and reflection efficiencies can be obtained, and light having various wavelengths can be reflected in a well-balanced manner. That is, it is possible to realize a brighter and whiter reflector when viewed from any direction as compared with a conventional reflector.
[0027]
In addition, when the master 9 for forming the reflector is manufactured, the diamond indenter 8 and the mother substrate 7 are simply moved by moving the diamond indenter 8 up and down to press the surface of the mother substrate 7. No rubbing. As a result, the surface state of the tip of the diamond indenter 8 is reliably transferred to the matrix 9 side, and if the tip of the indenter 8 is mirror-finished, the inner surface of the concave portion of the mother die 9 and, consequently, the inner surface of the concave portion of the reflector can easily be mirror-finished. can do. Furthermore, unlike the conventional reflector in which the uneven surface is formed by heating a resin film such as polyester, the depth, diameter, pitch, and other dimensions of the recess in the reflector 1 of the present embodiment, and the inner surface of the recess are different. The surface condition and the like are all controlled, and the concave shape of the reflecting plate can be created almost as designed by using a high-precision rolling device. Therefore, according to the present method, the reflection characteristics such as the reflection angle and the reflection efficiency of the reflection plate to be produced are easier to control than in the past, and a desired reflector can be obtained.
[0028]
Note that the specific numerical values such as the depth, diameter, and pitch of the concave portion 4 of the reflector 1 in the present embodiment and the rolling pattern of the concave portion shown in FIG. 4 are merely examples, and the design can be changed as appropriate. Of course. In addition, materials of various base materials such as a base material for a reflector and a base material for a matrix, and a constituent material of a transfer mold can be appropriately changed.
[0029]
Next, a reflective liquid crystal display device of the STN (Super Twisted Nematic) type including the above-described reflector will be described.
As shown in FIG. 7, this reflection type liquid crystal display device has a liquid crystal layer 15 provided between a pair of display side glass substrates 13 and a rear side glass substrate 14 having a thickness of, for example, 0.7 mm. A single retardation plate 16 made of a polycarbonate resin, a polyarylate resin, or the like is provided on the upper surface side of the substrate, and a first polarizing plate 17 is disposed on the upper surface side of the retardation plate 16. The second polarizing plate 18 and the reflector 1 of the present embodiment shown in FIG. 1 are sequentially provided on the lower surface side of the rear glass substrate 14.
[0030]
The reflector 1 is mounted such that the surface on which the concave portion 4 is formed faces the lower surface side of the second polarizing plate 18, and between the second polarizing plate 18 and the reflector 1, light such as glycerin is applied. An adhesive 19 made of a material that does not adversely affect the refractive index is filled. Transparent electrode layers 20 and 21 made of ITO (indium tin oxide) or the like are formed on the opposing surfaces of the two glass substrates 13 and 14, respectively, and an alignment film 22 made of a polyimide resin or the like is formed on the transparent electrode layers 20 and 21. 23 are provided. The liquid crystal in the liquid crystal layer 15 is twisted 240 degrees due to the relationship between the alignment films 22 and 23 and the like.
[0031]
Further, a color filter (not shown) may be formed between the rear glass substrate 14 and the transparent electrode layer 21 by printing or the like, so that the liquid crystal display device can perform color display.
[0032]
In the liquid crystal display device according to the present embodiment, as described above, since the reflector 1 itself has the characteristic that the reflection angle of incident light is wide in all directions and the reflection efficiency is high, the user can change the display surface. When viewed from any direction, the viewing angle is wider than that of the conventional liquid crystal display device, and a bright display surface can be obtained.
[0033]
In the reflection type liquid crystal display device of the present embodiment, an example has been described in which the reflection plate is disposed outside the second polarizing plate, that is, a so-called external reflection plate is provided. It may be disposed on the side to be a built-in type. Although the STN type liquid crystal display device has been described as an example of the liquid crystal display device, the reflector of the present invention is also applied to a TN (Twisted Nematic) type liquid crystal display device in which the twist angle of liquid crystal molecules in the liquid crystal layer is set to 90 degrees. Of course, you can.
[0034]
【The invention's effect】
As described above in detail, in the reflector of the present invention, the inner surface has a shape that forms a part of a spherical surface,The indenter having a spherical tip is formed individually by pressing at a random pitch and a random depth.A large number of recesses determined by the shape of the indenter are formed so that the ends overlap on the surface, and the depth of the recesses is defined, the pitch of the adjacent recesses is random, and the reflector is omnidirectional in all directions. Since the inclination angle distribution of the inner surface of the concave portion is substantially constant in a certain angle range, uniform reflection efficiency can be obtained in all directions, and light having various wavelengths can be reflected in a well-balanced manner. That is, it is possible to realize a brighter and whiter reflector when viewed from any direction as compared with a conventional reflector. According to the reflection type liquid crystal display device of the present invention, a liquid crystal display device having a wide viewing angle and a bright display surface can be realized by including the reflector having the above excellent characteristics.
In the present invention, a large number of concave portions having an inner surface that forms a part of a spherical surface are formed so as to overlap the ends with the surface, and furthermore, the depth of the concave portions is defined, and the pitch of the adjacent concave portions is made random,Since the entire surface is formed by repeatedly and continuously forming a pattern in which a plurality of concave portions having a plurality of depths, a plurality of different pitches, and a plurality of different radii are individually formed in regions defined by vertical and horizontal rows,By repeatedly arranging a pattern in which the inclination angle distribution of the inner surface of the concave portion is substantially constant in a certain angle range with respect to all directions of the reflector, the entire surface of the reflector can be constituted.
Further, in the present invention,Each one is determined by the shape of the indenter,A large number of recesses with the inner surface forming a part of a spherical surface are formed so that the edges overlap each other on the surface, the depth of the recesses is specified, the pitch of the adjacent recesses is randomized, and the reflector is omnidirectional. It is possible to obtain a reflector by resin transfer via a transfer mold from a matrix base material that is almost constant in a certain angle range with respect to the inclination angle distribution of the inner surface of the concave portion,A plurality of recesses having the same depth are formed by pressing the indenter at the same depth in the region, and a random number is formed by repeating the same operation by changing the pressing depth in the region. Since a plurality of concave portions having different radii at random pitches at a depth are formed continuously in a pattern formed in a region defined by the vertical and horizontal rows,Uniform reflection efficiency can be obtained in all directions, and light with various wavelengths can be reflected in a well-balanced manner, realizing a brighter white reflector when viewed from any direction compared to conventional reflectors. There is an effect that can be done.
In the present invention, a reflector having a flattened surface can be obtained by providing a reflective film and a flattening film. In this case, by setting the depth of the concave portion to be in the range of 0.1 to 3 μm, the flattening film can be filled and flattened, and desired flatness can be obtained.
Further, according to the present invention, it is possible to obtain a reflection type liquid crystal display device provided with a reflector having the above-mentioned excellent effects externally or internally.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a reflector according to an embodiment of the present invention.
FIG. 2 is a process flow chart showing a manufacturing process of the reflector in order.
FIG. 3 is a view showing a process of manufacturing a matrix used for forming the reflector, showing a state where the matrix base material is pressed by a diamond indenter.
FIG. 4 is a plan view showing a pattern of rolling by a diamond indenter in the same manufacturing process of the mother die.
FIG. 5 is a plan view showing the shape of the entire concave portion after rolling.
FIG. 6 is a diagram showing the distribution of the inclination angle of the inner surface of the concave portion in the reflector.
FIG. 7 is a sectional view showing a reflective liquid crystal display device according to an embodiment of the present invention.
FIG. 8 is a view for explaining an inclination angle of an inner surface of a concave portion of the reflector according to the present invention.
FIG. 9 is a perspective view showing an example of a conventional reflector.
FIG. 10 is a cross-sectional view illustrating an example of a conventional reflective liquid crystal display device.
[Explanation of symbols]
1 Reflector
2 Substrate
3 Resin substrate (substrate for reflector)
4 recess
5 Reflective film
7 Matrix substrate
8 Diamond indenter
9 Matrix for forming reflector
12 Transfer type

Claims

The inner surface of the reflector surface forms a part of a spherical shape , and a tip spherical indenter is formed individually by pressing the indenter at a random pitch and a random depth, and a large number determined by the shape of the indenter recesses are formed so as to overlap the end portions each other in the recesses adjacent to each other in succession, to the 0.1 depth of the recess formed at random in the range of 3 [mu] m, the pitch between adjacent concave portions is randomly A reflector, wherein the reflector has a constant distribution in a range of −10 degrees to +10 degrees of the inclination angle of the inner surface of the concave portion.

The inner surface of the reflector surface forms a part of a spherical shape , and a tip spherical indenter is formed individually by pressing the indenter at a random pitch and a random depth, and a large number determined by the shape of the indenter recesses are formed so as to overlap the end portions each other in the recesses adjacent to each other in succession, to the 0.1 depth of the recess formed at random in the range of 3 [mu] m, the pitch between adjacent concave portions is randomly The arranged pattern is repeatedly arranged to form a reflector surface, and the inclination angle of the inner surface of the concave portion shows a constant distribution in a range of -10 degrees to +10 degrees, and the reflection light is diffused over the entire reflector surface. returned Rutotomoni set corners to a predetermined angle within the pattern formed in the area defined by a plurality of depths and a plurality of different pitches and different radii individually aspect column recesses repeated Reflector, characterized in that those which are continuously formed.

A matrix substrate having a number of recesses formed by pressing an indenter having a spherical tip at the surface of the matrix substrate, wherein the depth of the plurality of recesses is set by the pressing depth of the indenter. Randomly set on the surface of the base material, the pitch of the recesses is randomly set on the surface of the matrix base material by the pitch of the pressing position of the indenter, and the large number of recesses are formed between the ends of the recesses adjacent to each other. A transfer mold is formed by transfer from a matrix base material formed so as to be overlapped, and a reflector formed by transfer with a resin from the transfer mold, wherein an inner surface of the reflector surface is formed of the indenter. form a part of the spherical, single one but is formed continuously a number of recesses defined in the form of individually indenter, the depth of the recess Ru are formed at random in the range to the 3μm 0.1 With multiple depths Reflector, characterized in that in which the pattern formed in the area defined with different pitches and different radii of the concave portion of several individually vertical and horizontal rows are repeated continuously formed.

A plurality of recesses having the same depth are formed by pressing the indenter at the same depth in the area at intervals, and then the indenter is formed in the area by repeatedly performing the same operation by changing the pressing depth. 4. The reflector according to claim 3, wherein a pattern in which a plurality of recesses having different radii at different depths and random pitches are formed in a region defined by the vertical and horizontal rows is repeatedly and continuously formed .

The reflector according to any one of claims 1 to 4, wherein a reflection film and a flattening film are formed on the reflector surface.

A reflective liquid crystal display device comprising the reflector according to claim 1.

2. A liquid crystal layer is provided between a display-side substrate and a rear-side substrate that form a pair, a polarizing plate and a phase difference plate are provided on an upper surface of the display-side substrate, and a polarizing plate is provided on a lower surface of the rear-side substrate. A reflective liquid crystal display device, comprising the reflector according to any one of claims 1 to 5.

6. A liquid crystal layer is provided between the display-side substrate and the rear-side substrate that form a pair, a polarizing plate and a phase difference plate are provided on the upper surface of the display-side substrate, and the opposing surface of the rear-side substrate. A reflective liquid crystal display device, comprising the reflector according to any one of the above.