JP3973996B2

JP3973996B2 - Light guide plate and flat illumination device

Info

Publication number: JP3973996B2
Application number: JP2002240911A
Authority: JP
Inventors: カリルカランタル
Original assignee: 日本ライツ株式会社
Priority date: 2002-08-21
Filing date: 2002-08-21
Publication date: 2007-09-12
Anticipated expiration: 2022-08-21
Also published as: JP2004078015A

Description

【０００１】
【発明の属する技術分野】
本発明は、液晶表示装置等に用いられる導光板および平面照明装置に関し、導光板の入射部を複数有して、各入射部を中心として同心円弧で囲まれる領域壁を有した形状の光偏向素子を表面部や裏面部等に設けて表面部や裏面部等から各入射部より入射した光線が同程度の輝度で出射する導光板と、導光板の複数の入射部に単色光の光源を備えて、各光源に対して液晶表示装置等の三原色の各ピクセルに画像制御信号と同期した光源制御信号により選択光を導光板の入射部から供給することによりカラーフィルタを用いずにカラー表示をすることができる導光板および平面照明装置に関するものである。
【０００２】
【従来の技術】
従来の導光板および平面照明装置は、導光板の裏面部に散乱を利用する方法を用いるものが知られている。具体的には、酸化チタン等の白色材料を混入させたインクを用いて円形状や矩形状のドットを導光板の裏面部に対して光源から離れるほど多くなるようにドット印刷を行う。これにより、光源から離れるほど散乱光を得るようにして導光板からの出射光の均一性を得ようとしていた。
さらに、射出成形法を用いたものとして、導光板の表面部や裏面部にランダムに微細な凸凹形状を成形し、この微細な凸凹形状により散乱を利用する方法が知られている。
【０００３】
また同様に、射出成形法を用いたものとして、導光板の表面部や裏面部に凸形状や凹形状を単に光源から離れるほど多く分布（グラデーション）するように成形し、凸形状や凹形状により屈折や反射を利用する方法を用いるものが知られている。この方法により、光源から離れるほど屈折や反射等の確率を高くし、導光板からの出射光を均一させている。
【０００４】
さらに、上述した導光板の一側面や両側面にＣＣＦＬ等の蛍光ランプを用いたり、例えば携帯電話等の液晶表示装置等に用いられる小さな平面照明装置の場合に、白色発光のＬＥＤ光源を導光板の一側面に並べて設けたり、導光板の隅に設けたりする方法が知られている。
【０００５】
【発明が解決しようとする課題】
従来の導光板および平面照明装置は、導光板の裏面部に散乱を利用する方法を用いるもので、酸化チタン等の白色材料を混入させたインクを用いて円形状や矩形状のドットを導光板の裏面部に対して光源から離れるほど多くなるようにドット印刷を行っていた。これにより、光源から離れるほど散乱光を得るようにして導光板からの出射光の均一性を得ようとしていた。この場合、白色材料やインク等によって光を吸収してしまうとともに光が散乱してしまう。その結果、出射面のみに光線が到達せず、絶対出射光量が低いために輝度に課題がある。
【０００６】
また、射出成形によって導光板の表面部や裏面部にランダムに微細な凸凹形状を成形し、光源からの光線を散乱する方法では、光の吸収による損失はないが、上記の印刷法と同様に光が散乱してしまう。このため、出射面のみに光線が到達せず、出射光の輝度が低いという課題がある。しかも、凸凹形状の分布がランダムなため、輝度斑等に課題がある。
【０００７】
また同様に、凸形状や凹形状を単に光源から離れるほど多く分布（グラデーション）する場合には、インク等の印刷や微細な凸凹形状のランダム成形等と比べると改善されている。しかし、単に光源から離れるほど屈折や反射等の確率を高くさせているだけで、光源の指向性（輝度分布）や光源の形状等に対応していない。このため、光源の持つ光量と指向性やエネルギを十分引き出して利用されていない課題がある。
【０００８】
さらに、上述した導光板の一側面や両側面にＣＣＦＬ等の蛍光ランプを用いたり、例えば携帯電話等の液晶表示装置等に用いられる小さな平面照明装置の場合に、白色発光のＬＥＤ光源を導光板の一側面に並べて設けたり、導光板の隅に設けたりする方法では、液晶表示装置に於いて光の三原色をコントロールするために、平面照明装置からの白色光を三原色に分離する必要がある。このため、液晶の各ピクセルに対応した赤色、緑色および青色のカラーフィルタを必要とする課題がある。
【０００９】
また、単にＲＧＢの光の三原色の色度図に於けるＸ，Ｙ座標からの白色を得る範囲内のＲＧＢに対応したＸおよびＹの値からでは光度に対してのＲＧＢの各光度を得ることができない課題がある。
【００１０】
何れにせよ、これら従来の方法では、完全に光をコントロールできず、液晶表示装置を用いる時に光の三原色を分離するために三原色のカラーフィルタを必要としていた。このため、常に従来の平面照明装置からの光を３枚のカラーフィルタを透過する必要があった。そして、これらカラーフィルタによる光（エネルギ）の損失が有るため、これら従来の方法では輝度の向上に限界があった。
【００１１】
本発明は、上記のような課題を解決するためになされたもので、入射部を複数有するとともに表面部または／および裏面部に各入射部を中心とした同心円弧で囲まれる領域壁を有した形状とし、導光板のどの位置でも入射部からの光を全反射することができる光偏向素子を設け、表面部または／および裏面部から各入射部より入射した光線が同程度の輝度で出射する導光板と、入射部近傍に赤色光源、緑色光源および青色光源を備え、また各光源を液晶表示装置等の赤色信号と緑色信号と青色信号とに同期し、各光源と各信号の色とが対応して各信号によりオン・オフ点灯を行い液晶表示装置に於いて、カラーフィルタの必要性を省くことができる導光板および平面照明装置を提供することにある。
【００１２】
【課題を解決するための手段】
上記課題を解決するため本発明の請求項１に係る導光板は、入射部を複数有するとともに表面部または／および裏面部に各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子を設け、表面部または／および裏面部から各入射部より入射した光線が同程度の輝度で出射することを特徴とする。
【００１３】
請求項１に係る導光板は、入射部を複数有するとともに表面部または／および裏面部に各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子を設け、表面部または／および裏面部から各入射部より入射した光線が同程度の輝度で出射するので、任意の位置での異なる入射部からの光でも一定の出射輝度を出射することができる。
【００１４】
また、請求項２に係る導光板は、光偏向素子を、少なくとも３つの各入射部を中心とした所定曲率の同心円弧で囲まれる領域壁を有した形状とすることを特徴とする。
【００１５】
請求項２に係る導光板は、光偏向素子を、少なくとも３つの各入射部を中心とした所定曲率の同心円弧で囲まれる領域壁を有した形状とするので、導光板のどの位置でも入射部からの光を全反射することができる。
【００１６】
さらに、請求項３に係る導光板は、傾斜面が、表面部と裏面部との厚さ方向に対し、所定の曲率を有する凹面または凸面または平面であることを特徴とする。
【００１７】
請求項３に係る導光板は、傾斜面が、表面部と裏面部との厚さ方向に対し、所定の曲率を有する凹面または凸面または平面であるので、各入射部から傾斜面への進行方向に対しての全反射光を偏向することができる。
【００１８】
また、請求項４に係る平面照明装置は、赤色光源と緑色光源と青色光源とを有する光源と、光源からの光を導く入射部を複数有し、表面部または／および裏面部に各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子を設け、表面部または／および裏面部から各入射部より入射した光線が同程度の輝度で出射する導光板とを備えたことを特徴とする。
【００１９】
請求項４に係る平面照明装置は、赤色光源と緑色光源と青色光源とを有する光源と、光源からの光を導く入射部を複数有し、表面部または／および裏面部に各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子を設け、表面部または／および裏面部から各入射部より入射した光線が同程度の輝度で出射する導光板とを備えたので、必要な単色光や赤色、緑色、青色等の混合色の光を出射面から出射することができる。
【００２０】
さらに、請求項５に係る平面照明装置は、赤色光源と、赤色光源からの光を導く入射部を複数有し、各入射部より入射した赤色光線が表面部または／および裏面部に設けられた各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により表面部から同程度の輝度で赤色光を出射する第１の導光板と、緑色光源と、緑色光源からの光を導く入射部を複数有し、各入射部より入射した緑色光線が表面部または／および裏面部に設けられた各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により表面部から同程度の輝度で緑色光を出射する第２の導光板と、青色光源と、青色光源からの光を導く入射部を複数有し、各入射部より入射した青色光線が表面部または／および裏面部に設けられた各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により表面部から同程度の輝度で青色光を出射する第３の導光板とを備え、第１の導光板と第２の導光板と第３の導光板とが重ねて配置され、下方から上方に３原色光を出射することを特徴とする。
請求項５に係る平面照明装置は、赤色光源と、赤色光源からの光を導く入射部を複数有し、各入射部より入射した赤色光線が表面部または／および裏面部に設けられた各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により表面部から同程度の輝度で赤色光を出射する第１の導光板と、緑色光源と、緑色光源からの光を導く入射部を複数有し、各入射部より入射した緑色光線が表面部または／および裏面部に設けられた各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により表面部から同程度の輝度で緑色光を出射する第２の導光板と、青色光源と、青色光源からの光を導く入射部を複数有し、各入射部より入射した青色光線が表面部または／および裏面部に設けられた各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により表面部から同程度の輝度で青色光を出射する第３の導光板とを備え、第１の導光板と第２の導光板と第３の導光板とが重ねて配置され、下方から上方に３原色光を出射するので、各導光板から必要な単色光を出射でき、赤色出射の導光板、緑色出射の導光板、青色出射の導光板等により上方に単色光や混合色の光を出射することができる。
【００２１】
また、請求項６に係る平面照明装置は、各光源を赤色信号と緑色信号と青色信号の各色毎に同期し、各光源と各信号の色とが対応して各信号によりオン・オフ点灯を行うことを特徴とする。
請求項６に係る平面照明装置は、各光源を赤色信号と緑色信号と青色信号の各色毎に同期し、各光源と各信号の色とが対応して各信号によりオン・オフ点灯を行うので、液晶表示装置等の各色信号に対応して必要時のみに出射することができる。
【００２２】
【発明の実施の形態】
以下、本発明の実施の形態を添付図面に基づき説明する。
尚、本発明による平面照明装置は、入射部を複数有し、表面部や裏面部に各入射部を中心とした所定曲率の同心円弧で囲まれる領域壁を有した形状の光偏向素子を設けて導光板のどの位置でも入射部からの光を全反射して各入射部より入射した光線が同程度の輝度で出射する導光板と、入射部近傍に赤色光源、緑色光源および青色光源を備える。また、導光板としては、各発光色に対応した導光板を３つ用いても良い。さらに、各光源を液晶表示装置等の赤色信号と緑色信号と青色信号の各色毎に同期し、各光源と各信号の色とが対応して各信号によりオン・オフ点灯を行う。これにより、液晶表示装置等に於いて、カラーフィルタの必要性を省くことができる導光板と平面照明装置を提供する。
【００２３】
図１は本発明に係る平面照明装置の略分解組立図、図２は本発明に係る導光板の平面図、図３（ａ），（ｂ）は本発明に係る光偏向素子の代表的な略拡大斜視図であって、表面部側から見た凹形状の斜視図、図４は本発明に係る光偏向素子への光線の軌跡図、図５は本発明に係る平面照明装置の他の構成例を示す略分解組立図である。
【００２４】
導光板２は、屈折率が１．４〜１．７程度の透明なアクリル樹脂（ＰＭＭＡ）やポリカーボネート（ＰＣ）等で形成される。導光板２は、側面部４と、光の出射目的である表面部５と、その反対側に位置する裏面部６を有する矩形状をなしている。導光板２の４つの隅部分は、平坦面をなしており、光源８からの光を導く入射部３を形成している。なお、導光板２の４つの隅部分は、平坦面に限られるものではない。目的に応じて例えば凸状、凹状や微細プリズム状などの面としても良い。例えば、光源８からの光を広げて入射させるために凹状にすることも可能である。また、光源８からの光を導く入射部３は、図１に示すような隅部分に限らず、例えば側面部４の中央部分など側面部４の一部に形成することができる。
【００２５】
導光板２の表面部５や裏面部６には、各入射部３を中心とした所定曲率の同心円弧の４辺で囲まれる領域壁を有した形状の光偏向素子７が設けられる。この光偏向素子７は、光源８から各入射部３より入射した光線を同程度の輝度やエネルギで出射させる。
【００２６】
ここで、図２に導光板２に設けられる光偏向素子７（７ｃｃ，７ｃ１，７ｃ２，７ｃ３，７ｃ４）を詳しく説明する。
【００２７】
図２に示すように、導光板２の中央に設けられる光偏向素子７ｃｃは、各側面部４が直角に接続する位置の４つの隅位置Ｐ１，Ｐ２，Ｐ３，Ｐ４を中心とする同一曲率の同心円弧Ｌ１１，Ｌ２１，Ｌ３１，Ｌ４１の４辺で囲まれる領域壁Ｗ１，Ｗ２，Ｗ３，Ｗ４を有した凹形状となっている。
【００２８】
また、導光板２の各側面部４から等距離に位置する４つの光偏向素子７ｃ１，７ｃ２，７ｃ３，７ｃ４は、各側面部４が直角に接続する位置の４つの隅位置Ｐ１，Ｐ２，Ｐ３，Ｐ４を中心とする所定曲率の同心円弧の４辺で囲まれる領域壁を有した凹形状となっている。
【００２９】
例えば光偏向素子７ｃ４は、各側面部４が直角に接続する位置の４つの隅位置Ｐ１，Ｐ２，Ｐ３，Ｐ４を中心とする所定曲率の同心円弧Ｌ１２，Ｌ２２，Ｌ３２，Ｌ４２の４辺で囲まれる領域壁Ｗ１１，Ｗ２２，Ｗ３３，Ｗ４４を有する凹形状となっている。
【００３０】
そして、光偏向素子７ｃｃは、図３（ａ）に示すように、各導光板２の直角な隅位置Ｐ１，Ｐ２，Ｐ３，Ｐ４からの同心円弧による領域壁Ｗ１，Ｗ２，Ｗ３，Ｗ４によって囲まれた凹形状を成している。また、光偏向素子７ｃｃの各領域壁Ｗ１，Ｗ２，Ｗ３，Ｗ４は、図４に示すように、凹形状の底部の平坦面１１から裏面部６の面にかけて導光板２の厚さ方向にテーパ面を形成している。同様に、光偏向素子７ｃ１，７ｃ２，７ｃ３，７ｃ４も、図３（ｂ）に示すように、各導光板２の直角な隅位置Ｐ１，Ｐ２，Ｐ３，Ｐ４からの同心円弧による領域壁Ｗ１１，Ｗ２２，Ｗ３３，Ｗ４４によって囲まれた凹形状を成している。また、光偏向素子７ｃ１，７ｃ２，７ｃ３，７ｃ４の各領域壁も、光偏向素子７ｃｃと同様に、凹形状の底部に当たる平坦面から裏面部６の面にかけて導光板２の厚さ方向にテーパ面を形成している。
【００３１】
尚、ここでは５つの光偏向素子７ｃｃおよび７ｃ１，７ｃ２，７ｃ３，７ｃ４について説明したが、光偏向素子７は導光板２の表面部５や裏面部６の面上に各入射部３を中心とした所定曲率の同心円弧で囲まれる領域壁を有し、各領域壁が導光板２の厚さ方向に傾斜面（所定の曲率を有するテーパ面を含む）を形成していれば良い。そして、これら各入射部３を中心とした同心円弧で囲まれる領域壁は、常に入射部３（結果として光源８）に向いている。また、光偏向素子７は、導光板２内に導かれた光を全反射等の反射角度（最終の出射角度）をコントロールするため、反ったり（凹）膨らんだり（凸）した傾斜面を持つ凹形状や凸形状で形成することができる。さらに、拡散を目的として、凹形状と同様の凸形状の光偏向素子７を導光板２の表面部５や裏面部６に部分的に形成することもできる。
【００３２】
従って、各入射部３を中心とした同心円弧で囲まれる領域壁は、全ての入射部３（光源８）に対応している。そのため、これら光偏向素子７（７ｃｃ，７ｃ１，７ｃ２，７ｃ３，７ｃ４）は、光偏向素子７の存在する位置によって形状が異なっている。
【００３３】
また、光偏向素子７は、図４に示すように、凹形状の光偏向素子７の領域壁Ｗ１やＷ４が光源８の方向からの同心円弧状に位置している。このため、各光源８から導光板２内に進入して来た光線は、光偏向素子７の領域壁Ｗ１や領域壁Ｗ４によって全反射して光偏向素子７を設けた面とは反対側の面方向に進み、最終的に導光板２の面から出射する。
【００３４】
尚、光偏向素子７の凹形状の領域壁Ｗ１や領域壁Ｗ４の裏面部６と成す角度は、光偏向素子７の導光板２に存在する位置によって変化させても良い。
【００３５】
このように、光偏向素子７は、光源８からの光を導く各入射部３を中心とした所定曲率の同心円弧で囲まれる領域壁を有した凹形状により表面部５や裏面部６に設られる。これにより、導光板２の表面部５や裏面部６の任意の位置に存在する光偏向素子７から出射面方向に出射する光が各光源８に依存せずに同方向に出射することができる。
【００３６】
ところで、上述した例は、図１に示すように、１枚の矩形状の導光板２の四隅に平坦面からなる入射部３を設け、各入射部３の近傍に光源８を配置している。そして、導光板２の表面部５や裏面部６には、各入射部３を中心とした所定曲率の同心円弧で囲まれる領域壁を有した凹形状の光偏向素子７が設けられる。
【００３７】
そこで、この図１の平面照明装置を基本構成として、例えば図５に示す平面照明装置を構成することができる。図５の平面照明装置１は、１枚の矩形状の導光板２に対して４つの光源８が四隅の各入射部３の近傍に対向配置されたものを１つのユニットとして３つのユニットで構成されたものである。
【００３８】
さらに説明すると、１つ目のユニットは、赤色光源８ａ（８）と第１の導光板２ａ（２）を備えて構成される。そして、第１の導光板２ａは、赤色光源８ａからの光を導く入射部３を四隅に有し、各入射部３より入射した赤色光線が表面部５や裏面部６に設けられる凹形状の光偏向素子７により表面部５から同程度の輝度で赤色光を出射する。
【００３９】
２つ目のユニットは、緑色光源８ｂ（８）と第２の導光板２ｂ（２）を備えて構成される。そして、第２の導光板２ｂは、緑色光源８ｂからの光を導く入射部３を四隅に有し、各入射部３より入射した緑色光線が表面部５や裏面部６に設けられる凹形状の光偏向素子７により表面部５から同程度の輝度で緑色光を出射する。
【００４０】
３つ目のユニットは、青色光源８ｃ（８）と第３の導光板２ｃ（２）を備えて構成される。そして、第３の導光板２ｃは、青色光源８ｃからの光を導く入射部３を四隅に有し、各入射部３より入射した青色光線が表面部５や裏面部６に設けられる凹形状の光偏向素子７により表面部５から同程度の輝度で青色光を出射する。
【００４１】
そして、上述した３つのユニットを第１の導光板２ａ、第２の導光板２ｂ、第３の導光板２ｃと順不同に重ねて配置することにより、下方から上方に３原色光を出射する。なお、各導光板２ａ，２ｂ，２ｃの表面部５や裏面部６に設けられる光偏向素子７は、前述した構成と同様である。
【００４２】
光源８は、半導体発光素子であって、ＬＥＤやレーザ等からなり、ＲＧＢ（赤色、緑色、青色）の各単色光を各入射部３に設けたり、ＲＧＢ（赤色、緑色、青色）を組み合わせたユニットを各入射部３に設けても良い。
【００４３】
また、光源８は入射部３が大きい場合や導光板自体が大きい場合に単色発光のＣＣＦＬ（冷陰管）を用いても良い。この場合、これらの光源は線状をなし、直接光は導光板２の入射部３から導光板２内に入射し、他の光は図示しないリフレクタで反射されながら光源８とリフレクタとの空間を通って導光板２内に入射する。
【００４４】
尚、導光板自体が大きい場合、光源８の入射部３は、図示しないが導光板２の側面部４の近傍に設けても良い。
【００４５】
また、この場合、光偏向素子７は、各線状光源８からの輝度やエネルギが等しい等輝度線に囲まれる領域壁を有していれば良い。そして、これら各入射部３または各側面部４からの等輝度線での領域壁は、常に入射部３や側面部４（結果として光源８）に向いている。
【００４６】
従って、各入射部３や各側面部４からの等輝度線で囲まれる領域壁は、全ての入射部３や側面部４（光源８）に対応している。そのため、これら光偏向素子７は、光偏向素子７の存在する位置によって形状が異なっている。
【００４７】
また、この際の光偏向素子７は、図４に示した場合と同様に，各光源８から導光板２内に進入して来た光線Ｌ１やＬ２が光偏向素子７の壁Ｗ１や壁Ｗ４によって全反射させる。そして、この全反射した光線Ｌ１ＲやＬ２Ｒは、光偏向素子７を設けた面とは反対側の面方向に進み、最終的に導光板２の面から光線Ｌ１０やＬ２０が出射する。
【００４８】
尚、光偏向素子７の凹形状の壁Ｗ１や壁Ｗ４の裏面部６と成す角度は、光偏向素子７の導光板２に存在する位置によって変化させても良い。
【００４９】
さらに、光源８の各赤色発光のＬＥＤと緑色発光のＬＥＤと青色発光のＬＥＤにより色度図のｘ，ｙ座標からの白色を得る範囲内のＲＧＢに対応した色度バランス比率として、色度図に於けるｘ，ｙ座標に於いて目的とする白色と各発光色との距離と光度との関数で表せる。この関数は下記数１の式で示すことができる。
【００５０】
【数１】

【００５１】
例えば、ｘ，ｙ座標に於いて、赤色発光のＬＥＤの座標が（０．６７，０．３）、緑色発光のＬＥＤの座標が（０．１４，０．７４）、青色発光のＬＥＤの座標が（０．１１，０．１０）で、これら各ＬＥＤの印加電流値（ＩＦ（ｍＡ））を２０ｍＡにした時の絶対光度Ｉｖ（ｍｃｄ）は、赤色発光ＬＥＤで５６０ｍｃｄ、緑色発光ＬＥＤで１２０ｍｃｄ、青色発光ＬＥＤで１８０ｍｃｄであるので、上記関数の式に代入すると白色時の色度図のｘ，ｙ座標は、（ｘｍ，ｙｍ）＝（０．４７８８，０．３３９１）となる。
【００５２】
このように、この関数は光度因子に左右されるので、色度図から目的の白色光を得る場合に、各赤色発光ＬＥＤ、緑色発光ＬＥＤ、青色発光ＬＥＤのｘ，ｙ座標に対して各光度のコントロールにより希望する白色光を得ることができる。故に、目的とする白色光を得るために、各赤色発光ＬＥＤ、緑色発光ＬＥＤ、青色発光ＬＥＤに印加する電流比率を変化させる。これにより、必要とする白色光の最適な色度および光度が得られる。
【００５３】
尚、本実施の形態では、導光板２を四角形として入射部３も４箇所としたが、導光板２を六角形にし入射部３も６箇所とし、ＲＧＢに発光する光源８（赤色発光ＬＥＤ、緑色発光ＬＥＤ、青色発光ＬＥＤ）を交互に設けても良い。
【００５４】
また、ここでは図示しないが、リフレクタは白色の絶縁性材料やアルミニウム等の金属を蒸着したシート状または金属等からなる。このリフレクタは、導光板２の入射部３および光源８を囲するように設けられ、光源８からの光を反射し、反射光を導光板２の入射部７に再び入射させる。
【００５５】
また、同様に図示しないが、光源８が半導体発光素子の場合でも光源８に対して同様な材料により導光板２の入射部３および光源８を囲するようにしても良い。これにより、光源８からの漏れや他の要素による反射光等を反射し、反射光を導光板２の入射部３に再び入射させる。
【００５６】
さらに、各光源８を例えば液晶表示装置での１ピクセル中の各赤色、緑色、青色に対応する液晶への各赤色信号、緑色信号、青色信号を光源８の赤色光源、緑色光源、青色光源の各光源８の色毎に同期させて、液晶表示装置の液晶への各信号の色に対応して各信号により各光源８のオン・オフ点灯を行うようにしても良い。
【００５７】
そのために、液晶表示装置の各色信号に対応して各光源８のオン・オフ点灯を行い、液晶表示装置の各色信号のオン信号の時のみ各光源８をオン動作させて各色光の必要な時のみ出射することができる。
【００５８】
これにより、従来のようなカラーフィルタ等を用いることなく、直接赤色、緑色、青色を出射するので、クリアな色が再現できる。しかも、常時出射せず、必要なときだけ出射するので、省エネ等経済性に優れている。
【００５９】
【発明の効果】
以上のように、請求項１に係る導光板は、入射部を複数有するとともに表面部または／および裏面部に各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子を設け、表面部または／および裏面部から各入射部より入射した光線が同程度の輝度で出射するので、任意の位置での異なる入射部からの光でも一定の出射輝度を出射することができる。これにより、入射部に異なる発光色を入射することで異なる各種の色の出射光を得ることができる。
【００６０】
また、請求項２に係る導光板は、光偏向素子を、少なくとも３つの各入射部を中心とした所定曲率の同心円弧で囲まれる領域壁を有した形状とするので、導光板のどの位置でも入射部からの光を全反射することができ、高輝度の出射光を得ることができる。しかも、光源に左右されないで設計をすることができる。
【００６１】
さらに、請求項３に係る導光板は、傾斜面が、表面部と裏面部との厚さ方向に対し、所定の曲率を有する凹面または凸面または平面であるので、各入射部から傾斜面への進行方向に対しての全反射光を偏向することができる。そのために、出射面で各入射部からの光を互いにより混合することができる。
【００６２】
また、請求項４に係る平面照明装置は、赤色光源と緑色光源と青色光源とを有する光源と、光源からの光を導く入射部を複数有し、表面部または／および裏面部に各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子を設け、表面部または／および裏面部から各入射部より入射した光線が同程度の輝度で出射する導光板とを備えたので、必要な単色光や赤色、緑色、青色等の混合色の光を出射面から出射することができる。
【００６３】
さらに、請求項５に係る平面照明装置は、赤色光源と、赤色光源からの光を導く入射部を複数有し、各入射部より入射した赤色光線が表面部または／および裏面部に設けられた各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により表面部から同程度の輝度で赤色光を出射する第１の導光板と、緑色光源と、緑色光源からの光を導く入射部を複数有し、各入射部より入射した緑色光線が表面部または／および裏面部に設けられた各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により表面部から同程度の輝度で緑色光を出射する第２の導光板と、青色光源と、青色光源からの光を導く入射部を複数有し、各入射部より入射した青色光線が表面部または／および裏面部に設けられた各入射部を中心とした所定曲率の同心円弧で囲まれ、表面部と裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により表面部から同程度の輝度で青色光を出射する第３の導光板とを備え、第１の導光板と第２の導光板と第３の導光板とが重ねて配置され、下方から上方に３原色光を出射するので、各導光板から必要な単色光を出射でき、赤色出射の導光板、緑色出射の導光板、青色出射の導光板等により上方に単色光や混合色の光を出射することができる。これにより、液晶表示装置等に用いるときにカラーフィルタを必要とせず、カラーフィルタによる吸収が無いので、効率良く光源からの光を利用することができる。
また、請求項６に係る平面照明装置は、各光源を赤色信号と緑色信号と青色信号の各色毎に同期し、各光源と各信号の色とが対応して各信号によりオン・オフ点灯を行うので、液晶表示装置等の各色信号に対応して必要時のみに出射することができる。これにより、クリアな色を出射できるとともに常時出射しないので、省エネ等経済性に優れている。
【図面の簡単な説明】
【図１】本発明に係る平面照明装置の略構成図
【図２】本発明に係る導光板の略平面図
【図３】（ａ），（ｂ）本発明に係る光偏向素子の代表的な略拡大斜視図であって、表面部側から見た凹形状の斜視図
【図４】本発明に係る導光板の光線の略軌跡図
【図５】本発明に係る平面照明装置の他の構成例を示す略構成図
【符号の説明】
１…平面照明装置、２，２ａ，２ｂ，２ｃ…導光板、３…入射部、４…側面部、５，５ａ，５ｂ，５ｃ…表面部、６，６ａ，６ｂ，６ｃ…裏面部、７，７ｃｃ，７ｃ１，７ｃ２，７ｃ３，７ｃ４…光偏向素子、８，８ａ，８ｂ，８ｃ…光源、１１…平坦面、Ｐ１，Ｐ２，Ｐ３，Ｐ４…隅、Ｗ１，Ｗ２，Ｗ３，Ｗ４，Ｗ１１，Ｗ２２，Ｗ３３，Ｗ４４…壁、Ｌ１１，Ｌ１２，Ｌ２１，Ｌ２２，Ｌ３１，Ｌ３２，Ｌ４１，Ｌ４２…同心円弧、Ｌ１，Ｌ１ｒ，Ｌ１０，Ｌ２，Ｌ２ｒ，Ｌ２０…光線。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light guide plate and a flat illumination device used for a liquid crystal display device or the like, and has a plurality of incident portions of the light guide plate, and has a shape with a region wall surrounded by a concentric arc around each incident portion. An element is provided on the front surface, the back surface, etc., and a light guide plate from which light incident from each incident portion from the front surface, the back surface, etc. is emitted with the same brightness, and a light source of monochromatic light at a plurality of incident portions of the light guide plate In addition, for each light source, color light can be displayed without using a color filter by supplying selection light from the incident part of the light guide plate to each pixel of the three primary colors such as a liquid crystal display device by a light source control signal synchronized with the image control signal. The present invention relates to a light guide plate and a flat illumination device.
[0002]
[Prior art]
As the conventional light guide plate and flat illumination device, one using a method utilizing scattering on the back surface of the light guide plate is known. Specifically, dot printing is performed using an ink mixed with a white material such as titanium oxide so that the number of circular or rectangular dots increases as the distance from the light source increases with respect to the back surface of the light guide plate. As a result, the uniformity of the emitted light from the light guide plate is obtained by obtaining scattered light as the distance from the light source increases.
Furthermore, as a method using an injection molding method, there is known a method in which fine uneven shapes are randomly formed on the front surface portion and the back surface portion of the light guide plate, and scattering is used by the fine uneven shapes.
[0003]
Similarly, using the injection molding method, the convex shape and concave shape are simply distributed on the front and back surfaces of the light guide plate so that they are more distributed (gradient) away from the light source. A method using a method utilizing refraction or reflection is known. By this method, the probability of refraction and reflection increases as the distance from the light source increases, and the light emitted from the light guide plate is made uniform.
[0004]
Further, when a fluorescent lamp such as CCFL is used on one side surface or both side surfaces of the light guide plate described above, or a small flat illumination device used for a liquid crystal display device such as a mobile phone, a white light emitting LED light source is used as the light guide plate. There are known methods of arranging them side by side or providing them at the corners of the light guide plate.
[0005]
[Problems to be solved by the invention]
Conventional light guide plates and flat illumination devices use a method of utilizing scattering on the back surface of a light guide plate, and circular or rectangular dots are guided using ink mixed with a white material such as titanium oxide. Dot printing was performed so that the back surface portion increased as the distance from the light source increased. As a result, the uniformity of the emitted light from the light guide plate is obtained by obtaining scattered light as the distance from the light source increases. In this case, the light is absorbed and scattered by the white material or ink. As a result, the light beam does not reach only the exit surface, and there is a problem in luminance because the absolute amount of emitted light is low.
[0006]
In addition, the method of randomly forming fine irregularities on the front and back parts of the light guide plate by injection molding and scattering the light from the light source does not cause loss due to light absorption, but as with the above printing method Light is scattered. For this reason, there is a problem that the light beam does not reach only the emission surface and the luminance of the emitted light is low. In addition, since the uneven distribution is random, there is a problem with luminance spots and the like.
[0007]
Similarly, when the convex shape or concave shape is distributed more (gradient) as it is farther from the light source, it is improved as compared with printing of ink or the like or random molding of fine concave and convex shapes. However, the probability of refraction or reflection is simply increased as the distance from the light source is increased, and it does not correspond to the directivity (luminance distribution) of the light source, the shape of the light source, or the like. For this reason, there is a problem that the light quantity, directivity, and energy of the light source are not sufficiently utilized.
[0008]
Further, when a fluorescent lamp such as CCFL is used on one side surface or both side surfaces of the light guide plate described above, or a small flat illumination device used for a liquid crystal display device such as a mobile phone, a white light emitting LED light source is used as the light guide plate. In order to control the three primary colors of light in the liquid crystal display device, it is necessary to separate the white light from the flat illumination device into the three primary colors. For this reason, there exists a subject which requires the color filter of red, green, and blue corresponding to each pixel of a liquid crystal.
[0009]
In addition, in the chromaticity diagram of the three primary colors of RGB light, the RGB luminosity is obtained with respect to the luminosity from the X and Y values corresponding to RGB within the range for obtaining white from the X and Y coordinates. There is a problem that cannot be done.
[0010]
In any case, these conventional methods cannot completely control light, and when using a liquid crystal display device, a color filter of three primary colors is required to separate the three primary colors of light. For this reason, it has been necessary to always transmit the light from the conventional flat illumination device through the three color filters. Further, since there is a loss of light (energy) due to these color filters, these conventional methods have a limit in improving luminance.
[0011]
The present invention has been made to solve the above-described problems, and has a plurality of incident portions and a region wall surrounded by a concentric arc centered on each incident portion on the front surface portion and / or the back surface portion. A light deflecting element that can totally reflect the light from the incident part at any position of the light guide plate is provided, and light incident from each incident part is emitted from the front part or / and the rear part with the same brightness. The light guide plate includes a red light source, a green light source, and a blue light source in the vicinity of the incident portion, and each light source is synchronized with a red signal, a green signal, and a blue signal of a liquid crystal display device, etc. Correspondingly, it is an object to provide a light guide plate and a flat illumination device which can be turned on / off by each signal to eliminate the need for a color filter in a liquid crystal display device.
[0012]
[Means for Solving the Problems]
  In order to solve the above problems, a light guide plate according to claim 1 of the present invention has a plurality of incident portions and is provided on the front surface portion and / or the back surface portion.A shape having a region wall that is surrounded by concentric arcs of a predetermined curvature centered on each incident portion, and has inclined surfaces in the thickness direction of the front surface portion and the back surface portion.An optical deflecting element is provided, and light rays incident from each incident portion from the front surface portion and / or the back surface portion are emitted with the same luminance.
[0013]
  The light guide plate according to claim 1 has a plurality of incident portions and has a front surface portion and / or a back surface portion.A shape having a region wall that is surrounded by concentric arcs of a predetermined curvature centered on each incident portion, and has inclined surfaces in the thickness direction of the front surface portion and the back surface portion.A light deflection element is provided, and light beams incident from each incident part from the front surface part and / or the back surface part are emitted with the same level of brightness, so that even from light from different incident parts at any position, a constant emission brightness is emitted. be able to.
[0014]
  Further, according to claim 2Light guide plateIsThe optical deflecting element has a shape having a region wall surrounded by a concentric arc having a predetermined curvature centered on at least three incident portions.It is characterized by that.
[0015]
  According to claim 2Light guide plateIsThe optical deflecting element has a shape having a region wall surrounded by a concentric arc having a predetermined curvature centered on at least three incident portions.SoTotal reflection of light from the incident part at any position on the light guide platecan do.
[0016]
  Furthermore, the light guide plate according to claim 3 is:The inclined surface is a concave surface, a convex surface, or a flat surface having a predetermined curvature with respect to the thickness direction of the front surface portion and the back surface portion.It is characterized by that.
[0017]
  The light guide plate according to claim 3 is:The inclined surface is a concave surface, a convex surface, or a flat surface having a predetermined curvature with respect to the thickness direction of the front surface portion and the back surface portion.SoDeflection of total reflected light in the traveling direction from each incident part to the inclined surfacecan do.
[0018]
  A flat illumination device according to claim 4 includes a red light source andA light source having a green light source and a blue light source, and a plurality of incident portions for guiding light from the light source, and is surrounded by a concentric arc having a predetermined curvature centered on each incident portion on the front surface portion and / or the back surface portion; A light deflecting element having an area wall with an inclined surface formed in the thickness direction between the back surface and the back surface is provided, and light incident from each incident portion from the front surface or / and the back surface is emitted with the same brightness. With a light guide plateIt is characterized by that.
[0019]
  The flat illumination device according to claim 4 includes a red light source andA light source having a green light source and a blue light source, and a plurality of incident portions for guiding light from the light source, and is surrounded by a concentric arc having a predetermined curvature centered on each incident portion on the front surface portion and / or the back surface portion; A light deflecting element having an area wall with an inclined surface formed in the thickness direction between the back surface and the back surface is provided, and light incident from each incident portion from the front surface or / and the back surface is emitted with the same brightness. With a light guide plateSoNecessary monochromatic light, red, green, blue, etc.Mixed color light can be emitted from the exit surface.
[0020]
  Furthermore, the flat illumination device according to claim 5 is:A red light source and a plurality of incident portions for guiding light from the red light source, and a concentric arc having a predetermined curvature centered on each incident portion provided on the front surface portion and / or the back surface portion with red light incident from each incident portion. A first light guide plate that emits red light with the same brightness from the surface portion by a light deflecting element having a region wall having a sloped surface in the thickness direction between the front surface portion and the back surface portion. A green light source and a plurality of incident portions for guiding light from the green light source, and a green ray incident from each incident portion is concentric with a predetermined curvature centered on each incident portion provided on the front surface portion and / or the back surface portion A second light guide plate that emits green light with the same brightness from the front surface portion by a light deflection element having a region wall that is surrounded by an arc and has an inclined surface in the thickness direction between the front surface portion and the back surface portion. A blue light source and a plurality of incident portions for guiding light from the blue light source. A region in which a more incident blue ray is surrounded by a concentric arc having a predetermined curvature centered on each incident portion provided on the front surface portion and / or the back surface portion, and an inclined surface is formed in the thickness direction of the front surface portion and the back surface portion A third light guide plate that emits blue light from the surface portion with the same brightness by a light deflecting element having a wall shape, the first light guide plate, the second light guide plate, and the third light guide plate; Are arranged in an overlapping manner and emit light of the three primary colors from below to aboveIt is characterized by that.
  The flat illumination device according to claim 5 includes a red light source and a plurality of incident portions that guide light from the red light source, and each incident portion in which red light incident from each incident portion is provided on the front surface portion and / or the back surface portion. Red with the same level of brightness from the front surface by a light deflecting element that is surrounded by a concentric arc with a predetermined curvature centered on the surface and has an area wall with an inclined surface in the thickness direction between the front surface and the back surface Each of the first light guide plate that emits light, the green light source, and a plurality of incident portions that guide light from the green light source, and the green light incident from each incident portion is provided on the front surface portion and / or the back surface portion It is surrounded by a concentric arc with a predetermined curvature centered on the incident part, and has the same brightness from the surface part by a light deflecting element having a shape with an area wall that forms an inclined surface in the thickness direction between the front part and the back part. A second light guide plate for emitting green light, a blue light source, and light from the blue light source There are a plurality of leading incident portions, and blue light incident from each incident portion is surrounded by concentric arcs of a predetermined curvature centered on each incident portion provided on the front surface portion and / or the back surface portion, and the front surface portion and the back surface portion A third light guide plate that emits blue light from the surface portion with the same level of brightness by a light deflecting element having a shape having an area wall formed with an inclined surface in the thickness direction of the first light guide plate and the first light guide plate. Since the two light guide plates and the third light guide plate are arranged so as to emit the three primary color lights from below to above, the necessary single color light can be emitted from each light guide plate. Monochromatic light or mixed color light can be emitted upward by a light guide plate, a blue light guide plate, or the like.
[0021]
  Further, the flat illumination device according to claim 6 synchronizes each light source for each color of a red signal, a green signal, and a blue signal, and each light source corresponds to the color of each signal and is turned on / off by each signal. It is characterized by performing.
  Claim6In the flat illumination device according to the present invention, each light source is synchronized for each color of the red signal, the green signal, and the blue signal, and each light source corresponds to the color of each signal and is turned on / off by each signal. The light can be emitted only when necessary corresponding to each color signal of the apparatus or the like.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
The flat illumination device according to the present invention includes a plurality of incident portions, and a light deflection element having a shape including a region wall surrounded by a concentric arc having a predetermined curvature centering on each incident portion on the front surface portion and the back surface portion. A light guide plate that totally reflects the light from the incident part at any position of the light guide plate and emits light incident from each incident part with the same brightness, and a red light source, a green light source, and a blue light source in the vicinity of the incident part . Moreover, as a light guide plate, you may use three light guide plates corresponding to each luminescent color. Further, each light source is synchronized for each color of a red signal, a green signal, and a blue signal of a liquid crystal display device or the like, and each light source and each signal color are turned on / off by each signal. This provides a light guide plate and a flat illumination device that can eliminate the need for a color filter in a liquid crystal display device or the like.
[0023]
1 is a schematic exploded view of a flat illumination device according to the present invention, FIG. 2 is a plan view of a light guide plate according to the present invention, and FIGS. 3 (a) and 3 (b) are representative of light deflecting elements according to the present invention. FIG. 4 is a schematic perspective view of a concave shape as viewed from the front surface side, FIG. 4 is a locus diagram of light rays to the light deflection element according to the present invention, and FIG. 5 is another view of the flat illumination device according to the present invention. FIG. 6 is a schematic exploded view showing a configuration example.
[0024]
The light guide plate 2 is formed of a transparent acrylic resin (PMMA) or polycarbonate (PC) having a refractive index of about 1.4 to 1.7. The light guide plate 2 has a rectangular shape having a side surface portion 4, a front surface portion 5 for light emission, and a back surface portion 6 located on the opposite side. The four corner portions of the light guide plate 2 form a flat surface, and form an incident portion 3 that guides light from the light source 8. The four corner portions of the light guide plate 2 are not limited to flat surfaces. Depending on the purpose, for example, a convex, concave, or fine prism surface may be used. For example, it is possible to form a concave shape so that light from the light source 8 is spread and incident. Moreover, the incident part 3 which guides the light from the light source 8 is not limited to the corner part as shown in FIG. 1, but can be formed on a part of the side part 4 such as the center part of the side part 4.
[0025]
On the front surface portion 5 and the back surface portion 6 of the light guide plate 2, a light deflection element 7 having a shape having a region wall surrounded by four sides of a concentric arc having a predetermined curvature centering on each incident portion 3 is provided. The light deflecting element 7 emits the light beam incident from each incident portion 3 from the light source 8 with the same brightness and energy.
[0026]
Here, the light deflection element 7 (7cc, 7c1, 7c2, 7c3, 7c4) provided on the light guide plate 2 will be described in detail with reference to FIG.
[0027]
As shown in FIG. 2, the light deflection element 7cc provided at the center of the light guide plate 2 has the same curvature centering around the four corner positions P1, P2, P3, P4 where the side surface portions 4 are connected at right angles. It has a concave shape having region walls W1, W2, W3, W4 surrounded by four sides of concentric arcs L11, L21, L31, L41.
[0028]
Further, the four light deflection elements 7c1, 7c2, 7c3, 7c4 located at equal distances from the side surface parts 4 of the light guide plate 2 are arranged at four corner positions P1, P2, P3 at which the side surface parts 4 are connected at right angles. , P4, and a concave shape having a region wall surrounded by four sides of a concentric circular arc having a predetermined curvature.
[0029]
For example, the optical deflection element 7c4 is surrounded by four sides of concentric arcs L12, L22, L32, and L42 having a predetermined curvature centering around the four corner positions P1, P2, P3, and P4 where the side surface portions 4 are connected at right angles. It has a concave shape having area walls W11, W22, W33, W44.
[0030]
Then, as shown in FIG. 3A, the light deflection element 7cc is surrounded by region walls W1, W2, W3, W4 by concentric arcs from the right corner positions P1, P2, P3, P4 of each light guide plate 2. It has a concave shape. Further, as shown in FIG. 4, each region wall W1, W2, W3, W4 of the light deflection element 7cc is tapered in the thickness direction of the light guide plate 2 from the flat surface 11 of the bottom of the concave shape to the surface of the back surface portion 6. A surface is formed. Similarly, the light deflection elements 7c1, 7c2, 7c3, and 7c4 also have region walls W11, which are formed by concentric arcs from the right-angled corner positions P1, P2, P3, and P4 of each light guide plate 2, as shown in FIG. It has a concave shape surrounded by W22, W33 and W44. Similarly to the light deflection element 7 cc, the region walls of the light deflection elements 7 c 1, 7 c 2, 7 c 3, and 7 c 4 are also tapered in the thickness direction of the light guide plate 2 from the flat surface that hits the bottom of the concave shape to the surface of the back surface portion 6. Is forming.
[0031]
Here, the five light deflecting elements 7 cc and 7 c 1, 7 c 2, 7 c 3 and 7 c 4 have been described. However, the light deflecting element 7 is centered on each incident portion 3 on the surface 5 or the back surface 6 of the light guide plate 2. It suffices to have a region wall surrounded by a concentric arc having a predetermined curvature, and each region wall forms an inclined surface (including a tapered surface having a predetermined curvature) in the thickness direction of the light guide plate 2. And the area | region wall enclosed with the concentric circular arc centering on each of these incident part 3 is always facing the incident part 3 (resulting in the light source 8). The light deflection element 7 has an inclined surface that warps (concave) or bulges (convex) in order to control the reflection angle (final emission angle) such as total reflection of the light guided into the light guide plate 2. It can be formed in a concave shape or a convex shape. Furthermore, for the purpose of diffusion, a convex light deflection element 7 similar to the concave shape can be partially formed on the front surface portion 5 and the rear surface portion 6 of the light guide plate 2.
[0032]
Therefore, the region wall surrounded by the concentric arc centering on each incident portion 3 corresponds to all the incident portions 3 (light sources 8). Therefore, the shapes of these light deflection elements 7 (7cc, 7c1, 7c2, 7c3, 7c4) are different depending on the position where the light deflection element 7 exists.
[0033]
Further, as shown in FIG. 4, the area walls W <b> 1 and W <b> 4 of the concave optical deflection element 7 are positioned in a concentric arc shape from the direction of the light source 8. For this reason, the light beam that has entered the light guide plate 2 from each light source 8 is totally reflected by the region wall W1 and the region wall W4 of the light deflection element 7 and is opposite to the surface on which the light deflection element 7 is provided. The light travels in the surface direction and finally exits from the surface of the light guide plate 2.
[0034]
The angle formed between the concave region wall W1 of the light deflection element 7 and the back surface portion 6 of the region wall W4 may be changed depending on the position of the light deflection element 7 on the light guide plate 2.
[0035]
As described above, the light deflection element 7 is provided on the front surface portion 5 and the back surface portion 6 by a concave shape having a region wall surrounded by a concentric arc having a predetermined curvature around each incident portion 3 that guides light from the light source 8. It is done. Thereby, the light radiate | emitted from the light deflection element 7 which exists in the arbitrary positions of the surface part 5 and the back surface part 6 of the light-guide plate 2 to an output surface direction can be radiate | emitted in the same direction without depending on each light source 8. .
[0036]
By the way, in the above-described example, as shown in FIG. 1, the incident portions 3 made of flat surfaces are provided at the four corners of one rectangular light guide plate 2, and the light source 8 is disposed in the vicinity of each incident portion 3. . A concave-shaped light deflection element 7 having a region wall surrounded by a concentric arc having a predetermined curvature centering on each incident portion 3 is provided on the front surface portion 5 and the rear surface portion 6 of the light guide plate 2.
[0037]
Therefore, for example, the flat illumination device shown in FIG. 5 can be configured with the flat illumination device of FIG. 1 as a basic configuration. The flat illumination device 1 shown in FIG. 5 is composed of three units in which one light guide plate 2 and four light sources 8 are arranged opposite to each other near the incident portions 3 at the four corners. It has been done.
[0038]
More specifically, the first unit includes a red light source 8a (8) and a first light guide plate 2a (2). And the 1st light-guide plate 2a has the incident part 3 which guides the light from the red light source 8a in four corners, and the concave shape by which the red light ray which injected from each incident part 3 is provided in the surface part 5 and the back surface part 6 is provided. The light deflecting element 7 emits red light from the surface portion 5 with the same luminance.
[0039]
The second unit includes a green light source 8b (8) and a second light guide plate 2b (2). And the 2nd light-guide plate 2b has the incident part 3 which guides the light from the green light source 8b in four corners, and the concave shape by which the green light ray which injected from each incident part 3 is provided in the surface part 5 or the back surface part 6 is provided. Green light is emitted from the surface portion 5 by the light deflection element 7 with the same brightness.
[0040]
The third unit includes a blue light source 8c (8) and a third light guide plate 2c (2). And the 3rd light-guide plate 2c has the incident part 3 which guides the light from the blue light source 8c in four corners, and the concave shape by which the blue light ray which injected from each incident part 3 is provided in the surface part 5 or the back surface part 6 is provided. Blue light is emitted from the surface portion 5 with the same brightness by the light deflection element 7.
[0041]
The three units described above are arranged in a random order with the first light guide plate 2a, the second light guide plate 2b, and the third light guide plate 2c, thereby emitting the three primary color lights from below to above. In addition, the light deflection elements 7 provided on the front surface portion 5 and the back surface portion 6 of each

light guide plate

2a, 2b, 2c have the same configuration as described above.
[0042]
The light source 8 is a semiconductor light emitting element, and is composed of an LED, a laser, or the like. Each single color light of RGB (red, green, blue) is provided in each incident portion 3, or RGB (red, green, blue) is combined. A unit may be provided in each incident portion 3.
[0043]
The light source 8 may be a monochromatic CCFL (cold tube) when the incident portion 3 is large or the light guide plate itself is large. In this case, these light sources are linear, direct light enters the light guide plate 2 from the incident portion 3 of the light guide plate 2, and other light is reflected by a reflector (not shown) while passing through the space between the light source 8 and the reflector. The light passes through and enters the light guide plate 2.
[0044]
When the light guide plate itself is large, the incident portion 3 of the light source 8 may be provided in the vicinity of the side surface portion 4 of the light guide plate 2 (not shown).
[0045]
In this case, the light deflection element 7 only needs to have a region wall surrounded by isoluminance lines having equal luminance and energy from the respective linear light sources 8. And the area | region wall in the isoluminance line from each incident part 3 or each side part 4 has always faced the incident part 3 and the side part 4 (resulting in the light source 8).
[0046]
Therefore, the region walls surrounded by the isoluminance lines from the respective incident portions 3 and the respective side surface portions 4 correspond to all the incident portions 3 and the side surface portions 4 (light sources 8). Therefore, the shapes of these light deflection elements 7 differ depending on the position where the light deflection element 7 exists.
[0047]
Further, in this case, the light deflecting element 7 has the light beams L1 and L2 that have entered the light guide plate 2 from the respective light sources 8 into the walls W1 and W4 of the light deflecting element 7, as in the case shown in FIG. To totally reflect. Then, the totally reflected light beams L1R and L2R travel in the surface direction opposite to the surface on which the light deflection element 7 is provided, and finally light beams L10 and L20 are emitted from the surface of the light guide plate 2.
[0048]
The angle formed between the concave wall W1 of the light deflection element 7 and the back surface portion 6 of the wall W4 may be changed depending on the position of the light deflection element 7 on the light guide plate 2.
[0049]
Further, the chromaticity diagram as a chromaticity balance ratio corresponding to RGB within a range in which white is obtained from the x and y coordinates of the chromaticity diagram by each of the red light emitting LED, the green light emitting LED, and the blue light emitting LED of the light source 8. In the x and y coordinates, the distance between the target white color and each emission color and the luminous intensity can be expressed as a function. This function can be expressed by the following equation (1).
[0050]
[Expression 1]

[0051]
For example, in the x and y coordinates, the coordinates of the red light emitting LED are (0.67, 0.3), the coordinates of the green light emitting LED are (0.14, 0.74), and the coordinates of the blue light emitting LED. (0.11, 0.10), and the applied current value (IF (mA)) of each LED is 20 mA, the absolute luminous intensity Iv (mcd) is 560 mcd for the red light emitting LED and 120 mcd for the green light emitting LED. Since it is 180 mcd for a blue light emitting LED, the x and y coordinates of the chromaticity diagram when white are (xm, ym) = (0.4788, 0.3391) when substituted into the above equation of the function.
[0052]
Thus, since this function depends on the light intensity factor, when obtaining the desired white light from the chromaticity diagram, each light intensity with respect to the x and y coordinates of each red light emitting LED, green light emitting LED, and blue light emitting LED is obtained. The desired white light can be obtained by the control. Therefore, in order to obtain the target white light, the current ratio applied to each red light emitting LED, green light emitting LED, and blue light emitting LED is changed. Thereby, the optimal chromaticity and luminous intensity of the required white light can be obtained.
[0053]
In this embodiment, the light guide plate 2 has a rectangular shape and the incident portion 3 has four places. However, the light guide plate 2 has a hexagonal shape and the incident portion 3 has six places, and the light source 8 (red light emitting LED, Green light emitting LED and blue light emitting LED) may be provided alternately.
[0054]
Further, although not shown here, the reflector is made of a sheet-like material in which a white insulating material or a metal such as aluminum is vapor deposited, or a metal. The reflector is provided so as to surround the incident portion 3 and the light source 8 of the light guide plate 2, reflects light from the light source 8, and causes the reflected light to enter the incident portion 7 of the light guide plate 2 again.
[0055]
Similarly, although not shown in the figure, even when the light source 8 is a semiconductor light emitting element, the incident portion 3 of the light guide plate 2 and the light source 8 may be surrounded by the same material as the light source 8. As a result, leakage from the light source 8 or reflected light from other elements is reflected, and the reflected light is incident on the incident portion 3 of the light guide plate 2 again.
[0056]
Further, each light source 8 is, for example, a red signal, a green signal, or a blue signal to a liquid crystal corresponding to each red, green, and blue in one pixel in a liquid crystal display device. In synchronization with the color of each light source 8, each light source 8 may be turned on / off by each signal corresponding to the color of each signal to the liquid crystal of the liquid crystal display device.
[0057]
For this purpose, each light source 8 is turned on / off corresponding to each color signal of the liquid crystal display device, and each light source 8 is turned on only when each color signal of the liquid crystal display device is on, and each color light is required. Only can be emitted.
[0058]
As a result, since red, green, and blue are directly emitted without using a conventional color filter or the like, a clear color can be reproduced. In addition, since it does not always emit and emits only when necessary, it is excellent in economic efficiency such as energy saving.
[0059]
【The invention's effect】
  As described above, the light guide plate according to claim 1 has a plurality of incident portions and is provided on the front surface portion and / or the back surface portion.A shape having a region wall that is surrounded by concentric arcs of a predetermined curvature centered on each incident portion, and has inclined surfaces in the thickness direction of the front surface portion and the back surface portion.A light deflection element is provided, and light beams incident from each incident part from the front surface part and / or the back surface part are emitted with the same level of brightness, so that even from light from different incident parts at any position, a constant emission brightness is emitted. be able to. Thereby, the emitted light of various different colors can be obtained by injecting different luminescent colors into the incident part.
[0060]
  Further, according to claim 2Light guide plateIsThe optical deflecting element has a shape having a region wall surrounded by a concentric arc having a predetermined curvature centered on at least three incident portions.SoLight from the incident part can be totally reflected at any position of the light guide plate, and high-luminance outgoing light can be obtained. Moreover, the design is not influenced by the light sourcecan do.
[0061]
  Furthermore, the light guide plate according to claim 3 is:The inclined surface is a concave surface, a convex surface, or a flat surface having a predetermined curvature with respect to the thickness direction of the front surface portion and the back surface portion.SoTotally reflected light with respect to the traveling direction from each incident portion to the inclined surface can be deflected. For that purpose, the light from each incident part is more mixed with each other at the exit surface.can do.
[0062]
  The flat illumination device according to claim 4 is a red light source.A light source having a green light source and a blue light source, and a plurality of incident portions for guiding light from the light source, and is surrounded by a concentric arc having a predetermined curvature centered on each incident portion on the front surface portion and / or the back surface portion. An optical deflection element having a region wall having an inclined surface formed in the thickness direction between the front and back surfaces is provided, and light incident from each incident portion from the front surface portion and / or the back surface portion is emitted with the same brightness. With a light guide plateSoNecessary single color light or mixed color light such as red, green, blue is emitted from the emission surfacecan do.
[0063]
  Furthermore, the flat illumination device according to claim 5 is:A red light source and a plurality of incident portions for guiding light from the red light source, and a concentric arc having a predetermined curvature centered on each incident portion provided on the front surface portion and / or the back surface portion with red light incident from each incident portion. A first light guide plate that emits red light with the same brightness from the surface portion by a light deflecting element having a region wall having a sloped surface in the thickness direction between the front surface portion and the back surface portion. A green light source and a plurality of incident portions for guiding light from the green light source, and a green ray incident from each incident portion is concentric with a predetermined curvature centered on each incident portion provided on the front surface portion and / or the back surface portion A second light guide plate that emits green light with the same brightness from the front surface portion by a light deflection element having a region wall that is surrounded by an arc and has an inclined surface in the thickness direction between the front surface portion and the back surface portion. A blue light source and a plurality of incident portions for guiding light from the blue light source. A region in which a more incident blue ray is surrounded by a concentric arc having a predetermined curvature centered on each incident portion provided on the front surface portion and / or the back surface portion, and an inclined surface is formed in the thickness direction of the front surface portion and the back surface portion A third light guide plate that emits blue light from the surface portion with the same brightness by a light deflecting element having a wall shape, the first light guide plate, the second light guide plate, and the third light guide plate; Since the three primary color lights are emitted from the lower side to the upper side, the necessary monochromatic light can be emitted from each light guide plate. In addition, monochromatic light or mixed color light can be emitted. As a result, when used in a liquid crystal display device or the like, a color filter is not required and there is no absorption by the color filter, so that light from the light source can be used efficiently.
  A flat illumination device according to claim 6 is:Each light source is synchronized with each color of the red signal, green signal and blue signal, and each light source corresponds to the color of each signal and is turned on / off by each signal, so it corresponds to each color signal of liquid crystal display devices etc. Thus, it can be emitted only when necessary. Thereby, since a clear color can be emitted and it does not always emit, it is excellent in economic efficiency such as energy saving.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a flat illumination device according to the present invention.
FIG. 2 is a schematic plan view of a light guide plate according to the present invention.
FIGS. 3A and 3B are representative enlarged perspective views of a light deflector according to the present invention, and are perspective views of a concave shape when viewed from the surface side. FIGS.
FIG. 4 is a schematic locus diagram of light rays of a light guide plate according to the present invention.
FIG. 5 is a schematic configuration diagram showing another configuration example of the flat illumination device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ...

Plane illumination apparatus

2, 2a, 2b, 2c ... Light guide plate, 3 ... Incident part, 4 ... Side part, 5, 5a, 5b, 5c ... Front surface part, 6, 6a, 6b, 6c ... Back surface part, 7 , 7 cc, 7 c 1, 7 c 2, 7 c 3, 7 c 4... Light deflection element, 8, 8 a, 8 b, 8 c... Light source, 11. W22, W33, W44 ... wall, L11, L12, L21, L22, L31, L32, L41, L42 ... concentric arcs, L1, L1r, L10, L2, L2r, L20 ... light rays.

Claims

光源からの光を導く入射部と、当該入射部と略直角に交わる表面部と裏面部とを有する導光板において、前記入射部を複数有するとともに前記表面部または／および前記裏面部に前記各入射部を中心とした所定曲率の同心円弧で囲まれ、前記表面部と前記裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子を設け、前記表面部または／および前記裏面部から各前記入射部より入射した光線が同程度の輝度で出射することを特徴とする導光板。An incident portion for guiding light from the light source, the light guide plate having a surface portion and the back portion intersecting substantially at right angles and the incident portion, the respective incident on said surface portion and / or the back portion and having a plurality of said incident portion A light deflection element having a shape having a region wall surrounded by a concentric arc having a predetermined curvature centered on a portion and having an inclined surface formed in a thickness direction between the front surface portion and the back surface portion; And the light-guide plate characterized by the light beam which inject | emitted from each said incident part from the said back surface part radiate | emitted with comparable brightness | luminance.

前記光偏向素子は、少なくとも３つの前記各入射部を中心とした所定曲率の同心円弧で囲まれる領域壁を有した形状とすることを特徴とする請求項１記載の導光板。2. The light guide plate according to claim 1, wherein the light deflecting element has a shape having a region wall surrounded by a concentric arc having a predetermined curvature with at least three of the incident portions as centers.

前記傾斜面は、前記表面部と前記裏面部との厚さ方向に対し、所定の曲率を有する凹面または凸面または平面であることを特徴とする請求項１記載の導光板。The light guide plate according to claim 1, wherein the inclined surface is a concave surface, a convex surface, or a flat surface having a predetermined curvature with respect to a thickness direction of the front surface portion and the back surface portion.

赤色光源と緑色光源と青色光源とを有する光源と、前記光源からの光を導く入射部を複数有し、前記表面部または／および前記裏面部に前記各入射部を中心とした所定曲率の同心円弧で囲まれ、前記表面部と前記裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子を設け、前記表面部または／および前記裏面部から各前記入射部より入射した光線が同程度の輝度で出射する導光板とを備えたことを特徴とする平面照明装置。A light source having a red light source, a green light source, and a blue light source, and a plurality of incident portions for guiding light from the light source, and concentric with a predetermined curvature around the respective incident portions on the front surface portion and / or the back surface portion A light deflection element having a shape having a region wall surrounded by an arc and having inclined surfaces in the thickness direction of the front surface portion and the back surface portion is provided, and each incident portion is provided from the front surface portion or / and the back surface portion. A flat illumination device comprising: a light guide plate from which more incident light beams are emitted with substantially the same luminance.

赤色光源と、前記赤色光源からの光を導く入射部を複数有し、各前記入射部より入射した赤色光線が表面部または／および裏面部に設けられた前記各入射部を中心とした所定曲率の同心円弧で囲まれ、前記表面部と前記裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により前記表面部から同程度の輝度で赤色光を出射する第１の導光板と、緑色光源と、前記緑色光源からの光を導く入射部を複数有し、各前記入射部より入射した緑色光線が表面部または／および裏面部に設けられた前記各入射部を中心とした所定曲率の同心円弧で囲まれ、前記表面部と前記裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により前記表面部から同程度の輝度で緑色光を出射する第２の導光板と、青色光源と、前記青色光源からの光を導く入射部を複数有し、各前記入射部より入射した青色光線が表面部または／および裏面部に設けられた前記各入射部を中心とした所定曲率の同心円弧で囲まれ、前記表面部と前記裏面部との厚さ方向に傾斜面を形成した領域壁を有した形状の光偏向素子により前記表面部から同程度の輝度で青色光を出射する第３の導光板とを備え、前記第１の導光板と前記第２の導光板と前記第３の導光板とが重ねて配置され、下方から上方に３原色光を出射することを特徴とする平面照明装置。A red light source and a plurality of incident portions for guiding light from the red light source, and a predetermined curvature centering on each incident portion provided on the front surface portion and / or the back surface portion with the red light incident from each incident portion. The red light is emitted from the front surface portion with the same brightness by the light deflecting element having the shape of the region wall that is surrounded by the concentric arc and has an inclined wall in the thickness direction of the front surface portion and the back surface portion. a first light guide plate, a green light source has a plurality of incident portions for guiding light from the green light source, the respective incident green light beam incident from the said incident portion is provided in the surface portion and / or back surface portion The optical deflection element having a shape having an area wall that is surrounded by a concentric arc having a predetermined curvature centered on the portion and has an inclined surface in the thickness direction of the front surface portion and the back surface portion, is approximately equal to the surface portion. A second light guide plate that emits green light with luminance, a blue light source, It has a plurality of incident portions for guiding light from the blue light source, in concentric arcs of a predetermined curvature blue light beam incident from each of said incidence portion around the respective incident portions provided on the surface portion and / or back surface portion A third light guide that emits blue light with the same brightness from the front surface portion by a light deflection element having a region wall that is surrounded and has an area wall that is inclined in the thickness direction of the front surface portion and the back surface portion. A planar illumination device comprising: a light plate, wherein the first light guide plate, the second light guide plate, and the third light guide plate are arranged to overlap each other, and emit light of three primary colors from below to above .

前記各光源は、赤色信号と緑色信号と青色信号の各色毎に同期し、前記各光源と前記各信号の色とが対応して前記各信号によりオン・オフ点灯を行うことを特徴とする請求項４または請求項５記載の平面照明装置。Each of the light sources is synchronized with each color of a red signal, a green signal, and a blue signal, and the respective light sources correspond to the colors of the signals to perform on / off lighting according to the signals. Item 6. The flat illumination device according to item 4 or item 5 .