JP3684737B2 - Surface light source device - Google Patents

Surface light source device Download PDF

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Publication number
JP3684737B2
JP3684737B2 JP01732897A JP1732897A JP3684737B2 JP 3684737 B2 JP3684737 B2 JP 3684737B2 JP 01732897 A JP01732897 A JP 01732897A JP 1732897 A JP1732897 A JP 1732897A JP 3684737 B2 JP3684737 B2 JP 3684737B2
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Japan
Prior art keywords
light
light source
guide plate
light guide
source device
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Expired - Fee Related
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JP01732897A
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Japanese (ja)
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JPH10199316A (en
Inventor
正幸 篠原
茂 青山
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Omron Corp
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Omron Corp
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/002—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
    • G02B6/0021—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces for housing at least a part of the light source, e.g. by forming holes or recesses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0016—Grooves, prisms, gratings, scattering particles or rough surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055—Reflecting element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/0068—Arrangements of plural sources, e.g. multi-colour light sources

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Liquid Crystal (AREA)
  • Planar Illumination Modules (AREA)
  • Led Device Packages (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は面光源装置に関する。具体的にいうと、本発明は液晶表示装置や照明装置などに用いられる面光源装置に関する。
【０００２】
【従来の技術】
従来例の面光源装置１を図１の分解斜視図及び図２の断面図により示す。面光源装置１は、光を閉じ込めるための導光板２と発光部３と反射板４とから構成されている。導光板２はポリカーボネイト樹脂やメタクリル樹脂等の透明で屈折率の大きな樹脂により成形されており、導光板２の下面には凹凸加工や拡散反射インクのドット印刷等によって拡散パターン５が形成されている。発光部３は、回路基板６上に複数の発光ダイオード（ＬＥＤ）等のいわゆる点光源７を実装したものであって、導光板２の側面（光入射面８）に対向している。反射板４は、反射率の高い例えば白色樹脂シートによって形成されており、両面テープ９によって両側部を導光板２の下面に貼り付けられている。
【０００３】
しかして、図２に示すように、発光部３から出射されて光入射面８から導光板２の内部に導かれた光ｆは、導光板２内部で全反射することによって導光板２内部に閉じ込められる。導光板２内部の光ｆは拡散パターン５に入射すると拡散反射され、光出射面１０へ向けて全反射の臨界角よりも小さな角度で反射された光ｆが光出射面１０から外部へ取り出される。また、導光板２下面の拡散パターン５の存在しない箇所を透過した光ｆは、反射板４によって反射されて再び導光板２内部へ戻るので、導光板２下面からの光量損失を防止される。
【０００４】
【発明が解決しようとする課題】
点光源を用いた上記のような面光源装置１は、低消費電力化のため、点光源７で疑似的に線状光源化を図ったものであった。すなわち、点光源７を一列に配列することによって冷陰極線管のような線状光源を模したものである。従って、より低消費電力化を図るためには、点光源の数を減らして、好ましくは１つの点光源により高輝度で輝度ばらつきの少ない面光源装置を得ることが望まれる。
【０００５】
しかしながら、１つの点光源７で面光源装置１を光らせようとすると、図３に示すように、導光板２の光入射面側の隅部分１１（図３で斜線を施した領域）が暗くなり、均一な輝度分布を得ることができなかった。
【０００６】
本発明は叙上の従来例の欠点に鑑みてなされたものであり、その目的とするところは、導光板の寸法に比較して小さな光源を用いた面光源装置において、光入射面側の隅部分が暗くなるのを防止し、輝度分布の均一化を図ることにある。
【００１１】
【発明の開示】
請求項１に記載の面光源装置は、光入射面より導入された光を閉じこめて光り出射面から外部へ取り出すための導光板と、導光板の光入射面側に配置された、導光板の光入射面の幅と比較して小さな光源とを備えた面光源装置において、前記光源は、発光素子チップを透明樹脂で封止してなる発光素子を、表面反射率の大きな外装部材の内部に埋め込んで形成し、前記外装部材の光出射面には、前記導光板の光入射面に形成された凹部に合致する形状の突部が突出しており、前記突部の、前記導光板の光出射面と垂直方向の中央部に、該突部全幅にわたって前記発光素子からの出射光を透過するためのスリットを開口し、前記スリットの開口高さを前記発光素子の高さより狭く形成したことを特徴としている。
【００１３】
この面光源装置にあっては、導光板の光入射面に設けた凹部に光源を配置しているので、光源から出た光は凹部から導光板へ広い範囲にわたって入射する。従って、導光板の光入射面側の隅部分にも光が拡散され、当該隅部分が暗くなるのを防止することができる。従って、導光板に比較して小さな光源を用いる場合にも、面光源装置の輝度分布を均一化することができる。
【００１４】
また、光源と凹部の間の空間の光出射面側及びその反対面側を光反射性の部材により覆っているから、光源から出射された光が導光板に入射することなく、光源と導光板の隙間から上方もしくは下方へ逃げるのを防止することができ、光の結合効率を向上させ、面光源装置の輝度を高くできる。また、スリットの開口高さは点光源（発光素子）の高さよりも小さくなっているので、光の結合効率が向上する。
【００１５】
さらに、凹部及び光反射性の部材を略反円形状に形成すれば、光源からの光を各方向に均等に広がらせることができ、輝度分布をより均一化することができる。
【００１６】
【発明の実施の形態】
図４は本発明の一実施形態による面光源装置２１を示す分解斜視図である。屈折率の大きな透明樹脂材料によって形成されている導光板２２の上面が光出射面２３となっており、下面には凹凸加工や拡散反射インクのドット印刷等によって拡散パターン２４が形成されている。この導光板２２の下面両側部には、溝状をした反射板保持部２５が設けられており、導光板２２の光入射面２６と反対側の端面には、下方へ向けてストッパー２７が垂下されている。
【００１７】
発光部２８は、白色樹脂等の表面反射率の高い材質からなる外装部材２９によって点光源３０、すなわち導光板２２に比べて小さな光源を包んだものである。例えば、樹脂モールド型発光ダイオードのような発光素子（点光源３０）を外装部材２９で包んだものである。この点光源３０は光出射側の面だけが外装部材２９から露出している。しかして、点光源３０から背面方向や側面方向へ出射された光は、外装部材２９の内面で反射され、点光源３０の光は前面のみから効率よく出射される。なお、豆電球などの点光源３０を白色樹脂等からなる外装部材２９内に納めて発光部２８を形成してもよい。
【００１８】
反射板３１は表面反射率の高い材料によって形成されており、例えば硬質もしくは比較的軟質の白色プラスチックシートによって形成されている。この反射板３１は、光入射面２６側から反射板保持部２５に差し込んでストッパー２７に当てることにより、導光板２２下面に保持される。
【００１９】
また、導光板２２の光入射面２６からは一対の弾性片３２が一体成形されており、両弾性片３２の先端部内面には係合爪３３が突出している。一方、外装部材２９の両側面には、弾性片３２がぴったりと納まるような側面溝３４が凹設されている。しかして、発光部２８は弾性片３２を側面溝３４に納めるようにして弾性片３２間に挟持されており、弾性片３２の係合爪３３を背面に係合することによって脱落しないよう保持されている。
【００２０】
光入射面２６の発光部２８と対向する位置、すなわち弾性片３２間の部分には、多数のプリズムからなるプリズムアレイ状の光学的パターン３５が形成されている。
【００２１】
図５は導光板２２の下面に設けられた拡散パターン２４を示す平面図である。この拡散パターン２４は多数の拡散パターン素子２４ａからなり、拡散パターン素子２４ａは、点光源３０を中心として導光板２２の下面全面に同心円状に配置されている。また、拡散パターン素子２４ａはランダムに配置されており、各拡散パターン素子２４ａどうしは点光源３０からの距離が遠くなるにつれてピッチが短くなっており、点光源３０から離れるに従って拡散パターン密度が次第に大きくなっている。
【００２２】
しかして、プリズムアレイ状の光学的パターン３５に対向して配置された発光部２８から出射された光ｆは、前方に偏って導光板２２内に導入されることがなく、図６に示すように、光学的パターン３５を構成する各プリズムで屈折することによって広い範囲にわたって導光板２２内部へ導かれる。従って、光入射面２６の両側の隅部分にも光が到達し、当該隅部分が明るくなって面光源装置２１の輝度分布が均一化される。さらに、導光板２２の下面には、図５に示したような拡散パターン２４が形成されているので、発光部２８から導光板２２へ入射した光は、導光板２２の各領域で均等に出射され、導光板２２の全面で均等な輝度分布を得ることができる。
【００２３】
なお、上記光学的パターン３５としては、点光源３０から入射してきた光を両側へ散らばらせることができるようなものであればよく、特に限定されるものではない。例えば、図７に示すような略凹面状のレンズ部分からなるレンズアレイ状の光学的パターン３５でもよく、しぼ加工などでもよい。
【００２４】
（第２の実施形態）
図８は本発明の別な実施形態による面光源装置４１を示す平面図である。この面光源装置４１にあっては、導光板２２の光入射面２６に凹部４２を設け、当該凹部４２の奥に光学的パターン３５を形成している。発光部２８からは全面及び両側面に光を出射するようになっている。
【００２５】
従って、発光部２８から両側方へ出射された光ｆは、凹部４２の側面から導光板２２に入射して隅部分に達する。また、発光部２８から前方へ出射された光ｆは、凹部４２の前面から導光板２２に入射し、光学的パターン３５で拡散されて導光板２２の全体に広がる。従って、この面光源装置４１にあっても、導光板２２の隅部分が暗くなることがなく、面光源装置４１の輝度分布を均一化することができる。
【００２６】
（第３の実施形態）
図９は本発明のさらに別な実施形態による面光源装置４３を示す分解斜視図である。この面光源装置４３にあっては、導光板２２の光入射面２６側の端部中央部に略半円形をした凹部４４を設けてある。一方、発光部２８は、発光ダイオード等の発光素子チップ４５を透明樹脂４６で封止した点光源３０（発光素子）を、表面反射率の大きな白色樹脂等からなる外装部材２９内に埋め込んだものである。この外装部材２９の前面には、導光板２２の凹部４４に合致する形状の突部４７が突出しており、突部４７の上下方向中央部には、突部４７全幅にわたってスリット４８が開口されており、スリット４８を通して点光源３０が露出している。図１１に示すように、スリット４８の開口高さは、点光源３０の高さよりも狭くなっている。
【００２７】
しかして、点光源３０から出射された光ｆは、白色樹脂等からなる外装部材２９で反射されることによって外装部材２９内に閉じ込められてスリット４８からのみ外部へ出射される。しかも、スリット４８の開口高さは点光源３０の高さよりも小さくなっているので、光の結合効率が向上する。
【００２８】
また、図１０に示すように、発光部２８のスリット４８を通して略１８０゜の角度で放射された光ｆは、導光板２２の凹部４４内面から導光板２２内部に導かれる。よって、光ｆは導光板２２の全体に広がり、特に導光板２２の隅部分にも達して隅部分の輝度を高くすることができ、面光源装置４３の輝度分布を均一化することができる。
【００２９】
（照明装置）
図１２は本発明にかかる面光源装置を利用した照明装置７１を示す分解斜視図である。この照明装置７１においては、光量を大きくして輝度を高くするため、４つの発光部２８を用いて導光板２２の略半円形をした凹部４４にはめ込んでいる。この照明装置７１は室内照明用や自動車のテールランプなどに用いられるものである。
【００３０】
（液晶表示装置）
図１３は本発明にかかる面光源装置８０を用いた液晶表示装置８１を示す分解斜視図である。この面光源装置８０にあっては、導光板２２の光入射面２６に赤（Ｒ）、緑（Ｇ）、青（Ｂ）の３色の点光源３０（発光部）が設けられている。面光源装置８０の前面には、拡散反射シート８２が配置され、その前面に液晶表示パネル８３が配設されている。液晶表示パネル８３は、透明電極やＴＦＴ、カラーフィルタ、ブラックマトリクス等を形成された２枚の液晶基板（ガラス基板、フィルム基板）８４，８５間に液晶材料を封止し、液晶基板８４，８５の両外面に偏光板８６を配設したものである。
【００３１】
このような液晶表示装置８１によれば、表示面の輝度分布が均一にすることができ、液晶表示装置８１の高品質化を図ることができる。
【００３２】
（液晶表示装置を備えた電子装置）
本発明にかかる液晶表示装置は、携帯電話や弱電力無線機のような無線情報伝達装置、携帯用パソコン、電子手帳や電卓のような情報処理装置などに用いるのに好ましい。図１４は本発明にかかる例えば図１３に示したような液晶表示装置８１をディスプレイ用に備えた携帯電話８９を示す斜視図、図１５はその機能ブロック図である。携帯電話８９の正面にはダイアル入力用のテンキー等のボタンスイッチ９０を備え、その上方に液晶表示装置８１が配設され、上面にアンテナ９１が設けられている。しかして、ボタンスイッチ９０からダイアル等を入力すると、入力されたダイアル情報等が送信回路９２を通じてアンテナ９１から電話会社の基地局へ送信される。一方、入力されたダイアル情報等は液晶駆動回路９３へ送られ、液晶表示装置８１が液晶駆動回路９３により駆動されてダイアル情報等が液晶表示装置８１に表示される。
【００３３】
また、図１６は本発明にかかる例えば図１３に示したような液晶表示装置８１をディスプレイ用に備えた電子手帳９４を示す斜視図、図１７はその機能ブロック図である。電子手帳９４は、カバー９５を開くと、キー入力部９６と液晶表示装置８１を備えており、内部には液晶駆動回路９３や演算処理回路９７等が設けられている。しかして、例えばキー入力部９６からテンキーやカナキー等を入力すると、入力情報が液晶駆動回路９３に送られて液晶表示装置８１に表示される。ついで、演算キー等の制御キーを押すと、演算処理回路９７で所定の処理や演算が実行され、その結果が液晶駆動回路９３に送られて液晶表示装置８１に表示される。
【図面の簡単な説明】
【図１】点光源を用いた従来の面光源装置を示す分解斜視図である。
【図２】同上の面光源装置の断面図である。
【図３】同上の面光源装置における輝度分布のばらつきを示す平面図である。
【図４】本発明の一実施形態による面光源装置を示す分解斜視図である。
【図５】同上の面光源装置の拡散パターンを示す平面図である。
【図６】同上の面光源装置における光学的パターンの作用説明図である。
【図７】別な光学的パターンの形状を示す平面図である。
【図８】本発明の別な実施形態による面光源装置を示す平面図である。
【図９】本発明のさらに別な実施形態による面光源装置を示す分解斜視図である。
【図１０】同上の面光源装置の作用説明図である。
【図１１】同上の面光源装置の作用説明図である。
【図１２】本発明の面光源装置を用いた照明装置の分解斜視図である。
【図１３】本発明の面光源装置を用いた液晶表示装置の分解斜視図である。
【図１４】本発明にかかる液晶表示装置をディスプレイ用に備えた携帯電話を示す斜視図である。
【図１５】同上の携帯電話において液晶表示装置を駆動するための構成を示すブロック図である。
【図１６】本発明にかかる液晶表示装置をディスプレイ用に備えた電子手帳を示す斜視図である。
【図１７】同上の電子手帳において液晶表示装置を駆動するための構成を示すブロック図である。
【符号の説明】
２２ 導光板
２３ 光出射面
２６ 光入射面
３０ 点光源
３５ 光学的パターン
４２ 凹部
４４ 凹部
４７ 突部
４８ スリット[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface light source device. Specifically, the present invention relates to a surface light source device used for a liquid crystal display device, a lighting device, and the like.
[0002]
[Prior art]
A conventional surface light source device 1 is shown in an exploded perspective view of FIG. 1 and a sectional view of FIG. The surface light source device 1 includes a light guide plate 2 for confining light, a light emitting unit 3, and a reflection plate 4. The light guide plate 2 is formed of a transparent resin having a large refractive index such as polycarbonate resin or methacrylic resin, and a diffusion pattern 5 is formed on the lower surface of the light guide plate 2 by concavo-convex processing or dot printing of diffuse reflection ink. . The light emitting unit 3 is a component in which a so-called point light source 7 such as a plurality of light emitting diodes (LEDs) is mounted on a circuit board 6, and faces the side surface (light incident surface 8) of the light guide plate 2. The reflection plate 4 is formed of, for example, a white resin sheet having a high reflectance, and both side portions are attached to the lower surface of the light guide plate 2 by a double-sided tape 9.
[0003]
As shown in FIG. 2, the light f emitted from the light emitting unit 3 and guided to the inside of the light guide plate 2 from the light incident surface 8 is totally reflected inside the light guide plate 2 to be inside the light guide plate 2. Be trapped. The light f inside the light guide plate 2 is diffused and reflected when entering the diffusion pattern 5, and the light f reflected toward the light emitting surface 10 at an angle smaller than the critical angle of total reflection is extracted from the light emitting surface 10 to the outside. . Further, the light f that has passed through the portion where the diffusion pattern 5 does not exist on the lower surface of the light guide plate 2 is reflected by the reflecting plate 4 and returns to the inside of the light guide plate 2 again, thereby preventing light loss from the lower surface of the light guide plate 2.
[0004]
[Problems to be solved by the invention]
The surface light source device 1 using a point light source as described above has been a pseudo linear light source using the point light source 7 in order to reduce power consumption. That is, a linear light source such as a cold cathode ray tube is imitated by arranging the point light sources 7 in a line. Therefore, in order to further reduce power consumption, it is desired to reduce the number of point light sources, and preferably to obtain a surface light source device with high luminance and less luminance variation by one point light source.
[0005]
However, when the surface light source device 1 is made to shine with one point light source 7, as shown in FIG. 3, the corner portion 11 (the hatched area in FIG. 3) on the light incident surface side of the light guide plate 2 becomes dark. A uniform luminance distribution could not be obtained.
[0006]
The present invention has been made in view of the drawbacks of the conventional example described above, and the object of the present invention is to provide a corner on the light incident surface side in a surface light source device using a light source smaller than the size of the light guide plate. This is to prevent the portion from becoming dark and to make the luminance distribution uniform.
[0011]
DISCLOSURE OF THE INVENTION
The surface light source device according to claim 1 includes: a light guide plate for confining light introduced from the light incident surface and extracting the light from the light emitting surface to the outside; and a light guide plate disposed on the light incident surface side of the light guide plate. In a surface light source device having a light source that is smaller than the width of a light incident surface , the light source includes a light emitting element formed by sealing a light emitting element chip with a transparent resin inside an exterior member having a large surface reflectance. The light emitting surface of the exterior member is formed to be embedded, and a protrusion having a shape that matches the recess formed on the light incident surface of the light guide plate protrudes, and the light emission of the light guide plate of the protrusion is made. A slit for transmitting light emitted from the light emitting element is opened over the entire width of the protrusion at a central portion in a direction perpendicular to the surface, and the opening height of the slit is narrower than the height of the light emitting element. It is said.
[0013]
In this surface light source device, since the light source is arranged in the concave portion provided on the light incident surface of the light guide plate, the light emitted from the light source enters the light guide plate from a wide range. Accordingly, it is possible to prevent the light from being diffused also in the corner portion on the light incident surface side of the light guide plate and darkening the corner portion. Therefore, even when a light source smaller than the light guide plate is used, the luminance distribution of the surface light source device can be made uniform.
[0014]
Further, since the light emitting surface side and the opposite surface side of the space between the light source and the recess are covered with the light reflecting member, the light source and the light guiding plate are not incident on the light guiding plate. Escaping upward or downward from the gap can be prevented, the light coupling efficiency can be improved, and the luminance of the surface light source device can be increased. Further, since the opening height of the slit is smaller than the height of the point light source (light emitting element), the light coupling efficiency is improved.
[0015]
Furthermore, it is possible to spread lever be formed substantially in a counter-circular recesses and light reflective member, the light from the light source evenly in each direction, it can be made more uniform luminance distribution.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 4 is an exploded perspective view showing the surface light source device 21 according to one embodiment of the present invention. An upper surface of the light guide plate 22 formed of a transparent resin material having a large refractive index is a light emitting surface 23, and a diffusion pattern 24 is formed on the lower surface by uneven processing, dot printing of diffuse reflection ink, or the like. On both sides of the lower surface of the light guide plate 22, groove-shaped reflection plate holding portions 25 are provided, and a stopper 27 hangs downward on the end surface opposite to the light incident surface 26 of the light guide plate 22. Has been.
[0017]
The light emitting unit 28 is a member that wraps a light source smaller than the point light source 30, that is, the light guide plate 22, with an exterior member 29 made of a material having high surface reflectance such as white resin. For example, a light emitting element (point light source 30) such as a resin mold type light emitting diode is wrapped with an exterior member 29. This point light source 30 is exposed from the exterior member 29 only on the light emitting side. Thus, the light emitted from the point light source 30 in the back direction or the side surface direction is reflected by the inner surface of the exterior member 29, and the light from the point light source 30 is efficiently emitted only from the front surface. Alternatively, the light source 28 may be formed by placing a point light source 30 such as a miniature bulb in an exterior member 29 made of white resin or the like.
[0018]
The reflector 31 is made of a material having a high surface reflectance, and is made of, for example, a hard or relatively soft white plastic sheet. The reflection plate 31 is held on the lower surface of the light guide plate 22 by being inserted into the reflection plate holding portion 25 from the light incident surface 26 side and hitting the stopper 27.
[0019]
A pair of elastic pieces 32 are integrally formed from the light incident surface 26 of the light guide plate 22, and an engaging claw 33 protrudes from the inner surfaces of the distal ends of both elastic pieces 32. On the other hand, side grooves 34 are provided in both side surfaces of the exterior member 29 so that the elastic pieces 32 can be snugly accommodated. Thus, the light emitting portion 28 is sandwiched between the elastic pieces 32 so that the elastic piece 32 is accommodated in the side groove 34, and is held so as not to fall off by engaging the engaging claw 33 of the elastic piece 32 with the back surface. ing.
[0020]
A prism array-like optical pattern 35 made up of a large number of prisms is formed at a position facing the light emitting portion 28 of the light incident surface 26, that is, between the elastic pieces 32.
[0021]
FIG. 5 is a plan view showing the diffusion pattern 24 provided on the lower surface of the light guide plate 22. The diffusion pattern 24 includes a large number of diffusion pattern elements 24 a, and the diffusion pattern elements 24 a are arranged concentrically on the entire lower surface of the light guide plate 22 with the point light source 30 as the center. Further, the diffusion pattern elements 24a are arranged at random, and the pitch between the diffusion pattern elements 24a decreases as the distance from the point light source 30 increases, and the diffusion pattern density gradually increases as the distance from the point light source 30 increases. It has become.
[0022]
Accordingly, the light f emitted from the light emitting portion 28 arranged to face the optical pattern 35 in the prism array shape is not biased forward and is not introduced into the light guide plate 22, as shown in FIG. Further, the light is refracted by each prism constituting the optical pattern 35 and guided to the inside of the light guide plate 22 over a wide range. Accordingly, light reaches the corner portions on both sides of the light incident surface 26, the corner portions become brighter, and the luminance distribution of the surface light source device 21 is made uniform. Further, since the diffusion pattern 24 as shown in FIG. 5 is formed on the lower surface of the light guide plate 22, the light incident on the light guide plate 22 from the light emitting portion 28 is emitted uniformly in each region of the light guide plate 22. Thus, a uniform luminance distribution can be obtained over the entire surface of the light guide plate 22.
[0023]
The optical pattern 35 is not particularly limited as long as it can diffuse light incident from the point light source 30 to both sides. For example, it may be a lens array-like optical pattern 35 composed of substantially concave lens portions as shown in FIG.
[0024]
(Second Embodiment)
FIG. 8 is a plan view showing a surface light source device 41 according to another embodiment of the present invention. In the surface light source device 41, a recess 42 is provided on the light incident surface 26 of the light guide plate 22, and an optical pattern 35 is formed in the back of the recess 42. Light is emitted from the light emitting unit 28 to the entire surface and both side surfaces.
[0025]
Therefore, the light f emitted from the light emitting portion 28 to both sides enters the light guide plate 22 from the side surface of the recess 42 and reaches the corner portion. The light f emitted forward from the light emitting unit 28 enters the light guide plate 22 from the front surface of the recess 42, is diffused by the optical pattern 35, and spreads over the entire light guide plate 22. Therefore, even in the surface light source device 41, the corner portions of the light guide plate 22 are not darkened, and the luminance distribution of the surface light source device 41 can be made uniform.
[0026]
(Third embodiment)
FIG. 9 is an exploded perspective view showing a surface light source device 43 according to still another embodiment of the present invention. In the surface light source device 43, a concave portion 44 having a substantially semicircular shape is provided at the center of the end portion of the light guide plate 22 on the light incident surface 26 side. On the other hand, the light emitting section 28 is obtained by embedding a point light source 30 (light emitting element) in which a light emitting element chip 45 such as a light emitting diode is sealed with a transparent resin 46 in an exterior member 29 made of a white resin having a high surface reflectance. It is. A protrusion 47 having a shape matching the recess 44 of the light guide plate 22 protrudes from the front surface of the exterior member 29, and a slit 48 is opened at the center of the protrusion 47 in the vertical direction over the entire width of the protrusion 47. The point light source 30 is exposed through the slit 48. As shown in FIG. 11, the opening height of the slit 48 is narrower than the height of the point light source 30.
[0027]
Thus, the light f emitted from the point light source 30 is confined in the exterior member 29 by being reflected by the exterior member 29 made of white resin or the like, and is emitted to the outside only from the slit 48. In addition, since the opening height of the slit 48 is smaller than the height of the point light source 30, the light coupling efficiency is improved.
[0028]
As shown in FIG. 10, the light f emitted at an angle of about 180 ° through the slit 48 of the light emitting unit 28 is guided into the light guide plate 22 from the inner surface of the recess 44 of the light guide plate 22. Therefore, the light f spreads over the entire light guide plate 22, and particularly reaches the corner portion of the light guide plate 22 to increase the luminance of the corner portion, so that the luminance distribution of the surface light source device 43 can be made uniform.
[0029]
(Lighting device)
FIG. 12 is an exploded perspective view showing a lighting device 71 using the surface light source device according to the present invention. In this illuminating device 71, in order to increase the amount of light and increase the luminance, the light emitting plate 28 is fitted into the substantially semicircular concave portion 44 using the four light emitting portions 28. The lighting device 71 is used for indoor lighting, automobile tail lamps, and the like.
[0030]
(Liquid crystal display device)
FIG. 13 is an exploded perspective view showing a liquid crystal display device 81 using the surface light source device 80 according to the present invention. In the surface light source device 80, point light sources 30 (light emitting units) of three colors of red (R), green (G), and blue (B) are provided on the light incident surface 26 of the light guide plate 22. A diffuse reflection sheet 82 is disposed on the front surface of the surface light source device 80, and a liquid crystal display panel 83 is disposed on the front surface thereof. The liquid crystal display panel 83 seals a liquid crystal material between two liquid crystal substrates (glass substrate, film substrate) 84 and 85 on which transparent electrodes, TFTs, color filters, black matrices and the like are formed. Are provided with polarizing plates 86 on both outer surfaces.
[0031]
According to such a liquid crystal display device 81, the luminance distribution on the display surface can be made uniform, and the quality of the liquid crystal display device 81 can be improved.
[0032]
(Electronic device with liquid crystal display)
The liquid crystal display device according to the present invention is preferable for use in a wireless information transmission device such as a mobile phone or a low power wireless device, a portable personal computer, an information processing device such as an electronic notebook or a calculator. FIG. 14 is a perspective view showing a mobile phone 89 equipped with a liquid crystal display device 81 as shown in FIG. 13, for example, according to the present invention, and FIG. 15 is a functional block diagram thereof. A button switch 90 such as a numeric keypad for dial input is provided on the front surface of the mobile phone 89, a liquid crystal display device 81 is provided above the button switch 90, and an antenna 91 is provided on the upper surface. When a dial or the like is input from the button switch 90, the input dial information or the like is transmitted from the antenna 91 to the telephone company base station through the transmission circuit 92. On the other hand, the input dial information or the like is sent to the liquid crystal drive circuit 93, and the liquid crystal display device 81 is driven by the liquid crystal drive circuit 93 and the dial information or the like is displayed on the liquid crystal display device 81.
[0033]
FIG. 16 is a perspective view showing an electronic notebook 94 provided with a liquid crystal display device 81 as shown in FIG. 13, for example, according to the present invention, and FIG. 17 is a functional block diagram thereof. When the cover 95 is opened, the electronic notebook 94 includes a key input unit 96 and a liquid crystal display device 81. A liquid crystal driving circuit 93, an arithmetic processing circuit 97, and the like are provided therein. Thus, for example, when a numeric keypad, a kana key, or the like is input from the key input unit 96, the input information is sent to the liquid crystal drive circuit 93 and displayed on the liquid crystal display device 81. Next, when a control key such as a calculation key is pressed, predetermined processing or calculation is executed by the calculation processing circuit 97, and the result is sent to the liquid crystal drive circuit 93 and displayed on the liquid crystal display device 81.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a conventional surface light source device using a point light source.
FIG. 2 is a cross-sectional view of the above surface light source device.
FIG. 3 is a plan view showing variations in luminance distribution in the surface light source device of the above.
FIG. 4 is an exploded perspective view showing a surface light source device according to an embodiment of the present invention.
FIG. 5 is a plan view showing a diffusion pattern of the above surface light source device.
FIG. 6 is an operation explanatory diagram of an optical pattern in the above surface light source device.
FIG. 7 is a plan view showing the shape of another optical pattern.
FIG. 8 is a plan view showing a surface light source device according to another embodiment of the present invention.
FIG. 9 is an exploded perspective view showing a surface light source device according to still another embodiment of the present invention.
FIG. 10 is an operation explanatory diagram of the surface light source device according to the embodiment.
FIG. 11 is an operation explanatory view of the above surface light source device.
FIG. 12 is an exploded perspective view of an illumination device using the surface light source device of the present invention.
FIG. 13 is an exploded perspective view of a liquid crystal display device using the surface light source device of the present invention.
FIG. 14 is a perspective view showing a mobile phone equipped with a liquid crystal display device according to the present invention for a display.
FIG. 15 is a block diagram showing a configuration for driving a liquid crystal display device in the mobile phone;
FIG. 16 is a perspective view showing an electronic notebook provided with a liquid crystal display device according to the present invention for a display.
FIG. 17 is a block diagram showing a configuration for driving a liquid crystal display device in the electronic notebook.
[Explanation of symbols]
22 Light guide plate 23 Light exit surface 26 Light entrance surface 30 Point light source 35 Optical pattern 42 Recess 44 Recess 47 Protrusion 48 Slit

Claims (1)

光入射面より導入された光を閉じこめて光出射面から外部へ取り出すための導光板と、導光板の光入射面側に配置された、導光板の光入射面の幅と比較して小さな光源とを備えた面光源装置において、
前記光源は、発光素子チップを透明樹脂で封止してなる発光素子を、表面反射率の大きな外装部材の内部に埋め込んで形成し、
前記外装部材の光出射面には、前記導光板の光入射面に形成された凹部に合致する形状の突部が突出しており、
前記突部の、前記導光板の光出射面と垂直方向の中央部に、該突部全幅にわたって前記発光素子からの出射光を透過するためのスリットを開口し、
前記スリットの開口高さを前記発光素子の高さより狭く形成したことを特徴とする面光源装置。A light guide plate for confining light introduced from the light incident surface and taking it out from the light exit surface, and a light source smaller than the width of the light incident surface of the light guide plate disposed on the light incident surface side of the light guide plate In a surface light source device comprising:
The light source is formed by embedding a light emitting element formed by sealing a light emitting element chip with a transparent resin inside an exterior member having a large surface reflectance,
On the light exit surface of the exterior member, a protrusion having a shape that matches the recess formed on the light incident surface of the light guide plate protrudes.
Opening a slit for transmitting the emitted light from the light emitting element over the entire width of the protrusion at the center of the protrusion in the direction perpendicular to the light exit surface of the light guide plate,
A surface light source device characterized in that an opening height of the slit is narrower than a height of the light emitting element .
JP01732897A 1997-01-14 1997-01-14 Surface light source device Expired - Fee Related JP3684737B2 (en)

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