JP2004139901A

JP2004139901A - Lighting device

Info

Publication number: JP2004139901A
Application number: JP2002304953A
Authority: JP
Inventors: Hiroyuki Takeuchi; 竹内　弘幸; Junichi Kubo; 久保　淳一; Kimihide Hatate; 幡手　公英
Original assignee: Nalux Co Ltd
Current assignee: Nalux Co Ltd
Priority date: 2002-10-18
Filing date: 2002-10-18
Publication date: 2004-05-13

Abstract

<P>PROBLEM TO BE SOLVED: To provide a space-saving lighting device for setting an irradiation luminous flux with uniform and high brightness into an intended direction with an intended open angle. <P>SOLUTION: The lighting device comprises a rod-shaped light guide body 20, a luminous flux irradiation part formed at the side surface in a length direction of the light guide body 20, and a light source formed on at least a part of the light guide body 20 having a relatively small light emission area compared with the luminous flux irradiation part. A light control structure 21 controlling the direction and open angle of the irradiation light flux is imposed on the luminous flux irradiation part. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】本発明は、照明装置および照明機能を有する液晶等の表示装置に関し、更に詳細には照明光束の出射方向や光束の開き角制御が必要な線状の照明装置に関する。
【０００２】
【従来の技術】
従来、線状光源と言えば、冷陰極放電管または熱陰極放電管等の直線状の光源ランプが用いられていたが、近年消費電力の少ない、発光ダイオード（ＬＥＤ）の点状光源素子を線状光源に変換して用いるようになっている。
【０００３】発光ダイオードを点状光源とする照明装置の構成は、図１４に示すように導光板３０の端面に複数の光源１０を設けて線状光源と見立てる方法がある。例えば、同様の例として、特開２００２−２４５８３２はプリズムシートにより多数の仮想光源をつくり均一性を増している。
【０００４】また、図１５に示されるように、導光板３０の一端に設けられた導光体２０を線状光源とする線状照明装置、特開２０００−１１７２３が実用化されている。該導光体２０は少なくとも１つ以上の光源１０を長手方向の一端に設け、導光板３０とは反対側の面にプリズム状の構造体が設けられる。さらに導光体２０は導光板３０に対向する面を除いて鏡面、白色、乳白色等の反射材５０で囲まれている。
【０００５】図１６に示されるように、導光体２０の上下面にＶ字型の溝を設けた線状照明装置があり、図１５の導光体２０と置き換えて実用化されている。
【０００６】上記図１４から図１６に示される照明装置は点状光源を線状光源に変換して、冷陰極放電管または熱陰極放電管の代用としているが、図１７に示されるように、導光板３０のコーナー部を斜めにカットし、このカット面に対向するように光源１０が配置され、導光板にＶ字型の溝７１が放射状に配置される照明装置、特開２００２−１０９９２８のように、点状光源を面状光源に変換する液晶表示装置の照明装置が提供されている。
【０００７】
【発明が解決しようとする課題】
上記に示した、図１４の従来の方法ではスジ状のムラが発生する問題が見受けられた。
【０００８】また、図１４から図１６の従来の方法では光線の拡がり角度を任意に制御することができず、拡散させることにより強度の均一性を確保しムラを抑えているが、輝度の低下を招く要因であった。この為輝度を上げる為には、光源の数を増やすか、より大光量の光源を用いる必要があり、コスト高の要因となっていた。
【０００９】また、図１７に示される方法では、発光ダイオードの拡がり角度に左右される為、均一性が低く、円弧の小さい溝構造を持ちピーク光度の光線の出射角度が異なる為、見る方向によって輝度ムラが発生し、視認性が低くなる問題が考えられる。
【００１０】
【課題を解決する為の手段】
上記課題を解決する為の手段として、請求項１記載の発明では、柱状導光体と、この柱状導光体の長手方向の側面に設けられた光束出射部と、該柱状導光体の少なくとも一部に設けられ該光束出射部に比較し小さな発光面積を有する光源とからなる照明装置において、該光束出射部に、出射光束の方向ならびに開き角の光線制御構造を付与したことを特徴とする。
【００１１】請求項２記載の発明では、前記柱状導光体の光束出射部に設けられた光線制御構造が、柱状導光体を導光する光線を取り込む接合面と、光線を出射する出射面と、出射面と接合面をつなぐ側面とを有する凸状の単位構造から構成され、該単位構造を柱状導光体の長手方向にアレイ状に配置したことを特徴とする。
【００１２】請求項３記載の発明では、前記単位構造の出射面の面積が、接合面の面積より大きいことを特徴とする。
【００１３】請求項４記載の発明では、前記柱状導光体の短手方向に前記単位構造を複数配置するとともに、各単位構造を長手方向にシフトしたことを特徴とする。
【００１４】請求項５記載の発明では、前記単位構造の配置ピッチが可変であることを特徴とする。
【００１５】請求項６記載の発明では、前記単位構造の各々が、それぞれ異なる形状を有することを特徴とする。
【００１６】請求項７記載の発明では、前記柱状導光体の少なくとも一方の端面を反射面としたことを特徴とする。
【００１７】請求項８記載の発明では、前記柱状導光体の端面に平行な断面積が、長手方向の位置により変化することを特徴とする。
【００１８】請求項９記載の発明では、前記柱状導光体の出射面にある各構造体を一体化する事で、導光体の強度及び加工性を向上させる事を特徴とする。
【００１９】
【発明の実施の形態】
以下、図を参照しながら、本発明の導光体及びこれを用いた照明装置の実施形態につきさらに詳細に説明する。
【００２０】図１は本発明の第１の実施形態に係る線状照明装置１を概略的に示す構成説明図である。この実施形態に係る線状照明装置１は、柱状の透明性の導光体２０と、導光体２０の一側端に設けられる発光ダイオード等の点状光源１０から構成されており、導光体２０には光線制御構造２１を有する。導光体２０の光線制御構造２１を除いた形状は角柱状導光体に限定される必要はない。また、光源は導光体の一端から効率よく光線を利用できれば、面状光源でもよく、発光ダイオードに限定されるものではない。
【００２１】光線制御構造２１の構成は図２に示すように、出射側導光面２０４と、接合面２１１と、光線角度制御面２１２と、出射面２１３より構成される単位構造を導光体２０の長手方向にアレイ状に配置する。また、導光体２０、および光線制御構造２１を構成する各面は平面で表されているが、図３に示すように、射出光線の方向制御のため適宜曲面等を使用してもよい。
【００２２】次に導光体内を通過する光線の挙動を図１および図２の光線４１及び４２にて説明する。光源１０から出射した光線４１は導光体２０の一端面である光源入射面２０１より導光体２０の内部へ入射する。このとき光源１０からの光線は大きな開き角を持つが、導光体２０に入ることにより角度が狭まる。具体的には導光体２０の材質がアクリル樹脂の場合、８５度の角度にて入射した光線は約４２度の角度で導光体２０に入射する。光線は導光体２０と空気の界面による全反射効果により光源入射面２０１から反光源入射面２０２の方向へ全反射を繰り返し進行する。断面図において説明すると、反出射側導光面２０３と光線制御構造２１の出射側導光面２０４により全反射を繰り返す。導光面同士が平行の場合、図４に示す角度Ａが０度から約４２度迄の一定範囲の角度で光線は進行する。その為、光線制御構造２１に入射する光線は場所によらず一定範囲の角度である。
【００２３】ここで、光線制御構造２１側の出射側導光面２０４に至らず、接合面２１１を通過した光線４２は、光線角度制御面２１２にて全反射し、出射面２１３より出射する。光線制御構造２１が同じ形であれば、出射する光束は同じ範囲の方向、開き角に制御される。
【００２４】上記光線制御構造２１の構成を、図２に示されるように出射面２１３の面積を接合面２１１の面積より大きくすることにより、光線角度制御面２１２にて全反射をし、光線の拡がり角度を狭め、輝度を向上することができる。
【００２５】従来の装置と比較すると、光線制御構造２１を付与したことにより、導光体としての機能と、光束収束機能を兼ね備えている点が特徴である。
【００２６】導光体２０の幅（反出射側導光面２０３と出射側導光面２０４の間隔）を薄くして反射回数が増しても、上記の光線制御構造２１の原理は変わらず、光源１０から出射する光量の利用効率を極端に落とさない程度に薄く出来る。
【００２７】次に線状照明装置１の光量均一性の向上について説明する。導光体２０の光線制御構造２１の出射側導光面２０４と接合面２１１の比が可変の導光体を用いることにより、輝度ムラを低減することができる。より具体的には、１つの発光ダイオード光源を配置する線状照明装置１においては、光源側に近い出射側導光面２０４は大きく接合面２１１は小さく、光源から離れるに従い出射側導光面２０４は小さく接合面２１１は大きく配置する。２つの発光ダイオード光源を導光体の両端に配置する線状照明装置１においては、導光体２０の両端部では出射側導光面２０４は大きく接合面２１１は小さく、導光体２０中心部では、例えば出射側導光面２０４は小さく接合面２１１は大きく変化する導光体とする。光源に近い位置の光線制御構造２１の例を図５（ａ）に、光源から離れた位置の光線制御構造２１を図５（ｂ）に示す。
【００２８】また、光線制御構造２１の単位構造は同一形状で、配置ピッチを可変にすることによっても線状照明装置１の光量均一化が可能である。
【００２９】より一層の光量均一性を要する用途については単位構造、および配置ピッチ共に可変とすることにより可能である。
【００３０】さらに均一性を向上させる手段について説明する。図６は導光体２０の光線制御構造２１を短手方向に二分割し配置を半ピッチずらした導光体である。この構造により光線制御構造２１のピッチが広く輝度ムラが発生する場合においても、光線制御構造２１直後の照度分布強度の山部と谷部を重ねることにより、輝度ムラの発生を抑えることができる。このような構造を採用することで、成型上も有利となる。
【００３１】次に出射面２１３から出射する光量を増す手段について説明する。導光体２０の反光源入射面２０２に反射構造を付与することにより、光源の反対側に仮想光源を配置した効果が得られ、出射面２１３から出射する強度を増すことができる。反射構造の具体例としては、反光源入射面２０２に銀や、アルミニウム等の反射率の高い材質にて蒸着を施したり、ミラーを設けることが挙げられる。
【００３２】また、導光体２０の反出射側導光面２０３の法線を光線制御構造２１に対して垂直な方向からわずかに光源方向に変えることにより、この二面による光線の進行角度は反光源入射面２０２に近づくにつれ、出射面２１３の法線方向に近づく。この構造により出射面２１３より出射する反光源入射面２０２側の光量を増し、光源入射面２０１側との光量比を低減することができる。例えば、導光体２０を光源入射面２０１の面積が反光源入射面２０２の面積よりも大きく、反出射側導光面を斜面とするくさび形状とすることができる。
【００３３】線状照明装置１の機能をまとめると、少なくとも一つ以上の点状光源を均一で輝度ムラの少ない線状光源に変換する役割を担い、特に長手方向の光線の出射方向を要求される所定の方向にまとめることにより、輝度の向上を図ることが可能である。
【００３４】次に本発明の線状照明装置１の光量均一性、および出射角度強度分布特性を示す。図７に光線制御構造２１から出射する光線の強度分布を示す。光源側と反光源側での強度の差はほとんどなく均一であることがわかる。
【００３５】図８に光線制御構造２１から出射した光線の出射角度強度分布を示す。垂直方向の角度強度分布は図９に示す発光ダイオードの角度強度分布とほぼ同一の分布である、しかし、光線制御構造２１が並ぶ水平方向は拡がり角が垂直方向に比べ小さい。尚、垂直方向は導光体２０の短手方向を表し、水平方向は導光体２０の長手方向を表す。
【００３６】本発明の線状照明装置１における好ましい態様において、導光体２０及び、導光板３０は樹脂材料によって成形され特にアクリル系樹脂、ポリカーボネート系樹脂、ポリエステル系樹脂、又は環状ポリオレフィン系樹脂が好適に用いられる。
【００３７】本発明の線状照明装置１における好ましい使用形態として、反射型液晶ディスプレイパネルの前面に配して液晶パネルを照明するフロントライトとして使用できる。また、透過型液晶パネルの後面に配してバックライトとして使用することも可能であり、さらに従来蛍光ランプを光源としている全ての照明装置に適用可能である。
【００３８】
【実施例】
以下において、本発明の線状照明装置１を液晶のフロントライトあるいはバックライトとして用いた場合を取り上げ、その具体的な実施例について説明する。
【００３９】図１０に本発明の線状照明装置１とフロントライトパネル又はバックライトパネルの導光板３０を組み合わせた、本発明の第１の実施例である面状照明装置を示す。フロントライト照明装置において要求される項目の１つに、光束の整った光線を液晶面に照射することがあげられる。これは液晶表示装置の構造が液晶板や偏光板等による複層構造である為、光束のバラツキを持つ光線は遮断や偏光により反射光が減少する為である。液晶表示装置がこのような構造を持つ為、例えば図１５に示される従来のフロントライト照明装置では、導光体２０から導光板３０への光線は水平垂直方向、共に拡がっており、フロントライトパネルにより液晶に照射される光線は水平方向への拡がり角を制御することが出来ず、効率よく液晶表示装置を照明できない問題がある。そこで本発明の線状照明装置１を用いることにより、水平方向への拡がり角の少ない光束が導光板に入射し、液晶表示装置に光束の整った光線を照射することができ、輝度の高い液晶表示装置を得ることが出来る。
【００４０】図１１に光線制御構造２１を導光板３０と一体構成とした、本発明の第２の実施例である面状照明装置を示す。これまで上記の説明では光線制御構造２１は導光体２０と一体構成の形態を示してきたが、導光板３０と一体にしてもよい。但しこの場合は導光体２０と光線制御構造２１を屈折媒質にて接続する必要がある。２素子の間に空気層が存在すると、導光体２０を導光する光線は光線入射部２０１から反光線入射部２０２まで全反射を繰り返し、導光板３０の方向へ光線は出射しない。屈折媒質には導光体２０と光線制御構造２１の屈折率に近似の媒質であればどのような物でも構わないが、紫外線硬化樹脂等の接着剤を用いれば容易に固着することが可能である。
【００４１】図１２に光線制御構造２１を導光体２０及び導光板３０と一体構成とした、本発明の第３の実施例である面状照明装置を示す。光線制御構造２１と導光体２０及び導光板３０と一体構成にすることによりこれらの素子の界面がなくなり、エネルギー損失が減少する。
【００４２】図１３に光線制御構造２１と導光体２０と光線制御構造２１の出射側に設けた第２の柱状体とを一体構成とした、本発明の第４の実施例である線状照明装置を示す。図１の構成では形状構造強度が弱いと考えられる、そこで光線制御構造２１の出射側に第２の柱状体を設けて一体構成とすることにより、強度を増すことができる。
【００４３】
【発明の効果】以上説明したように、本発明によれば、導光板に隣する導光体の長手方向の側面に光線制御構造を付与したことにより、導光体からの出射光の水平方向の拡がり角度を抑えることができ、輝度が高く、省スペース且つ照度ムラの少ない照明装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の線状照明装置の一実施例を示す構成図。
【図２】導光体２０の光線制御構造２１の拡大図。
【図３】曲面にて構成される光線制御構造２１の拡大図。
【図４】導光面同士が平行な導光体２０の光路図。
【図５】（ａ）可変形状光線制御構造（光源側）。
（ｂ）可変形状光線制御構造（反光源側）。
【図６】導光体２０の光線制御構造２１を短手方向に二分割し半ピッチずらして配置した導光体の見取図。
【図７】光線制御構造２１直後の照度分布図。
【図８】光線制御構造２１直後の角度強度分布図。
【図９】発光ダイオード光源の角度強度分布図。
【図１０】導光体に光線制御構造を有する面状照明装置の平面図。
【図１１】導光板に光線制御構造を有する面状照明装置の平面図。
【図１２】導光体、光線制御構造、導光板を一体構成とした面状照明装置の平面図。
【図１３】隣合う光線制御構造の接合面、及び出射面を光線制御構造と同一の媒質にて接続した線状照明装置の平面図。
【図１４】導光板の端面に複数の発光ダイオードを設けた照明装置の平面図。
【図１５】導光板に対向する面の対向面にプリズム状の構造体を設けた導光体を備え、導光体が反射材にて囲まれる照明装置の見取図。
【図１６】上下面に溝を設けた導光体の見取図。
【図１７】導光板のコーナー部を斜めにカットし発光ダイオード光源を配置した円状の溝構造を持つ面状照明装置の見取図。
【符号の説明】
１　　　線状照明装置
１０　　光源
２０　　導光体
２０１　光源入射面
２０２　反光源入射面（反射部）
２０３　反出射側導光面
２０４　出射側導光面
２１　　光線制御構造
２１１　接合面
２１２　光線角度制御面
２１３　出射面
３０　　導光板（フロントライトパネル又はバックライトパネル）
４１　　光源から出射し全反射により反光源側へ導光する光線
４２　　出射面より出射する光線
５０　　導光体を囲む反射材
６１　　Ｖ字型の溝構造を持つ導光体の上面部
６２　　Ｖ字型の溝構造を持つ導光体の下面部
７１　　放射状に配されるＶ字型の溝
Ａ　　　反出射側導光面２０３及び、出射側導光面２０４にて全反射する光線のなす角度[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device and a display device such as a liquid crystal device having a lighting function, and more particularly, to a linear lighting device which needs to control an emission direction of a light beam and an opening angle of the light beam.
[0002]
[Prior art]
Conventionally, a linear light source, such as a cold cathode discharge tube or a hot cathode discharge tube, has been used as a linear light source. The light source is converted into a shape light source.
As a configuration of a lighting device using a light emitting diode as a point light source, there is a method in which a plurality of light sources 10 are provided on an end face of a light guide plate 30 as shown in FIG. For example, as a similar example, Japanese Patent Application Laid-Open No. 2002-245832 creates a large number of virtual light sources by using a prism sheet to increase uniformity.
Further, as shown in FIG. 15, a linear illuminator using a light guide 20 provided at one end of a light guide plate 30 as a linear light source, Japanese Patent Laid-Open No. 2000-11723, has been put to practical use. The light guide 20 has at least one or more light sources 10 provided at one end in the longitudinal direction, and a prism-shaped structure is provided on a surface opposite to the light guide plate 30. Further, the light guide 20 is surrounded by a reflective material 50 of a mirror surface, white, milky white or the like except for a surface facing the light guide plate 30.
As shown in FIG. 16, there is a linear illumination device having V-shaped grooves provided on the upper and lower surfaces of the light guide 20, and has been put to practical use in place of the light guide 20 of FIG.
The lighting apparatus shown in FIGS. 14 to 16 converts a point light source to a linear light source and substitutes for a cold cathode discharge tube or a hot cathode discharge tube. As shown in FIG. Japanese Patent Application Laid-Open No. 2002-109928 discloses a lighting device in which a corner portion of a light guide plate 30 is cut obliquely, a light source 10 is arranged to face the cut surface, and a V-shaped groove 71 is radially arranged in the light guide plate. Thus, an illumination device for a liquid crystal display device that converts a point light source into a planar light source has been provided.
[0007]
[Problems to be solved by the invention]
In the conventional method shown in FIG. 14 described above, a problem that streak-like unevenness occurs was observed.
Further, in the conventional methods shown in FIGS. 14 to 16, the spread angle of the light beam cannot be arbitrarily controlled, and the uniformity of the intensity is secured by diffusing the light beam to suppress unevenness. Was a factor inviting Therefore, in order to increase the brightness, it is necessary to increase the number of light sources or use a light source with a larger light amount, which has been a factor of high cost.
Further, in the method shown in FIG. 17, since the light emitting diode is affected by the spread angle, the uniformity is low, the groove structure has a small circular arc, and the light emission angle of the peak luminous intensity is different. There may be a problem that luminance unevenness occurs and visibility deteriorates.
[0010]
[Means for solving the problem]
As means for solving the above problems, in the invention according to claim 1, a columnar light guide, a light beam emitting portion provided on a side surface in a longitudinal direction of the columnar light guide, and at least one of the columnar light guides In a lighting device comprising a light source provided in a part and having a light emitting area smaller than that of the light beam emitting portion, the light beam emitting portion is provided with a light beam control structure of a direction of an emitted light beam and an opening angle. .
In the invention according to claim 2, the light beam control structure provided in the light beam emitting portion of the columnar light guide includes a joining surface for taking in a light beam for guiding the columnar light guide, and an emission surface for emitting the light beam. And a convex unit structure having a side surface connecting the light emitting surface and the joining surface, and the unit structures are arranged in an array in the longitudinal direction of the columnar light guide.
According to a third aspect of the present invention, the area of the emission surface of the unit structure is larger than the area of the bonding surface.
According to a fourth aspect of the present invention, a plurality of the unit structures are arranged in a lateral direction of the columnar light guide, and each unit structure is shifted in a longitudinal direction.
According to a fifth aspect of the present invention, the arrangement pitch of the unit structures is variable.
According to a sixth aspect of the present invention, each of the unit structures has a different shape.
According to a seventh aspect of the present invention, at least one end face of the columnar light guide is a reflecting surface.
According to an eighth aspect of the present invention, the sectional area parallel to the end face of the columnar light guide changes depending on the position in the longitudinal direction.
According to a ninth aspect of the present invention, the strength and workability of the light guide are improved by integrating the respective structures on the emission surface of the columnar light guide.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a light guide of the present invention and a lighting device using the same will be described in more detail with reference to the drawings.
FIG. 1 is an explanatory view schematically showing the configuration of a linear illumination device 1 according to a first embodiment of the present invention. The linear lighting device 1 according to this embodiment includes a columnar transparent light guide 20 and a point light source 10 such as a light emitting diode provided at one end of the light guide 20. The body 20 has a light control structure 21. The shape of the light guide 20 excluding the light control structure 21 does not need to be limited to a prismatic light guide. The light source may be a planar light source as long as light can be efficiently used from one end of the light guide, and is not limited to a light emitting diode.
As shown in FIG. 2, the configuration of the light beam control structure 21 is a unit structure composed of an output side light guide surface 204, a joint surface 211, a light angle control surface 212, and an output surface 213. 20 are arranged in an array in the longitudinal direction. In addition, each surface constituting the light guide 20 and the light beam control structure 21 is represented by a plane, but as shown in FIG. 3, a curved surface or the like may be appropriately used for controlling the direction of the emitted light beam.
Next, the behavior of the light beam passing through the light guide will be described with reference to light beams 41 and 42 in FIGS. The light beam 41 emitted from the light source 10 enters the inside of the light guide 20 from a light source incident surface 201 which is one end surface of the light guide 20. At this time, the light beam from the light source 10 has a large opening angle, but the angle is narrowed by entering the light guide 20. Specifically, when the material of the light guide 20 is an acrylic resin, a light beam incident at an angle of 85 degrees enters the light guide 20 at an angle of about 42 degrees. The light rays repeatedly undergo total reflection in the direction from the light source incident surface 201 to the anti-light source incident surface 202 due to the total reflection effect by the interface between the light guide 20 and air. Explaining in a cross-sectional view, total reflection is repeated by the non-emission-side light guide surface 203 and the emission-side light guide surface 204 of the light beam control structure 21. When the light guide surfaces are parallel to each other, the light beam travels at an angle A shown in FIG. 4 within a certain range from 0 degrees to about 42 degrees. Therefore, the light beam incident on the light beam control structure 21 has an angle within a certain range regardless of the location.
Here, the light beam 42 that has not reached the light exit side light guide surface 204 on the light beam control structure 21 side and has passed through the joint surface 211 is totally reflected by the light beam angle control surface 212 and exits from the light exit surface 213. If the light beam control structures 21 have the same shape, the emitted light beams are controlled in the same range of directions and opening angles.
As shown in FIG. 2, by making the area of the light exit surface 213 larger than the area of the joint surface 211, the light beam control structure 21 is totally reflected by the light angle control surface 212, The spread angle can be narrowed, and the luminance can be improved.
Compared with the conventional apparatus, the provision of the light beam control structure 21 is characterized in that it has both a function as a light guide and a light beam converging function.
Even if the width of the light guide 20 (the distance between the anti-emission-side light guide surface 203 and the exit-side light guide surface 204) is reduced to increase the number of reflections, the principle of the light beam control structure 21 does not change. It can be made thin so that the utilization efficiency of the amount of light emitted from the light source 10 is not extremely reduced.
Next, the improvement of the light quantity uniformity of the linear illumination device 1 will be described. By using a light guide having a variable ratio between the light-emitting side light guide surface 204 and the bonding surface 211 of the light beam control structure 21 of the light guide 20, luminance unevenness can be reduced. More specifically, in the linear lighting device 1 in which one light-emitting diode light source is arranged, the emission-side light guide surface 204 near the light source is large and the bonding surface 211 is small, and the emission-side light guide surface 204 increases as the distance from the light source increases. Are small and the bonding surface 211 is large. In the linear lighting device 1 in which the two light emitting diode light sources are arranged at both ends of the light guide, the light-emitting side light guide surface 204 is large at both ends of the light guide 20, the bonding surface 211 is small, and the center of the light guide 20 is located at the center. For example, the light guide surface 204 on the emission side is small and the bonding surface 211 is a light guide that changes greatly. FIG. 5A shows an example of the light beam control structure 21 near the light source, and FIG. 5B shows the light beam control structure 21 far from the light source.
Further, the unit structure of the light beam control structure 21 has the same shape, and the light quantity of the linear illumination device 1 can be made uniform by changing the arrangement pitch.
For applications requiring more uniform light quantity, it is possible to make both the unit structure and the arrangement pitch variable.
The means for further improving the uniformity will be described. FIG. 6 shows a light guide in which the light beam control structure 21 of the light guide 20 is divided into two in the lateral direction and the arrangement is shifted by a half pitch. With this structure, even in the case where the pitch of the light control structure 21 is large and luminance unevenness occurs, the occurrence of luminance unevenness can be suppressed by overlapping the peaks and valleys of the illuminance distribution intensity immediately after the light control structure 21. Employing such a structure is advantageous in terms of molding.
Next, the means for increasing the amount of light emitted from the emission surface 213 will be described. By providing a reflection structure on the anti-light source incident surface 202 of the light guide 20, an effect of disposing the virtual light source on the opposite side of the light source can be obtained, and the intensity of light emitted from the light exit surface 213 can be increased. As a specific example of the reflection structure, the anti-light source incident surface 202 may be formed by depositing a material having high reflectivity such as silver or aluminum, or by providing a mirror.
Also, by changing the normal line of the light exit surface light guide surface 203 of the light guide 20 slightly from the direction perpendicular to the light beam control structure 21 to the light source direction, the traveling angle of the light beam by these two surfaces can be reduced. As it approaches the anti-light source entrance surface 202, it approaches the normal direction of the exit surface 213. With this structure, it is possible to increase the amount of light emitted from the light exit surface 213 on the side opposite to the light source incident surface 202 and to reduce the light amount ratio with respect to the light source incident surface 201 side. For example, the light guide 20 can have a wedge shape in which the area of the light source incident surface 201 is larger than the area of the anti-light source incident surface 202 and the anti-emission side light guide surface is an inclined surface.
The function of the linear illuminator 1 can be summarized as follows: at least one point light source is converted into a linear light source having a uniform brightness with less unevenness. It is possible to improve the luminance by grouping in a predetermined direction.
Next, the light intensity uniformity and the emission angle intensity distribution characteristics of the linear illumination device 1 of the present invention will be described. FIG. 7 shows an intensity distribution of a light beam emitted from the light beam control structure 21. It can be seen that there is almost no difference in intensity between the light source side and the opposite light source side, and the intensity is uniform.
FIG. 8 shows an emission angle intensity distribution of a light beam emitted from the light beam control structure 21. The angular intensity distribution in the vertical direction is almost the same as the angular intensity distribution of the light emitting diode shown in FIG. 9, but the divergence angle is smaller in the horizontal direction where the light control structures 21 are arranged than in the vertical direction. Note that the vertical direction indicates the short direction of the light guide 20, and the horizontal direction indicates the long direction of the light guide 20.
In a preferred embodiment of the linear illuminating device 1 of the present invention, the light guide 20 and the light guide plate 30 are formed of a resin material, and are preferably made of an acrylic resin, a polycarbonate resin, a polyester resin, or a cyclic polyolefin resin. It is preferably used.
As a preferred mode of use of the linear illumination device 1 of the present invention, the linear illumination device 1 can be used as a front light for illuminating a liquid crystal panel by being arranged in front of a reflection type liquid crystal display panel. Further, it can be disposed on the rear surface of the transmissive liquid crystal panel to be used as a backlight, and can be applied to all lighting devices which conventionally use a fluorescent lamp as a light source.
[0038]
【Example】
Hereinafter, a case where the linear illumination device 1 of the present invention is used as a liquid crystal front light or a backlight will be described, and specific examples thereof will be described.
FIG. 10 shows a spread illuminating apparatus according to a first embodiment of the present invention in which the linear illuminating apparatus 1 of the present invention is combined with the light guide plate 30 of a front light panel or a backlight panel. One of the items required in a front light illuminating device is to irradiate a liquid crystal surface with a light beam having a uniform light flux. This is because, since the structure of the liquid crystal display device is a multilayer structure including a liquid crystal plate, a polarizing plate, and the like, a light beam having a variation in light flux is blocked or polarized light, and reflected light is reduced. Since the liquid crystal display device has such a structure, for example, in the conventional front light illuminating device shown in FIG. 15, the light rays from the light guide 20 to the light guide plate 30 spread in both the horizontal and vertical directions, and the front light panel As a result, there is a problem that a light beam applied to the liquid crystal cannot control the spread angle in the horizontal direction, and cannot illuminate the liquid crystal display device efficiently. Therefore, by using the linear illumination device 1 of the present invention, a light beam having a small divergence angle in the horizontal direction can be incident on the light guide plate, and the liquid crystal display device can be irradiated with a light beam with a uniform light beam. A display device can be obtained.
FIG. 11 shows a spread illuminating apparatus according to a second embodiment of the present invention in which the light beam control structure 21 is integrally formed with the light guide plate 30. In the above description, the light beam control structure 21 has been shown to be integrated with the light guide 20, but may be integrated with the light guide plate 30. However, in this case, it is necessary to connect the light guide 20 and the light beam control structure 21 with a refraction medium. When an air layer exists between the two elements, the light beam that guides the light guide 20 repeats total reflection from the light beam incident portion 201 to the anti-light beam incident portion 202, and no light beam is emitted toward the light guide plate 30. As the refraction medium, any medium may be used as long as it is a medium similar to the refractive index of the light guide 20 and the light beam control structure 21. However, if an adhesive such as an ultraviolet curable resin is used, it can be easily fixed. is there.
FIG. 12 shows a spread illuminating apparatus according to a third embodiment of the present invention in which the light beam control structure 21 is integrated with the light guide 20 and the light guide plate 30. Integrating the light control structure 21 with the light guide 20 and the light guide plate 30 eliminates the interface between these elements and reduces energy loss.
FIG. 13 shows a fourth embodiment of the present invention, in which the light beam control structure 21, the light guide 20, and the second columnar member provided on the exit side of the light beam control structure 21 are integrally formed. 3 shows a lighting device. In the configuration of FIG. 1, it is considered that the strength of the shape and structure is weak. Therefore, the strength can be increased by providing a second columnar body on the emission side of the light beam control structure 21 to form an integral structure.
[0043]
As described above, according to the present invention, the light guide structure is provided on the longitudinal side surface of the light guide adjacent to the light guide plate, so that the light emitted from the light guide in the horizontal direction is provided. It is possible to provide an illuminating device that can suppress the spread angle of the illuminated light, has high luminance, saves space, and has less illuminance unevenness.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of a linear illumination device according to the present invention.
FIG. 2 is an enlarged view of a light beam control structure 21 of the light guide 20.
FIG. 3 is an enlarged view of a light beam control structure 21 formed of a curved surface.
FIG. 4 is an optical path diagram of a light guide 20 whose light guide surfaces are parallel to each other.
FIG. 5A shows a variable shape light control structure (light source side).
(B) Variable-shape light control structure (on the side opposite to the light source).
FIG. 6 is a schematic view of a light guide in which a light control structure 21 of the light guide 20 is divided into two in a lateral direction and is shifted by a half pitch.
7 is an illuminance distribution diagram immediately after the light beam control structure 21. FIG.
8 is an angular intensity distribution diagram immediately after the light beam control structure 21. FIG.
FIG. 9 is an angular intensity distribution diagram of a light emitting diode light source.
FIG. 10 is a plan view of a spread illuminating apparatus having a light control structure in a light guide.
FIG. 11 is a plan view of a spread illuminating device having a light guide structure on a light guide plate.
FIG. 12 is a plan view of a planar lighting device in which a light guide, a light beam control structure, and a light guide plate are integrally configured.
FIG. 13 is a plan view of a linear illuminator in which a joining surface and an emission surface of adjacent light control structures are connected by the same medium as the light control structure.
FIG. 14 is a plan view of a lighting device in which a plurality of light emitting diodes are provided on an end surface of a light guide plate.
FIG. 15 is a perspective view of a lighting device including a light guide in which a prism-shaped structure is provided on a surface facing a light guide plate, and the light guide is surrounded by a reflective material.
FIG. 16 is a sketch of a light guide having grooves on upper and lower surfaces.
FIG. 17 is a plan view of a planar lighting device having a circular groove structure in which a light guide diode light source is arranged by obliquely cutting a corner portion of a light guide plate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Linear lighting device 10 Light source 20 Light guide 201 Light source incidence surface 202 Anti-light source incidence surface (reflection part)
203 Anti-outgoing light guide surface 204 Outgoing light guide surface 21 Ray control structure 211 Joint surface 212 Ray angle control surface 213 Outgoing surface 30 Light guide plate (front light panel or backlight panel)
41 Light rays emitted from the light source and guided toward the anti-light source side by total reflection 42 Light rays emitted from the emission surface 50 Reflector surrounding the light guide 61 Upper surface part 62 of the light guide having a V-shaped groove structure V-shaped Lower surface portion 71 of light guide having groove structure V-shaped groove A arranged radially Angle formed by light rays totally reflected by anti-emission-side light guide surface 203 and emission-side light guide surface 204

Claims

A columnar light guide, a light beam emitting portion provided on a side surface in the longitudinal direction of the columnar light guide, and a light source provided on at least a part of the columnar light guide and having a smaller light emitting area than the light beam emitting portion The lighting device according to claim 1, wherein a light beam control structure for controlling the direction of the emitted light beam and the opening angle is provided to the light beam emitting portion.

The light beam control structure provided in the light beam emitting portion of the columnar light guide has a joining surface that captures a light beam that guides the columnar light guide, an exit surface that emits the light beam, and a side surface that connects the exit surface and the joining surface. The lighting device according to claim 1, comprising a convex unit structure having the following, and the unit structures are arranged in an array in the longitudinal direction of the columnar light guide.

3. The lighting device according to claim 2, wherein the area of the emission surface of the unit structure is larger than the area of the bonding surface.

The lighting device according to claim 2, wherein a plurality of the unit structures are arranged in a short direction of the columnar light guide, and each unit structure is shifted in a long direction.

3. The lighting device according to claim 2, wherein an arrangement pitch of the unit structures is variable.

The lighting device according to claim 2, wherein each of the unit structures has a different shape.

The lighting device according to claim 1, wherein at least one end surface of the columnar light guide is a reflection surface.

The lighting device according to claim 1, wherein a cross-sectional area parallel to an end surface of the columnar light guide changes depending on a position in a longitudinal direction.

The lighting device according to claim 1, wherein the respective structures on the emission surface of the columnar light guide are integrated.