JPH07128665A - Back light - Google Patents

Abstract

PURPOSE:To provide a back light with high power consumption-luminance conversion efficiency and with high luminance by making at least a part of a light reflection surface a continuous body with a shape where a light beam tangentially outgoing from a light emitting point of a bar-shaped light source to a side far from a light transmission plate in the direction perpendicular to the longitudinal central axis of the bar-shaped light source is reflected to the light emitting point. CONSTITUTION:This back light is constituted of the light transmission plate 1 made of translucent material and provided with a light diffusion action and/or a light scattering action, the bar-shaped light source 4 arranged close to at least one side surface end part of the light transmission plate 1 and the light reflection surface 7 covering the light source 4. At least a part of the light reflection surface 7 is constituted so as to be the continuous body 7a with the shape where the light beam tangentially outgoing from the light emitting point of the bar-shaped light source 4 to the side far from the light transmission plate 1 in the direction perpendicular to the longitudinal central axis of the bar-shaped light source is reflected to the light emitting point. That is, the continuous body 7a of the light reflection body is made to much with an involute of a curve smoothly linking plural light emitting points of the bar-shaped light source 4 substantially.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、透過型又は、半透過型
パネルを背面より照射するエッジライト方式のバックラ
イトに用いられる導光板に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate used for an edge light type backlight for illuminating a transmissive or semi-transmissive panel from the back side.

【０００２】[0002]

【従来の技術】近時、ラップトップ型又は、ブック型の
ワ−ドプロセッサ−やコンピュ−タ等の表示装置とし
て、薄型でしかも見易いバックライト機構を有する液晶
表示装置が用いられている。このようなバックライトに
は、図１に示すように透光性の導光板（図中１）の一端
部に、蛍光管のような棒状光源（図中４）を併設するエ
ッジライト方式が用いられている。このエッジライト方
式の場合、図２に示すように、導光板の一方の広い面に
光拡散反射物質をドット状、ストライプ状などの形状で
部分的に被覆すか、導光板の裏面に多数の凸状突起又は
凹部を形成するなどして、その面のほぼ全面を光拡散反
射シ−ト（図中３）で覆い、導光板の出光面を光拡散シ
−ト（図中２）で覆うように配置されたものが多い。2. Description of the Related Art Recently, a liquid crystal display device having a backlight mechanism which is thin and easy to see has been used as a display device for a laptop or book type word processor, a computer or the like. For such a backlight, an edge light system is used in which a rod-shaped light source (4 in the figure) such as a fluorescent tube is provided at one end of a light-transmitting light guide plate (1 in the figure) as shown in FIG. Has been. In the case of this edge light method, as shown in FIG. 2, one wide surface of the light guide plate is partially covered with a light diffusive / reflecting material in the shape of dots, stripes or the like, or a large number of protrusions are formed on the back surface of the light guide plate. By forming a protrusion or a recess, almost the entire surface is covered with a light diffusion reflection sheet (3 in the figure), and the light emitting surface of the light guide plate is covered with a light diffusion sheet (2 in the figure). Many are located in.

【０００３】特に近時、バックライトがバッテリ−駆動
されるようになり消費電力−輝度変換効率のよりいっそ
うの向上が望まれているため、線状光源を覆う反射器
（図中５）の形状を、その長手方向に対して垂直に切断
した形状が放物線形状、楕円形状にしたり、又特開平４
−２５７８２３号公報に開示されているような特殊な形
状にしたりして、光源から出射した光線を効率良く導光
板の端面に入射させる方法が提案されている。Particularly in recent years, since the backlight is driven by a battery and further improvement in power consumption-luminance conversion efficiency is desired, the shape of the reflector (5 in the figure) covering the linear light source is desired. Is cut into a parabolic shape or an elliptical shape in a direction perpendicular to the longitudinal direction,
There has been proposed a method in which a light beam emitted from a light source is efficiently incident on the end face of a light guide plate by forming a special shape as disclosed in Japanese Patent No. 257823.

【０００４】しかし、前記したいずれの方法において
も、消費電力−輝度変換効率は向上するものの、未だ充
分ではなく、更により一層の向上が望まれている。However, in any of the above-mentioned methods, although the power consumption-luminance conversion efficiency is improved, it is still not sufficient, and further improvement is desired.

【０００５】[0005]

【発明が解決しようとする課題】本発明の目的は、消費
電力−輝度変換効率が高く、かつ高輝度が得られるバッ
クライトを提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a backlight which has high power consumption-luminance conversion efficiency and high luminance.

【０００６】[0006]

【課題を解決するための手段】本発明者等は、上述の点
につき種々の検討を行った結果、エッジライト方式のバ
ックライトに於いて、棒状光源を覆う反射器の形状をあ
る形状にすると、前記した消費電力−輝度変換効率の高
いバックライトとなることを見出した。Means for Solving the Problems As a result of various studies on the above points, the present inventors found that in an edge light type backlight, the shape of a reflector for covering a rod-shaped light source was changed to a certain shape. Have found that the above-mentioned backlight has high power consumption-luminance conversion efficiency.

【０００７】前記反射器の形状が、従来の多くがそうで
あるように、ある特定の１点（多くの場合棒状光源の中
心点）から出射する光線を基準として設計されているも
のは、棒状光源から出射した光線の多くが、再び棒状光
源に戻り、吸収されて（棒状光源は蛍光体、電極、水
銀、ガラス等の光を吸収する性質を有する材料から形成
されている）相当の量の光線が熱になるなどして失われ
ることが考えられる。The shape of the reflector is designed based on a light beam emitted from one specific point (often the center point of a rod-shaped light source), as is the case with most conventional ones. Most of the light emitted from the light source returns to the rod-shaped light source again and is absorbed (the rod-shaped light source is made of a material having a property of absorbing light, such as a fluorescent substance, an electrode, mercury, and glass), and a considerable amount of light is emitted. It is conceivable that the light rays become heat and are lost.

【０００８】エッジライト方式のバックライトに用いら
れる棒状光源（線状光源）は、多くの場合、冷陰極管、
熱陰極管、冷熱陰極管などの蛍光管で、これらの蛍光管
は蛍光物質を棒状のガラス管の内壁に塗布し、ガラス管
内で発生させた紫外線を前記蛍光物質で可視光線に変換
しているため、可視光線が出射される点は棒状のガラス
管の内壁に被覆した蛍光物質である。従って、前述した
様に反射器の形状がある特定の１点から出射する光線を
効率良く導光板端面に入射する様に設計されていても、
実際に発光している複数の点（例えば前記蛍光物質）か
ら出射した光線は充分な効率で導光板端面に入射しない
のである。In many cases, a rod-shaped light source (linear light source) used for an edge light type backlight is a cold cathode tube,
Fluorescent tubes such as hot-cathode tubes and cold-cathode tubes.These fluorescent tubes apply a fluorescent substance to the inner wall of a rod-shaped glass tube, and the ultraviolet rays generated in the glass tube are converted into visible light by the fluorescent substance. Therefore, the point at which visible light is emitted is the fluorescent substance coated on the inner wall of the rod-shaped glass tube. Therefore, as described above, even if the light beam emitted from one specific point with the shape of the reflector is efficiently incident on the end surface of the light guide plate,
Light rays emitted from a plurality of actually emitting points (for example, the fluorescent substance) do not enter the end surface of the light guide plate with sufficient efficiency.

【０００９】本発明は、エッジライト方式のバックライ
トの棒状光源を覆う反射器の形状を、前述した実際に発
光している複数の点（発光点を滑らかに結んだ曲線）か
ら出射する光線を基準として設計したことが特徴であ
る。この様に設計したことによって、前述した消費電力
−輝度変換効率が飛躍的に向上することの知見を得た。According to the present invention, the shape of a reflector that covers a rod-shaped light source of an edge-light type backlight is defined as a light beam emitted from a plurality of points that actually emit light (curves that smoothly connect the light-emitting points). The feature is that it was designed as a standard. It has been found that the power consumption-luminance conversion efficiency described above is dramatically improved by designing as described above.

【００１０】即ち本発明は、透光性材料からなり、光拡
散及び／又は光散乱作用を有する導光板、前記導光板の
少なくとも１側面端部に近接して配置した棒状光源とそ
の光源を覆う光反射面からなるバックライトであって、
前記光反射面の少なくとも一部分が、棒状光源の発光点
から、その接線方向で棒状光源の長手中心軸に対して垂
直方向の、導光板に遠い側に出光した光がその発光点に
反射される形状の連続体であるバックライトに関するも
のである。That is, according to the present invention, a light guide plate made of a translucent material and having a light diffusion and / or light scattering action, a rod-shaped light source arranged in proximity to at least one side end portion of the light guide plate, and the light source are covered. A backlight composed of a light reflecting surface,
At least a part of the light-reflecting surface emits light emitted from a light emitting point of the rod-shaped light source to a side farther from the light guide plate in a direction tangential to the longitudinal center axis of the rod-shaped light source and reflected to the light emitting point. The present invention relates to a backlight which is a continuous body of shapes.

【００１１】本発明者等はさらに検討を行った結果、光
源を覆う光反射面の、棒状光源と導光板との間の部分の
形状をある特定の形状とすることにより、光源から出射
する光線が効率良く導光板端面に入射することを見出し
た。As a result of further studies by the present inventors, the light emitted from the light source is formed by setting the shape of the portion of the light reflecting surface covering the light source between the rod-shaped light source and the light guide plate to a certain shape. It was found that the light efficiently enters the end surface of the light guide plate.

【００１２】即ち本発明の他の態様は、透光性材料から
なり、光拡散及び／又は光散乱作用を有する導光板、前
記導光板の少なくとも１側面端部に近接して配置した棒
状光源とその光源を覆う光反射面からなるバックライト
であって、棒状光源の長手中心軸の垂直断面での、棒状
光源と導光板との間の前記光反射面の形状が、放物線の
一部からなり、かつ前記放物線の焦点が導光板の端部面
又は導光板の広い面の端部面近傍に実質的に一致する形
状であるバックライトに関するものである。That is, another aspect of the present invention is that a light guide plate made of a translucent material and having a light diffusing and / or light scattering action, a rod-shaped light source disposed near at least one side end of the light guide plate. A backlight comprising a light-reflecting surface that covers the light source, wherein the shape of the light-reflecting surface between the rod-shaped light source and the light guide plate in a vertical cross section of the longitudinal center axis of the rod-shaped light source is a part of a parabola. The present invention also relates to a backlight having a shape in which the focal point of the parabola is substantially coincident with the end surface of the light guide plate or the vicinity of the end surface of the wide surface of the light guide plate.

【００１３】次に本発明を図面に基づいて更に詳述す
る。Next, the present invention will be described in more detail with reference to the drawings.

【００１４】図３〜図２１は本発明の棒状光源とその周
囲を覆う光反射面の一部実施態様の断面図である。図中
１は導光板であり、光拡散及び／又は光散乱作用を有
し、かつ光を効率良く通過させる物質であればよく、石
英、ガラス、透光性の天然又は合成樹脂、例えばアクリ
ル系樹脂等である。光拡散及び／又は光散乱作用を導光
板に付与するには導光板の内部又は表面にこれらの機能
を付与すれば良い。導光板の内部に、その側面端部から
入射した光線を広い面から出射させる光拡散及び／又は
光散乱作用を付与する方法は、用いる導光板が屈折率が
異なる２種以上の物質から成るようにすれば良く特に限
定されないが、例えば２種以上の屈折率が異なるポリマ
−等が微細な間隔で多数存在する状態にするなどしても
良い。FIGS. 3 to 21 are sectional views of a rod-shaped light source according to the present invention and a partial embodiment of a light-reflecting surface covering the periphery thereof. In the figure, reference numeral 1 denotes a light guide plate, which may be any substance that has a light diffusion and / or light scattering effect and allows light to efficiently pass therethrough, such as quartz, glass, and a translucent natural or synthetic resin, for example, an acrylic resin. It is a resin or the like. In order to impart the light diffusion and / or the light scattering effect to the light guide plate, these functions may be imparted to the inside or the surface of the light guide plate. A method of imparting a light diffusion and / or a light scattering effect to the inside of the light guide plate so that the light rays incident from the side end portions thereof are emitted from a wide surface is such that the light guide plate used is composed of two or more kinds of substances having different refractive indexes. However, it is not particularly limited, but it is also possible to make a state in which, for example, two or more kinds of polymers or the like having different refractive indexes are present at a fine interval.

【００１５】導光板の広い面の表面に、導光板の側面端
部から入射した光線を広い面から出射させる光拡散及び
／又は光散乱作用を付与する方法は特に限定されない
が、光拡散及び／又は光散乱物質（図中６）、例えば、
シリカ、硫酸バリウム、酸化マグネシウム、酸化アルミ
ニウム、炭酸カルシウム、チタンホワイト、ガラスビ−
ズ、樹脂ビ−ズ、微細な気泡等を、透光性物質、例え
ば、アクリルエステル系樹脂、ビニル系樹脂等に分散さ
せた塗料、印刷インキ等の媒体をスクリ−ン印刷等の方
法で導光板面上にドット状又はストライプ状等に印刷す
るなどして行うか、導光板の表面上に微細な円錐、多角
錐、直線状、台形状などの光学的に導光板と接合された
凸部を多数形成するか、導光板の表面上に微細な円錐、
多角錐、直線状、台形状などの光学的に導光板と接合さ
れた凹部を多数形成するか、導光板の表面を粗面化して
も良い。The method of imparting the light diffusion and / or the light scattering effect of causing the light rays incident from the side end portion of the light guide plate to be emitted from the wide surface on the surface of the wide surface of the light guide plate is not particularly limited, but the light diffusion and / or Alternatively, a light scattering material (6 in the figure), for example,
Silica, barium sulfate, magnesium oxide, aluminum oxide, calcium carbonate, titanium white, glass beer
Screen, resin beads, fine air bubbles, etc. are introduced by a method such as screen printing into a medium such as a paint or printing ink in which a light-transmitting substance such as an acrylic ester resin or vinyl resin is dispersed. It is done by printing in a dot shape or a stripe shape on the light plate surface, or a convex portion such as a fine cone, a polygonal pyramid, a straight line shape, a trapezoid shape, etc. optically joined to the light guide plate on the surface of the light guide plate. Or a fine cone on the surface of the light guide plate,
A large number of recesses that are optically joined to the light guide plate, such as a polygonal pyramid, a straight line, and a trapezoid, may be formed, or the surface of the light guide plate may be roughened.

【００１６】４は棒状光源で、好ましい態様としては、
導光板の端部に光が入射するように棒状光源の中心軸が
同端面と略平行となるように配置し、棒状光源の、導光
板の端部と相対する面以外の表面を光反射面（図中７）
で覆う状態で配置することである。前記棒状光源は、蛍
光管、タングステン白熱管、オプティカルロッド、ＬＥ
Ｄを棒状に配列した物等があるが、蛍光管が好ましく、
有効発光面積の輝度分布の均一性の面及び省電力の面か
ら、電極部を除く均一発光部の長さが近接する導光板の
端部の長さとほぼ等しいことが好ましい。Reference numeral 4 is a rod-shaped light source, and in a preferred embodiment,
The rod-shaped light source is arranged so that the central axis of the rod-shaped light source is substantially parallel to the same end face so that light is incident on the end portion of the light-guide plate. (7 in the figure)
It is to be placed in a state of being covered with. The rod-shaped light source is a fluorescent tube, a tungsten incandescent tube, an optical rod, an LE.
There are things such as D arranged in a rod shape, but a fluorescent tube is preferable,
From the viewpoint of the uniformity of the luminance distribution of the effective light emitting area and the power saving, it is preferable that the length of the uniform light emitting portion excluding the electrode portion is substantially equal to the length of the end portion of the light guide plate that is adjacent to the light emitting plate.

【００１７】本発明でいう棒状光源とは、蛍光管に於け
るガラス管内壁面に被覆された蛍光物質の様に、棒状光
源の長手方向に対して垂直方向の断面に於いて、複数の
発光点を滑らかに結んだ時にある曲線が形成（例えば、
円形状、楕円形状、等）される様なものをいう。棒状光
源の長手方向に垂直な方向の断面の大きさは点でなけれ
ばよく特に限定されないが、バックライトの小形化のた
めには小さい方が良く、好ましくは最大外形が８mm以
下、より好ましくは４mm以下である。特に棒状光源とし
て冷陰極管などの蛍光管を用いる場合は、機械的強度、
寿命などの点から前記最大外形は１mm以上であることが
好ましい。The rod-shaped light source in the present invention means a plurality of light-emitting points in a cross section perpendicular to the longitudinal direction of the rod-shaped light source, like a fluorescent substance coated on the inner wall surface of the glass tube in the fluorescent tube. A curve is formed when the two are connected smoothly (for example,
Circular shape, elliptical shape, etc.). The size of the cross section of the rod-shaped light source in the direction perpendicular to the longitudinal direction is not particularly limited as long as it is not a point, but it is better to be small for downsizing the backlight, preferably the maximum outer shape is 8 mm or less, more preferably It is 4 mm or less. Especially when using a fluorescent tube such as a cold cathode tube as a rod-shaped light source, mechanical strength,
It is preferable that the maximum outer shape is 1 mm or more in terms of life.

【００１８】本発明はこの棒状光源を覆う光反射面の形
状をある形状にして配置したことが特徴である。即ち、
光反射面（図中７）の一部は、少なくとも棒状光源の発
光点から導光板に遠い側の前記発光点接線方向に出射し
た光線が実質的に同一な位置の発光点に反射するように
形成した光反射面の連続体（図中７ａ）であることであ
る。The present invention is characterized in that the rod-shaped light source is arranged with a light-reflecting surface having a certain shape. That is,
A part of the light reflecting surface (7 in the figure) is arranged so that at least light rays emitted in the tangential direction of the light emitting point on the side far from the light emitting point of the rod-shaped light source are reflected to the light emitting point at substantially the same position. That is, it is a continuous body (7a in the figure) of the formed light reflecting surface.

【００１９】本発明で用いる光反射面は鏡面反射面が好
ましい。鏡面反射面は入射した光線を実質的に鏡面反射
（正反射、反射面に下ろした法線に対して角度θで入射
した光線が角度−θで反射する状態）する性質を有すれ
ば良くその材質は特に限定されないが、例えば、銀、ア
ルミニウム、白金、ニッケル、クロム、金、銅等からな
る材質で、好ましくは銀、アルミニウムである。鏡面反
射は理想的な状態、すなわち光拡散反射がない状態が最
も好ましいが、実際には製造上の理由からも若干の光拡
散反射は避けられず、このようなものを用いても、本発
明の効果は充分に得られる。The light reflecting surface used in the present invention is preferably a specular reflecting surface. It suffices for the specular reflection surface to have a property of substantially specularly reflecting an incident light ray (regular reflection, a state in which a light ray incident at an angle θ with respect to a normal line lowered on the reflection surface is reflected at an angle −θ). The material is not particularly limited, but for example, a material made of silver, aluminum, platinum, nickel, chromium, gold, copper or the like, preferably silver or aluminum. The ideal state of specular reflection, that is, the state where there is no light diffuse reflection is the most preferable, but in reality, some light diffuse reflection is unavoidable for manufacturing reasons. The effect of is fully obtained.

【００２０】本発明では、光反射面を構成する材料とし
て、高分子化合物の成型品の表面に鏡面反射面を形成し
たものを用いることができる。例えば透明高分子材料、
例えばＡＢＳ、ＡＣＳ、ＰＣなどの樹脂を用いて射出成
型によって予め光反射面の形状を形成し、その表面にＡ
ｇ、Ａｌなどを蒸着させて鏡面反射面を形成させたも
の、又、金属板の表面に鏡面反射面を形成した板で成型
し光反射面の形状としてものなどである。In the present invention, as the material for forming the light reflecting surface, a molded product of a polymer compound having a specular reflecting surface formed on the surface can be used. Transparent polymeric material,
For example, a resin such as ABS, ACS, PC, etc. is used to form the shape of the light reflecting surface in advance by injection molding, and A
Examples thereof include those having a specular reflection surface formed by vapor deposition of g, Al or the like, or those having a light reflection surface formed by molding a metal plate having a specular reflection surface formed thereon.

【００２１】本発明での光反射面の構成条件を図１１を
用いて更に詳述すると、例えば棒状光源の発光点（図中
Ａ）から、この発光点の接線方向で導光板（図中１）に
遠い側（図中の線分ＡＢ）に出射した光線が、光反射面
の連続体（図中７ａ）に当たる微小面（図中Ｂ）と実質
的に直交することである。即ち、棒状光源の複数の発光
点を滑らかに結んだ曲線上の任意の発光点から、その点
の接線方向に出射した光線が、光反射面の連続体の前記
光線が当たる面の法線に実質的に一致していることであ
る。言い換えれば、光反射面の連続体が、前記した複数
の発光点を滑らかに結んだ曲線の伸開線に実質的に一致
している状態とすることである。図１１中で、Ｏ：棒状
光源の中心点、ｒ：棒状光源の半径、θ：角度を夫々示
す。The constitutional conditions of the light reflecting surface in the present invention will be described in more detail with reference to FIG. 11. For example, from the light emitting point (A in the figure) of the rod-shaped light source, the light guide plate (1 in the figure) in the tangential direction of this light emitting point. ), The light beam emitted to the side farther from () (line segment AB in the figure) is substantially orthogonal to the minute surface (B in the figure) which strikes the continuum of the light reflecting surface (7a in the figure). That is, from any light emitting point on a curve that smoothly connects a plurality of light emitting points of a rod-shaped light source, a ray emitted in the tangential direction of the point is the normal line of the surface of the continuous body of the light reflecting surface on which the ray hits. That is, they are substantially the same. In other words, the continuum of the light-reflecting surface is in a state of being substantially in agreement with the extended line of the curve that smoothly connects the plurality of light emitting points. In FIG. 11, O is the center point of the rod-shaped light source, r is the radius of the rod-shaped light source, and θ is the angle.

【００２２】尚、光反射面の連続体（図中７ａ）の棒状
光源の長手方向に対して垂直方向の断面に於ける少なく
とも一部の形状は前記した伸開線に実質的に一致してい
ることが本発明の必須な条件であるが、製造上の理由で
若干の凹凸や曲線自体の公差が出るが、このようなもの
も本発明の範疇に入ることは言うまでもない。Incidentally, at least part of the shape of the continuous body (7a in the figure) of the light-reflecting surface in the cross section in the direction perpendicular to the longitudinal direction of the rod-shaped light source substantially coincides with the above-mentioned extension line. Although it is an essential condition of the present invention, some irregularities and tolerances of the curve itself appear due to manufacturing reasons, and it goes without saying that such a thing also falls within the scope of the present invention.

【００２３】光反射面に入射する光線が、光反射面の法
線に一致していれば、その光線は反射面で反射されて発
光点（出射点）に戻る。本発明で言う光反射面の連続体
とはこのような条件を満たす微小反射面の連続体をい
う。尚、前記微小反射面の連続体は製造上可能な範囲で
微小面が滑らかに連続していることが、本発明の効果を
より向上させる上で特に好ましい。If the light ray incident on the light reflecting surface coincides with the normal line of the light reflecting surface, the light ray is reflected by the reflecting surface and returns to the light emitting point (emission point). The continuum of light-reflecting surfaces referred to in the present invention means a continuum of minute reflecting surfaces that satisfy such a condition. In addition, it is particularly preferable for the continuous body of the minute reflection surface to have a smooth continuous minute surface within a range that can be manufactured, in order to further improve the effect of the present invention.

【００２４】光反射面（図中７）がこのような反射面の
連続体（図中７ａ）を有していると棒状光源から出射し
た光線が極めて効率良く導光板の端面に入射し、結果的
に消費電力−輝度変換効率が飛躍的に向上する。その理
由は、光反射面の連続体の任意の微小面、例えば図１１
中Ｂに注目すると、微小面の法線は前述したように棒状
光源の発光点（図中Ａ）の接線に実質的に一致している
ので、棒状光源の他の任意の発光点（例えば図中Ｃ）か
ら出射した光線が今注目している微小面（図中Ｂ）に当
たった場合、微小面（図中Ｃ）の法線は発光点（図中
Ａ）の接線に実質的に一致しているから棒状光源には反
射されない。つまり、棒状光源の（発光点の接線から出
射された光線を除く）任意の発光点から出射され、光反
射面の連続体で反射された光線が再び棒状光源に戻るこ
とはないのである。If the light reflecting surface (7 in the figure) has such a continuum of reflecting surfaces (7a in the figure), the light beam emitted from the rod-shaped light source is incident on the end surface of the light guide plate very efficiently, and the result is The power consumption-luminance conversion efficiency is dramatically improved. The reason is that an arbitrary minute surface of the continuum of the light reflecting surface, for example, FIG.
Focusing on the middle B, since the normal line of the minute surface substantially coincides with the tangent line of the light emitting point (A in the figure) of the rod-shaped light source as described above, any other light emitting point of the rod-shaped light source (for example, in the figure When the light beam emitted from the middle C) hits the minute surface (B in the figure) that is currently focused, the normal line of the minute surface (C in the figure) is substantially equal to the tangent line of the light emitting point (A in the figure). Therefore, it is not reflected by the rod-shaped light source. In other words, a light ray emitted from an arbitrary light emitting point (excluding a light ray emitted from the tangent line of the light emitting point) of the rod-shaped light source and reflected by the continuum of the light reflection surface does not return to the rod-shaped light source again.

【００２５】蛍光管の様に発光点と光反射面の連続体と
の間に、空気とは屈折率の異なるガラスなどが存在する
場合、発光点から出射した光線は屈折率の異なる物質の
境界で屈折されるが、その方向はスネルの法則より容易
に計算出来るので、本発明に於いて発光点と光反射面の
連続体との間に空気とは屈折率の異なる物質が存在する
場合も、発光点接線方向で発光点から導光板に遠い側に
出射した光線が実質的に同一な位置の発光点に反射する
ように光反射面の連続体を形成すれば良い。When glass such as a fluorescent tube having a refractive index different from that of air exists between the light emitting point and the continuous body of the light reflecting surface, the light beam emitted from the light emitting point is a boundary of substances having different refractive indexes. Although it is refracted by, the direction can be easily calculated from Snell's law, so in the present invention, when a substance having a refractive index different from that of air exists between the light emitting point and the continuum of the light reflecting surface. The light reflection surface continuum may be formed so that the light rays emitted from the light emitting point in the tangential direction of the light emitting point to the side farther from the light guide plate are reflected at the light emitting points at substantially the same positions.

【００２６】前述したように、棒状光源の発光点から出
射された光線が再び棒状光源に戻ることがなければ、棒
状光源に戻って吸収される光線がなくなるので、消費電
力−輝度変換効率が高く、従って高輝度なバックライト
が得られる。尚、発光点の接線から出射された光線は前
記発光点からあらゆる方向に出射される全ての光線に比
較すれば無視出来る程の量である。As described above, if the light beam emitted from the light emitting point of the rod-shaped light source does not return to the rod-shaped light source again, there is no light beam that returns to the rod-shaped light source and is absorbed, so that the power consumption-luminance conversion efficiency is high. Therefore, a high brightness backlight can be obtained. The amount of light emitted from the tangent line of the light emitting point is negligible compared to all the light emitted from the light emitting point in all directions.

【００２７】光反射面の連続体（図中７ａ）は、棒状光
源が導光板と相対する側以外の面をほぼ覆った状態であ
れば充分であるが、好ましい態様としては、棒状光源の
任意の発光点から前記発光点の接線方向に出射した光線
の一方が、導光板に直接入射しない状態となる部分にあ
り、その状態で同じ光線の直進方向の他方の光線が光反
射面に当たる部分に少なくとも形成されていれば良い。
光反射面の連続体をこのような状態とすることによっ
て、棒状光源から出射する光線のなかで損失となる部分
が大きかった棒状光源の導光板と相対していない部分か
ら出た光線を効率良く導光板に入射させることが出来
る。The continuous body (7a in the figure) of the light-reflecting surface suffices if it substantially covers the surface other than the side opposite to the light guide plate. One of the light rays emitted from the light emitting point in the tangential direction of the light emitting point is in a portion that does not directly enter the light guide plate, and in that state, the other light ray in the straight traveling direction of the same light ray hits the light reflecting surface. At least it should be formed.
By setting the continuous body of the light reflecting surface in such a state, the light rays emitted from the portion not facing the light guide plate of the rod-shaped light source, which has a large loss portion in the light emitted from the rod-shaped light source, can be efficiently used. It can be incident on the light guide plate.

【００２８】光反射面の連続体と棒状光源との最短距離
は光反射面の連続体と棒状光源とが部分的に接している
状態でも良いが、棒状光源として直流電圧ではなく高周
波電圧が加えられる蛍光管等が用いられる場合は前記最
短距離は光反射面の連続体と棒状光源との間での高周波
電流のロスを極力減少させるために０．１mm以上、より
好ましくは０．５mm以上とすることである。The shortest distance between the continuous body of the light-reflecting surface and the rod-shaped light source may be a state where the continuous body of the light-reflecting surface and the rod-shaped light source are partially in contact with each other, but a high-frequency voltage is applied as the rod-shaped light source instead of the DC voltage. When a fluorescent tube or the like is used, the shortest distance is 0.1 mm or more, more preferably 0.5 mm or more in order to reduce loss of high frequency current between the continuous body of the light reflecting surface and the rod-shaped light source as much as possible. It is to be.

【００２９】光反射面（図中７）で本発明の条件を満た
す光反射面の連続体とそれ以外の部分の接合状態は特に
限定されないが、光線をより有効に利用する上で、これ
らは光学的に滑らかに接合されている状態が好ましい。
光反射面の連続体（図中７ａ）以外の部分の形状は特に
限定されず、直線状、楕円の一部分、放物線の一部分、
円の一部分などがあるが、より光線を有効に利用する上
で、楕円の一部分又は放物線の一部分が好ましい。The joining state of the continuous body of the light-reflecting surface (7 in the figure) satisfying the conditions of the present invention and the other portions is not particularly limited, but in order to use the light ray more effectively, these are The state where they are optically smoothly bonded is preferable.
The shape of the portion other than the continuous body (7a in the figure) of the light reflecting surface is not particularly limited, and is linear, a part of an ellipse, a part of a parabola,
Although there is a part of a circle, etc., a part of an ellipse or a part of a parabola is preferable for more effective use of light rays.

【００３０】光反射面の、棒状光源の長手中心軸の垂直
断面での光反射面の形状は、導光板の広い面とほぼ平行
で棒状光源の中心を通る直線に対して、実質的に対称な
形状を有することが光の有効利用の面、製作上の面から
も好ましい。このことは後述する他の好ましい態様の光
反射面についても同様である。又、機構上の理由でバッ
クライトの広い面の一方をより平滑な状態にする場合は
図１０に示した形状にしても良い。The shape of the light-reflecting surface in a cross section perpendicular to the longitudinal center axis of the rod-shaped light source is substantially symmetric with respect to a straight line which is substantially parallel to the wide surface of the light guide plate and which passes through the center of the rod-shaped light source. It is preferable to have such a shape in terms of effective use of light and manufacturing. This also applies to other preferred embodiments of the light reflecting surface described later. Further, when one of the wide surfaces of the backlight is made smoother for mechanical reasons, the shape shown in FIG. 10 may be used.

【００３１】本発明者らは更に検討した結果、棒状光源
から出射した光線を反射して導光板の側面端部に効率良
く入射するようにするために、棒状光源の長手方向に対
して垂直方向の、導光板と棒状光源との間の部分の光反
射面の断面形状が、少なくとも一部分放物線の一部分の
形状を有しており、かつ、その放物線の焦点が導光板の
端部面又は導光板上の端部面近傍に実質的に一致するよ
うに形成した部分（図中７ｂ）を有すると好ましいこと
を見出した。As a result of further study by the present inventors, in order to reflect the light beam emitted from the rod-shaped light source and efficiently enter the side end portion of the light guide plate, the direction perpendicular to the longitudinal direction of the rod-shaped light source. The cross-sectional shape of the light reflecting surface of the portion between the light guide plate and the rod-shaped light source has at least a part of a parabola, and the focus of the parabola is the end surface of the light guide plate or the light guide plate. It has been found that it is preferable to have a portion (7b in the figure) formed so as to substantially coincide with the vicinity of the upper end face.

【００３２】本発明における前記条件を図１７及び図１
８を用いて更に詳述すると、放物線の一部分の形状を持
つ光反射面の連続体（図中７ｂ）の焦点（図中８）が導
光板の端面部に実質的に一致することである。すなわ
ち、例えば、ある方向から平行な光線（図中９）が光反
射面の連続体（図中７ｂ）に入射した場合、前記光線が
導光板の端面部に集められることである。尚、光反射面
の連続体は、製造上の理由で若干の凹凸や曲線自体の公
差が出るが、このようなものも本発明の範疇に入ること
は言うまでもない。FIG. 17 and FIG. 1 show the conditions in the present invention.
More specifically, the focus (8 in the figure) of the continuous body (7b in the figure) of the light-reflecting surface having the shape of a part of a parabola substantially coincides with the end face of the light guide plate. That is, for example, when parallel light rays (9 in the drawing) from a certain direction are incident on the continuum of the light reflecting surface (7b in the drawing), the light rays are collected at the end surface portion of the light guide plate. Incidentally, the continuous body of the light reflecting surface has some irregularities and the tolerance of the curve itself due to manufacturing reasons, but it goes without saying that such a thing also falls within the scope of the present invention.

【００３３】光反射面（図中７）がこのような反射面の
連続体（図中７ｂ）からなっていると棒状光源から出射
した光線が極めて効率良く導光板の端面に入射し、結果
的に消費電力−輝度変換効率が飛躍的に向上する。その
理由は、光反射面の連続体の任意の微小面、例えば図中
Ｅに注目すると、前述したようにある方向から平行な光
線（図中９）が微小面に入射した場合、反射された光線
は焦点（図中８）に集められる。従って、ある方向
（９）から微小面の接線方向側に角度αだけズレて入射
した光線（図中１０）は−αだけズレて反射され、焦点
（８）よりも図において右側の導光板の端面部に入射す
る。つまり、ある方向（９）から微小面の接線方向まで
の角度で入射した光線は全て導光板の端面部に入射する
のである。When the light reflecting surface (7 in the figure) is made of such a continuum of reflecting surfaces (7b in the figure), the light beam emitted from the rod-shaped light source enters the end surface of the light guide plate very efficiently, resulting in In addition, the power consumption-luminance conversion efficiency is dramatically improved. The reason is that, when attention is paid to an arbitrary minute surface of the continuum of light reflecting surfaces, for example, E in the figure, when a parallel light ray (9 in the figure) is incident on the minute surface from a certain direction as described above, it is reflected. The light beam is focused on the focal point (8 in the figure). Therefore, a light ray (10 in the figure) that is incident from the certain direction (9) on the tangential side of the minute surface by an angle α is reflected by being shifted by −α, and is reflected by the light guide plate on the right side of the figure with respect to the focus (8). It is incident on the end face. That is, all the light rays incident at an angle from a certain direction (9) to the tangential direction of the minute surface are incident on the end surface portion of the light guide plate.

【００３４】ある方向（９）から微小面の接線方向まで
の角度で入射した光線が全て導光板の端面部に入射すれ
ば、棒状光源に戻って吸収される光線がなくなるので、
消費電力−輝度変換効率が高く、かつ高輝度なバックラ
イトが得られる。If all the light rays incident at an angle from a certain direction (9) to the tangential direction of the minute surface are incident on the end face portion of the light guide plate, there is no light ray that is absorbed back to the rod-shaped light source.
A backlight with high power consumption-luminance conversion efficiency and high luminance can be obtained.

【００３５】光反射面の連続体（７ｂ）と棒状光源との
位置関係は、向かい合った反射面の連続体の間に棒状光
源が存在する状態でも良いが、相対する反射面の連続体
の端部同士を交差して結んだ、相対する反射面内にでき
る交点より遠い（導光板より遠い）側に棒状光源が位置
することが本発明の効果をより向上させる上で好まし
い。The positional relationship between the continuous body (7b) of light reflecting surfaces and the rod-shaped light source may be such that the rod-shaped light source exists between the continuous bodies of the reflecting surfaces facing each other, but the end of the continuous body of the opposing reflecting surfaces. In order to further improve the effect of the present invention, it is preferable that the rod-shaped light source is located on the side farther (farther from the light guide plate) than the intersection formed in the opposing reflecting surfaces, which is formed by intersecting and connecting the portions.

【００３６】上記したように本発明では光反射面の少な
くとも一部分が特定の形状であることが必須であるが、
例えばこの光反射面が、鏡面反射面である場合、光源を
覆うそれ以外の光反射部分は、鏡面反射面でも良いが光
拡散反射面であることが好ましい。それは、導光板の端
部面（光入射面）に入射しない光線を光拡散反射させる
ことにより効率良く導光板に入射させることが出来るか
らである。この面の形状は特に限定されず、直線状、楕
円の一部分、放物線の一部分、円の一部分などがある
が、より光線を有効に利用する上で、楕円の一部分又は
放物線の一部分が好ましい。又、光拡散反射面と他の光
反射面との接合状態は特に限定されないが、より光線を
有効に利用する上で、両者は光学的に滑らかに接合され
ている状態が好ましい。As described above, in the present invention, it is essential that at least a part of the light reflecting surface has a specific shape.
For example, when this light reflecting surface is a specular reflecting surface, the other light reflecting portion that covers the light source may be a specular reflecting surface, but is preferably a light diffusing reflecting surface. This is because light rays that do not enter the end surface (light incident surface) of the light guide plate can be efficiently incident on the light guide plate by diffusing and reflecting the light rays. The shape of this surface is not particularly limited and may be a straight line, a part of an ellipse, a part of a parabola, a part of a circle, or the like, but a part of an ellipse or a part of a parabola is preferable for more effective use of light rays. Further, the joining state of the light diffusing / reflecting surface and the other light reflecting surface is not particularly limited, but it is preferable that both are optically and smoothly joined in order to effectively use the light rays.

【００３７】光反射面（７）の端面は導光板の側面端部
近傍の広い表面及び／又は裏面に光学的に接合されてい
ることが好ましい。このような状態にすることによっ
て、棒状光源から出射した光線及び光反射面で反射した
光線を効率良く導光板に入射させることが出来る。
（尚、本明細書で言う「光学的に接合」とは、光の損失
を最小限度に抑制できる接合状態を意味する）本発明の
主要部は、このような構成からなっているが、更に以下
に示すような構成とすることが好ましい。The end surface of the light reflecting surface (7) is preferably optically joined to a wide front surface and / or back surface near the side end of the light guide plate. With such a state, the light beam emitted from the rod-shaped light source and the light beam reflected by the light reflection surface can be efficiently incident on the light guide plate.
(The term "optically bonded" as used herein means a bonded state in which the loss of light can be suppressed to a minimum.) The main part of the present invention has such a structure, It is preferable to have the following structure.

【００３８】即ち、図１６に示したように、放物線の一
部分の形状の光反射面の連続体（図中７ｂ）と同じく本
発明の第一発明を構成する光反射面の連続体（図中７
ａ）とを併用して構成したものは、本発明の効果をより
向上させることができ好ましい。その理由は、光反射面
の連続体（図中７ａ）を棒状光源に用いた場合には光の
出射角度がある特定の範囲内に集まるからである。即
ち、導光板側の方向に、導光板の広い面に対してより平
行に近い角度の光線を集めることができるからである。
従って、多くの光線が、もう一方の光反射面の連続体
（図中７ｂ）に対して前述したように、ある方向（図中
９）以内で入射することが出来るので、極めて効率良く
棒状光源から出射した光線を有効に利用できるからであ
る。That is, as shown in FIG. 16, the continuum of light reflecting surfaces (7b in the figure), which constitutes the first invention of the present invention, is the same as the continuum of light reflecting surfaces in the shape of a part of a parabola (7b in the figure). 7
It is preferable to use a together with a) because the effect of the present invention can be further improved. The reason is that when a continuous body of light reflecting surfaces (7a in the figure) is used for the rod-shaped light source, the light emission angle is gathered within a certain range. That is, it is possible to collect light rays having an angle closer to parallel to the wide surface of the light guide plate in the direction of the light guide plate side.
Therefore, since many light rays can be incident on the other continuous body (7b in the figure) of the light reflecting surface within a certain direction (9 in the figure), the rod-shaped light source can be extremely efficiently. This is because the light rays emitted from the can be effectively used.

【００３９】光反射面の連続体（図中７ｂ）の端面が導
光板の側面端部近傍の広い表面及び／又は裏面に光学的
に接合されていることが好ましい。このような状態にす
ることによって、より効果的に光線を導光板の端面部に
入射できる。It is preferable that the end face of the continuous body of the light reflecting surface (7b in the figure) is optically joined to the wide front surface and / or back surface near the side end portion of the light guide plate. With such a state, the light beam can be more effectively incident on the end surface portion of the light guide plate.

【００４０】図１９に示したように、棒状光源と導光板
との間で、対向した光反射面の連続体（図中７ｂ）の間
に、屈折率が空気よりも大きい透光性物質（図中１１）
を配置することが、導光板の広い面に対するある方向
（図中９）の角度を光学的に大きくすることができ、よ
り多くの光を有効に利用できる上い好ましい。As shown in FIG. 19, between the rod-shaped light source and the light guide plate, between the continuous bodies (7b in the figure) of the light-reflecting surfaces which face each other, the translucent material (having a refractive index larger than that of air ( 11 in the figure)
It is preferable to dispose because the angle of a certain direction (9 in the figure) with respect to the wide surface of the light guide plate can be optically increased and more light can be effectively used.

【００４１】さらに、図２０に示したように、透光性物
質（図中１１）と光反射面の連続体（図中７ｂ）との間
に、空気層（図中１２）を介在させると、透光性物質
（１１）の内部に入射した光線を透光性物質の表面（空
気と接している面）で全反射をさせることが出来るので
更に光を有効に利用できる。Further, as shown in FIG. 20, if an air layer (12 in the figure) is interposed between the translucent material (11 in the figure) and the continuum of the light reflecting surface (7b in the figure). Further, since the light ray incident on the inside of the transparent substance (11) can be totally reflected on the surface of the transparent substance (the surface in contact with air), the light can be used more effectively.

【００４２】又、図２１に示したように、透光性物質
（１１）と導光板（１）の端部面間に空気層（１２）を
介在させることも、導光板の端部面に入射する光線を導
光板内で全反射を繰り返す光線とすることが出来、面状
発光の状態を比較的容易に均一にすることが可能となる
ので好ましい。Further, as shown in FIG. 21, an air layer (12) may be interposed between the light-transmitting substance (11) and the end surface of the light guide plate (1) so that the end surface of the light guide plate can be formed. It is preferable that the incident light beam can be a light beam that is repeatedly totally reflected in the light guide plate, and the state of planar light emission can be relatively easily made uniform.

【００４３】光拡散シ−ト（図中２）は、導光板面より
出光した光を散乱させて通過させるものであり、この光
拡散板を必要に応じて一枚又は複数枚用いる。光反射シ
−ト（図中３）は導光板の光散乱透過及び／又は光拡散
反射部を施した導光板の面のほぼ全面を覆うように配置
し、光を反射するものである。The light diffusion sheet (2 in the figure) scatters the light emitted from the light guide plate surface and allows it to pass therethrough, and one or more light diffusion plates are used as necessary. The light reflection sheet (3 in the figure) is arranged so as to cover almost the entire surface of the light guide plate provided with the light-scattering / transmitting and / or light-diffusing / reflecting portion of the light guide plate, and reflects light.

【００４４】[0044]

【発明の効果】本発明は消費電力−輝度変換効率が高
く、かつ高輝度が得られるバックライトとして使用でき
る。INDUSTRIAL APPLICABILITY The present invention can be used as a backlight having high power consumption-luminance conversion efficiency and high luminance.

【００４５】[0045]

【比較例及び実施例】図２に示すような厚さ３mm（225
mm×127 mm）のＰＭＭＡからなる長方形導光板（旭化成
株式会社製）の短手の端部に、外径３mm、内径２mmで、
ガラス管の長手方向に対して直角方向の断面形状が円形
で、内面に蛍光物質が被覆された冷陰極蛍光管（ハリソ
ン電機株式会社製）を中心軸が導光板端面と略平行とな
るように配置し、その管の外周を内面に銀を烝着したＡ
ＢＳ製の反射器で覆った。反射器の銀を烝着した面（鏡
面反射面）のガラス管の長手方向に対して直角方向の断
面形状は円形状になるようにした。導光板の裏面はチタ
ニアを含むインクをスクリ−ン印刷で、光源から離れる
にしたがって単位面積当たりの被覆の割合が密になるよ
うにドット状に施し、導光板端面から入射した光線が出
光面から均一な状態で出射するようにした。導光板の裏
面には白色のＰＥＴからなる光拡散反射シ−ト（ＩＣＩ
製メリネックス 329）を、出光面（表面）にはＰＣから
なる光拡散シ−ト（三省物産株式会社製８Ｂ３６）を配
置した。[Comparative Example and Example] As shown in FIG.
mm x 127 mm) PMMA rectangular light guide plate (made by Asahi Kasei Corp.) with a 3 mm outer diameter and 2 mm inner diameter at the short edge.
A cold cathode fluorescent tube (made by Harrison Electric Co., Ltd.) with a circular cross-section in the direction perpendicular to the longitudinal direction of the glass tube and a fluorescent material coated on the inner surface so that the central axis is substantially parallel to the end surface of the light guide plate. Arranged, the outer circumference of the tube was coated with silver on the inner surface A
It was covered with a BS reflector. The silver-bonded surface of the reflector (specular reflection surface) had a circular cross-section in the direction perpendicular to the longitudinal direction of the glass tube. The back surface of the light guide plate is screen-printed with ink containing titania, and the dots are applied so that the ratio of coating per unit area becomes denser as the distance from the light source increases. The light was emitted in a uniform state. A light diffusion reflection sheet (ICI) made of white PET is formed on the back surface of the light guide plate.
Melinex 329) and a light diffusion sheet made of PC (8B36 manufactured by Sansho Bussan Co., Ltd.) were arranged on the light emitting surface (surface).

【００４６】冷陰極管に、インバ−タ（ＴＤＫ株式会社
製）より３０ KHzの交番電圧をかけて一定電力で駆動さ
せたときの面輝度を輝度計（トプコン株式会社製、ＢＭ
−８）により測定した。（比較例） 次に、図３に示す様に反射器の銀を烝着した面のガラス
管の長手方向に対して直角方向の断面形状が、前記した
冷陰極蛍光管の内径の伸開線に実質的に一致する部分
（図中８）を持つ状態となるように、次の式より、反射
器の断面形状を計算した。The surface luminance when a cold cathode tube was driven at a constant electric power by applying an alternating voltage of 30 KHz from an inverter (made by TDK Co., Ltd.), was measured by a luminance meter (BM made by Topcon Corporation, BM).
It was measured according to -8). (Comparative Example) Next, as shown in FIG. 3, the cross-sectional shape of the surface of the reflector on which silver was adhered was perpendicular to the longitudinal direction of the glass tube. The cross-sectional shape of the reflector was calculated from the following equation so that the state (8 in the figure) substantially coincides with.

【００４７】図１２に於いて、x =-r ×sin θ＋ r×θ
×cos θ、y =r×cos θ＋ r×θ×sin θ、すなわち、
反射器の断面形状がＰ（ｘ、ｙ）と実質的に一致する部
分を持つ状態とした以外は比較例と同様に組み立て、測
定した所、輝度は比較例と比較して向上した。（実施例
１） 前記した冷陰極蛍光管の内径の伸開線に実質的に一致す
る部分（図中８）を反射器の反射面の中でどの部分に用
いると最も光の利用効率が高くなるかについて検討した
結果、棒状光源の任意の発光点から導光板に近い側の接
線方向に出射した光線が導光板に直接入射しない部分の
発光点を基準として、少なくとも導光板に遠い側の接線
方向の部分に形成すると良いことが判明した。（実施例
２） 光反射面の端面が導光板の側面端部近傍の広い表面に光
学的に接合した場合と接合しない場合とを比較したとこ
ろ、接合した場合の方が輝度は向上した。（実施例３） 又、反射器の反射面の中で前記伸開線に実質的に一致す
る部分（図中８）以外の部分も同様に銀を烝着した鏡面
反射面とすると、反射器の作成が容易にかつ輝度は向上
した。（実施例４） さらに、反射器の反射面の中で前記伸開線に実質的に一
致する部分（図中８）以外の部分を光拡散反射シ−ト
（ＩＣＩ製メリネックス３２９）で形成すると、反射器
の反射面の中で前記伸開線に実質的に一致する部分（図
中８）以外の部分の形状に若干の凹凸があっても極端に
輝度が低下するようなことはなかった。（実施例５） 次に、図１３に示す様に光反射面の長手方向に対して直
角方向の断面形状が少なくとも放物線の一部を有してお
り、かつ、放物線の焦点が導光板の端部面に実質的に一
致するようにした以外は比較例と同様に組み立て、測定
した所、輝度は比較例と比較して向上した。（実施例
６） 放物線の焦点が導光板の端部面の前記導光板の広い面近
傍に実質的に一致するようにした場合とそうでない場合
とを比較したところ、輝度は放物線の焦点が導光板の端
部面の前記導光板の広い面近傍に実質的に一致するよう
にした場合の方が向上した。（実施例７） 次に、図１４に示す様に光反射面の長手方向に対して直
角方向の断面形状が少なくとも放物線の一部を有してお
り、かつ、放物線の焦点が導光板の端部面に実質的に一
致する部分をも持つようにしたした以外は実施例１と同
様に組み立て、測定した所、輝度は実施例１よりも向上
した。（実施例８） 次に、図１９に示す様に断面形状が実質的に放物線状で
ある対向した鏡面反射面の連続体の間に、屈折率が空気
よりも大きい透光性物質（ＰＭＭＡ）を配置した以外は
実施例６と同様に組み立て、測定した所、輝度は実施例
６よりも向上した。（実施例９） 透光性物質と鏡面反射面との間に、空気層を配置した以
外は実施例９と同様に組み立て、測定した所、輝度は実
施例９よりも向上した。（実施例１０） 透光性物質と導光板の端部面間に空気層を配置した以外
は実施例９と同様に組み立て、測定した所、輝度の均一
性は実施例９よりも向上した。（実施例１１）In FIG. 12, x = -r × sin θ + r × θ
× cos θ, y = r × cos θ + r × θ × sin θ, that is,
Assembling and measurement were performed in the same manner as in the comparative example except that the cross-sectional shape of the reflector had a portion substantially matching with P (x, y). As a result, the brightness was improved as compared with the comparative example. (Embodiment 1) When the portion (8 in the figure) that substantially corresponds to the above-mentioned extended line of the inner diameter of the cold cathode fluorescent tube is used in any portion of the reflecting surface of the reflector, the light utilization efficiency is highest. As a result of the examination, whether the light emitted from the arbitrary light emitting point of the rod-shaped light source in the tangential direction on the side closer to the light guide plate does not directly enter the light guide plate is used as a reference, and at least the tangent line far from the light guide plate is used as a reference. It turned out that it is better to form in the direction part. (Example 2) When the end face of the light reflecting surface was optically joined to a wide surface near the end of the side surface of the light guide plate and the case where the end face was not joined, the luminance was improved when joined. (Embodiment 3) Also, in the reflecting surface of the reflector, a portion other than the portion (8 in the figure) that substantially corresponds to the above-mentioned inflection line is a specular reflecting surface on which silver is adhered. Is easy to make and the brightness is improved. (Embodiment 4) Furthermore, in the reflecting surface of the reflector, a portion other than the portion (8 in the figure) that substantially corresponds to the stretched line is formed by a light diffusion reflection sheet (Melinex 329 made by ICI). In the reflecting surface of the reflector, even if there were some irregularities in the shape of the portion other than the portion (8 in the figure) that substantially coincides with the stretched line, the brightness did not drop extremely. . Example 5 Next, as shown in FIG. 13, the cross-sectional shape of the light-reflecting surface in the direction perpendicular to the longitudinal direction has at least a part of a parabola, and the focus of the parabola is at the end of the light guide plate. Assembling and measurement were carried out in the same manner as in the comparative example except that they were substantially aligned with the surface, and the luminance was improved as compared with the comparative example. (Example 6) When the focal point of a parabola is made to substantially coincide with the end surface of the light guide plate near the wide surface of the light guide plate and the case where it is not, the brightness is determined by the focus of the parabola. This is improved when the end surface of the light plate is substantially aligned with the vicinity of the wide surface of the light guide plate. Example 7 Next, as shown in FIG. 14, the cross-sectional shape of the light-reflecting surface in the direction perpendicular to the longitudinal direction has at least a part of a parabola, and the focus of the parabola is at the end of the light guide plate. Assembling and measuring were performed in the same manner as in Example 1 except that a part substantially matching the surface of the part was also provided, and the luminance was improved as compared with Example 1. (Embodiment 8) Next, as shown in FIG. 19, a translucent material (PMMA) having a refractive index larger than that of air between a series of opposed specular reflection surfaces having a substantially parabolic cross section. Assembling and measurement were performed in the same manner as in Example 6 except that was arranged, and the luminance was improved as compared with Example 6. (Example 9) Assembling and measurement were performed in the same manner as in Example 9 except that an air layer was disposed between the translucent material and the specular reflection surface. As a result, the luminance was improved as compared with Example 9. (Example 10) Assembling and measuring were performed in the same manner as in Example 9 except that an air layer was arranged between the translucent material and the end surface of the light guide plate, and the uniformity of luminance was improved as compared with Example 9. (Example 11)

【図面の簡単な説明】[Brief description of drawings]

【図１】従来のバックライトの斜視図FIG. 1 is a perspective view of a conventional backlight.

【図２】従来のバックライトの断面図FIG. 2 is a sectional view of a conventional backlight.

【図３】本発明のバックライトの一例を示す断面図FIG. 3 is a sectional view showing an example of the backlight of the present invention.

【図４】本発明のバックライトの棒状光源付近の一例を
示す断面図FIG. 4 is a sectional view showing an example of the vicinity of a rod-shaped light source of the backlight of the present invention.

【図５】本発明のバックライトの棒状光源付近の一例を
示す断面図FIG. 5 is a sectional view showing an example of the vicinity of a rod-shaped light source of the backlight of the present invention.

【図６】本発明のバックライトの棒状光源付近の一例を
示す断面図FIG. 6 is a sectional view showing an example of the vicinity of a rod-shaped light source of the backlight of the present invention.

【図７】本発明のバックライトの棒状光源付近の一例を
示す断面図FIG. 7 is a sectional view showing an example of the vicinity of a rod-shaped light source of the backlight of the present invention.

【図８】本発明のバックライトの棒状光源付近の一例を
示す断面図FIG. 8 is a sectional view showing an example of the vicinity of a rod-shaped light source of the backlight of the present invention.

【図９】本発明のバックライトの棒状光源付近の一例を
示す断面図FIG. 9 is a sectional view showing an example of the vicinity of a rod-shaped light source of the backlight of the present invention.

【図１０】本発明のバックライトの棒状光源付近の一例
を示す断面図FIG. 10 is a sectional view showing an example of the vicinity of a rod-shaped light source of the backlight of the present invention.

【図１１】本発明のバックライトの鏡面反射面の連続体
の作用を示す図FIG. 11 is a diagram showing the action of a continuum of specular reflection surfaces of the backlight of the present invention.

【図１２】棒状光源の断面が円形である場合に、本発明
のバックライトの鏡面反射面の連続体の形状を求める計
算式を説明する図FIG. 12 is a diagram illustrating a calculation formula for obtaining the shape of a continuum of the specular reflection surface of the backlight of the present invention when the cross section of the rod-shaped light source is circular.

【図１３】本発明のバックライトの一例を示す断面図FIG. 13 is a sectional view showing an example of the backlight of the present invention.

【図１４】本発明のバックライトの一例を示す断面図FIG. 14 is a sectional view showing an example of the backlight of the present invention.

【図１５】本発明のバックライトの棒状光源付近の一例
を示す断面図FIG. 15 is a sectional view showing an example of the vicinity of a rod-shaped light source of the backlight of the present invention.

【図１６】本発明のバックライトの棒状光源付近の一例
を示す断面図FIG. 16 is a sectional view showing an example of the vicinity of a rod-shaped light source of the backlight of the present invention.

【図１７】本発明のバックライトの鏡面反射面の連続体
の作用を示す図FIG. 17 is a view showing the action of a continuum of specular reflection surfaces of the backlight of the present invention.

【図１８】本発明のバックライトの鏡面反射面の連続体
の作用を示す図FIG. 18 is a diagram showing the action of a continuum of specular reflection surfaces of the backlight of the present invention.

【図１９】本発明のバックライトの対向した鏡面反射面
の連続体の間に透光性物質を配置した場合の作用を示す
図FIG. 19 is a diagram showing an operation when a translucent substance is arranged between the continuous bodies of the mirror-reflecting surfaces of the backlight of the present invention which face each other.

【図２０】本発明のバックライトの鏡面反射面の連続体
と透光性物質との間に空気層を配置した場合の作用を示
す図FIG. 20 is a diagram showing an operation when an air layer is arranged between a continuous body of specular reflection surfaces of a backlight of the present invention and a translucent material.

【図２１】本発明のバックライトの透光性物質と導光板
との間に空気層を配置した場合の作用を示す図FIG. 21 is a diagram showing an operation when an air layer is arranged between the light-transmitting substance and the light guide plate of the backlight of the present invention.

【符号の説明】[Explanation of symbols]

１：導光板 ２：光拡散シ−ト ３：光反射シ−ト ４：棒状光源 ５：光反射面 ６：光散乱透過及び／又は光拡散反射部 ７：光反射面 ７ａ：断面が伸開線状の鏡面反射面の連続体 ７ｂ：断面が放物線状の鏡面反射面の連続体 １１：透光性物質 １２：空気層 1: Light guide plate 2: Light diffusion sheet 3: Light reflection sheet 4: Rod-shaped light source 5: Light reflection surface 6: Light scattering / transmission and / or light diffusion reflection section 7: Light reflection surface 7a: Cross section is expanded Continuum of linear specular reflection surface 7b: Continuity of specular reflection surface having parabolic cross section 11: Translucent substance 12: Air layer

Claims (13)

【特許請求の範囲】[Claims] 【請求項１】透光性材料からなり、光拡散及び／又は光
散乱作用を有する導光板、前記導光板の少なくとも１側
面端部に近接して配置した棒状光源とその光源を覆う光
反射面からなるバックライトであって、前記光反射面の
少なくとも一部分が、棒状光源の発光点から、その接線
方向で棒状光源の長手中心軸に対して垂直方向の、導光
板に遠い側に出光した光がその発光点に反射される形状
の連続体であるバックライト。1. A light guide plate made of a translucent material and having a light diffusing and / or light scattering action, a rod-shaped light source arranged in proximity to at least one side end portion of the light guide plate, and a light reflecting surface covering the light source. And a light emitted from a light emitting point of the rod-shaped light source to a side far from the light guide plate in a direction perpendicular to the longitudinal center axis of the rod-shaped light source in a tangential direction thereof. A backlight that is a continuum of shapes that are reflected by the light emitting point. 【請求項２】発光点に反射され、その直進方向の光で発
光点より導光板に近い側の光が、導光板の側面端部の入
光面以外に位置する状態となる部分に少なくとも光反射
面の連続体を形成した請求項１記載のバックライト。2. The light reflected by the light emitting point, which is closer to the light guide plate than the light emitting point in the light traveling straight, is at least incident on a portion of the side end portion of the light guide plate which is in a state other than the light incident surface. The backlight according to claim 1, wherein a continuous body of reflective surface is formed. 【請求項３】透光性材料からなり、光拡散及び／又は光
散乱作用を有する導光板、前記導光板の少なくとも１側
面端部に近接して配置した棒状光源とその光源を覆う光
反射面からなるバックライトであって、棒状光源の長手
中心軸の垂直断面での、棒状光源と導光板との間の前記
光反射面の形状の少なくとも一部分が、放物線の一部か
らなり、かつ、前記放物線の焦点が導光板の端部面又は
導光板の広い面の端部面近傍に実質的に一致する形状で
あるバックライト。3. A light guide plate made of a translucent material and having a light diffusion and / or light scattering action, a rod-shaped light source arranged in proximity to at least one side end of the light guide plate, and a light reflection surface covering the light source. A backlight consisting of, in a vertical cross section of the longitudinal center axis of the rod-shaped light source, at least a part of the shape of the light-reflecting surface between the rod-shaped light source and the light guide plate consists of a part of a parabola, and, A backlight having a shape in which the focal point of a parabola substantially coincides with the end surface of the light guide plate or the vicinity of the end surface of the wide surface of the light guide plate. 【請求項４】放物線の焦点が導光板の端部面の前記導光
板の広い面近傍に実質的に一致した形状の光反射面であ
る請求項３記載のバックライト。4. The backlight according to claim 3, wherein the focal point of the parabola is a light reflecting surface having a shape that substantially coincides with an end surface of the light guide plate near a wide surface of the light guide plate. 【請求項５】光反射面の少なくとも一部分が、棒状光源
の発光点から、その接線方向で、棒状光源の長手中心軸
に対して垂直方向の、導光板に遠い側に出光した光がそ
の発光点に反射される形状の連続体である請求項３又は
４記載のバックライト。5. Light emitted from at least a part of the light-reflecting surface to a side far from the light guide plate in a tangential direction from a light emitting point of the rod-shaped light source and in a direction perpendicular to the longitudinal center axis of the rod-shaped light source. The backlight according to claim 3 or 4, which is a continuous body having a shape reflected by a point. 【請求項６】棒状光源、導光板、光反射面とで構成され
る空間に、屈折率が空気よりも大きい透光性物質を配置
した請求項３〜５いずれか記載のバックライト。6. The backlight according to claim 3, wherein a translucent substance having a refractive index larger than that of air is arranged in a space formed by the rod-shaped light source, the light guide plate and the light reflecting surface. 【請求項７】光反射面と透光性物質とを、空気層を介し
て配置した請求項６記載のバックライト。7. The backlight according to claim 6, wherein the light-reflecting surface and the translucent material are arranged with an air layer in between. 【請求項８】導光板と透光性物質とを空気層を介して配
置した請求項６又は７記載のバックライト。8. The backlight according to claim 6, wherein the light guide plate and the translucent material are arranged with an air layer in between. 【請求項９】光反射面の導光板側の端面が導光板の広い
表面及び／又は裏面側面端部近傍に光学的に接合されて
いる請求項１又は８いづれか記載のバックライト。9. The backlight according to claim 1, wherein an end surface of the light reflecting surface on the light guide plate side is optically joined to the vicinity of a wide front surface and / or a rear surface side end portion of the light guide plate. 【請求項１０】光反射面が鏡面反射面である請求項１〜
９いづれか記載のバックライト。10. The light reflecting surface is a specular reflecting surface.
Backlight described in any one of 9. 【請求項１１】棒状光源の長手中心軸の垂直断面での光
反射面の形状が、導光板の広い面とほぼ平行で棒状光源
の中心を通る直線に対して、実質的に対称な形状を有す
る請求項１〜１０いずれか記載のバックライト。11. The shape of a light reflecting surface in a cross section perpendicular to the longitudinal center axis of the rod-shaped light source is substantially parallel to a wide surface of the light guide plate and is substantially symmetrical with respect to a straight line passing through the center of the rod-shaped light source. The backlight according to claim 1, which has. 【請求項１２】光反射面の連続体が、高分子化合物の成
型品の表面に鏡面反射面を形成したことを特徴とする請
求項１〜１１いずれか記載のバックライト。12. The backlight according to claim 1, wherein the continuous body of light-reflecting surfaces has a mirror-reflecting surface formed on the surface of a molded article of a polymer compound. 【請求項１３】光反射面の連続体が、金属板の表面に鏡
面反射面を形成したことを特徴とする請求項１〜１２い
ずれか記載のバックライト。13. The backlight according to claim 1, wherein the continuous body of light reflecting surfaces has a mirror reflecting surface formed on the surface of a metal plate.