JP2000258636A - Light transmission plate and surface light device and display device using the light transmission plate - Google Patents
Light transmission plate and surface light device and display device using the light transmission plateInfo
- Publication number
- JP2000258636A JP2000258636A JP11065310A JP6531099A JP2000258636A JP 2000258636 A JP2000258636 A JP 2000258636A JP 11065310 A JP11065310 A JP 11065310A JP 6531099 A JP6531099 A JP 6531099A JP 2000258636 A JP2000258636 A JP 2000258636A
- Authority
- JP
- Japan
- Prior art keywords
- light
- incident
- guide plate
- light guide
- facing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Liquid Crystal (AREA)
- Planar Illumination Modules (AREA)
- Light Guides In General And Applications Therefor (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、導光板、その導光
板を用いた面光源装置及び表示装置に関し、特に外光を
取入れて照明を行う導光板に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate, a surface light source device and a display device using the light guide plate, and more particularly to a light guide plate that receives external light to perform illumination.
【０００２】[0002]
【従来の技術】液晶表示装置に代表される非発光表示装
置においては、例えば、デジタルスチルカメラやビデオ
カメラ、あるいは携帯用液晶テレビ等の製品に組み込ま
れる際に、その照明のため背面にはバックライトユニッ
トが設けられる。このバックライトユニットの一構造と
して、光源と、光源からの光を側方から入射し出射面か
ら出射する導光板と、出射面から出射される光（出射
光）を視野角内に集光し輝度を向上させるためのレンズ
シートから構成されるものが知られている。2. Description of the Related Art In a non-light-emitting display device represented by a liquid crystal display device, for example, when it is incorporated in a product such as a digital still camera, a video camera, or a portable liquid crystal television, a back light is provided on the rear surface for illumination. A light unit is provided. As one structure of the backlight unit, a light source, a light guide plate that receives light from the light source from the side and emits the light from an emission surface, and condenses light emitted from the emission surface (emission light) within a viewing angle. 2. Description of the Related Art There has been known an image forming apparatus including a lens sheet for improving luminance.
【０００３】さて、バックライトユニットを組み込む装
置には小型化が要求されるため、バックライトユニット
にも小型化あるいは薄型化が要求される。バックライト
ユニットの薄型化には、導光板の薄型化が不可欠である
が、導光板側方から光を取入れるエッジライトタイプの
ものでは、導光板の厚さを薄くしすぎると、入射面の面
積が小さくなり導光板に入射される光が少なくなってし
まう。そこで、例えば、特開平６−３１７７９７号公報
では、導光板の形状を、入射面付近において、光出射面
部分の厚さ（導光板の厚さ）部分から徐々に厚さが広が
り、光出射面部分の厚さ（導光板の厚さ）の幅よりも広
い幅の入射面を備えるものとしている。これにより、導
光板の薄型化と光源からの光の有効利用を実現してい
る。[0003] Since a device incorporating a backlight unit is required to be reduced in size, the backlight unit is also required to be reduced in size or thickness. To reduce the thickness of the backlight unit, it is essential to make the light guide plate thinner.However, in the case of an edge light type that takes in light from the side of the light guide plate, if the thickness of the light guide plate is too thin, the incident surface The area is reduced, and the light incident on the light guide plate is reduced. Therefore, for example, in JP-A-6-317797, the shape of the light guide plate is gradually increased from the thickness of the light exit surface portion (thickness of the light guide plate) near the incident surface, and the light exit surface is increased. The incident surface has a width wider than the width of the thickness of the portion (the thickness of the light guide plate). Thus, the light guide plate is made thinner and light from the light source is effectively used.
【０００４】また、例えば液晶テレビや電子カメラのよ
うに携帯用電子機器においては、低消費電力化も要求さ
れており、バックライトユニットについても同様に低消
費電力化が求められている。そこで、内部光源からの光
の代わりに、太陽光や室内光等の外光を取入れることに
よって照明を行い、低消費電力化を図るものが開発され
ている。[0004] For portable electronic devices such as liquid crystal televisions and electronic cameras, for example, low power consumption is also required, and backlight units are also required to have low power consumption. In view of the above, there has been developed a lighting device that illuminates by taking in external light such as sunlight or indoor light instead of light from an internal light source, thereby reducing power consumption.
【０００５】さて、上述のような出射面部分の厚さより
も広い幅の入射面を備える面光源装置では、入射面と対
向配置する内部光源の周りに、光源からの光を効率良く
入射面に入射させるための反射シートが設けられる。そ
して、入射面から入射した光のなかには、入射面から出
射面部分への徐々に厚さが変わる斜面にて反射して入射
面から導光板外部へと出てしまう光があるが、そのよう
な光は入射面の外方に設けられた反射シートで反射され
て、再び入射面（導光板）へと入射されるので、入射面
の広さに応じた集光能力が発揮され、光源からの光を効
率よく利用することが可能である。In a surface light source device having an entrance surface having a width wider than the thickness of the exit surface portion as described above, light from the light source is efficiently transmitted to the entrance surface around an internal light source disposed opposite to the entrance surface. A reflection sheet for incidence is provided. And, among the light incident from the incident surface, there is light that is reflected on the slope whose thickness gradually changes from the incident surface to the exit surface portion and exits from the incident surface to the outside of the light guide plate. The light is reflected by the reflection sheet provided outside the incident surface and is incident again on the incident surface (light guide plate). Therefore, the light condensing ability according to the width of the incident surface is exhibited, and the light from the light source is exhibited. It is possible to use light efficiently.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、このよ
うな出射面部分の厚さよりも広い幅の入射面を備える面
光源装置において、入射面に太陽光や室内光等の外光を
取入れて照明を行う場合には、入射面の外方に入射面か
ら出射する光を再度入射面に入射させるための反射シー
トを設けることはできない。このため、入射面の幅を出
射面部分の厚さよりも広くしても、入射した一部の光が
入射面から出てしまい、再度入射することはないので、
集光能力が低下し、入射面に入射した光の効率的利用が
なされなくなる。However, in such a surface light source device having an entrance surface having a width wider than the thickness of the exit surface portion, illumination is performed by taking in external light such as sunlight or room light into the entrance surface. In such a case, it is not possible to provide a reflection sheet outside of the incident surface so that the light emitted from the incident surface is incident on the incident surface again. For this reason, even if the width of the incident surface is wider than the thickness of the exit surface portion, part of the incident light exits from the incident surface and does not enter again,
The light-collecting ability is reduced, and the light incident on the incident surface is not efficiently used.
【０００７】特に外光を取入れる場合、入射面を外光の
入射方向と直角方向に向けることが望ましい。しかし、
入射面を外光と直角方向に向けたとしても、一部の光が
入射面から外に出てしまっては、入射光を効率的に利用
できない虞があった。更に、入射面が外光との直角方向
からずれた場合には、入射面と外光の角度によっては入
射した光の大半が入射面から外に出てしまい適当な照明
ができないことにもなりかねなかった。In particular, when taking in external light, it is desirable to direct the incident surface in a direction perpendicular to the incident direction of the external light. But,
Even if the incident surface is oriented at right angles to the external light, there is a possibility that the incident light cannot be used efficiently if a part of the light goes out of the incident surface. Furthermore, if the incident surface is deviated from the direction perpendicular to the external light, most of the incident light exits from the incident surface depending on the angle between the incident surface and the external light, and appropriate illumination cannot be performed. I couldn't.
【０００８】本発明は、斯様な点に鑑みてなされたもの
であって、出射面部分の厚さよりも広い幅の入射面を備
えた導光板において、入射面に入射した光が入射面から
出射することを抑えて、効率的な集光が可能な導光板を
提供することを目的とし、更にはこの導光板を用いた、
入射面に入射した光の有効的な利用が可能な面光源装置
及び表示装置を提供することを目的とするものである。The present invention has been made in view of such a point, and in a light guide plate having an entrance surface having a width wider than the thickness of the exit surface portion, light incident on the entrance surface is reflected from the entrance surface. With the aim of providing a light guide plate capable of efficiently condensing by suppressing emission, and further using this light guide plate,
It is an object of the present invention to provide a surface light source device and a display device capable of effectively utilizing light incident on an incident surface.
【０００９】[0009]
【課題を解決するための手段】請求項１に係る本発明の
導光板は、光が入射される入射面と、入射した光を出射
する出射面と、出射面と対向する対向面と、入射面と出
射面の間で入射面と対向し出射面と辺で接する斜面と、
を備える導光板であって、入射面における出射面と直交
する方向の長さｒは、出射面と斜面が接する辺における
出射面と直交する方向の導光板の厚さｄよりも長く、出
射面を入射面側に延長した仮想面に対する斜面の傾きを
角度θとしたとき、角度θは、 １０°<=θ <= (９０°- Arc sin (１/ｎ) )/２ であることを特徴とする。According to a first aspect of the present invention, there is provided a light guide plate, comprising: an incident surface on which light is incident; an exit surface for emitting the incident light; a facing surface facing the exit surface; A slope facing the entrance surface between the surface and the exit surface and contacting the exit surface with the side,
Wherein the length r of the incident surface in the direction orthogonal to the emission surface is longer than the thickness d of the light guide plate in the direction orthogonal to the emission surface on the side where the emission surface and the slope are in contact, and the emission surface When the inclination of the inclined surface with respect to the virtual surface extending from the incident surface is defined as an angle θ, the angle θ is 10 ° <= θ <= (90 ° −Arc sin (1 / n)) / 2. And
【００１０】請求項２に係る本発明の導光板は、光が入
射される入射面と、入射した光を出射する出射面と、出
射面と対向する対向面と、入射面と対向面の間で入射面
と対向し対向面と辺で接する斜面と、を備える導光板で
あって、入射面における出射面と直交する方向の長さｒ
は、対向面と斜面が接する辺における出射面と直交する
方向の導光板の厚さｄよりも長く、対向面を入射面側に
延長した仮想面に対する斜面の傾きを角度θとしたと
き、角度θは、 １０°<=θ <= (９０°- Arc sin (１/ｎ) )/２ であることを特徴とする。According to a second aspect of the present invention, there is provided a light guide plate according to the present invention, wherein an incident surface on which light is incident, an exit surface for exiting the incident light, a facing surface facing the emitting surface, and a gap between the incident surface and the facing surface. A light guide plate having an inclined surface facing the incident surface and being in contact with the opposed surface at the sides, wherein a length r of the incident surface in a direction orthogonal to the emission surface is provided.
Is greater than the thickness d of the light guide plate in the direction perpendicular to the exit surface on the side where the opposing surface and the inclined surface are in contact, and the inclination of the inclined surface with respect to a virtual surface having the opposing surface extended toward the incident surface is defined as an angle θ. θ is characterized in that 10 ° <= θ <= (90 ° −Arc sin (1 / n)) / 2.
【００１１】請求項３に係る本発明の導光板は、請求項
１または２に記載の発明において、入射面における出射
面と直交する方向の長さｒは、 ｒ >= (ｄ/２)*(１ + ( tan２θ + tanθ)/( tan２θ -
tanθ) であることを特徴とする。According to a third aspect of the present invention, in the light guide plate according to the first or second aspect, the length r of the incident surface in the direction orthogonal to the emission surface is r> = (d / 2) * (1 + (tan2θ + tanθ) / (tan2θ-
tan θ).
【００１２】請求項４に係る本発明の導光板は、光が入
射される入射面と、入射した光を出射する出射面と、出
射面と対向する対向面と、入射面と出射面の間で入射面
と対向し出射面と辺で接する第１斜面と、入射面と対向
面の間で入射面と対向し対向面と辺で接する第２斜面
と、を備える導光板であって、入射面における出射面と
直交する方向の長さｒは、出射面と第１斜面が接する辺
と対向面と第２斜面が接する辺の間の出射面と直交する
方向の導光板の厚さｄよりも長く、出射面を入射面側に
延長した仮想面に対する第１斜面の傾きを角度θ１、及
び対向面を入射面側に延長した仮想面に対する第２斜面
の傾きを角度θ２としたとき、角度θ１及び角度θ２
は、 １０°<=θ1 <= (９０°- Arc sin (１/ｎ) )/２ １０°<=θ２ <= (９０°- Arc sin (１/ｎ) )/２ であることを特徴とする。According to a fourth aspect of the present invention, there is provided the light guide plate, wherein the light incident surface, the light exit surface for emitting the incident light, the opposing surface facing the light exit surface, and the light incident surface and the light exit surface. A light guide plate comprising: a first inclined surface facing the incident surface and contacting the exit surface at a side at a side; and a second inclined surface facing the incident surface and contacting the opposite surface at the side between the incident surface and the opposing surface. The length r of the surface in the direction orthogonal to the emission surface is determined by the thickness d of the light guide plate in the direction orthogonal to the emission surface between the side where the emission surface contacts the first slope and the side where the opposing surface contacts the second slope. When the inclination of the first slope with respect to the imaginary plane whose output surface is extended toward the incident surface is angle θ1, and the inclination of the second slope with respect to the imaginary surface whose opposite surface is extended toward the incident surface is angle θ2, the angle is θ1 and angle θ2
Is characterized by 10 ° <= θ1 <= (90 ° -Arc sin (1 / n)) / 2 10 ° <= θ2 <= (90 ° -Arc sin (1 / n)) / 2 I do.
【００１３】請求項５に係る本発明の導光板は、請求項
４に記載の発明において、入射面における出射面と直交
する方向の長さｒは、 ｒ >= ｄ*( tan２θ + tanθ)/( tan２θ - tanθ) （但しθはθ1もしくはθ2）であることを特徴とする。According to a fifth aspect of the present invention, in the light guide plate according to the fourth aspect, a length r of the incident surface in a direction orthogonal to the emission surface is r> = d * (tan2θ + tanθ) / (tan2θ-tanθ) (where θ is θ1 or θ2).
【００１４】請求項６に係る本発明の面光源装置は、請
求項１乃至５のいずれかに記載の導光板と、導光板の対
向面側に反射手段を備えることを特徴とする。According to a sixth aspect of the present invention, there is provided a surface light source device, comprising: the light guide plate according to any one of the first to fifth aspects; and a reflecting means on a surface facing the light guide plate.
【００１５】請求項７に係る本発明の表示装置は、請求
項６に記載の面光源装置と、導光板の出射面側に設けら
れた非発光表示手段とを備えることを特徴とする。According to a seventh aspect of the present invention, there is provided a display device comprising the surface light source device according to the sixth aspect and non-light emitting display means provided on the light exit surface side of the light guide plate.
【００１６】尚、いずれもｎは導光板材料の屈折率を示
す。In each case, n indicates the refractive index of the light guide plate material.
【００１７】[0017]
【実施の形態】以下、本発明の実施の形態を図に基づい
て説明する。Embodiments of the present invention will be described below with reference to the drawings.
【００１８】図１は本発明に係る導光板、面光源装置、
及び表示装置の一実施例の概略構成図である。FIG. 1 shows a light guide plate, a surface light source device,
FIG. 1 is a schematic configuration diagram of an embodiment of a display device.
【００１９】１はアクリル樹脂等の透光性材料からなる
導光板で、光が入射される入射面１１、入射面１１より
入射した光を導光板１外部に出射する出射面１２、出射
面１２と対向する対向面である裏面１３を備え、更に、
入射面１１と出射面１２、及び入射面１１と裏面１３の
間に入射面１１と対向し、鏡面状態である第１斜面１４
と第２斜面１５を備えている。Reference numeral 1 denotes a light guide plate made of a light-transmitting material such as an acrylic resin, which is an incident surface 11 on which light is incident, an exit surface 12 for emitting light incident from the incident surface 11 to the outside of the light guide plate 1, and an exit surface 12 And a back surface 13 which is a facing surface facing the
A first inclined surface 14 facing the incident surface 11 between the incident surface 11 and the exit surface 12 and between the incident surface 11 and the back surface 13 and in a mirror-finished state.
And a second slope 15.
【００２０】２は導光板１の裏面１３側に設けられ裏面
１３から洩れた光を再度導光板１内に戻すための反射
板、３は出射面１２と対向して設けられ出射光を均一に
分布させるための拡散板、４は出射面１２側に拡散板３
を介して設けられた非発光表示手段である液晶表示パネ
ルである。尚、図示しないが、必要に応じてレンズシー
トを液晶表示パネル４と拡散板３の間あるいは拡散板３
と導光板１との間に設けても良い。Reference numeral 2 denotes a reflector provided on the back surface 13 side of the light guide plate 1 for returning light leaked from the back surface 13 into the light guide plate 1 again. A diffusion plate 4 for distributing the light, and a diffusion plate 3
And a liquid crystal display panel which is a non-light emitting display means provided through the liquid crystal display panel. Although not shown, a lens sheet may be placed between the liquid crystal display panel 4 and the diffusion plate 3 or the diffusion plate 3 if necessary.
And the light guide plate 1.
【００２１】さて、第１斜面１４は、出射面１２と辺ｐ
で接しており、出射面１２を入射面１１側に延長させた
仮想面（破線）に対して角度θ１で傾斜している。同様
に、第２斜面１５は裏面１３と辺ｑで接しており、裏面
１３を入射面１１側に延長させた仮想面（破線）に対し
て角度θ２で傾斜している（従って、長さｒ（後述）は
厚さｄ（後述）よりも大きいものである）。尚、本実施
例ではθ１＝θ２＝θとし、以下はθで説明を行う。Now, the first slope 14 is formed by the light exit surface 12 and the side p.
, And is inclined at an angle θ1 with respect to a virtual plane (broken line) extending the emission surface 12 toward the incidence surface 11 side. Similarly, the second slope 15 is in contact with the back surface 13 at the side q, and is inclined at an angle θ2 with respect to a virtual plane (dashed line) extending the back surface 13 toward the incident surface 11 (accordingly, the length r (Described later) is larger than the thickness d (described later). In this embodiment, θ1 = θ2 = θ, and the following description will be made with θ.
【００２２】辺ｐと辺ｑの間の出射面１２と直交する方
向の導光板１の厚さ（即ち、辺ｐにおける出射面１２と
直交する方向の導光板１の厚さであり、また辺ｑにおけ
る出射面１２と直交する方向の導光板１の厚さである；
第１斜面１４が出射面１２と接する部分もしくは第２斜
面１５が裏面１３と接する部分における導光板１の厚さ
を意味する）をｄとし、導光板材料の屈折率をｎとした
場合、第１斜面１４及び第２斜面１５は共に、 １０°<=θ <= (９０°- Arc sin (１/ｎ) )/２ （１） を満足する角度θに形成されている。尚、Arc sinは主
値を示すものである。The thickness of the light guide plate 1 between the side p and the side q in the direction perpendicular to the light exit surface 12 (ie, the thickness of the light guide plate 1 in the direction perpendicular to the light exit surface 12 on the side p. q is the thickness of the light guide plate 1 in the direction orthogonal to the emission surface 12;
If the thickness of the light guide plate 1 at the portion where the first slope 14 contacts the emission surface 12 or the portion where the second slope 15 contacts the back surface 13 is d) and the refractive index of the light guide plate material is n, The first slope 14 and the second slope 15 are both formed at an angle θ that satisfies 10 ° <= θ <= (90 ° −Arc sin (1 / n)) / 2 (1). Incidentally, Arc sin indicates the main value.
【００２３】ここで、入射光が入射面１１に直角に方向
から入射される場合、入射面１１における出射面１２と
直交する方向の長さｒが ｒ =ｄ*( tan２θ + tanθ)/( tan２θ - tanθ) （２） で与えられる値以内であれば、入射光の殆どは、入射面
１１から入射して直接辺ｐ−ｑ間を通過するか、角度θ
で傾斜する第１斜面１４あるいは第２斜面１５で１回反
射して辺ｐ−ｑ間を通過して導光板１内を進行してい
く。即ち、入射面１１から入射した光は出射面１２へと
効率良く出射されることになる。Here, when the incident light is incident on the incident surface 11 at right angles from the direction, the length r of the incident surface 11 in the direction orthogonal to the exit surface 12 is given by r = d * (tan2θ + tanθ) / (tan2θ). If the value is within the value given by (2), most of the incident light enters from the incident surface 11 and passes directly between the sides p and q, or the angle θ
The light is reflected once by the first slope 14 or the second slope 15 which is inclined at the angle, passes through the side pq, and travels in the light guide plate 1. That is, the light incident from the incident surface 11 is efficiently emitted to the emission surface 12.
【００２４】また、長さｒが（２）式で与えられる場
合、斜面部の長さａ（図１参照）は、 ａ = (ｒ -ｄ)/(２tanθ) （３） で、与えられる。When the length r is given by the equation (2), the length a of the slope portion (see FIG. 1) is given by a = (r−d) / (2 tan θ) (3)
【００２５】尚、このとき入射面１１における出射面１
２と直交する方向の長さｒは、（２）式で与えられる値
以上であることが望ましい（図３Ｃ破線部分参照）。な
ぜなら、長さｒが（２）式で与えられる値までは、その
範囲内に入射される光の殆どが辺ｐ−ｑ間を通過するの
で、第１、第２斜面１４、１５の傾斜を角度θとするこ
とによる集光能力が最大に発揮されるからである。長さ
ｒが（２）式で与えられる値より長い範囲については、
入射光の一部が入射面から出ていく虞があるが、多少は
辺ｐ−ｑ間を通過するので、集光には寄与する。At this time, the exit surface 1 of the entrance surface 11
It is desirable that the length r in the direction orthogonal to 2 is equal to or larger than the value given by the equation (2) (see the broken line in FIG. 3C). This is because, until the length r reaches the value given by the equation (2), most of the light incident within the range passes between the sides p and q, and the inclination of the first and second slopes 14 and 15 is reduced. This is because the light collecting ability is maximized by setting the angle θ. In the range where the length r is longer than the value given by the equation (2),
Although there is a possibility that a part of the incident light may go out of the incident surface, the light slightly passes between the sides p and q and thus contributes to the light collection.
【００２６】更に、長さｒが決まれば、斜面部の長さａ
も決まるが、長さａについても（３）式以上の長さであ
ることが望まれる。例えば、厚さｄ＝２．７ｍｍとする
と、アクリルの屈折率ｎ＝１．４９であるので、角度θ
は１０°以上２３．９２°以下、長さｒは６．３３ｍｍ
以上、長さａは４．０９ｍｍ以上となる。Further, when the length r is determined, the length a of the slope portion is determined.
However, it is desirable that the length a is also equal to or longer than the expression (3). For example, if the thickness d is 2.7 mm, the refractive index n of acrylic is 1.49, so that the angle θ
Is 10 ° or more and 23.92 ° or less, and the length r is 6.33 mm.
As described above, the length a is 4.09 mm or more.
【００２７】図２に、入射面１１に入射する平行光の入
射面１１に対する入射角と辺ｐ−ｑ間を通過した光量
（但し、第１あるいは第２斜面を反射した直後に出射面
から出射する光を除く）との関係を示す。各ラインは厚
さｄ＝２．７ｍｍ、アクリルの屈折率ｎ＝１．４９で、
長さｒを固定とし、第１、第２斜面１４、１５の傾斜す
る角度θが異なるものを示す。この図から明らかなよう
に、適度な集光が行える平行光の入射角度の許容範囲
は、入射面１１の直角方向を中心として、角度θが上限
に近いほど狭く、下限近くで飽和する。そして、角度θ
が１０°より小さい場合には、入射面１１に直角方向か
ら平行光が入射しても、適当に照明できる光量を得られ
ない虞が高いので、角度θは１０°以上が好ましい。FIG. 2 shows the angle of incidence of the parallel light incident on the incident surface 11 with respect to the incident surface 11 and the amount of light passing between the sides pq (however, the light exits from the exit surface immediately after being reflected on the first or second slope). (Excluding light that excites). Each line has a thickness d = 2.7 mm, a refractive index n = 1.49 of acrylic,
The case where the length r is fixed and the inclination angles θ of the first and second slopes 14 and 15 are different is shown. As is clear from this figure, the allowable range of the incident angle of the parallel light in which the light can be appropriately condensed becomes narrower as the angle θ becomes closer to the upper limit and becomes saturated near the lower limit with respect to the direction perpendicular to the incident surface 11. And the angle θ
Is smaller than 10 °, there is a high possibility that even if parallel light is incident on the incident surface 11 from a right angle direction, there is a high possibility that an amount of light that can be appropriately illuminated will not be obtained. Therefore, the angle θ is preferably 10 ° or more.
【００２８】従って、角度θを下限近くに設定すること
で、入射光（平行光）が入射面と直角でなく、多少直角
からずれた角度で入ってきても、効率よく集光すること
が可能となる。Therefore, by setting the angle θ close to the lower limit, even if the incident light (parallel light) enters at an angle slightly deviated from the right angle instead of the right angle with the incident surface, the light can be efficiently collected. Becomes
【００２９】斯様な導光板は、通常、アクリル樹脂を始
めとする熱可塑性樹脂を用いた射出成形により形成され
るので、金型に第１、第２斜面部分を形成しておけば、
一般的な成形工程により簡単に形成可能である。Since such a light guide plate is usually formed by injection molding using a thermoplastic resin such as an acrylic resin, if the first and second slope portions are formed in a mold,
It can be easily formed by a general molding process.
【００３０】而して、図１の表示装置においては、上述
のように、入射面１１を外光（太陽光や室内光）と直角
方向（多少ずれていても良い）に向けた状態では、入射
面１１から入射された光が、直接、あるいは第１斜面１
４や第２斜面１５で１回反射して辺ｐ−ｑ間を通過して
導光板１内を進行していく。更にその光は、裏面１３側
に設けられる図示しない拡散手段（拡散パターン）で拡
散され、あるいは反射板２で反射されて、出射面１２か
ら出射される。入射面１１から入射した光の殆どが出射
面１２から出射され、出射した光は、拡散板３で更に拡
散されて液晶表示パネル４を背面から照明する。As described above, in the display device shown in FIG. 1, when the incident surface 11 is oriented in a direction perpendicular to the external light (sunlight or room light) (may be slightly shifted), The light incident from the entrance surface 11 is directly or the first slope 1
The light is reflected once at the fourth slope 4 and the second slope 15, passes through the side pq, and travels in the light guide plate 1. Further, the light is diffused by a diffusion means (diffusion pattern) (not shown) provided on the back surface 13 side, or is reflected by the reflection plate 2 and is emitted from the emission surface 12. Most of the light incident from the incident surface 11 is emitted from the emission surface 12, and the emitted light is further diffused by the diffusion plate 3 to illuminate the liquid crystal display panel 4 from the back.
【００３１】図３は本発明に係る他の実施例を示す図で
あり、いずれも導光板部分だけを図示している。FIG. 3 is a view showing another embodiment of the present invention, in which only a light guide plate portion is shown.
【００３２】図３Ａは斜面が出射面１２側のみ、即ち図
１における第１斜面１４のみ設けられているものであ
り、図３Ｂは斜面が裏面１３側のみ、即ち図１における
第２斜面１５のみ設けられているものである。いずれの
場合も、長さｒ及び長さａは次式を満足するものとな
る。 ｒ >= (ｄ/２)*(１ + ( tan２θ + tanθ)/( tan２θ -
tanθ) ａ >= (ｒ -ｄ)/(２tanθ) 図３Ｃは、長さｒ及び長さａが（２）、（３）式で与え
られるもの（実線で示す）に対して、それよりも長いも
の（破線で示す）、それよりも短いもの（一点鎖線で示
す）を示すものである。好ましくは破線あるいは実線で
示す形状のものの方が、高い集光能力を得られるが、角
度θが条件を満すものであれば一点鎖線で示す形状のも
のであっても良い。FIG. 3A shows that the slope is provided only on the emission surface 12 side, that is, only the first slope 14 in FIG. 1, and FIG. 3B shows that the slope is only on the back surface 13 side, that is, only the second slope 15 in FIG. It is provided. In any case, the length r and the length a satisfy the following expression. r> = (d / 2) * (1 + (tan2θ + tanθ) / (tan2θ-
tan θ) a> = (r−d) / (2 tan θ) FIG. 3C shows a case where the length r and the length a are given by the equations (2) and (3) (shown by a solid line). A long one (shown by a dashed line) and a shorter one (shown by a dashed line) are shown. Preferably, a shape indicated by a broken line or a solid line can obtain a higher light-collecting ability, but a shape indicated by a dashed line may be used as long as the angle θ satisfies the condition.
【００３３】尚、斜面が出射面側と裏面側に設けられる
場合、上述の説明ではθ１＝θ２＝θとしたが、θ１と
θ２が夫々（１）式を満たせば、θ１とθ２が等しい必
要はない。In the case where the slopes are provided on the emission surface side and the back surface side, θ1 = θ2 = θ in the above description. There is no.
【００３４】[0034]
【発明の効果】本発明は、以上の説明から明らかなよう
に、入射面と出射面の間で入射面と対向し出射面と辺で
接する斜面、あるいは入射面と裏面の間で入射面と対向
し裏面と辺で接する斜面を備え、この斜面を（１）式を
満たす値の角度に傾斜させることで、入射面に入射した
光が入射面から出射することを抑えることができる。こ
れにより入射面に入射した光の有効利用が図られ、ま
た、入射面が外光との直角方向から多少ずれた場合でも
効率よく集光ができ、外光による適当な照明が可能にな
る。そして、この導光板を用いることにより、小型化、
更には低消費電力化が可能な面光源装置あるいは表示装
置を提供することができる。As is apparent from the above description, the present invention provides a slope between the entrance surface and the exit surface, which faces the entrance surface and is in contact with the exit surface, or an entrance surface between the entrance surface and the back surface. By providing an inclined surface that is opposed to and contacts the back surface at the sides, and by inclining the inclined surface at an angle that satisfies the expression (1), it is possible to suppress light that has entered the incident surface from exiting the incident surface. As a result, the light incident on the incident surface can be effectively used, and even when the incident surface slightly deviates from the direction perpendicular to the external light, the light can be efficiently collected, and appropriate illumination by the external light can be achieved. And by using this light guide plate, miniaturization,
Further, a surface light source device or a display device which can reduce power consumption can be provided.
【図1】本発明に係る一実施例の概略構成図である。FIG. 1 is a schematic configuration diagram of an embodiment according to the present invention.
【図２】本発明に係る入射する平行光の入射面に対する
入射角と光量との関係を示す図である。FIG. 2 is a diagram showing a relationship between an incident angle of the incident parallel light with respect to an incident surface and a light amount according to the present invention.
【図３】本発明に係る他の実施例を示す図である。FIG. 3 is a diagram showing another embodiment according to the present invention.
１ 導光板 １１ 入射面 １２ 出射面 １３ 裏面（対向面） １４ 第1斜面 １５ 第２斜面 ２ 反射板（反射部材） ３ 拡散板 ４ 液晶表示パネル（非発光表示手段） REFERENCE SIGNS LIST 1 light guide plate 11 entrance surface 12 exit surface 13 back surface (opposing surface) 14 first slope 15 second slope 2 reflection plate (reflection member) 3 diffusion plate 4 liquid crystal display panel (non-light emitting display means)
Claims (7)
出射する出射面と、出射面と対向する対向面と、入射面
と出射面の間で入射面と対向し出射面と辺で接する斜面
と、を備える導光板において、 入射面における出射面と直交する方向の長さｒは、出射
面と斜面が接する辺における出射面と直交する方向の導
光板の厚さｄよりも長く、 出射面を入射面側に延長した仮想面に対する斜面の傾き
を角度θとしたとき、角度θは、 １０°<=θ <= (９０°- Arc sin (１/ｎ) )/２ （但し、ｎは導光板材料の屈折率である）であることを
特徴とする導光板。1. An incident surface on which light is incident, an exit surface for emitting incident light, a facing surface facing the exit surface, and an exit surface facing the incident surface between the incident surface and the exit surface. A length r in the direction perpendicular to the exit surface on the incident surface is longer than a thickness d of the light guide plate in a direction perpendicular to the exit surface on the side where the exit surface contacts the slope. When the inclination of the inclined surface with respect to the virtual surface extending from the exit surface to the entrance surface is defined as an angle θ, the angle θ is 10 ° <= θ <= (90 ° −Arc sin (1 / n)) / 2 (however, , N is the refractive index of the light guide plate material).
出射する出射面と、出射面と対向する対向面と、入射面
と対向面の間で入射面と対向し対向面と辺で接する斜面
と、を備える導光板において、 入射面における出射面と直交する方向の長さｒは、対向
面と斜面が接する辺における出射面と直交する方向の導
光板の厚さｄよりも長く、 対向面を入射面側に延長した仮想面に対する斜面の傾き
を角度θとしたとき、角度θは、 １０°<=θ <= (９０°- Arc sin (１/ｎ) )/２ （但し、ｎは導光板材料の屈折率である）であることを
特徴とする導光板。2. An incident surface on which light is incident, an exit surface for emitting the incident light, an opposing surface facing the exit surface, and an opposing surface facing the incident surface between the incident surface and the opposing surface. A length r in the direction orthogonal to the emission surface on the incident surface is longer than a thickness d of the light guide plate in a direction orthogonal to the emission surface on the side where the opposing surface and the slope are in contact with each other. When the inclination of the inclined surface with respect to the virtual surface in which the opposing surface is extended toward the incident surface is defined as an angle θ, the angle θ is 10 ° <= θ <= (90 ° −Arc sin (1 / n)) / 2 (however, , N is the refractive index of the light guide plate material).
長さｒは、 ｒ >= (ｄ/２)*(１ + ( tan２θ + tanθ)/( tan２θ -
tanθ) であることを特徴とする請求項１または２に記載の導光
板。3. The length r of the incident surface in the direction orthogonal to the exit surface is: r> = (d / 2) * (1+ (tan2θ + tanθ) / (tan2θ−
The light guide plate according to claim 1, wherein tan θ).
出射する出射面と、出射面と対向する対向面と、入射面
と出射面の間で入射面と対向し出射面と辺で接する第１
斜面と、入射面と対向面の間で入射面と対向し対向面と
辺で接する第２斜面と、を備える導光板において、 入射面における出射面と直交する方向の長さｒは、出射
面と第１斜面が接する辺と対向面と第２斜面が接する辺
の間の出射面と直交する方向の導光板の厚さｄよりも長
く、 出射面を入射面側に延長した仮想面に対する第１斜面の
傾きを角度θ１、及び対向面を入射面側に延長した仮想
面に対する第２斜面の傾きを角度θ２としたとき、角度
θ１及び角度θ２は、 １０°<=θ1 <= (９０°- Arc sin (１/ｎ) )/２ １０°<=θ２ <= (９０°- Arc sin (１/ｎ) )/２ （但し、ｎは導光板材料の屈折率である）であることを
特徴とする導光板。4. An incident surface on which light is incident, an exit surface for emitting incident light, a facing surface facing the exit surface, and an exit surface facing the incident surface between the incident surface and the exit surface. First contact
In a light guide plate including a slope, and a second slope facing the incident surface between the incident surface and the facing surface and being in contact with the facing surface at a side, a length r of the incidence surface in a direction orthogonal to the emission surface is defined as an emission surface. The length d is longer than the thickness d of the light guide plate in the direction orthogonal to the exit surface between the side where the first inclined surface contacts and the side where the opposing surface contacts the second inclined surface, and the imaginary surface extends the exit surface toward the entrance surface. Assuming that the inclination of one slope is an angle θ1 and the inclination of the second slope with respect to a virtual plane in which the facing surface is extended toward the incident surface is an angle θ2, the angles θ1 and θ2 are 10 ° <= θ1 <= (90 ° -Arc sin (1 / n)) / 2 10 ° <= θ2 <= (90 °-Arc sin (1 / n)) / 2 (where n is the refractive index of the light guide plate material) Characteristic light guide plate.
長さｒは、 ｒ >= ｄ*( tan２θ + tanθ)/( tan２θ - tanθ) （但しθはθ1もしくはθ2）であることを特徴とする請
求項４記載の導光板。5. A length r of the incident surface in a direction orthogonal to the emission surface is r> = d * (tan2θ + tanθ) / (tan2θ-tanθ) (where θ is θ1 or θ2). The light guide plate according to claim 4, wherein
板と、導光板の対向面側に反射手段を備えることを特徴
とする面光源装置。6. A surface light source device, comprising: the light guide plate according to claim 1; and a reflection unit on a surface facing the light guide plate.
の出射面側に設けられた非発光表示手段とを備えること
を特徴とする表示装置。7. A display device comprising: the surface light source device according to claim 6; and a non-light-emitting display unit provided on an emission surface side of the light guide plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06531099A JP3408184B2 (en) | 1999-03-11 | 1999-03-11 | Light guide plate, surface light source device and display device using the light guide plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06531099A JP3408184B2 (en) | 1999-03-11 | 1999-03-11 | Light guide plate, surface light source device and display device using the light guide plate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000258636A true JP2000258636A (en) | 2000-09-22 |
| JP3408184B2 JP3408184B2 (en) | 2003-05-19 |
Family
ID=13283218
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP06531099A Expired - Fee Related JP3408184B2 (en) | 1999-03-11 | 1999-03-11 | Light guide plate, surface light source device and display device using the light guide plate |
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| Country | Link |
|---|---|
| JP (1) | JP3408184B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013127854A (en) * | 2011-12-16 | 2013-06-27 | Panasonic Corp | Lighting device |
| KR102064340B1 (en) * | 2013-05-10 | 2020-01-09 | 현대모비스 주식회사 | Light guide device |
-
1999
- 1999-03-11 JP JP06531099A patent/JP3408184B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013127854A (en) * | 2011-12-16 | 2013-06-27 | Panasonic Corp | Lighting device |
| KR102064340B1 (en) * | 2013-05-10 | 2020-01-09 | 현대모비스 주식회사 | Light guide device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3408184B2 (en) | 2003-05-19 |
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