JPH06317797A - Surface light source device - Google Patents

Surface light source device

Info

Publication number
JPH06317797A
JPH06317797A JP5106663A JP10666393A JPH06317797A JP H06317797 A JPH06317797 A JP H06317797A JP 5106663 A JP5106663 A JP 5106663A JP 10666393 A JP10666393 A JP 10666393A JP H06317797 A JPH06317797 A JP H06317797A
Authority
JP
Japan
Prior art keywords
light
incident
light source
transparent substrate
substrate
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.)
Pending
Application number
JP5106663A
Other languages
Japanese (ja)
Inventor
Yoshinao Mukasa
由直 武笠
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Petrochemical Co Ltd
Original Assignee
Mitsubishi Petrochemical Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Mitsubishi Petrochemical Co Ltd filed Critical Mitsubishi Petrochemical Co Ltd
Priority to JP5106663A priority Critical patent/JPH06317797A/en
Publication of JPH06317797A publication Critical patent/JPH06317797A/en
Pending legal-status Critical Current

Links

Landscapes

  • Liquid Crystal (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Light Guides In General And Applications Therefor (AREA)

Abstract

PURPOSE:To provide a surface light source device which is thinned, has the high utilization efficiency of light and is excellent in brightness. CONSTITUTION:Illuminating light from a bar-like light source 5 is made incident inside from the incident surface 1a of a substrate 1 as incident light and advances while most of incident light is reflected inside the substrate 1 because of an optical density difference at a boundary between the substrate 1 and air. When the incident light reaches a light irregular reflection part 2 provided on the substrate 1 in the midst of advancing, it is irregularly reflected and radiated from an exiting surface 1b to the outside. The substrate 1 is formed to be thicker and thicker near the incident surface 1a and the thickness of the incident surface 1a is made nearly equal to the diameter of the light source 5. Therefore, since the illuminating light from the light source 5 is reflected on the inner surface of a housing 6 and efficiently made incident from the incident surface 1a, the brightness of a backlight device is improved.

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、液晶ディスプレイ(L
CD)のバックライト装置等に用いられる面光源装置に
関するものである。
BACKGROUND OF THE INVENTION The present invention relates to a liquid crystal display (L
The present invention relates to a surface light source device used for a backlight device of a CD) or the like.

【0002】[0002]

【従来の技術】LCDは薄型、軽量、低消費電力などの
優れた特徴を生かし、平面ディスプレイとして広く用い
られている。そして、このLCDの画質改善に用いられ
るバックライト装置に関して従来より数多くの提案がな
されている。例えば、特開平2−17には、透明基板の
1側端を入射面とした、いわゆるエッジライトタイプの
第1エレメントと、多数のレンズ単位を有して光の出射
角度を制御する第2エレメントとを有するバックライト
装置が開示されている。このようなバックライト装置に
おいては、薄型化の平面ディスプレイを実現するべく、
より一層の薄型化が望まれている。
2. Description of the Related Art LCDs are widely used as flat displays because of their excellent characteristics such as thinness, light weight and low power consumption. Many proposals have been made in the past regarding the backlight device used for improving the image quality of the LCD. For example, in Japanese Patent Application Laid-Open No. 2-17, a so-called edge light type first element having one side end of a transparent substrate as an incident surface and a second element having a large number of lens units to control a light emission angle are disclosed. A backlight device having a and is disclosed. In such a backlight device, in order to realize a thin flat display,
Further thinning is desired.

【0003】[0003]

【発明が解決しようとする課題】しかしながら、上記従
来のバックライト装置においてより一層の薄型化を実現
しようとした場合、下記のような問題がある。
However, when attempting to achieve a further reduction in thickness in the above-mentioned conventional backlight device, there are the following problems.

【0004】バックライト装置を薄型にするためにはい
わゆるエッジライトタイプとすることが有効であるが、
更に薄型化を進めるためには導光体を形成する透明基板
の厚みを薄くする必要がある。しかしながら、透明基板
を薄くすると、棒状光源から透明基板への光の導入の際
の光の損失が大きくなり、棒状光源の光量を有効に利用
できなくなる。この結果として、透明基板の厚みを薄く
すると、バックライト装置の輝度が低下してしまうとい
う問題生じる。この問題を解決するために、次のような
様々な対策が検討されている。
To make the backlight device thin, it is effective to use a so-called edge light type.
In order to further reduce the thickness, it is necessary to reduce the thickness of the transparent substrate forming the light guide. However, when the transparent substrate is made thin, the light loss at the time of introducing light from the rod-shaped light source into the transparent substrate becomes large, and the light amount of the rod-shaped light source cannot be effectively used. As a result, when the thickness of the transparent substrate is reduced, the brightness of the backlight device is reduced. In order to solve this problem, the following various measures are being studied.

【0005】(1)透明基板の厚みの減少に見合う様に
棒状光源の太さを減少させることが実施され、現在で
は、直径3mmの冷陰極管も開発されている。しかしな
がら、価格や性能上、棒状光源の細型化には限界があ
る。
(1) The thickness of the rod-shaped light source is reduced so as to correspond to the reduction in the thickness of the transparent substrate. At present, a cold cathode tube having a diameter of 3 mm has also been developed. However, there is a limit to the downsizing of the rod-shaped light source in terms of price and performance.

【0006】(2)特願平1−144381には棒状光
源のハウジングに工夫をし、透明基板の側端部に光を導
く方法が開示されている。しかしながらこの方法では、
ハウジング部分が大きくなってしまい、薄型化の実現に
支障をきたすという問題がある。
(2) Japanese Patent Application No. 1-144381 discloses a method of introducing a light to a side end portion of a transparent substrate by devising a housing of a rod-shaped light source. However, with this method,
There is a problem that the housing portion becomes large, which hinders realization of a thin structure.

【0007】本発明は上記の問題点に鑑みてなされたも
のであり、薄型で光の利用効率が高く輝度の優れた面光
源装置を提供することを目的とする。
The present invention has been made in view of the above problems, and an object of the present invention is to provide a surface light source device that is thin and has high light utilization efficiency and excellent brightness.

【0008】[0008]

【課題を解決するための手段】上記の目的は、光源と、
前記光源よりの光を入射する入射面及び該入射面とほぼ
直交する方向に光を放出する出射面を有するほぼ透明な
基板と、前記基板内を進行する入射光の方向を変化さ
せ、該入射光を前記出射面より放出せしめる光方向変化
部とを備え、前記基板は入射面側の付近においてその厚
みが入射面に向かって徐々に増加して形成されることを
特徴とする面光源装置により達成される。
The above-mentioned object is to provide a light source,
A substantially transparent substrate having an incident surface on which light from the light source is incident and an emission surface that emits light in a direction substantially orthogonal to the incident surface, and changing the direction of incident light traveling in the substrate to change the incident direction. A surface light source device, comprising: a light direction changing portion that emits light from the emission surface, wherein the substrate is formed such that its thickness gradually increases toward the incidence surface in the vicinity of the incidence surface side. To be achieved.

【0009】[0009]

【作用】本発明は、上記構成において、光源からの照明
光が、基板の入射面から内部に入射光として入射し、基
板と空気との界面の光学的密度差により、大部分の入射
光が基板内を反射しながら進行する。この進行中に基板
に設けた光乱反射部あるいは光の方向変更用凹凸等の入
射光の進行方向を変化させる方向変化手段に達すると、
乱反射あるいは、光の進行角度等の変化が生じ、基板と
空気との界面において光の進入角度が所謂臨界角以下に
なって基板の表面(出射面)から外部に光が放射され
る。基板の厚みが入射面付近で徐々に大きく形成され、
入射面に効率よく光源からの照明光が入射されるため、
面光源装置の輝度が向上する。
According to the present invention, in the above structure, the illumination light from the light source is incident as incident light from the incident surface of the substrate to the inside, and most of the incident light is caused by the difference in optical density at the interface between the substrate and air. It advances while reflecting in the substrate. During this process, when it reaches the direction changing means for changing the traveling direction of the incident light, such as the irregular diffuser provided on the substrate or the unevenness for changing the direction of the light,
Diffuse reflection or change in the traveling angle of light occurs, and the incident angle of light at the interface between the substrate and air becomes a so-called critical angle or less, and light is emitted from the surface (emission surface) of the substrate to the outside. The thickness of the substrate is gradually increased near the incident surface,
Since the illumination light from the light source is efficiently incident on the incident surface,
The brightness of the surface light source device is improved.

【0010】[0010]

【実施例】以下に、本発明の好適な実施例について添付
の図面を参照して説明する。
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

【0011】<実施例1>実施例1のバックライト装置
について図1,図2及び図3を参照して説明する。図1
は本実施例1のバックライト装置の断面図であり、図2
は本実施例1のバックライト装置の平面図である。
<Embodiment 1> A backlight device of Embodiment 1 will be described with reference to FIGS. 1, 2 and 3. Figure 1
2 is a cross-sectional view of the backlight device according to the first embodiment, and FIG.
FIG. 3 is a plan view of the backlight device according to the first embodiment.

【0012】図1及び図2において、1は透明基板であ
り、光源から出射された照明光を入射光として入射する
ための入射面1aと、透明基板1内を伝わる入射光を放
出するための出射面1bとを有する。図1に示されるよ
うに、透明基板1は、入射面1a付近において所定の傾
斜で透明基板1の厚みが増すように成型されている。透
明基板1の材質としては、ガラス板、アクリル樹脂板や
ポリカーボネート樹脂板等、無機質もしくは合成樹脂製
の透明板を使用する。尚、実施例1では、透明基板1の
材質としてアクリル樹脂を用いている。透明基板1は、
板を切削して作成することも可能だが、インジェクショ
ン形成で作成する方法が生産費用の面等において好まし
い。尚、透明基板1の全ての面は鏡面仕上げとなってい
る。
In FIGS. 1 and 2, reference numeral 1 denotes a transparent substrate, which has an incident surface 1a on which the illumination light emitted from the light source is incident as incident light and an incident light transmitted through the transparent substrate 1 to be emitted. It has an emission surface 1b. As shown in FIG. 1, the transparent substrate 1 is molded so that the thickness of the transparent substrate 1 increases at a predetermined inclination in the vicinity of the incident surface 1a. As the material of the transparent substrate 1, a transparent plate made of an inorganic or synthetic resin such as a glass plate, an acrylic resin plate or a polycarbonate resin plate is used. In the first embodiment, acrylic resin is used as the material of the transparent substrate 1. The transparent substrate 1 is
Although it is possible to cut the plate, the method of forming by injection is preferable in terms of production cost. In addition, all surfaces of the transparent substrate 1 are mirror-finished.

【0013】2は光乱反射部であり、入射面1aより入
射された入射光を乱反射して出射面1bより入射光を放
出せしめる。光乱反射部2は透明基板1の出射面1bの
裏側の面(以後、後面と称する)の発光領域7に相当す
る領域内において、反射率の大きな白色インクをドット
状として、棒状光源5からの距離を隔てるに従って密度
が高まる様に、スクリーン印刷により描写されている。
棒状光源5からの距離に応じて光乱反射部2の密度を高
める方法としては、ドットの径を距離に応じて大きくし
ていく方法と、ドットの単位面積当たりの個数を距離に
応じて増やしていく方法とがある。本実施例1では前者
を用い、ドットの直径は棒状光源5の近くで0.12m
m、最も遠いところで0.85mmとした。又、ドット
は千鳥配列とし、その間隔は1mmとした。
Reference numeral 2 is a diffused light reflecting portion, which diffusely reflects the incident light incident from the incident surface 1a and emits the incident light from the outgoing surface 1b. The diffused light reflection portion 2 forms a dot-like white ink having a large reflectance in the area corresponding to the light emitting area 7 on the back surface (hereinafter referred to as the rear surface) of the emission surface 1b of the transparent substrate 1 from the rod-shaped light source 5. Screen-printed as density increases with increasing distance.
As a method of increasing the density of the diffused reflection portion 2 according to the distance from the rod-shaped light source 5, a method of increasing the diameter of dots according to the distance and a method of increasing the number of dots per unit area according to the distance are used. There is a way to go. In the first embodiment, the former is used, and the dot diameter is 0.12 m near the rod-shaped light source 5.
m and 0.85 mm at the furthest point. Moreover, the dots were arranged in a staggered pattern, and the interval between them was 1 mm.

【0014】3は光反射部であり、透明基板1の後面に
洩れ出た光を出射面1b側へ反射するために、透明基板
1の後面側に設けられる。光反射部3は反射率の大きい
白色のプラスチックシートで構成される。4は光拡散シ
ートであり、出射面1b上に設けられ、出射面1bより
放出された入射光を拡散し、輝度の均一化を図る。尚、
光拡散シート4には光拡散性を有するポリエステルフィ
ルムを用いた。5は棒状光源であり、蛍光灯等が用いら
れる。本実施例1では松下電器産業株式会社製の冷陰極
蛍光灯K−C162T3Eを5mAのランプ電流で用い
た。このとき、棒状光源5の中央部輝度は、25000
cd/m2 であった。又、棒状光源5の直径は、3mm
である。尚、棒状光源5を点灯させるための電源システ
ムは通常の点灯回路を用いるが図1及び図2では省略し
てある。
Reference numeral 3 denotes a light reflecting portion, which is provided on the rear surface side of the transparent substrate 1 in order to reflect the light leaked to the rear surface of the transparent substrate 1 to the emission surface 1b side. The light reflecting portion 3 is composed of a white plastic sheet having a high reflectance. Reference numeral 4 denotes a light diffusion sheet, which is provided on the emission surface 1b and diffuses the incident light emitted from the emission surface 1b to make the brightness uniform. still,
A polyester film having a light diffusing property was used for the light diffusing sheet 4. Reference numeral 5 is a rod-shaped light source, and a fluorescent lamp or the like is used. In Example 1, a cold cathode fluorescent lamp K-C162T3E manufactured by Matsushita Electric Industrial Co., Ltd. was used with a lamp current of 5 mA. At this time, the central brightness of the rod-shaped light source 5 is 25000.
It was cd / m 2 . The diameter of the rod-shaped light source 5 is 3 mm.
Is. A power supply system for lighting the rod-shaped light source 5 uses a normal lighting circuit, but is omitted in FIGS. 1 and 2.

【0015】6はハウジングであり、棒状光源5を透明
基板1の入射面1a側の端面の近傍に固定する。棒状光
源5で発生した光を透明基板1の入射面1aに効率良く
導入するには、棒状光源5を入射面1aの近傍に配置
し、内面側に大きな反射率を有する材料で囲む手法が簡
便で実用的である。従って、ハウジング6の内面には棒
状光源5からの光の放散を防ぐために反射率の大きな白
色のプラスチックシートが設けられている。
Reference numeral 6 denotes a housing, which fixes the rod-shaped light source 5 in the vicinity of the end surface of the transparent substrate 1 on the incident surface 1a side. In order to efficiently introduce the light generated by the rod-shaped light source 5 to the incident surface 1a of the transparent substrate 1, it is simple to arrange the rod-shaped light source 5 in the vicinity of the incident surface 1a and surround the inner surface with a material having a large reflectance. Is practical. Therefore, a white plastic sheet having a large reflectance is provided on the inner surface of the housing 6 in order to prevent the light from the rod-shaped light source 5 from being diffused.

【0016】図3は入射面1a付近における透明基板1
の厚みの変化を説明する図である。透明基板1の厚さは
発光領域においては1.5mmであるが、入射面1aの
近傍ではその厚さが徐々に変化し、入射面1aの厚みは
棒状光源5の直径の1.0倍である3mmとなる。即
ち、図3に示すように、入射面1aの近傍で、開き角度
が片側2.5°、両側で5°の傾斜で透明基板1の厚み
を1.5mmから3mmまで増加させた。尚、図2に示
されるように透明基板1は長さ220mm、幅150m
mであり、発光領域は195mm×145mmである。
FIG. 3 shows the transparent substrate 1 near the incident surface 1a.
It is a figure explaining the change of the thickness of. The thickness of the transparent substrate 1 is 1.5 mm in the light emitting region, but the thickness gradually changes in the vicinity of the incident surface 1a, and the thickness of the incident surface 1a is 1.0 times the diameter of the rod-shaped light source 5. It will be 3 mm. That is, as shown in FIG. 3, in the vicinity of the incident surface 1a, the thickness of the transparent substrate 1 was increased from 1.5 mm to 3 mm with an opening angle of 2.5 ° on one side and 5 ° on both sides. As shown in FIG. 2, the transparent substrate 1 has a length of 220 mm and a width of 150 m.
m, and the light emitting area is 195 mm × 145 mm.

【0017】上述の構成を備えた本実施例1のバックラ
イト装置においては、棒上光源5からの照明光が、透明
基板1の入射面1aから内部に入射光として入射する。
透明基板1と空気との界面の光学的密度差により、大部
分の入射光が透明基板1内を反射しながら進行する。こ
の進行中に透明基板1に設けられた光乱反射部2に達し
た入射光は乱反射し、光の進行角度が変化する。進行角
度が変化することにより、透明基板1と空気との界面に
おいて光の進入角度が所謂臨界角以下になり、透明基板
1の出射面1bから外部に光が放射される。光乱反射部
2は棒状光源5からの距離に応じて密度が高まるパター
ンに形成されてあるので、棒状光源5からの距離を隔て
るに従って弱まる光量を補正し、出射面1bの発光領域
7の全面に亙って均一な光量が得られる。透明基板1か
ら放射された光は、光拡散シート4によって光乱反射部
2による放射むらをなくし、均一な輝度を持つバックラ
イト装置が得られる。
In the backlight device of the first embodiment having the above-mentioned configuration, the illumination light from the rod light source 5 enters the transparent substrate 1 from the entrance surface 1a as incident light.
Due to the difference in optical density at the interface between the transparent substrate 1 and air, most of the incident light travels while being reflected inside the transparent substrate 1. The incident light reaching the light diffuse reflection part 2 provided on the transparent substrate 1 during the progress is diffusely reflected, and the traveling angle of the light changes. Due to the change of the traveling angle, the entrance angle of light becomes equal to or less than the so-called critical angle at the interface between the transparent substrate 1 and the air, and the light is emitted from the emission surface 1b of the transparent substrate 1 to the outside. Since the irregular diffuser 2 is formed in a pattern in which the density increases according to the distance from the rod-shaped light source 5, the amount of light that weakens as the distance from the rod-shaped light source 5 increases is corrected, and the entire surface of the light emitting region 7 of the emission surface 1b is corrected. A uniform amount of light can be obtained. The light emitted from the transparent substrate 1 is eliminated by the light diffusing sheet 4 to prevent uneven emission due to the irregular diffuser 2, and a backlight device having uniform brightness can be obtained.

【0018】又、透明基板1の厚みを徐々に増加させて
形成された入射面1aと、棒状光源5が発生する照明光
を入射面に集中させるハウジング6とにより、棒状光源
5からの照明光が入射面1aより効率よく入射される。
このため、バックライト装置の輝度が向上するという効
果がある。尚、輝度の向上については比較例を挙げて後
述する。
Illumination light from the rod-shaped light source 5 is formed by the incidence surface 1a formed by gradually increasing the thickness of the transparent substrate 1 and the housing 6 which concentrates the illumination light generated by the rod-shaped light source 5 on the incidence surface. Is more efficiently incident from the incident surface 1a.
Therefore, there is an effect that the brightness of the backlight device is improved. The improvement of brightness will be described later with reference to a comparative example.

【0019】このように、実施例1によれば、発光領域
の全面に亙って輝度を均一に保つと共に、高い輝度を有
するバックライト装置が得られる。
As described above, according to the first embodiment, it is possible to obtain a backlight device having a high brightness while keeping the brightness uniform over the entire light emitting region.

【0020】<実施例2>図4及び図5は、実施例2の
バックライト装置を説明するための図である。図4は実
施例2のバックライト装置の断面図であり、図2は実施
例2のバックライト装置の平面図である。また棒状光源
5を配設する透明基板1の入射面1a側の近傍の厚く成
型した部分は実施例1の図3と同様である。更に、図4
及び図5において前述の図1及び図2と同じの構成には
同一の参照番号を付しここではその説明を省略する。
<Embodiment 2> FIG. 4 and FIG. 5 are views for explaining a backlight device of Embodiment 2. In FIG. FIG. 4 is a cross-sectional view of the backlight device of the second embodiment, and FIG. 2 is a plan view of the backlight device of the second embodiment. Further, the thickly molded portion near the incident surface 1a side of the transparent substrate 1 on which the rod-shaped light source 5 is arranged is the same as that in FIG. 3 of the first embodiment. Furthermore, FIG.
Also, in FIG. 5, the same configurations as those in FIGS. 1 and 2 described above are denoted by the same reference numerals, and the description thereof will be omitted here.

【0021】8は方向変更用凹凸部であり、透明基板1
と空気との界面への入射光の進入角度をいわゆる臨界角
以下とし、出射面1bより入射光を放出せしめるもので
ある。方向変更用凹凸部8は透明基板1の出射面1b上
に棒状光源5からの距離に応じて密度が高まるように配
置されている。また、光の放射方向は図4の上方、矢印
で示した向きである。
Reference numeral 8 denotes a direction-changing concave-convex portion, which is the transparent substrate 1.
The incident angle of the incident light to the interface between the air and the air is set to a so-called critical angle or less so that the incident light is emitted from the emission surface 1b. The direction changing concavo-convex portion 8 is arranged on the emission surface 1b of the transparent substrate 1 so that the density increases according to the distance from the rod-shaped light source 5. In addition, the emission direction of light is the direction shown by the arrow in the upper part of FIG.

【0022】棒状光源5より透明基板1に入射した入射
光は、空気との界面への光の進入角度が所謂臨界角以下
になると透明基板1の外に放散されるので、方向変更用
凹凸部8はこの目的に合致するように形成される。図6
に方向変更用凹凸部8の各種の凹凸形状を示す。図6の
(a)〜(d)のいずれの形状によってもよいが、実施
例2では(d)の凹凸形状を採用した。尚、図6に挙げ
た凹凸形状に限られないことは言うまでもない。
The incident light that is incident on the transparent substrate 1 from the rod-shaped light source 5 is diffused out of the transparent substrate 1 when the incident angle of the light to the interface with the air becomes a so-called critical angle or less, so that the direction changing concavo-convex portion is used. 8 is formed to meet this purpose. Figure 6
The various concave-convex shapes of the direction-changing concave-convex portion 8 are shown in FIG. Although the shape may be any one of (a) to (d) of FIG. 6, the uneven shape of (d) is adopted in Example 2. Needless to say, the shapes are not limited to those shown in FIG.

【0023】方向変更用凹凸部8を有する透明基板1
は、図6の(d)の基本形状を有する所定のドットパタ
ーンをフォトレジストによるエッチング技術で金属原板
に写し、この金属原板を成形金型に組み込み、インジェ
クション成形により作成される。
Transparent substrate 1 having direction-changing concave-convex portion 8
Is prepared by injection molding by copying a predetermined dot pattern having the basic shape of FIG. 6D onto a metal original plate by an etching technique using a photoresist, incorporating the metal original plate into a molding die.

【0024】上述の構成を備えた本実施例2のバックラ
イト装置においては、棒上光源5からの照明光が、透明
基板1の入射面1aから内部に入射光として入射する。
透明基板1と空気との界面の光学的密度差により、大部
分の入射光が透明基板1内を反射しながら進行する。こ
の進行中に透明基板1に設けられた方向変更用凹凸部8
に達した入射光はその反射方向が変化するので、光の進
行角度が変化する。進行角度が変化することにより、透
明基板1と空気との界面において光の進入角度が所謂臨
界角以下になり、透明基板1の出射面1bから外部に光
が放射される。方向変更用凹凸部8は棒状光源5からの
距離に応じて密度が高まるパターンに形成されてあるの
で、棒状光源5からの距離を隔てるに従って弱まる光量
を補正し、出射面1bの発光領域7の全面に亙って均一
な光量が得られる。透明基板1から放射された光は、光
拡散シート4によって方向変更用凹凸部8による放射む
らをなくし、均一な輝度を持つバックライト装置が得ら
れる。更に、入射面1aの面積を大きくするとともに、
ハウジング6により集光するので、棒状光源5の照射光
が透明基板1に入射する際に生じる光の損失が抑えら
れ、高い輝度が得られる。
In the backlight device of the second embodiment having the above-mentioned structure, the illumination light from the rod light source 5 enters the transparent substrate 1 through the entrance surface 1a as incident light.
Due to the difference in optical density at the interface between the transparent substrate 1 and air, most of the incident light travels while being reflected inside the transparent substrate 1. During this process, the direction changing concave-convex portion 8 provided on the transparent substrate 1
Since the incident light reaching the position changes its reflection direction, the traveling angle of the light changes. Due to the change of the traveling angle, the entrance angle of light becomes equal to or less than the so-called critical angle at the interface between the transparent substrate 1 and the air, and the light is emitted from the emission surface 1b of the transparent substrate 1 to the outside. Since the direction changing concave-convex portion 8 is formed in a pattern in which the density increases according to the distance from the rod-shaped light source 5, the amount of light that becomes weaker as the distance from the rod-shaped light source 5 is increased is corrected, and the light-emitting region 7 of the emission surface 1b is corrected. A uniform amount of light can be obtained over the entire surface. The light emitted from the transparent substrate 1 is eliminated by the light diffusing sheet 4 due to the unevenness of the direction changing concave-convex portion 8, and a backlight device having uniform brightness can be obtained. Furthermore, while increasing the area of the incident surface 1a,
Since the light is condensed by the housing 6, the loss of light generated when the irradiation light of the rod-shaped light source 5 enters the transparent substrate 1 is suppressed, and high brightness is obtained.

【0025】<各実施例及びバックライト装置の輝度評
価>次に、上述の各実施例と以下に示す構成例a〜構成
例dとで輝度の比較を行った結果について説明する。
<Evaluation of Luminance of Each Example and Backlight Device> Next, the result of comparison of luminance between each of the above-mentioned examples and the following structural examples a to d will be described.

【0026】先ず、構成例a〜構成例dについて図面を
参照して説明する。
First, configuration examples a to d will be described with reference to the drawings.

【0027】(構成例a)図7は構成例aのバックライ
ト装置を表し、その平面図は図2及び図5と同様であ
る。透明基板11の厚みは1.5mmで一様とし、棒状
光源5を配設する入射面11aの近傍において厚みを増
加するということは行っていない。厚み増加がないとい
う点を除く他の構成は実施例1と同様である。
(Structural Example a) FIG. 7 shows a backlight device of structural example a, and its plan view is the same as FIG. 2 and FIG. The transparent substrate 11 has a uniform thickness of 1.5 mm, and the thickness is not increased in the vicinity of the incident surface 11a on which the rod-shaped light source 5 is arranged. The other structure is the same as that of the first embodiment except that the thickness is not increased.

【0028】(構成例b)図8は、構成例bのバックラ
イト装置を表し、その平面図は図2及び図5と同一であ
る。透明基板21の厚みは全面3mmで一様であり、構
成例aと同様に棒状光源5を配設する入射面21aの近
傍において厚みを増加するということは行っていない。
即ち、透明基板21の厚みが3mmであるという点を除
く他の構成は構成例aと同様である。但し、光乱反射部
のドット径の増加のパターンについては、光の放射面の
輝度が均一になる様にすべく若干変更されている。
(Structural Example b) FIG. 8 shows a backlight device of structural example b, and its plan view is the same as FIG. 2 and FIG. The thickness of the transparent substrate 21 is uniform over the entire surface of 3 mm, and the thickness is not increased in the vicinity of the incident surface 21a on which the rod-shaped light source 5 is arranged as in the configuration example a.
That is, the other configuration is the same as the configuration example a except that the thickness of the transparent substrate 21 is 3 mm. However, the pattern of the increase in the dot diameter of the diffused reflection portion is slightly changed so that the luminance of the light emitting surface becomes uniform.

【0029】(構成例c)図9は、構成例cのバックラ
イト装置における透明基板の入射面近傍の形状を表す。
構成例cにおいては、透明基板31の棒状光源を配設す
る入射面31a側の厚み増加の具合のみが実施例1より
変更されている。構成例cにおいては、透明基板31の
端部の近傍の厚みを片側90°の開き角度で増加させて
いる。
(Structure example c) FIG. 9 shows a shape in the vicinity of the incident surface of the transparent substrate in the backlight device of structure example c.
In the configuration example c, only the increase in the thickness of the transparent substrate 31 on the side of the incident surface 31a where the rod-shaped light source is arranged is changed from that of the first embodiment. In the configuration example c, the thickness in the vicinity of the end of the transparent substrate 31 is increased at an opening angle of 90 ° on one side.

【0030】(構成例d)図10は、構成例dのバック
ライト装置における透明基板の入射面近傍の形状を表
す。構成例dにおいても構成例cと同様に、透明基板4
1の棒状光源を配設する入射面41a側の厚み増加の具
合のみが実施例1より変更されている。構成例dにおい
ては透明基板41の近傍の厚みを、片側7.5°、両側
で15°の開き角度で増加させている。
(Structural Example d) FIG. 10 shows a shape in the vicinity of the incident surface of the transparent substrate in the backlight device of Structural Example d. Also in the configuration example d, as in the configuration example c, the transparent substrate 4
Only the degree of increase in thickness on the incident surface 41a side where the rod-shaped light source No. 1 is arranged is changed from that of the first embodiment. In the configuration example d, the thickness in the vicinity of the transparent substrate 41 is increased at an opening angle of 7.5 ° on one side and 15 ° on both sides.

【0031】上記各構成例a〜d、実施例1及び実施例
2の各バックライト装置における輝度測定の結果を図1
1に示した。尚、図11に示されている輝度測定の結果
は、冷陰極蛍光灯のランプ電流を5mAとし、棒状光源
5の中央部において棒状光源5と直角に交差する線上の
発光領域を5mmピッチで輝度測定し、その平均を求め
たものである。
FIG. 1 shows the results of luminance measurement in each of the backlight devices of the above-mentioned structural examples a to d, Example 1 and Example 2.
Shown in 1. In addition, the result of the luminance measurement shown in FIG. 11 is that the lamp current of the cold cathode fluorescent lamp is 5 mA, and the light emitting area on the line that intersects the rod-shaped light source 5 at a right angle in the central portion of the rod-shaped light source 5 has a luminance of 5 mm pitch. It is measured and the average is obtained.

【0032】透明基板全体の厚さを3mmとした構成例
bの平均輝度は390cd/m2 であり、最も大きな平
均輝度を有する。単純に透明基板全体の厚さを1.5m
mとした構成例aでは、平均輝度が320cd/m2
大きく低下してしまう。本発明の課題としては、輝度の
低下をできる限り少なくして透明基板の薄型化を図るこ
とにある。本発明に基づいて透明基板の薄型化を図った
実施例1では平均輝度が370cd/m2 、実施例2で
は380cd/m2 と向上し、構成例bとほぼ同等の平
均輝度が得られた。透明基板の厚みが180゜の開き角
度で増加する構成例cでは平均輝度が310cd/m2
となり、透明基板の厚み増加による効果は得られない。
透明基板の厚みが開き角度15゜で増加する構成例dで
は、平均輝度が330cd/m2 となり、若干の輝度向
上が得られる。
The average brightness of the structural example b in which the thickness of the entire transparent substrate is 3 mm is 390 cd / m 2, which is the largest average brightness. Simply set the thickness of the entire transparent substrate to 1.5m
In the configuration example a where m is set, the average luminance is significantly reduced to 320 cd / m 2 . An object of the present invention is to reduce the brightness as much as possible and to reduce the thickness of the transparent substrate. The average luminance in Example 1 was attempted in the thickness of the transparent substrate in accordance with the present invention is 370cd / m 2, and improved 380 cd / m 2 In Example 2, the average luminance of approximately equivalent to configuration example b was obtained . In the configuration example c in which the thickness of the transparent substrate increases at an opening angle of 180 °, the average brightness is 310 cd / m 2.
Therefore, the effect of increasing the thickness of the transparent substrate cannot be obtained.
In the configuration example d in which the thickness of the transparent substrate increases at the opening angle of 15 °, the average luminance is 330 cd / m 2 , and a slight improvement in luminance can be obtained.

【0033】透明基板の厚みと棒状光源の直径の関係に
おいて、前者が後者より小さくなるにつれて棒状光源か
ら透明基板の端縁への光の導入の損失が増大する。透明
基板を薄くしても導入時における光の損失が少なくなる
ように種々の実験及び検討を行った結果、入射面の近傍
における厚みを徐々に増加させた透明基板を用いること
により導入時における入射光の損失の低減が可能となる
ことが判った。特に透明基板の厚み増加における開き角
度が入射光の損失に影響を与え、この開き角度は小さけ
れば小さいほど良いが、本発明の発明者等の実験によれ
ば、開き角度は両側で10゜以下が望ましい。
In the relationship between the thickness of the transparent substrate and the diameter of the rod-shaped light source, the loss of light introduced from the rod-shaped light source to the edge of the transparent substrate increases as the former becomes smaller than the latter. As a result of various experiments and studies to reduce the loss of light at the time of introduction even if the transparent substrate is made thin, the incidence at the time of introduction is improved by using a transparent substrate with a gradually increasing thickness in the vicinity of the incident surface. It was found that the loss of light can be reduced. In particular, the opening angle in increasing the thickness of the transparent substrate affects the loss of incident light, and the smaller the opening angle, the better. However, according to the experiments conducted by the inventors of the present invention, the opening angle is 10 ° or less on both sides. Is desirable.

【0034】又、上記実施例では入射面1aの厚みが棒
状光源5の直径と等しくしているがこれに限られるもの
ではない。入射面の厚みは大きければ大きいほど良い
が、本発明の発明者等の実験によれば、棒状光源の直径
の0.8倍から1.3倍が実用的な範囲である。
Further, in the above embodiment, the thickness of the incident surface 1a is made equal to the diameter of the rod-shaped light source 5, but the thickness is not limited to this. The thicker the incident surface, the better, but according to experiments conducted by the inventors of the present invention, the practical range is 0.8 to 1.3 times the diameter of the rod-shaped light source.

【0035】上記の如く、本実施例によれば、薄型で光
の利用効率の高い、言い換えれば、輝度の優れたバック
ライト装置が提供される。従って、本バックライト装置
を液晶ディスプレイ等の背後に設置することにより、薄
くて見易い画面を実現できるものとなる。又、透明基板
もインジェクション方式にすると容易に成型されるので
量産性にも優れている。
As described above, according to this embodiment, a backlight device which is thin and has high light utilization efficiency, in other words, excellent brightness is provided. Therefore, a thin and easy-to-see screen can be realized by installing the backlight device behind a liquid crystal display or the like. Also, the transparent substrate is easily molded by the injection method, so that it is excellent in mass productivity.

【0036】尚、上記各実施例では、透明基板の厚みを
両側に等しい開き角で傾斜させることにより増加させて
いるがこれに限られるものではなく、例えば図12に示
す如く片側のみを傾斜させて厚みを増加させても良い。
In each of the above embodiments, the thickness of the transparent substrate is increased by inclining the transparent substrate at the same opening angle on both sides, but the invention is not limited to this. For example, only one side is inclined as shown in FIG. The thickness may be increased.

【0037】[0037]

【発明の効果】以上説明したように本発明によれば、光
の利用効率が向上し、薄型でかつ高い輝度を保つ面光源
装置が提供され得る。
As described above, according to the present invention, it is possible to provide a surface light source device in which the utilization efficiency of light is improved, and which is thin and maintains high brightness.

【0038】[0038]

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

【図1】実施例1のバックライト装置の断面図である。FIG. 1 is a cross-sectional view of a backlight device according to a first embodiment.

【図2】実施例1のバックライト装置の平面図である。FIG. 2 is a plan view of the backlight device according to the first embodiment.

【図3】入射面付近における透明基板の厚みの変化を説
明する図である。
FIG. 3 is a diagram illustrating a change in thickness of the transparent substrate near the incident surface.

【図4】実施例2のバックライト装置の断面図である。FIG. 4 is a sectional view of a backlight device according to a second embodiment.

【図5】実施例2のバックライト装置の平面図である。FIG. 5 is a plan view of a backlight device according to a second embodiment.

【図6】方向変更用凹凸部の各種の凹凸形状を示す図で
ある。
FIG. 6 is a diagram showing various concave and convex shapes of a direction changing concave and convex portion.

【図7】構成例aのバックライト装置の断面図である。FIG. 7 is a cross-sectional view of a backlight device of configuration example a.

【図8】構成例bのバックライト装置の断面図である。FIG. 8 is a cross-sectional view of a backlight device of configuration example b.

【図9】構成例cのバックライト装置における透明基板
の入射面近傍の形状を表す図である。
FIG. 9 is a diagram illustrating a shape in the vicinity of an incident surface of a transparent substrate in the backlight device of configuration example c.

【図10】構成例dのバックライト装置における透明基
板の入射面近傍の形状を表す図である。
FIG. 10 is a diagram illustrating a shape in the vicinity of an incident surface of a transparent substrate in the backlight device of configuration example d.

【図11】各バックライト装置における輝度測定の結果
を表す図である。
FIG. 11 is a diagram showing a result of luminance measurement in each backlight device.

【図12】透明基板の厚み増加方法の他の例を表す図で
ある。
FIG. 12 is a diagram illustrating another example of the method of increasing the thickness of the transparent substrate.

【符号の説明】[Explanation of symbols]

1 透明基板 2 光乱反射部 3 光反射部 4 光拡散シート 5 棒状光源 6 ハウジング 1 Transparent substrate 2 Light diffuse reflection part 3 Light reflection part 4 Light diffusion sheet 5 Rod-shaped light source 6 Housing

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】 光源と、 前記光源よりの光を入射する入射面及び該入射面とほぼ
直交する方向に光を放出する出射面を有するほぼ透明な
基板と、 前記基板内を進行する入射光の方向を変化させ、該入射
光を前記出射面より放出せしめる光方向変化部とを備
え、 前記基板は入射面側の付近においてその厚みが入射面に
向かって徐々に増加して形成されることを特徴とする面
光源装置。
1. A substantially transparent substrate having a light source, an incident surface on which light from the light source is incident, and an emission surface for emitting light in a direction substantially orthogonal to the incident surface, and incident light traveling in the substrate. And a light-direction changing portion that changes the direction of the incident light so that the incident light is emitted from the exit surface, and the substrate is formed such that its thickness gradually increases toward the entrance surface in the vicinity of the entrance surface side. A surface light source device.
【請求項2】 前記光源は棒状光源であり、前記基板の
前記出射面における厚み幅が該棒状光源の径よりも小さ
く、 前記基板は入射面側の付近においてその厚みが10度以
下の開き角度で増加し、入射面における厚みが前記棒状
光源の径の0.8倍乃至1.3倍となることを特徴とす
る請求項1に記載の面光源装置。
2. The light source is a rod-shaped light source, the thickness width of the substrate at the emission surface is smaller than the diameter of the rod-shaped light source, and the substrate has an opening angle of 10 degrees or less near the incident surface side. 2. The surface light source device according to claim 1, wherein the thickness on the incident surface is 0.8 to 1.3 times the diameter of the rod-shaped light source.
JP5106663A 1993-05-07 1993-05-07 Surface light source device Pending JPH06317797A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP5106663A JPH06317797A (en) 1993-05-07 1993-05-07 Surface light source device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5106663A JPH06317797A (en) 1993-05-07 1993-05-07 Surface light source device

Publications (1)

Publication Number Publication Date
JPH06317797A true JPH06317797A (en) 1994-11-15

Family

ID=14439328

Family Applications (1)

Application Number Title Priority Date Filing Date
JP5106663A Pending JPH06317797A (en) 1993-05-07 1993-05-07 Surface light source device

Country Status (1)

Country Link
JP (1) JPH06317797A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010033730A (en) * 2008-07-25 2010-02-12 Sumitomo Electric Printed Circuit Inc Wiring module and electronic device
CN103018818A (en) * 2012-12-14 2013-04-03 京东方科技集团股份有限公司 Light guide device, backlight module and display device
US8814412B2 (en) 2008-08-07 2014-08-26 Omron Corporation Area light source device
JP2022008452A (en) * 2014-05-16 2022-01-13 コーニング インコーポレイテッド Edge light type backlight unit for liquid crystal display device

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63208001A (en) * 1987-02-25 1988-08-29 Mitsubishi Rayon Co Ltd Light transmission body for light diffusion
JPH04333803A (en) * 1991-05-10 1992-11-20 Sumitomo Chem Co Ltd Photoconductor for plane illumination device
JPH0553111A (en) * 1991-08-23 1993-03-05 Rohm Co Ltd Light guiding plate structure of thin edge light type liquid crystal display device
JP3104906B2 (en) * 1997-05-13 2000-10-30 日本電産リード株式会社 Substrate displacement detection apparatus and substrate displacement detection method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63208001A (en) * 1987-02-25 1988-08-29 Mitsubishi Rayon Co Ltd Light transmission body for light diffusion
JPH04333803A (en) * 1991-05-10 1992-11-20 Sumitomo Chem Co Ltd Photoconductor for plane illumination device
JPH0553111A (en) * 1991-08-23 1993-03-05 Rohm Co Ltd Light guiding plate structure of thin edge light type liquid crystal display device
JP3104906B2 (en) * 1997-05-13 2000-10-30 日本電産リード株式会社 Substrate displacement detection apparatus and substrate displacement detection method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010033730A (en) * 2008-07-25 2010-02-12 Sumitomo Electric Printed Circuit Inc Wiring module and electronic device
US8814412B2 (en) 2008-08-07 2014-08-26 Omron Corporation Area light source device
CN103018818A (en) * 2012-12-14 2013-04-03 京东方科技集团股份有限公司 Light guide device, backlight module and display device
JP2022008452A (en) * 2014-05-16 2022-01-13 コーニング インコーポレイテッド Edge light type backlight unit for liquid crystal display device

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