JP3077907B2 - Backlight device - Google Patents

Backlight device

Info

Publication number
JP3077907B2
JP3077907B2 JP01144380A JP14438089A JP3077907B2 JP 3077907 B2 JP3077907 B2 JP 3077907B2 JP 01144380 A JP01144380 A JP 01144380A JP 14438089 A JP14438089 A JP 14438089A JP 3077907 B2 JP3077907 B2 JP 3077907B2
Authority
JP
Japan
Prior art keywords
light
transparent substrate
light source
reflection layer
diffuse reflection
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.)
Expired - Lifetime
Application number
JP01144380A
Other languages
Japanese (ja)
Other versions
JPH039304A (en
Inventor
由直 武笠
達司 溝部
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 Chemical Corp
Original Assignee
Mitsubishi Chemical Corp
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
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Application filed by Mitsubishi Chemical Corp filed Critical Mitsubishi Chemical Corp
Priority to JP01144380A priority Critical patent/JP3077907B2/en
Publication of JPH039304A publication Critical patent/JPH039304A/en
Application granted granted Critical
Publication of JP3077907B2 publication Critical patent/JP3077907B2/en
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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/007—Incandescent lamp or gas discharge lamp
    • G02B6/0071—Incandescent lamp or gas discharge lamp with elongated shape, e.g. tube

Landscapes

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

Description

【発明の詳細な説明】 「産業上の利用分野」 本発明は、液晶ディスプレイ（LCD）の背面に配設さ
れて、該液晶ディスプレイを照射するバックライト装置
に関する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device disposed on the back of a liquid crystal display (LCD) and illuminating the liquid crystal display.

「従来の技術」 近年、液晶ディスプレイは、薄形，軽量、及び低消費
電力などの優れた特徴を有し、この特徴を充分発揮し得
る平面ディスプレイとして各種製品への利用に多大な期
待が寄せられている。しかしながら、液晶ディスプレイ
は、現在産業用及び民生用として広く使用されているCR
T（Cathode Ray Tube）に比較して画質面で劣ってお
り、この画質を改善するためにバックライト形式の液晶
ディスプレイが開発されるに至っている。[Prior art] In recent years, liquid crystal displays have excellent features such as thinness, light weight, and low power consumption, and there are great expectations for use in various products as flat displays that can sufficiently exhibit these features. Have been. However, liquid crystal displays are now widely used for industrial and consumer applications.
The image quality is inferior to T (Cathode Ray Tube), and a backlight type liquid crystal display has been developed to improve the image quality.

この種のバックライト装置は、薄形でかつ軽量である
ことが望まれ、又画面の全領域において輝度が均一であ
ることが必要条件とされている。バックライト装置にお
いて、輝度の均一性を高める技術としては、既に各種の
提案がされている。例えば、特開昭57−13478号公報記
載のものは、線状光源の上部に乳白色光散乱体を設け、
かつ該乳白色光散乱体の中央部の層厚を厚くし、端部に
至るに従って薄くして、照明むらをなくし、しかも薄型
でかつ小型化を図り得るようにしたものである。更に、
特開昭60−264039号公報記載のものでは、蛇行状の冷陰
極ランプを用い、特開昭61−219980号公報記載のもので
は、紫外線ランプ、及び該紫外線ランプの周辺に配設し
た蛍光体塗布層部を活用し、特開昭62−10621号公報記
載のものでは、導光板中に光源を組み込み、特開昭62−
127717号公報記載のものでは、複数個の光源の上下面に
凹凸レンズを配設し、特開昭63−125975号公報記載のも
のではＵ字型ランプを用い、これによりそれぞれ照明む
らをなくして輝度の均一化を図るようにしてある。更
に、輝度の均一化を図るべく、透明基板内に光散乱体
を、光源側では低濃度で光源より距離を隔たるに従って
高濃度になるように入れた特開昭54−105562号公報記載
のものや、コーティングされた透明基板に光反射手段
を、照明用光源からの距離と照度に反比例する密度分布
で描写する特開昭63−309918号公報記載のバックライト
装置が知られるところである。This type of backlight device is required to be thin and lightweight, and it is a necessary condition that the luminance is uniform over the entire area of the screen. In the backlight device, various proposals have already been made as a technique for improving the uniformity of luminance. For example, JP-A-57-13478 discloses a milky white light scatterer provided above a linear light source,
In addition, the layer thickness of the central portion of the milky light scatterer is increased, and the thickness is reduced toward the end portion, so that illumination unevenness is eliminated, and furthermore, the thickness and the size can be reduced. Furthermore,
JP-A-60-264039 discloses a meandering cold cathode lamp, and JP-A-61-219980 discloses an ultraviolet lamp and a phosphor disposed around the ultraviolet lamp. Utilizing the coating layer portion, the one described in JP-A-62-10621 incorporates a light source in the light guide plate,
In the method disclosed in Japanese Patent No. 127717, a concave / convex lens is arranged on the upper and lower surfaces of a plurality of light sources, and in the method described in Japanese Patent Application Laid-Open No. 63-125975, a U-shaped lamp is used, thereby eliminating uneven illumination. The brightness is made uniform. Further, in order to achieve uniform brightness, a light scatterer is provided in a transparent substrate, and the light source side is provided with a low density and a higher density as the distance from the light source is increased with a higher density as described in JP-A-54-105562. A backlight device described in JP-A-63-309918 is known in which a light reflecting means is depicted on a transparent substrate coated with a light source with a density distribution inversely proportional to the distance from the illumination light source and the illuminance.

「発明が解決しようとする課題」 しかしながら、上記従来のものは、下記の如き問題が
ある。"Problem to be solved by the invention" However, the above-mentioned conventional one has the following problems.

（１） 光散乱体の下面に光源を配設する場合には、バ
ックライト装置全体の厚みが厚くなり嵩張るといった問
題がある。(1) When the light source is provided on the lower surface of the light scatterer, there is a problem that the thickness of the entire backlight device becomes thick and bulky.

（２） 輝度の均一化を図るべく、ランプを複数個設け
る場合には、大面積にすればするほど多数のランプが必
要となってコスト高を招くといった問題がある。(2) When a plurality of lamps are provided in order to make the luminance uniform, there is a problem that as the area is increased, a larger number of lamps is required and the cost is increased.

（３） 蛇行状のランプを用いる場合には、大面積のも
のに適用すると、量産性に欠けるといった問題がある。(3) When a meandering lamp is used, if it is applied to a large-area lamp, there is a problem that mass productivity is lacking.

（４） 透明基板内に光散乱体を入れる場合は、輝度の
均一化を再現性良く製造することが容易でないといった
問題がある。(4) When a light scatterer is placed in a transparent substrate, there is a problem that it is not easy to manufacture a uniform luminance with good reproducibility.

（５） コーティングされた透明基板に光反射手段を描
写する場合は、コーティングしていない透明基板を用い
るものに比べてコスト高になるといった問題がある。(5) When the light reflecting means is described on the coated transparent substrate, there is a problem that the cost is higher than that using a transparent substrate without coating.

そこで、本発明は、上記問題点を克服すべくなされた
もので、薄型かつ軽量で大面積化によっても輝度の均一
性を保持し得るバックライト装置を提供せんとするもの
である。SUMMARY OF THE INVENTION The present invention has been made to overcome the above problems, and an object of the present invention is to provide a backlight device that is thin, lightweight, and can maintain uniform brightness even when the area is increased.

「課題を解決するための手段」 本発明は、上記目的を達成すべくなされたもので、請
求項（１）では、透明基板の四周のうちの少なくとも１
箇所に蛍光灯を配設し、透明基板の後面には蛍光灯から
の距離に応じて密度が高まるパターンでかつ透明基板の
表面の出光面積に対して５〜50％の占有率を持たせて光
乱反射層を形成し、透明基板の表面には光拡散層設け、
液晶ディスプレイの背面に配設されて、該液晶ディスプ
レイを照射するバックライト装置を特徴とするものであ
る。更に、請求項（２）では、上記光拡散層が、表面を
粗面化したフィルムから構成される光拡散層であること
を特徴とするものである。"Means for Solving the Problems" The present invention has been made to achieve the above object, and in claim (1), at least one of the four circumferences of the transparent substrate is provided.
A fluorescent lamp is provided at a location, and the rear surface of the transparent substrate has a pattern in which the density increases according to the distance from the fluorescent lamp and has an occupancy of 5 to 50% with respect to the light emission area of the surface of the transparent substrate. Forming a light diffuse reflection layer, providing a light diffusion layer on the surface of the transparent substrate,
The backlight device is provided on the back surface of the liquid crystal display and illuminates the liquid crystal display. Further, in claim (2), the light diffusion layer is a light diffusion layer composed of a film having a roughened surface.

「作用」 本発明は、上記構成において、請求項（１）では、光
源からの放射光が透明基板の端面から内部に入射し、透
明基板と空気との界面の光学的密度差に伴い大部分の光
が反射しながら進行する。この進行の途中で光乱反射層
に入射すると、光乱反射層で乱反射し、透明基板と空気
との界面において臨界角以下になって透明基板の前面の
光拡散層を経て外部に放射される。光乱反射層は、光源
から遠ざかる程高密度のパターンになっており、しかも
透明基板表面の出光面積に対して５〜50％の占有率で形
成させてあるから、透明基板の表面の全出光領域におい
て均一に外部に放射される。光拡散層は、透明基板内か
ら外部に向う放射光を拡散して、光乱反射層と光乱反射
層が形成されていないパターン間隔の領域との間の照射
むらの発生を防いでいる。[Operation] According to the present invention, in the above structure, in claim (1), the radiated light from the light source enters the inside from the end face of the transparent substrate, and most of the light is caused by the difference in optical density at the interface between the transparent substrate and air. Light travels while reflecting. When the light enters the light diffuse reflection layer in the course of this traveling, the light is diffusely reflected by the light diffuse reflection layer, becomes a critical angle or less at the interface between the transparent substrate and air, and is emitted outside through the light diffusion layer on the front surface of the transparent substrate. The light diffuse reflection layer has a pattern with a higher density as the distance from the light source increases, and is formed at an occupation ratio of 5 to 50% with respect to the light emission area of the transparent substrate surface. Is uniformly radiated to the outside. The light diffusion layer diffuses radiated light from the inside of the transparent substrate to the outside, thereby preventing the occurrence of irradiation unevenness between the light diffuse reflection layer and the area of the pattern interval where the light diffuse reflection layer is not formed.

請求項（２）では、光拡散層を表面を粗面化したフィ
ルムから構成される光拡散層として、耐久性等に優れる
特性を持たせるものである。According to claim (2), the light diffusion layer is made of a film having a roughened surface, and has properties such as excellent durability.

「実施例」 以下に、本発明に係るバックライト装置の実施例を図
面に基づき説明する。第１図及び第２図は各実施例にお
けるバックライト装置の構成図で、まず、その構成を説
明すれば、図中１は透明基板である。該透明基板１は、
光透過率の良好な肉厚の薄い板で、材質として例えばガ
ラス板、アクリル樹脂板、ポリカーボネート樹脂板等、
無機質若しくは合成樹脂製の透明板を使用する。透明基
板１の４周部のうちの一側縁に光源２を配設する。光源
２は、一般に広く用いられている蛍光灯の他、細い管径
の冷陰極管が、バックライト装置全体の薄形化及び液晶
ディスプレイ（LCD）パネルに対する温度の影響を押え
ることができて利用上有利である。又光源２としては、
アパーチャー型のランプを用いてもよい。上記透明基板
１の裏面には、光源２からの放射光を乱反射する光乱反
射層３を、光源２からの距離に比例して高密度化するパ
ターンで描写させてある。光乱反射層３は、反射微粒子
としての酸化チタンを含有する揮発硬化型の、若しくは
紫外線硬化型の白色インクを用い、又は利用する者の希
望に応じた色彩の着色インクを使用する。透明基板１の
裏面に光乱反射層３を形成する方法としては、スクリー
ン印刷やスタンプ方式等の公知の技術を用いて描写す
る。該光乱反射層３を透明基板１の裏面に形成するに際
しては、第３図に示す如く、単位面積当たりの点の数を
同一にし、光源から距離を隔てるに従って比例して点
（ドット）を径大に描写し、透明基板１の単位面積当た
りの光乱反射層３の占有率を変えるようにしてある。光
乱反射層３の点の直径は、１〜3000μ、好ましくは10〜
1000μに設定する。一方、透明基板１の表面には、光拡
散層４を添着する。光拡散層４は、所謂くもりガラス、
若しくは表面を粗面化したプラスチックフィルムが用い
られ、コストや耐久性等から表面を粗面化した光拡散層
を有するポリエスルフィルムが好適である。上記光乱反
射層３が形成された透明基板１と、光拡散層４と、光源
２とは、前面側を除いてハウジング５により囲繞させて
ある。ハウジング５は、透明基板１、若しくは光源２か
ら漏洩する光を透明基板１に戻す機能と、前面以外から
の光の漏洩を防ぐべく遮光する機能と、光源２から発生
する熱を外部に放散させる放熱機能とを持たせるための
もので、内面に光反射率の高い処理を施した金属あるい
はプラスチックよりなっている。例えば、ハウジング５
として、光反射率の高い白色塗料を塗布したアルミケー
スや、高反射率の金属蒸着を施したアルミケースが好適
である。又、上記透明基板１の光源２の光が入光する端
面以外に反射テープ６を貼着して、透明基板１の周縁か
らの光の漏洩を防ぐようにすることもできる。Hereinafter, an embodiment of a backlight device according to the present invention will be described with reference to the drawings. 1 and 2 are configuration diagrams of a backlight device in each embodiment. First, the configuration will be described. In the drawings, reference numeral 1 denotes a transparent substrate. The transparent substrate 1
A thin plate with good light transmittance and a thickness of, for example, a glass plate, an acrylic resin plate, a polycarbonate resin plate, etc.
A transparent plate made of an inorganic or synthetic resin is used. The light source 2 is disposed on one side edge of the four peripheral portions of the transparent substrate 1. As the light source 2, in addition to a fluorescent lamp generally used widely, a cold-cathode tube having a small diameter can be used because the backlight device can be made thinner and the influence of temperature on a liquid crystal display (LCD) panel can be suppressed. It is more advantageous. As the light source 2,
An aperture-type lamp may be used. On the rear surface of the transparent substrate 1, a light diffuse reflection layer 3 for irregularly reflecting light emitted from the light source 2 is depicted in a pattern of increasing density in proportion to the distance from the light source 2. For the light irregular reflection layer 3, a volatile curable or ultraviolet curable white ink containing titanium oxide as reflective fine particles, or a colored ink of a color desired by the user is used. As a method of forming the light diffuse reflection layer 3 on the back surface of the transparent substrate 1, description is made using a known technique such as screen printing or a stamp method. When forming the light diffuse reflection layer 3 on the back surface of the transparent substrate 1, as shown in FIG. 3, the number of points per unit area is the same, and the diameter of the points (dots) is proportional to the distance from the light source. The occupancy of the light diffusely reflecting layer 3 per unit area of the transparent substrate 1 is changed in large scale. The diameter of the point of the light irregular reflection layer 3 is 1 to 3000 μm, preferably 10 to
Set to 1000μ. On the other hand, the light diffusion layer 4 is attached to the surface of the transparent substrate 1. The light diffusion layer 4 is made of so-called frosted glass,
Alternatively, a plastic film having a roughened surface is used, and a polyester film having a light diffusion layer whose surface is roughened is preferable in view of cost, durability, and the like. The transparent substrate 1 on which the light diffuse reflection layer 3 is formed, the light diffusion layer 4 and the light source 2 are surrounded by a housing 5 except for the front side. The housing 5 has a function of returning light leaking from the transparent substrate 1 or the light source 2 to the transparent substrate 1, a function of blocking light to prevent light from leaking from a portion other than the front surface, and dissipating heat generated from the light source 2 to the outside. It has a heat radiation function and is made of metal or plastic whose inner surface is treated with high light reflectance. For example, housing 5
Preferably, an aluminum case coated with a white paint having a high light reflectance or an aluminum case coated with a metal having a high reflectance is suitable. Further, a reflective tape 6 may be attached to the transparent substrate 1 at an end other than the end face where the light of the light source 2 enters to prevent the light from leaking from the periphery of the transparent substrate 1.

そして、上記のバックライト装置では、まず光源２か
らの放射光が透明基板１の一端面から入光する。透明基
板１内に入光した光源２からの放射光は、透明基板１と
空気との界面での光学的密度差により入光角に依存した
反射を繰返しながら進行する。この進行に伴い、光乱反
射層３に達して入光すると、内部に含有する酸化チタン
で乱反射し、この結果、乱反射光は透明基板１の表面と
空気との界面に対して臨界角以下となって、該透明基板
１の表面から外部に放射する。この時、光乱反射層３で
乱反射した光は、透明基板１の表面の光拡散層４を通過
するが、光拡散層４が微小な点状又は凹凸状になってい
ることから、光が更に拡散されて外部に放射する。光乱
反射層３は、透明基板１の単位面積当たりの占有率が光
源２から距離を隔たるに従い増加させてあるから、光源
２からの距離による光の不均一を防止して、光量の多い
光源２の付近から光量の少ない距離の隔った箇所まで全
面に亙って均一な乱反射光量を得ることができる。光拡
散層４は、光乱反射層３と光乱反射層３のパターン以外
の領域との間の光量変化、所謂「影の発生」をなくし、
均一な輝度が得られるようにする。透明基板１より洩れ
た光は、特に光乱反射層３の間隔より洩れた光は、ハウ
ジング５の内面で反射されて再び透明基板１内に戻り、
透明基板１内で反射を繰返すうちに上記と同様に光乱反
射層３で乱反射した光拡散層４を経て外部に放射され
る。光源２から発生する熱は、ハウジング５を通じて外
部に放散する。In the backlight device described above, first, the radiated light from the light source 2 enters from one end surface of the transparent substrate 1. The radiated light from the light source 2 entering the transparent substrate 1 travels while repeating reflection depending on the incident angle due to the difference in optical density at the interface between the transparent substrate 1 and air. With this progress, when the light reaches the light diffuse reflection layer 3 and enters the light, the light is diffused and reflected by the titanium oxide contained therein. As a result, the light is diffused at a critical angle or less with respect to the interface between the surface of the transparent substrate 1 and air. Then, the light is radiated from the surface of the transparent substrate 1 to the outside. At this time, the light diffusely reflected by the light diffuse reflection layer 3 passes through the light diffusion layer 4 on the surface of the transparent substrate 1. However, since the light diffusion layer 4 has minute dots or irregularities, the light further increases. It diffuses and radiates outside. Since the occupation rate per unit area of the transparent substrate 1 increases as the distance from the light source 2 increases, the light diffuse reflection layer 3 prevents unevenness of the light due to the distance from the light source 2 and provides a light source with a large amount of light. A uniform diffuse reflection light amount can be obtained over the entire surface from the vicinity of 2 to a place separated by a small distance with a small amount of light. The light diffusion layer 4 eliminates a change in the amount of light between the light diffuse reflection layer 3 and a region other than the pattern of the light diffuse reflection layer 3, that is, a so-called “shadow generation”.
Make sure that uniform brightness is obtained. Light that has leaked from the transparent substrate 1, particularly light that has leaked from the space between the light diffuse reflection layers 3, is reflected by the inner surface of the housing 5 and returns to the inside of the transparent substrate 1 again.
While the light is repeatedly reflected in the transparent substrate 1, the light is radiated to the outside through the light diffusion layer 4 irregularly reflected by the light irregular reflection layer 3 as described above. The heat generated from the light source 2 is radiated outside through the housing 5.

次に、第１実施例について説明すれば、透明基板１と
して、長さ200mm、幅150mm、厚み5mmのアクリル樹脂板
を用いる。該透明基板１の表面に形成する光乱反射層３
は、透明基板１の後面の長さ190mm、幅140mmの範囲に、
スクリーン印刷により酸化チタンが含有する白色インク
で描写する。光乱反射層３は、各点間ピッチを1mmで固
定し、点の径を変化させるようにしてあり、光源２の付
近の点の直径を0.2mmとし、光源２から離れるに従って
点を径大にし、光源２から最も隔った位置の点の直径を
0.9mmにしてある。この時、光乱反射手段の描写面積
は、出光面積の25％になるように点の直径の変化の度合
を調整した。又出光面積は、透明基板１の表面から外部
に放射する面積であるが、透明基板１の裏面の光乱反射
層３が描写される面積と同一である。一方光源２は、管
径8mm、長さ250mmの冷陰極管を用い、透明基板１の長手
方向側の１端縁に配設する。Next, the first embodiment will be described. An acrylic resin plate having a length of 200 mm, a width of 150 mm and a thickness of 5 mm is used as the transparent substrate 1. Light diffusely reflecting layer 3 formed on the surface of transparent substrate 1
Is in the range of 190mm in length and 140mm in width on the rear surface of the transparent substrate 1,
The image is drawn with white ink contained in titanium oxide by screen printing. The light irregular reflection layer 3 has a fixed pitch of 1 mm between the points and changes the diameter of the point. The diameter of the point near the light source 2 is 0.2 mm, and the diameter of the point increases as the distance from the light source 2 increases. , The diameter of the point at the position farthest from the light source 2
0.9mm. At this time, the degree of change in the diameter of the point was adjusted so that the drawing area of the light diffuse reflection means was 25% of the light emission area. The light output area is an area radiated from the front surface of the transparent substrate 1 to the outside, and is the same as the area where the light diffuse reflection layer 3 on the back surface of the transparent substrate 1 is drawn. On the other hand, the light source 2 uses a cold-cathode tube having a tube diameter of 8 mm and a length of 250 mm, and is disposed at one end on the longitudinal direction side of the transparent substrate 1.

第１実施例では、バックライト装置上の輝度を、中心
の位置、中心から70mmだけ光源２側に近づいた位置、及
び中心から70mmだけ光源側から遠ざかった位置の３箇所
で輝度計により計測した。この計測値によると、輝度
は、３箇所とも160±20cd/m2の範囲内にあり、又目視で
は輝度むらが観測できず、良好な輝度の均一性を得るこ
とができた。In the first embodiment, the luminance on the backlight device was measured by a luminance meter at three positions: a center position, a position closer to the light source 2 by 70 mm from the center, and a position farther from the light source side by 70 mm from the center. . According to the measured values, the luminance was in the range of 160 ± 20 cd / m 2 at all three places, and the luminance unevenness could not be visually observed, and good luminance uniformity could be obtained.

次に、第２実施例について説明すると、第２実施例
は、光乱反射層３の描写形態を変更させたもので、その
他は第１実施例と同一である。つまり、光乱反射層３の
点間ピッチを1mmで固定し、光源２の付近での点の直径
を0.2mmとし、光源２から隔たるに従って点を径大に
し、光源から最も距離をおいた位置では点の直径を0.5m
mとした。この時の光乱反射層の描写面積は、出光面積
の８％になるように点の直径の変化の度合いを調整し
た。本実施例のバックライト装置も第１実施例と同一の
位置及び輝度計で輝度を計測した。この計測値によれ
ば、輝度は３箇所とも、140±30cd/m2の範囲内にあり、
又目視によって輝度むらを観測し得たが、著しいもので
はなかった。Next, a description will be given of a second embodiment. The second embodiment is different from the first embodiment in that the depiction form of the light diffusely reflecting layer 3 is changed. That is, the pitch between the points of the light diffuse reflection layer 3 is fixed at 1 mm, the diameter of the point near the light source 2 is 0.2 mm, and the diameter of the point increases as the distance from the light source 2 increases. Now the point diameter is 0.5m
m. At this time, the degree of change in the diameter of the point was adjusted so that the drawing area of the light diffuse reflection layer was 8% of the light emission area. In the backlight device of this embodiment, the luminance was measured using the same position and luminance meter as in the first embodiment. According to this measured value, the luminance is in the range of 140 ± 30 cd / m 2 at all three places,
In addition, luminance unevenness could be visually observed, but was not remarkable.

次に、上記第１実施例と第２実施例の計測値と比較す
べく比較例を設定して輝度を計測した。Next, a comparative example was set to compare the measured values of the first and second embodiments, and the luminance was measured.

第１比較例では、第１実施例の光乱反射層３の描写形
態に変更を加えたもので、その他は第１実施例と同一で
ある。つまり第１比較例では、光乱反射層３について、
点間ピッチを1mmで固定し、光源２の付近の点の直径を
0.15mmとし、光源から離れるに従って、点を径大にし、
光源２から最も隔った位置の点の直径を0.3mmとした。
この時、光乱反射層３の描写面積は、出光面積の４％に
なるように点の直径の変化の度合を調整した。本比較例
においても、第１実施例と同一の位置及び輝度計で計測
すると、輝度は３箇所とも100±50cd/m2の範囲内とな
り、しかも目視でも充分に輝度むらが判定できる不充分
な結果になった。又輝度の絶対値は、第１実施例及び第
２実施例に比較して低く、光の利用効率が悪い。The first comparative example is different from the first embodiment in that the descriptive form of the light diffuse reflection layer 3 of the first embodiment is changed. That is, in the first comparative example, regarding the light diffuse reflection layer 3,
The pitch between points is fixed at 1 mm, and the diameter of the point near the light source 2 is
0.15mm, the larger the point as the distance from the light source,
The diameter of the point farthest from the light source 2 was 0.3 mm.
At this time, the degree of change in the diameter of the point was adjusted so that the drawing area of the light diffuse reflection layer 3 was 4% of the light emission area. Also in this comparative example, when measured with the same position and luminance meter as in the first example, the luminance was in the range of 100 ± 50 cd / m 2 at all three positions, and the luminance unevenness was insufficient to visually determine the luminance unevenness. The result was. Also, the absolute value of the luminance is lower than in the first and second embodiments, and the light use efficiency is poor.

第２比較例においても第１実施例の光乱反射層３の描
写形態を変更したものであり、光乱反射層３の点間ピッ
チを1mmで固定し、光源２の付近での点の直径を0.8mmと
し、光源２から隔たるに従って点を径大にし、光源から
最も距離をおいた位置での点の直径を0.95mmとした。こ
の時、光乱反射層３の描写面積は、出光面積の60％とな
るように点の直径の変化の度合いを調整した。本比較例
のバックライト装置においても第１実施例と同一の位置
並びに輝度計で計測すると、輝度は３箇所とも150±120
cd/m2の範囲内であり、輝度むらが多く実用には供せな
い。In the second comparative example, the depiction form of the light diffuse reflection layer 3 of the first embodiment is changed. The pitch of the light diffuse reflection layer 3 is fixed at 1 mm, and the diameter of the point near the light source 2 is 0.8. mm, the diameter of the point was increased as the distance from the light source 2 was increased, and the diameter of the point at the position furthest from the light source was 0.95 mm. At this time, the degree of change in the diameter of the point was adjusted so that the drawing area of the light diffuse reflection layer 3 was 60% of the light emission area. Also in the backlight device of this comparative example, when measured by the same position and luminance meter as in the first embodiment, the luminance was 150 ± 120 at all three places.
It is within the range of cd / m 2 , and the luminance is so uneven that it cannot be used practically.

ところで、透明基板１の一端から光源２の放射光を入
射させた光の損失は、下記の部分で生ずる。By the way, the loss of the light emitted from the light source 2 from one end of the transparent substrate 1 occurs in the following portions.

透明基板中を通過する際の損失。Loss when passing through a transparent substrate.

透明基板と空気との界面で反射する際の損失。Loss when reflected at the interface between the transparent substrate and air.

光乱反射層で乱反射する際の損失。Loss due to irregular reflection on the light diffuse reflection layer.

透明基板の後面から洩れ出る光による損失。Loss due to light leaking from the rear surface of the transparent substrate.

透明基板の周縁部から洩れ出る光による損失。Loss due to light leaking from the periphery of the transparent substrate.

上記については、透明基板１の周縁に光反射手段を
付与することで光の漏洩を防げるが、光反射手段による
周縁部分からの所謂照り返しが輝度むらの原因となるの
で、透明基板１の周縁に光反射手段を付与した際には、
その周縁付近での光乱反射層３の密度パターンの調整を
要すると共に、その周縁の光反射手段での反射の際にも
損失が生ずる。上記からまでの損失を低く押えた光
乱反射層３の描写パターンの追求は、光の利用効率の高
いバックライト装置を得る上で極め重要な要素である。In the above, light leakage can be prevented by providing light reflecting means to the periphery of the transparent substrate 1. However, since so-called reflection from the peripheral portion by the light reflecting means causes luminance unevenness, the periphery of the transparent substrate 1 is When light reflecting means is added,
It is necessary to adjust the density pattern of the light irregular reflection layer 3 in the vicinity of the periphery, and a loss occurs when the light is reflected by the light reflection means on the periphery. Pursuit of a depiction pattern of the light diffusely reflecting layer 3 in which the loss from the above is suppressed is a very important factor in obtaining a backlight device with high light use efficiency.

従って、上記第１実施例、第２実施例、第１比較例及
び第２比較例の如く、上記からまでの損失を低減す
るための考察と、実証実験の結果、光乱反射層３の描写
割合を、透明基板１の出光面積の５〜50％、更に好まし
くは15〜40％とし、かつ光乱反射層３を光源からの距離
に比例した密度のパターンにすることで、最も効率の良
いバックライト装置が得られた。そして、光乱反射層３
の描写割合を、透明基板１の出光面積の15〜40％にする
のが、輝度の均一化が最も良好であり、透明基板１の端
面から入射した光の損失の発生が最も少ない特性を持た
せ得るものである。Therefore, as in the first embodiment, the second embodiment, the first comparative example, and the second comparative example, consideration for reducing the loss from the above and the result of the verification experiment show that the depiction ratio of the light diffuse reflection layer 3 is obtained. Is 5 to 50%, more preferably 15 to 40%, of the light emission area of the transparent substrate 1 and the light scattering layer 3 is formed into a pattern having a density proportional to the distance from the light source, so that the most efficient backlight can be obtained. The device was obtained. And the light diffuse reflection layer 3
Is set to 15% to 40% of the light emission area of the transparent substrate 1, the characteristics are the most uniform, and the loss of light incident from the end face of the transparent substrate 1 is minimized. It can be done.

尚、本発明において、上記光乱反射層として、上記実
施例の他に、光源からの距離に応じて単位面積当たりの
点の数を変え、又は光源からの距離に応じて点の径と単
位面積当たりの点の数の両者を変えることもでき、又、
点に限らず、線を用いて、その線の太さや線相互間の間
隔を変える形式をも採用できる。In the present invention, in addition to the above embodiment, the number of points per unit area is changed according to the distance from the light source, or the diameter and the unit area of the point are changed according to the distance from the light source. You can change both the number of points per hit,
Not limited to points, a form in which a line is used to change the thickness of the line and the interval between the lines can also be adopted.

又、光源２については、上記実施例では、透明基板１
の１端側にのみ配設したが、対向する両端部側に配設す
る２個用いた形式や、四周縁の総てに配設する形式にす
ることもでき、光源の数を増加させれば、輝度の向上を
図ることができる。この場合も、各光源からの距離に応
じた密度のパターンで光乱反射層を形成することは勿論
であり光の利用率を高めて輝度の均一性に優れるバック
ライト装置が達成できる。The light source 2 is the transparent substrate 1 in the above embodiment.
Although it is arranged only on one end side, it is also possible to adopt a form using two arranged on both end portions facing each other or a form arranged on all four edges, so that the number of light sources can be increased. Thus, the luminance can be improved. In this case as well, it is possible to form a light diffuse reflection layer with a pattern having a density corresponding to the distance from each light source, and it is also possible to achieve a backlight device having high uniformity of luminance by increasing light utilization.

「発明の効果」 上記の如く、本発明に係るバックライト装置によれ
ば、光源を透明基板の厚み方向ではなく周縁側に配設す
ることから、バックライト装置としての全体の厚みが、
光源の径を含む透明基板の厚み、光拡散層、光乱反射層
の重層厚、これをハウジングに組着する際の若干のクリ
アランス、その他必要とするハウジング等の部材の厚み
の合計値で済み、しかも輝度の均一性に優れ、従って従
来の技術では困難であった薄形でかつ軽量であり、更に
大面積化を図っても優れた輝度の均一性を得ることがで
きて、光の利用効率が高いバックライト装置を本発明に
おいて提供し得るものである。また、本発明に置ける光
拡散層を、表面を粗面化したフィルムから構成される光
拡散層にすれば、コストや耐久性等に優れる。以上の如
き本発明のバックライト装置は、液晶ディスプレイ（LC
D）の背後に設置することにより、薄形でしかも輝度む
らのない見易い画面を実現し得て、液晶ディスプレイ
（LCD）の機能の向上に多大に貢献でき、その他の各種
バックライト装置としても利用できるものである。"Effects of the Invention" As described above, according to the backlight device of the present invention, since the light source is disposed on the peripheral side instead of the thickness direction of the transparent substrate, the overall thickness of the backlight device is
The total value of the thickness of the transparent substrate including the diameter of the light source, the light diffusion layer, the multilayer thickness of the light diffuse reflection layer, some clearance when assembling this to the housing, and the thickness of other necessary components such as the housing, In addition, it has excellent brightness uniformity, so it is thin and lightweight, which was difficult with the conventional technology, and it is possible to obtain excellent brightness uniformity even if the area is increased, and it is possible to use light efficiently. The present invention can provide a backlight device having a high level of reliability. In addition, if the light diffusion layer according to the present invention is a light diffusion layer composed of a film having a roughened surface, cost and durability are excellent. As described above, the backlight device of the present invention is a liquid crystal display (LC).
By installing it behind D), it is possible to realize a thin and easy-to-view screen with no brightness unevenness, which can greatly contribute to the improvement of the function of the liquid crystal display (LCD), and can be used as various other backlight devices You can do it.

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

第１図は本発明に係るバックライト装置の実施例を示す
分解斜視図、第２図はそのバックライト装置の組立て時
の斜視図、第３図は透明基板の裏面に付した光乱反射層
の描写形態を示す説明図である。 １……透明基板、２……光源 ３……光乱反射層、４……光拡散層 ５……ハウジングFIG. 1 is an exploded perspective view showing an embodiment of a backlight device according to the present invention, FIG. 2 is a perspective view when the backlight device is assembled, and FIG. 3 is a view showing a light diffuse reflection layer attached to the back surface of a transparent substrate. It is explanatory drawing which shows a depiction form. DESCRIPTION OF SYMBOLS 1 ... Transparent board, 2 ... Light source 3 ... Light diffuse reflection layer 4, ... Light diffusion layer 5 ... Housing

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平２−269382（ＪＰ，Ａ) 特開 昭62−169105（ＪＰ，Ａ) 特開 昭57−128383（ＪＰ，Ａ) ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-269382 (JP, A) JP-A-62-169105 (JP, A) JP-A-57-128383 (JP, A)

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】透明基板の四周のうちの少なくとも１箇所
に蛍光灯を配設し、透明基板の後面には蛍光灯からの距
離に応じて密度が高まるパターンでかつ透明基板の表面
の出光面積に対して５〜50％の占有率を持たせて光拡散
反射層を形成し、透明基板の表面には光拡散層を設け、
液晶ディスプレイの背面に配設されて、該液晶ディスプ
レイを照射するバックライト装置。A fluorescent lamp is provided at at least one of the four circumferences of a transparent substrate, and a light emitting area on the rear surface of the transparent substrate has a pattern whose density increases according to a distance from the fluorescent lamp and a surface of the transparent substrate. To form a light diffusion / reflection layer with an occupancy of 5 to 50%, and a light diffusion layer on the surface of the transparent substrate;
A backlight device disposed on the back of the liquid crystal display and illuminating the liquid crystal display. 【請求項２】上記光拡散層が、表面を粗面化したフィル
ムから構成される光拡散層であることを特徴とする請求
項（１）記載のバックライト装置。2. The backlight device according to claim 1, wherein the light diffusion layer is a light diffusion layer composed of a film having a roughened surface.
JP01144380A 1989-06-07 1989-06-07 Backlight device Expired - Lifetime JP3077907B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP01144380A JP3077907B2 (en) 1989-06-07 1989-06-07 Backlight device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP01144380A JP3077907B2 (en) 1989-06-07 1989-06-07 Backlight device

Publications (2)

Publication Number Publication Date
JPH039304A JPH039304A (en) 1991-01-17
JP3077907B2 true JP3077907B2 (en) 2000-08-21

Family

ID=15360785

Family Applications (1)

Application Number Title Priority Date Filing Date
JP01144380A Expired - Lifetime JP3077907B2 (en) 1989-06-07 1989-06-07 Backlight device

Country Status (1)

Country Link
JP (1) JP3077907B2 (en)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04369619A (en) * 1991-06-18 1992-12-22 Nissha Printing Co Ltd Face light source device
US5450292A (en) * 1992-03-16 1995-09-12 Enplas Corporation Surface light source device
JPH05307177A (en) * 1992-04-30 1993-11-19 Riyoosan:Kk Back light device
JP2980776B2 (en) * 1992-06-04 1999-11-22 東ソー株式会社 Backlight
JPH07168025A (en) * 1993-12-13 1995-07-04 Nec Corp Flat light source apparatus
JP2830972B2 (en) * 1995-03-06 1998-12-02 株式会社日立製作所 Liquid crystal display
KR100490329B1 (en) * 1998-07-29 2005-08-02 삼성전자주식회사 Backlight assembly
JP3744289B2 (en) * 1999-11-26 2006-02-08 セイコーエプソン株式会社 Display device and electronic apparatus equipped with the same
JP3719359B2 (en) * 1999-11-26 2005-11-24 セイコーエプソン株式会社 Display device and electronic device including the same
JP3719360B2 (en) * 1999-11-26 2005-11-24 セイコーエプソン株式会社 Display device and electronic device including the same
JP3719361B2 (en) * 1999-11-26 2005-11-24 セイコーエプソン株式会社 Display device and electronic device including the same
JP2002091330A (en) * 2000-09-14 2002-03-27 Toshiba Electronic Engineering Corp Flat display device having backlight
JP2002231031A (en) * 2001-02-06 2002-08-16 Enplas Corp Flat light source device, image display device and light guide plate

Also Published As

Publication number Publication date
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