JPH09133918A - Surface light source element for liquid crystal display device - Google Patents
Surface light source element for liquid crystal display deviceInfo
- Publication number
- JPH09133918A JPH09133918A JP7288552A JP28855295A JPH09133918A JP H09133918 A JPH09133918 A JP H09133918A JP 7288552 A JP7288552 A JP 7288552A JP 28855295 A JP28855295 A JP 28855295A JP H09133918 A JPH09133918 A JP H09133918A
- Authority
- JP
- Japan
- Prior art keywords
- light
- light source
- light guide
- source element
- liquid crystal
- 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)
- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ノートパソコン、
液晶テレビ等に使用される液晶表示装置に使用される面
光源素子に関するものであり、さらに詳しくは、高い輝
度を有するとともに、斑点パターン等の均一化処理を施
すことなく光出射面内での均一な輝度分布が得られる面
光源素子に関するものである。The present invention relates to a notebook computer,
The present invention relates to a surface light source element used in a liquid crystal display device used in a liquid crystal television, etc., and more specifically, it has high brightness and is uniform in a light emitting surface without being subjected to uniformization processing such as spot patterns. The present invention relates to a surface light source element that can obtain a wide brightness distribution.
【０００２】[0002]
【従来の技術】近年、カラー液晶表示装置は、ノートパ
ソコンや、液晶テレビあるいはビデオ一体型液晶テレビ
等として種々の分野で広く使用されてきている。この液
晶表示装置は、基本的にバックライト部と液晶表示素子
部とから構成されている。バックライト部としては、液
晶表示素子の直下に光源を設けた直下方式や導光体の側
面に光源を設けたエッジライト方式があり、液晶表示装
置のコンパクト化からエッジライト方式が多用されてき
ている。このエッジライト方式は、板状の導光体の側面
部に光源を配置して、導光体の表面全体を発光させる方
式のバックライトであり、いわゆる面光源素子と呼ばれ
るものである。2. Description of the Related Art In recent years, color liquid crystal display devices have been widely used in various fields such as notebook personal computers, liquid crystal televisions, and video liquid crystal televisions. This liquid crystal display device is basically composed of a backlight section and a liquid crystal display element section. As the backlight part, there are a direct type in which a light source is provided directly below the liquid crystal display element and an edge light type in which a light source is provided on the side surface of the light guide body.The edge light type has been widely used due to the compactness of the liquid crystal display device. There is. The edge light method is a backlight of a method in which a light source is arranged on a side surface of a plate-shaped light guide to emit light on the entire surface of the light guide, and is a so-called surface light source element.
【０００３】このような面光源素子では、アクリル樹脂
板等の板状透明材料を導光体とし、その一端に配置され
た光源からの光を光入射面から導光体中に入射させ、入
射した光を導光体の表面（光出射面）あるいは裏面に形
成した光散乱部等の光出射機能を設けることにより、光
出射面から面状に出射させるものである。しかし、導光
体の表面あるいは裏面に光出射機能を均一に形成したも
のでは、光源から離れるに従って出射光の輝度が低下し
て、光出射面内における輝度が不均一となり、良好な表
示画面が得られないものであった。このような傾向は、
液晶表示素子の大型化に伴って顕著となり、１０インチ
以上の大型液晶表示装置においては実用に耐えうるもの
ではなかった。特に、最近の液晶画面の大型化に伴い、
ノートパソコンや液晶テレビ等に使用される液晶表示装
置においては、その画面内での輝度分布は非常に高い均
一性が要求されるものである。In such a surface light source element, a plate-shaped transparent material such as an acrylic resin plate is used as a light guide, and light from a light source disposed at one end of the light guide is made to enter the light guide from a light incident surface. By providing a light emitting function such as a light scattering portion formed on the front surface (light emitting surface) or the rear surface of the light guide, the light thus emitted is emitted from the light emitting surface in a planar manner. However, when the light emitting function is formed uniformly on the front surface or the back surface of the light guide, the brightness of the emitted light decreases as the distance from the light source increases, and the brightness within the light emitting surface becomes non-uniform. It could not be obtained. This trend is
It became remarkable with the enlargement of the liquid crystal display element, and was not practically usable in a large liquid crystal display device of 10 inches or more. In particular, with the recent enlargement of the LCD screen,
2. Description of the Related Art In a liquid crystal display device used for a notebook computer, a liquid crystal television, or the like, a very high uniformity of luminance distribution in a screen is required.
【０００４】このような面光源素子の輝度の不均一とい
う課題を解決するために、種々の提案がなされている。
例えば、特開平１−２４５２２号公報には、導光体の光
出射面に対向する裏面に光入射面から離れるに従って光
拡散物質を密に塗布または付着させた光出射機能を設け
た面光源素子が提案されている。また、特開平１−１０
７４０６号公報には、表面に光散乱物質からなる細かい
斑点を種々のパターンで形成した複数の透明板を積層し
て導光体としたのもが提案されている。このような面光
源素子においては、光散乱物質として酸化チタンや硫酸
バリウム等の白色顔料を使用しているため、光散乱物質
に当たった光が散乱する際に光吸収等の光のロスが生
じ、出射光の輝度の低下を招くため好ましくないもので
あった。Various proposals have been made to solve the problem of non-uniform brightness of the surface light source element.
For example, JP-A-1-24522 discloses a surface light source element having a light emitting function in which a light diffusing substance is densely applied or adhered to a back surface opposite to a light emitting surface of a light guide as the distance from the light incident surface increases. Has been proposed. Also, Japanese Patent Application Laid-Open No. 1-10
Japanese Patent No. 7406 proposes that a plurality of transparent plates having fine spots made of a light-scattering substance formed in various patterns on the surface thereof are laminated to form a light guide. In such a surface light source element, since a white pigment such as titanium oxide or barium sulfate is used as a light scattering substance, loss of light such as light absorption occurs when light hitting the light scattering substance is scattered. This is not preferable because it causes a decrease in the luminance of the emitted light.
【０００５】また、特開平１−２４４４９０号公報や特
開平１−２５２９３３号公報には、導光体の光出射面上
に出射光分布の逆数に見合う光反射パターンを有する出
射光調整部材や光拡散板を配置した面光源素子が提案さ
れている。しかし、このような面光源素子においても、
出射光調整部材や光拡散板で反射した光の再利用ができ
ないために光のロスが生じ、出射光の輝度の低下を招く
ものであった。さらに、特開平２−８４６１８号公報に
は、導光体の光出射面およびその裏面の少なくとも一方
の面を梨地面とし、光出射面上にプリズムシートを載置
した面光源素子が提案されている。しかし、このような
面光源素子は、非常に高い輝度が得られるものの、光出
射面における均一性の点で未だ満足できるものではなか
った。Also, Japanese Patent Application Laid-Open Nos. 1-244490 and 1-252933 disclose an output light adjusting member and a light control member having a light reflection pattern on the light output surface of a light guide, which is the inverse of the output light distribution. A surface light source element having a diffusion plate has been proposed. However, even in such a surface light source element,
Since the light reflected by the emission light adjusting member and the light diffusion plate cannot be reused, light loss occurs, and the luminance of the emission light is reduced. Further, Japanese Patent Application Laid-Open No. 2-84618 proposes a surface light source element in which at least one of the light emitting surface and the back surface of the light guide body is used as a matte surface and a prism sheet is placed on the light emitting surface. There is. However, although such a surface light source element can obtain extremely high brightness, it is still unsatisfactory in terms of uniformity on the light emitting surface.
【０００６】[0006]
【発明が解決しようとする課題】一方、出射光の輝度の
均一化とともに光のロスを低減して輝度を高める面光源
素子については、特開平３−３４５８９３号公報に提案
されているように、導光体の光出射面を梨地面とし、そ
の裏面に粗面部分と平滑部分を粗面部分の割合が光源か
ら離れるに従って増加するように形成するとともに、光
出射面上にプリズムシートを載置した面光源素子が提案
されている。しかしながら、このような面光源素子で
は、出射光の輝度の均一化と光のロスの低減を図れるも
のの、液晶表示装置として使用する場合に、液晶表示素
子を通して導光体の裏面に形成した粗面部分と平滑部分
とで形成されるパターンが観察され、画像の観察に支障
をきたすものであった。また、導光体の表面に均一光出
射機能を施すことは、導光体の生産性の観点からも好ま
しいものではない。そこで、本発明は、高い輝度を有す
るとともに、斑点パターン等の均一化処理を施すことな
く光出射面内での輝度の高い均一性が得られる面光源素
子を提供することを目的とする。On the other hand, as for the surface light source element for uniforming the brightness of the emitted light and reducing the loss of the light to increase the brightness, as disclosed in JP-A-3-345893, The light exit surface of the light guide is made to have a matte surface, and the rough surface portion and the smooth portion are formed on the back surface so that the ratio of the rough surface portion increases as the distance from the light source increases, and a prism sheet is placed on the light exit surface. A surface light source element has been proposed. However, in such a surface light source element, although the brightness of the emitted light can be made uniform and the loss of light can be reduced, when used as a liquid crystal display device, a rough surface formed on the back surface of the light guide through the liquid crystal display element. The pattern formed by the portion and the smooth portion was observed, which hindered the observation of the image. Also, providing a uniform light emitting function to the surface of the light guide is not preferable from the viewpoint of productivity of the light guide. Therefore, it is an object of the present invention to provide a surface light source element which has high brightness and can obtain high uniformity of brightness in a light emitting surface without performing a uniformization process of a spot pattern or the like.
【０００７】[0007]
【課題を解決するための手段】すなわち、本発明の液晶
表示装置用面光源素子は、光源と、該光源に対向する少
なくとも一つの光入射面およびこれと略直交する光出射
面を有する導光体からなり、導光体の光出射面およびそ
の裏面の少なくとも一方の面が平均傾斜角（θａ）０．
５〜７．５゜の凹凸を有する粗面から構成されて、導光
体の光出射面における輝度のバラツキ度（Ｒ％）が２０
％以下であることを特徴とするものである。That is, a surface light source element for a liquid crystal display device of the present invention is a light guide having a light source, at least one light incident surface facing the light source, and a light emitting surface substantially orthogonal to the light incident surface. At least one of the light emitting surface and the back surface of the light guide has an average inclination angle (θa) of 0.
It is composed of a rough surface having irregularities of 5 to 7.5 °, and the degree of variation in brightness (R%) on the light emitting surface of the light guide is 20.
% Or less.
【０００８】[0008]
【発明の実施の形態】本発明の面光源素子は、光源と、
この光源に対向する少なくとも一つの光入射面およびこ
れと略直交する光出射面を有する導光体から構成され
る。このような面光源素子において、導光体中に入射し
た光は、臨界角以内の分布の光が導光体の面で反射を繰
り返して導光体中を伝搬する。導光体の表面に粗面部分
を形成した場合には、粗面部分に到達した光のうち粗面
に対して臨界角を超える光は屈折して導光体の外へ出射
し、臨界角以内の光は反射して導光体を伝搬する。これ
は、光の進行方向が、スネルの法則に従って媒体の屈折
率と入射した面の法線に対する光の入射角によって決定
されることによる。BEST MODE FOR CARRYING OUT THE INVENTION The surface light source element of the present invention comprises a light source,
The light guide body has at least one light incident surface facing the light source and a light exit surface substantially orthogonal to the light incident surface. In such a surface light source element, the light incident on the light guide body propagates in the light guide body by repeating the reflection of light having a distribution within the critical angle on the surface of the light guide body. When a rough surface portion is formed on the surface of the light guide, light exceeding the critical angle with respect to the rough surface out of the light reaching the rough surface portion is refracted and emitted out of the light guide, and the critical angle The light within is reflected and propagates through the light guide. This is because the traveling direction of light is determined by the refractive index of the medium according to Snell's law and the incident angle of light with respect to the normal line of the incident surface.
【０００９】図１に、凹凸を有する粗面での光の屈折お
よび反射を模式的に示した。臨界角を超える入射角ｉで
凹凸部の斜面に入射した光Ａは、スネルの法則によりｎ
ｓｉｎｉ＝ｓｉｎｉ’（ｎは導光体の屈折率）の関係を
満足する出射角ｉ’で導光体外に出射する。一方、臨界
角内である入射角ｋで入射した光Ｂは、角度ｋ’（ｋ’
＝ｋ）で反射して導光体内を伝搬する。一旦、粗面部分
に入射して反射した光は、次に粗面部分に入射する際に
入射角が鋭くなるため、臨界角を超えやすくなり導光体
外へ出射しやすくなる。FIG. 1 schematically shows refraction and reflection of light on a rough surface having irregularities. The light A incident on the slope of the uneven portion at an incident angle i exceeding the critical angle is n according to Snell's law.
The light is emitted outside the light guide body at an emission angle i ′ that satisfies the relationship of sini = sini ′ (n is the refractive index of the light guide body). On the other hand, the light B incident at the incident angle k which is within the critical angle has an angle k ′ (k ′
= K) and propagate in the light guide. The light that once enters the rough surface portion and is reflected becomes sharp at an incident angle when it subsequently enters the rough surface portion, so that it is easy to exceed the critical angle and easily exit to the outside of the light guide.
【００１０】本発明者等は、面光源素子において、ある
点での光の出射強度（Ｉ）と光入射面端での出射光強度
（Ｉ0 ）との関係は、出射率（α）、光出射面端からの
距離（Ｌ’）および導光体の厚さ（ｔ）によって、実験
的に次の（１）式で表されることを見出した。The inventors of the present invention have found that in the surface light source element, the relationship between the light emission intensity (I) at a certain point and the light emission intensity (I 0 ) at the edge of the light incident surface is expressed by the emission rate (α), It was found experimentally that it is expressed by the following formula (1) depending on the distance (L ′) from the end of the light emitting surface and the thickness (t) of the light guide.
【００１１】[0011]
【数１】Ｉ＝Ｉ0（１−α）L'/20t ・・・ （１） （１）式から、導光体の長さ（Ｌ）と厚さ（ｔ）が決定
すれば、出射率（α）によって光出射面内での輝度の均
一性が決定されることがわかる。なお、厚さｔｍｍの導
光体の出射率（α）は、導光体の光入射面端から２０ｍ
ｍ間隔で輝度の測定を行い、光入射面端からの距離
（ｌ）と輝度の対数のグラフから、その勾配（Ｋ（ｍｍ
-1））を求めて、次の（２）式によって求められる。I = I 0 (1−α) L ′ / 20t (1) If the length (L) and the thickness (t) of the light guide are determined from the equation (1), the light is emitted. It can be seen that the uniformity of luminance in the light emitting surface is determined by the rate (α). The emission ratio (α) of the light guide having a thickness of tmm is 20 m from the light incident surface end of the light guide.
Luminance was measured at m intervals, and the gradient (K (mm
-1 )) is obtained by the following equation (2).
【００１２】[0012]
【数２】 α＝（１−１０20K）×１００ ・・・ （２） 本発明においては、輝度の均一性の尺度として、次の
（３）式で示されるバラツキ度（Ｒ％）を用いて、面光
源素子における輝度の均一性についての評価および検討
を行った。バラツキ度（Ｒ％）は、導光体のほぼ中央部
において光入射面端から２０ｍｍ離れた点から対向する
端部までの範囲内を２０ｍｍ間隔で輝度測定を行い、測
定輝度の最大値（Ｉmax ）、測定輝度の最小値
（Ｉmin ）、測定輝度の平均値（Ｉav）を求め、次の
（３）式によって求める。## EQU2 ## α = (1-10 20K ) × 100 (2) In the present invention, the variation degree (R%) shown in the following equation (3) is used as a measure of the uniformity of luminance. Then, the evaluation and examination on the uniformity of luminance in the surface light source element were performed. The degree of variation (R%) is measured by measuring the luminance at 20 mm intervals within a range from a point 20 mm away from the end of the light incident surface to the opposite end in the substantially central portion of the light guide, and measuring the maximum value (I max ), the minimum value of the measured luminance (I min ), and the average value of the measured luminance (I av ), and the following equation (3) is used.
【００１３】[0013]
【数３】 Ｒ％＝｛（Ｉmax−Ｉmin）／Ｉav｝×１００ ・・・ （３） その結果、出射率（α）とバラツキ度（Ｒ％）とは、導
光体の長さ（Ｌ）と厚さ（ｔ）に依存して特定の関係に
あることが見出され、出射率（α）が大きくなるとバラ
ツキ度（Ｒ％）はそれに伴って増加し、出射率（α）が
一定であれば導光体の長さ（Ｌ）と厚さ（ｔ）の比（Ｌ
／ｔ）が大きくなるに従ってバラツキ度（Ｒ％）も大き
くなる。すなわち、一定の大きさの導光体においては、
導光体の光出射面内での輝度の均一性（バラツキ度）
は、導光体からの出射率（α）に依存するものであり、
出射率（α）を制御することによって輝度の均一性を図
ることができることがわかる。Equation 3] R% = {(I max -I min) / I av} × 100 ··· (3) As a result, the output rate and (alpha) and variation degree (R%), the length of the light guide It has been found that there is a specific relationship depending on the thickness (L) and the thickness (t). When the emission rate (α) increases, the degree of variation (R%) increases accordingly, and the emission rate (α) increases. ) Is constant, the ratio (L) of the length (L) to the thickness (t) of the light guide is obtained.
/ T) increases, the degree of variation (R%) also increases. That is, in a light guide of a certain size,
Luminance uniformity (degree of variation) within the light exit surface of the light guide
Depends on the emission rate (α) from the light guide,
It can be seen that brightness uniformity can be achieved by controlling the emission rate (α).
【００１４】一方、本発明者等は、導光体の表面に形成
した凹凸形状を有する粗面において、凹凸形状を近似的
に１つの勾配を有する斜面であると考えると、粗面を構
成する凹凸の勾配に依存して、導光体から出射する光の
出射方向や出射率が変化することを見出した。ここで、
この勾配としてＩＳＯ４２８７／１−１９８７で規定さ
れる平均傾斜角（θａ）を用いることができる。すなわ
ち、平均傾斜角（θａ）が大きくなると、導光体からの
出射光は出射角が小さくなり法線方向に近づいた出射光
となる。また、平均傾斜角（θａ）が大きくなると、そ
れに伴って導光体からの出射率も高くなる。このことか
ら、面光源素子の光出射面内での輝度の均一性は、導光
体からの出射率を低くすることによって高めることがで
き、平均傾斜角（θａ）を小さくすれば均一化が図れる
ことがわかった。ノートパソコンや液晶テレビ等の液晶
表示装置において使用される面光源素子としては、その
バラツキ度（Ｒ％）が２０％以下であることが必要であ
れば、要求される輝度の均一性を満足することを見出
し、このためには粗面を構成する凹凸の平均傾斜角（θ
ａ）を７．５゜以下とすることが必要であることがわか
った。また、ノートパソコンや液晶テレビ等の液晶表示
装置に使用する面光源素子としては、そのバラツキ度
（Ｒ％）は好ましくは１５％以下であり、さらに好まし
くは１０％以下である。On the other hand, when the present inventors consider that the rough surface formed on the surface of the light guide has a rough surface, the rough surface constitutes a rough surface when the rough surface is a slope having approximately one gradient. It was found that the emitting direction and the emitting rate of the light emitted from the light guide body change depending on the gradient of the unevenness. here,
As this gradient, the average inclination angle (θa) defined by ISO4287 / 1-1987 can be used. That is, when the average inclination angle (θa) increases, the light emitted from the light guide has a smaller emission angle and becomes closer to the normal direction. Further, as the average inclination angle (θa) increases, the emission rate from the light guide body increases accordingly. From this, it is possible to improve the uniformity of the brightness in the light emitting surface of the surface light source element by decreasing the emission rate from the light guide body, and it is possible to make the uniformity uniform by reducing the average inclination angle (θa). I found that I could achieve it. As a surface light source element used in a liquid crystal display device such as a notebook computer or a liquid crystal television, if the degree of variation (R%) thereof is required to be 20% or less, the required uniformity of brightness is satisfied. It is found that the average inclination angle (θ
It has been found that it is necessary to set a) to 7.5 ° or less. As a surface light source element used in a liquid crystal display device such as a notebook computer or a liquid crystal television, the degree of variation (R%) is preferably 15% or less, more preferably 10% or less.
【００１５】従って、面光源素子の光出射面内における
輝度の均一化を図るためには、導光体の光出射面および
その裏面の少なくとも一方の面が平均傾斜角（θａ）
０．５〜７．５゜の凹凸を有する粗面から構成するが必
要である。これは、粗面を構成する凹凸の平均傾斜角
（θａ）が０．５゜未満であると、光出射面からの出射
光の出射角が大きくなり、プリズムシート等の変角部材
を使用しても十分に法線方向へ出射光を向けることがで
きなくなるためである。逆に、粗面を構成する凹凸の平
均傾斜角（θａ）が７．５゜を超えると、液晶表示装置
の面光源素子として輝度の均一性が損なわれるためであ
る。好ましくは、粗面を構成する凹凸の平均傾斜角（θ
ａ）が１〜５゜の範囲であり、さらに好ましくは２〜４
゜の範囲である。Therefore, in order to make the brightness uniform in the light emitting surface of the surface light source element, at least one of the light emitting surface and the back surface of the light guide body has an average inclination angle (θa).
It is necessary to form a rough surface having irregularities of 0.5 to 7.5 °. This is because if the average inclination angle (θa) of the irregularities that form the rough surface is less than 0.5 °, the output angle of the output light from the light output surface becomes large, and a bending member such as a prism sheet is used. However, it is impossible to sufficiently direct the emitted light in the normal direction. On the contrary, if the average inclination angle (θa) of the irregularities forming the rough surface exceeds 7.5 °, the uniformity of luminance is impaired as a surface light source element of the liquid crystal display device. Preferably, the average inclination angle (θ
a) is in the range of 1 to 5 °, more preferably 2 to 4
範 囲 range.
【００１６】本発明の面光源素子に使用される導光体と
しては、その大きさは特に限定されるものではないが、
本発明の効果をより顕著に発揮させるためには導光体の
長さ（Ｌ）と厚さ（ｔ）との比（Ｌ／ｔ）が１２０以下
の導光体として使用することが好ましい。Ｌ／ｔが１２
０を超えると、導光体の粗面を構成する凹凸の平均傾斜
角（θａ）を小さくしても、光出射面内での輝度の均一
性が十分に図れない傾向にあるためであり、さらに好ま
しくは１００以下、より好ましくは８０以下の範囲であ
る。The size of the light guide used in the surface light source element of the present invention is not particularly limited,
In order to bring out the effect of the present invention more remarkably, it is preferable to use as a light guide having a ratio (L / t) of the length (L) to the thickness (t) of the light guide of 120 or less. L / t is 12
This is because if it exceeds 0, even if the average inclination angle (θa) of the irregularities that form the rough surface of the light guide is reduced, it is likely that the luminance uniformity in the light emission surface cannot be sufficiently achieved. The range is more preferably 100 or less, and even more preferably 80 or less.
【００１７】本発明において、導光体としては、ガラス
や合成樹脂等の透明板状体を使用することができる。合
成樹脂としては、例えば、アクリル系樹脂、ポリカーボ
ネート系樹脂、塩化ビニル系樹脂等の高透明性の種々の
合成樹脂を用いることができ、この樹脂を押出成形、射
出成形等の通常の成形方法で板状体に成形することによ
って導光体を製造することができる。特に、メタクリル
樹脂が、その光線透過率の高さ、耐熱性、力学的特性、
成形加工性にも優れており、導光体用材料として最適で
ある。このようなメタクリル樹脂とは、メタクリル酸メ
チルを主成分とする樹脂であり、メタクリル酸メチルが
８０重量％以上であることが好ましい。また、導光体中
には、光拡散剤や微粒子等を混入してもよい。In the present invention, as the light guide, a transparent plate made of glass, synthetic resin or the like can be used. As the synthetic resin, for example, various highly transparent synthetic resins such as an acrylic resin, a polycarbonate resin, a vinyl chloride resin can be used, and this resin can be molded by a usual molding method such as extrusion molding or injection molding. The light guide can be manufactured by molding into a plate. In particular, methacrylic resin has high light transmittance, heat resistance, mechanical properties,
It has excellent moldability and is optimal as a light guide material. Such a methacrylic resin is a resin containing methyl methacrylate as a main component, and methyl methacrylate is preferably 80% by weight or more. Further, a light diffusing agent, fine particles or the like may be mixed in the light guide.
【００１８】導光体に特定の平均傾斜角（θａ）の凹凸
を有する粗面を形成する加工方法としては、平均傾斜角
（θａ）が特定の範囲となれば特に限定されるものでは
ないが、例えば、化学エッチングによって粗面を形成し
た金型、ガラスビーズ等の微粒子を吹き付けて粗面化し
た金型等を用いて、加熱プレス等によって粗面を転写す
る方法、印刷法等によって凹凸物質を塗布あるいは付着
する方法、導光体をサンドブラスト法やエッチング法等
によって直接加工する方法等が挙げられる。本発明の面
光源素子は、上記のような導光体の一方の端部に蛍光灯
等の光源を配置し、光出射面と対向する裏面には、反射
フィルム等によって反射層が形成される。光源から導光
体へ有効に光を導入するために、光源および導光体の光
入射面を内側に反射剤を塗布したケースやフィルムで覆
うように構成される。また、導光体としては、板状、く
さび状、船型状等の種々の形状のものが使用できる。The processing method for forming a rough surface having irregularities of a specific average inclination angle (θa) on the light guide is not particularly limited as long as the average inclination angle (θa) falls within a specific range. , For example, a mold having a rough surface formed by chemical etching, a mold having a rough surface formed by spraying fine particles such as glass beads, and the like, a method of transferring the rough surface by a heat press, a concavo-convex substance by a printing method, etc. And a method of directly processing the light guide by a sandblast method, an etching method, or the like. In the surface light source element of the present invention, a light source such as a fluorescent lamp is arranged at one end of the light guide as described above, and a reflection layer is formed by a reflection film or the like on the back surface facing the light emission surface. . In order to effectively introduce light from the light source to the light guide body, the light incident surfaces of the light source and the light guide body are covered with a case or film coated with a reflective agent on the inside. Further, as the light guide body, various shapes such as a plate shape, a wedge shape, and a boat shape can be used.
【００１９】本発明の面光源素子においては、通常、導
光体からの出射光の出射方向は、法線方向からずれた方
向となるため、法線方向から観察を行うような用途に使
用する場合には、導光体の上にレンズシートを載置する
等の手段を講じて、出射光を法線方向に変角することが
好ましい。この場合、使用されるレンズシートとして
は、少なくとも一方の面に多数のレンズ単位が平行に形
成されたレンズ面を有するものである。形成されるレン
ズ形状は、目的に応じて種々の形状のものが使用され、
例えば、プリズム形状、レンチキュラーレンズ形状、波
型形状等が挙げられる。レンズシートのレンズ単位のピ
ッチは３０μｍ〜０．５ｍｍ程度とすることが好まし
く、プリズムシートを使用する場合には、そのプリズム
頂角は導光体からの出射光の出射角によって適宜選定さ
れるが、一般的には５０〜１２０゜の範囲とすることが
好ましい。また、プリズムシートの向きについても、導
光体からの出射光の出射角によって適宜選定され、レン
ズ面が導光体側となるように載置してもよいし、逆向き
に載置してもよい。In the surface light source element of the present invention, since the outgoing direction of the outgoing light from the light guide is usually deviated from the normal direction, it is used for the purpose of observing from the normal direction. In this case, it is preferable to take measures such as placing a lens sheet on the light guide to change the angle of the emitted light in the normal direction. In this case, the lens sheet used has a lens surface in which a large number of lens units are formed in parallel on at least one surface. As the lens shape to be formed, various shapes are used according to the purpose,
For example, a prism shape, a lenticular lens shape, a corrugated shape, etc. may be mentioned. The pitch of the lens unit of the lens sheet is preferably about 30 μm to 0.5 mm, and when the prism sheet is used, the apex angle of the prism is appropriately selected according to the emission angle of the emitted light from the light guide. Generally, it is preferable that the angle is in the range of 50 to 120 °. Also, the orientation of the prism sheet is appropriately selected depending on the emission angle of the emitted light from the light guide, and the prism sheet may be placed so that the lens surface is on the light guide side, or may be placed in the opposite direction. Good.
【００２０】本発明のレンズシートは、可視光透過率が
高く、屈折率の比較的高い材料を用いて製造することが
好ましく、例えば、アクリル系樹脂、ポリカーボネート
系樹脂、塩化ビニル系樹脂、活性エネルギー線硬化型樹
脂等が挙げられる。中でも、レンズシートの耐擦傷性、
取扱い性、生産性等の観点から活性エネルギー線硬化型
樹脂が好ましい。また、レンズシートには、必要に応じ
て、酸化防止剤、紫外線吸収剤、黄変防止剤、ブルーイ
ング剤、顔料、拡散剤等の添加剤を添加することもでき
る。レンズシートを製造する方法としては、押出成形、
射出成形等の通常の成形方法が使用できる。活性エネル
ギー線硬化型樹脂を用いてレンズシートを製造する場合
には、ポリエステル系樹脂、アクリル系樹脂、ポリカー
ボネート系樹脂、塩化ビニル系樹脂、ポリメタクリルイ
ミド系樹脂、ポリオレフィン系樹脂等の透明樹脂からな
る透明フィルムあるいはシート等の透明基材上に、活性
エネルギー線硬化型樹脂によってレンズ部を形成する。
まず、所定のレンズパターンを形成したレンズ型に活性
エネルギー線硬化型樹脂液を注入し、透明基材を重ね合
わせる。次いで、透明基材を通して紫外線、電子線等の
活性エネルギー線を照射し、活性エネルギー線硬化型樹
脂液を重合硬化して、レンズ型から剥離してレンズシー
トを得る。本発明の面光源素子においては、上記したよ
うなレンズシートの他に、拡散シート、カラーフィルタ
ー、偏光膜等、光学的に光を変角、集束、拡散させた
り、その光学特性を変化させる種々の光学素子を使用す
ることができる。The lens sheet of the present invention is preferably manufactured by using a material having a high visible light transmittance and a relatively high refractive index. For example, acrylic resin, polycarbonate resin, vinyl chloride resin, active energy Examples include line curable resins. Among them, the scratch resistance of the lens sheet,
The active energy ray-curable resin is preferable from the viewpoints of handleability and productivity. In addition, additives such as an antioxidant, an ultraviolet absorber, an anti-yellowing agent, a bluing agent, a pigment and a diffusing agent may be added to the lens sheet, if necessary. As a method for manufacturing a lens sheet, extrusion molding,
A usual molding method such as injection molding can be used. When manufacturing a lens sheet using an active energy ray-curable resin, it is made of a transparent resin such as polyester resin, acrylic resin, polycarbonate resin, vinyl chloride resin, polymethacrylimide resin, or polyolefin resin. A lens portion is formed on a transparent base material such as a transparent film or sheet with an active energy ray-curable resin.
First, an active energy ray-curable resin liquid is injected into a lens mold having a predetermined lens pattern, and transparent base materials are superposed on each other. Next, active energy rays such as ultraviolet rays and electron rays are irradiated through the transparent base material to polymerize and cure the active energy ray-curable resin liquid, and peeled from the lens mold to obtain a lens sheet. In the surface light source element of the present invention, in addition to the lens sheet as described above, various materials such as a diffusion sheet, a color filter, a polarizing film, etc., which optically change the angle of light, converge, diffuse or change its optical characteristics. The optical element of can be used.
【００２１】[0021]
【実施例】以下、実施例により本発明を具体的に説明す
る。平均傾斜角（θａ） ＩＳＯ４２８７／１−１９８４に従って求めた。触針と
して０１０−２５２８（１μｍＲ、５５゜円錐、ダイヤ
モンド）を用いた触針式表面粗さ計（東京精器社製サー
フコム５７０Ａ）にて、粗面の表面粗さを駆動速度０．
０３ｍｍ／秒で測定した。この測定した平均線より、そ
の平均線を差し引いて傾斜を補正し、下記（４）〜
（５）式によって計算して求めた。The present invention will be described below in detail with reference to examples. Average tilt angle (θa) Determined according to ISO4287 / 1-1984. A stylus type surface roughness meter (Surfcom 570A manufactured by Tokyo Seiki Co., Ltd.) using 010-2528 (1 μmR, 55 ° cone, diamond) as a stylus was used to measure the surface roughness of the rough surface at a driving speed of 0.
It was measured at 03 mm / sec. The average line is subtracted from the measured average line to correct the inclination, and the following (4) to
The value was calculated by the equation (5).
【００２２】[0022]
【数４】 Δａ＝（１／Ｌ）∫0 Lｆ｜(ｄ／ｄｘ）ｆ（ｘ）｜ｄｘ ・・・ （４）[Formula 4] Δa = (1 / L) ∫ 0 L f | (d / dx) f (x) | dx (4)
【００２３】[0023]
【数５】θａ＝ｔａｎ-1Δａ ・・・ （５） 実施例１〜３、比較例１ ガラス板の表面をサンドブラスト処置を行った後にフッ
素処理を行うことにより化学エッチングした後、電鋳に
よりレプリカ型を取って得た電鋳型を用いて、厚さ４ｍ
ｍ、一辺が９０ｍｍ、他辺が６４ｍｍ、２１０ｍｍ、２
４８ｍｍ、４８８ｍｍの４種類の透明アクリル樹脂板の
一方の表面に熱転写によって粗面を転写し導光体とし
た。得られた導光体の平均傾斜角度（θａ）は２．０゜
であった。得られた導光体の９０ｍｍの二つの端面およ
び他の一方の端面に銀蒸着したＰＥＴフィルムを粘着加
工して貼り付け、粗面化した光出射面と対向する裏面に
銀蒸着したＰＥＴフィルムをテープ止めして反射面を形
成した。導光体の残りの一つの端面に銀蒸着したＰＥＴ
フィルムで冷陰極管（松下電器社製ＫＣ１３０Ｔ４Ｅ７
２、４ｍｍφ×１３０ｍｍ）を巻き付けて光源ランプと
して設置し、導光体の光出射面上にＰＥＴフィルムに屈
折率１．５３のアクリル系紫外線硬化樹脂で、頂角６３
゜、ピッチ５０μｍのプリズム列を平行に多数形成した
プリズムシートを、プリズム面が導光体の光出射面側に
向くように載置して面光源素子とした。得られた面光源
素子のバラツキ度（Ｒ％）を求めて表１に示した。一
方、９０ｍｍ×３００ｍｍで、厚さが２ｍｍ、４ｍｍ、
１０ｍｍの３種類の透明アクリル樹脂板を用いて、同様
の手順で導光体１を作製した。得られた導光体１の９０
ｍｍの二つの端面に銀蒸着したＰＥＴフィルムを粘着加
工して貼り付けた点以外は、上記と同様の方法で面光源
素子を作製し、得られた面光源素子の出射率を求めて表
２に示した。[Equation 5] θa = tan −1 Δa (5) Examples 1 to 3 and Comparative Example 1 The surface of the glass plate was chemically blasted by sandblasting and then fluorine treatment, and then electroformed. Using an electroforming mold obtained by taking a replica mold, a thickness of 4 m
m, 90 mm on one side, 64 mm, 210 mm on the other side, 2
A rough surface was transferred by thermal transfer to one surface of four types of transparent acrylic resin plates of 48 mm and 488 mm to obtain a light guide. The average inclination angle (θa) of the obtained light guide was 2.0 °. A PET film having silver vapor deposited on the two 90 mm end faces and the other one end face of the obtained light guide is adhered by sticking, and a PET film vapor deposited silver on the back face opposite to the roughened light emitting face is attached. Taped to form a reflective surface. PET vapor-deposited with silver on the other end face of the light guide
Cold cathode tube with film (KC130T4E7 manufactured by Matsushita Electric Industrial Co., Ltd.
(2, 4 mmφ × 130 mm) is installed as a light source lamp, and a PET film is provided on the light emitting surface of the light guide with an acrylic UV curable resin having a refractive index of 1.53 and an apex angle of 63.
A prism sheet having a large number of parallel prism rows each having a pitch of 50 μm was placed so that the prism surface faces the light exit surface side of the light guide to form a surface light source element. The degree of variation (R%) of the obtained surface light source element was determined and shown in Table 1. On the other hand, 90 mm x 300 mm, thickness 2 mm, 4 mm,
The light guide 1 was produced in the same procedure using three types of 10 mm transparent acrylic resin plates. 90 of the obtained light guide 1
A surface light source element was manufactured by the same method as described above except that a silver vapor-deposited PET film was attached to the two end surfaces of mm by adhesion processing, and the emission rate of the obtained surface light source element was calculated and Table 2 It was shown to.
【００２４】実施例４〜５、比較例２ サンドブラスト処理およびフッ素処理の条件を変更した
以外は、実施例１と同様にして厚さ４ｍｍ、一辺が９０
ｍｍ、他辺が６４ｍｍ、２１０ｍｍ、２４８ｍｍの３種
類の透明アクリル樹脂板の一方の表面に熱転写によって
粗面を転写し導光体とした。得られた導光体の平均傾斜
角度（θａ）は２．９゜であった。実施例１と同様にし
て面光源素子を組み立て、得られた面光源素子のバラツ
キ度（Ｒ％）を求めて表１に示した。一方、９０ｍｍ×
３００ｍｍで、厚さが２ｍｍ、４ｍｍ、１０ｍｍの３種
類の透明アクリル樹脂板を用いて、同様の手順で導光体
２を作製した。得られた導光体２を実施例１と同様の方
法で面光源素子を作製し、得られた面光源素子の出射率
を求めて表２に示した。Examples 4 to 5 and Comparative Example 2 A thickness of 4 mm and a side of 90 were obtained in the same manner as in Example 1 except that the conditions of the sandblast treatment and the fluorine treatment were changed.
mm, the other side is 64 mm, 210 mm, and 248 mm, and a rough surface is transferred onto one surface of three types of transparent acrylic resin plates by thermal transfer to obtain a light guide. The average inclination angle (θa) of the obtained light guide was 2.9 °. A surface light source element was assembled in the same manner as in Example 1, and the degree of variation (R%) of the obtained surface light source element was determined and shown in Table 1. On the other hand, 90 mm ×
The light guide 2 was produced by the same procedure using three types of transparent acrylic resin plates having a thickness of 300 mm and a thickness of 2 mm, 4 mm, and 10 mm. A surface light source element was produced from the obtained light guide 2 in the same manner as in Example 1, and the emission rate of the obtained surface light source element was determined and shown in Table 2.
【００２５】実施例６、比較例３ 真鍮板にガラスビーズを用いたサンドブラスト処理を行
うことにより粗面を形成した金型を用いて、厚さ４ｍ
ｍ、一辺が９０ｍｍ、他辺が６４ｍｍ、２１０ｍｍの２
種類の透明アクリル樹脂板の一方の表面に熱転写によっ
て粗面を転写し導光体とした。得られた導光体の平均傾
斜角度（θａ）は４．５゜であった。実施例１と同様に
して面光源素子を組み立て、得られた面光源素子のバラ
ツキ度（Ｒ％）を求めて表１に示した。一方、９０ｍｍ
×３００ｍｍで、厚さが２ｍｍ、４ｍｍ、１０ｍｍの３
種類の透明アクリル樹脂板を用いて、同様の手順で導光
体３を作製した。得られた導光体３を実施例１と同様の
方法で面光源素子を作製し、得られた面光源素子の出射
率を求めて表２に示した。Example 6, Comparative Example 3 A brass plate was sandblasted with glass beads to form a rough surface, and a mold having a thickness of 4 m was used.
m, one side is 90 mm, the other side is 64 mm, 210 mm 2
A rough surface was transferred onto one surface of one of the transparent acrylic resin plates of various types to obtain a light guide. The average inclination angle (θa) of the obtained light guide was 4.5 °. A surface light source element was assembled in the same manner as in Example 1, and the degree of variation (R%) of the obtained surface light source element was determined and shown in Table 1. On the other hand, 90 mm
× 300mm, thickness 2mm, 4mm, 10mm 3
The light guide 3 was produced by the same procedure using a transparent acrylic resin plate of a kind. A surface light source element was produced from the obtained light guide 3 in the same manner as in Example 1, and the emission rate of the obtained surface light source element was determined and shown in Table 2.
【００２６】比較例４ サンドブラスト処理の条件を変更した以外は、実施例６
と同様にして厚さ４ｍｍ、一辺が９０ｍｍ、他辺が６４
ｍｍの透明アクリル樹脂板の一方の表面に熱転写によっ
て粗面を転写し導光体を得た。得られた導光体の平均傾
斜角度（θａ）は７．９゜であった。実施例１と同様に
して面光源素子を組み立て、得られた面光源素子のバラ
ツキ度（Ｒ％）を求めて表１に示した。一方、９０ｍｍ
×３００ｍｍで、厚さが２ｍｍ、４ｍｍ、１０ｍｍの３
種類の透明アクリル樹脂板を用いて、同様の手順で導光
体４を作製した。得られた導光体４を実施例１と同様の
方法で面光源素子を作製し、得られた面光源素子の出射
率を求めて表２に示した。Comparative Example 4 Example 6 was repeated except that the conditions for sandblasting were changed.
4mm thick, 90mm on one side and 64 on the other
A rough surface was transferred by thermal transfer to one surface of a transparent acrylic resin plate of mm to obtain a light guide. The average inclination angle (θa) of the obtained light guide was 7.9 °. A surface light source element was assembled in the same manner as in Example 1, and the degree of variation (R%) of the obtained surface light source element was determined and shown in Table 1. On the other hand, 90 mm
× 300mm, thickness 2mm, 4mm, 10mm 3
The light guide 4 was produced in the same procedure by using different types of transparent acrylic resin plates. A surface light source element was produced from the obtained light guide 4 in the same manner as in Example 1, and the emission rate of the obtained surface light source element was determined and shown in Table 2.
【００２７】比較例５ 真鍮板に電気放電処理を行うことにより粗面を形成した
金型を用いて、厚さ４ｍｍ、一辺が９０ｍｍ、他辺が６
４ｍｍの透明アクリル樹脂板の一方の表面に熱転写によ
って粗面を転写し導光体とした。得られた導光体の平均
傾斜角度（θａ）は１５．５゜であった。実施例１と同
様にして面光源素子を組み立て、得られた面光源素子の
バラツキ度（Ｒ％）を求めて表１に示した。一方、９０
ｍｍ×３００ｍｍで、厚さが２ｍｍ、４ｍｍ、１０ｍｍ
の３種類の透明アクリル樹脂板を用いて、同様の手順で
導光体５を作製した。得られた導光体５を実施例１と同
様の方法で面光源素子を作製し、得られた面光源素子の
出射率を求めて表２に示した。Comparative Example 5 Using a mold having a rough surface formed by subjecting a brass plate to an electric discharge treatment, a thickness of 4 mm, one side of 90 mm, and the other side of 6
A rough surface was transferred onto one surface of a 4 mm transparent acrylic resin plate by thermal transfer to obtain a light guide. The average inclination angle (θa) of the obtained light guide was 15.5 °. A surface light source element was assembled in the same manner as in Example 1, and the degree of variation (R%) of the obtained surface light source element was determined and shown in Table 1. On the other hand, 90
mm × 300 mm, thickness 2 mm, 4 mm, 10 mm
The light guide body 5 was produced by the same procedure using the three types of transparent acrylic resin plates. A surface light source element was produced from the obtained light guide 5 in the same manner as in Example 1, and the emission rate of the obtained surface light source element was determined and shown in Table 2.
【００２８】比較例６ 電気放電処理の条件を変更した以外は、比較例５と同様
にして導光体を得た。得られた導光体の平均傾斜角度
（θａ）は２４．０゜であった。実施例１と同様にして
面光源素子を組み立て、得られた面光源素子のバラツキ
度（Ｒ％）を求めて表１に示した。一方、９０ｍｍ×３
００ｍｍで、厚さが２ｍｍ、４ｍｍ、１０ｍｍの３種類
の透明アクリル樹脂板を用いて、同様の手順で導光体６
を作製した。得られた導光体６を実施例１と同様の方法
で面光源素子を作製し、得られた面光源素子の出射率を
求めて表２に示した。Comparative Example 6 A light guide was obtained in the same manner as in Comparative Example 5 except that the conditions of electric discharge treatment were changed. The average inclination angle (θa) of the obtained light guide was 24.0 °. A surface light source element was assembled in the same manner as in Example 1, and the degree of variation (R%) of the obtained surface light source element was determined and shown in Table 1. On the other hand, 90 mm x 3
The light guide 6 is made in the same procedure by using three kinds of transparent acrylic resin plates of 00 mm and thicknesses of 2 mm, 4 mm, and 10 mm.
Was prepared. A surface light source element was produced from the obtained light guide 6 by the same method as in Example 1, and the emission rate of the obtained surface light source element was determined and shown in Table 2.
【００２９】[0029]
【表１】 [Table 1]
【００３０】[0030]
【表２】 [Table 2]
【００３１】実施例７ 実施例５で得た４ｍｍ×９０ｍｍ×１２０ｍｍの導光体
を用いた面光源素子の冷陰極管にインバーター（ＴＤＫ
社製ＣＸＡ−Ｍ１０Ｌ）を介して直流電源に接続し、Ｄ
Ｃ１２Ｖを印加して点灯させ、輝度計（ミノルタ社製ｎ
ｔ−１゜）を用いて、その正面輝度を測定した。その結
果、正面輝度は２７１５Ｃａ／ｍ2 であった。Example 7 An inverter (TDK) was used for a cold cathode tube of a surface light source element using the light guide of 4 mm × 90 mm × 120 mm obtained in Example 5.
CXA-M10L) manufactured by the company
C12V is applied and turned on, and a luminance meter (Minolta n
The front luminance was measured using (t-1 °). As a result, the front luminance was 2715 Ca / m 2 .
【００３２】比較例７ ４ｍｍ×９０ｍｍ×１２０ｍｍのアクリル樹脂製導光体
の裏面に、酸化チタン粒子を含んだ白色塗料を用いて、
光入射面から離れるに従って密度が高くなるように斑点
パターンをスクリーン印刷によって形成した。得られた
導光体の９０ｍｍの二つの端面および他の一方の端面に
銀蒸着したＰＥＴフィルムを粘着加工して貼り付け、粗
面化した光出射面と対向する裏面に銀蒸着したＰＥＴフ
ィルムをテープ止めして反射面を形成した。導光体の残
りの一つの端面に銀蒸着したＰＥＴフィルムで冷陰極管
（松下電器社製ＫＣ１３０Ｔ４Ｅ７２、４ｍｍφ×１３
０ｍｍ）を巻き付けて光源ランプとして設置した。次い
で、導光体の光出射面上に拡散フィルムを載置した。さ
らに、ＰＥＴフィルムに屈折率１．５３のアクリル系紫
外線硬化樹脂で、頂角９０゜、ピッチ５０μｍのプリズ
ム列を平行に多数形成した２枚のプリズムシートを、両
方のプリズム列が直交するように重ね、プリズム面が光
出射方向側に向くように載置して面光源素子とした。得
られた面光源素子のバラツキ度（Ｒ％）は１７．０％で
あった。得られた面光源素子の冷陰極管にインバーター
（ＴＤＫ社製ＣＸＡ−Ｍ１０Ｌ）を介して直流電源に接
続し、ＤＣ１２Ｖを印加して点灯させ、輝度計（ミノル
タ社製ｎｔ−１゜）を用いて、その正面輝度を測定し
た。その結果、正面輝度は２１４８Ｃａ／ｍ2 であっ
た。Comparative Example 7 A white paint containing titanium oxide particles was used on the back surface of a 4 mm × 90 mm × 120 mm acrylic resin light guide.
The spot pattern was formed by screen printing so that the density became higher as the distance from the light incident surface increased. A PET film having silver vapor deposited on the two 90 mm end faces and the other one end face of the obtained light guide is adhered by sticking, and a PET film vapor deposited silver on the back face opposite to the roughened light emitting face is attached. Taped to form a reflective surface. A cold cathode tube (KC130T4E72, 4 mmφ × 13 manufactured by Matsushita Electric Industrial Co., Ltd.) made of a PET film with silver vapor deposited on the other end face of the light guide.
(0 mm) was wound and installed as a light source lamp. Then, a diffusion film was placed on the light emitting surface of the light guide. Further, two prism sheets are formed on a PET film by using acrylic UV curable resin with a refractive index of 1.53, and a large number of prism rows with a vertical angle of 90 ° and a pitch of 50 μm are formed in parallel so that both prism rows are orthogonal to each other. They were stacked and placed so that the prism surface faces the light emission direction side to form a surface light source element. The degree of variation (R%) of the obtained surface light source element was 17.0%. A cold cathode tube of the obtained surface light source element was connected to a direct current power source through an inverter (CXA-M10L manufactured by TDK), and was turned on by applying DC12V, and a luminance meter (nt-1 ° manufactured by Minolta) was used. Then, the front luminance was measured. As a result, the front luminance was 2148 Ca / m 2 .
【００３３】表１から明らかなように、本発明の実施例
１〜６の面光源素子では、光出射面内での輝度のバラツ
キ度（Ｒ％）が１０％以下と均一性に優れており、液晶
表示装置用の面光源素子として十分に実用可能なもので
あった。一方、比較例１〜６の面光源素子では、光出射
面内での輝度のバラツキ度（Ｒ％）が２０％を超えるも
のであり、輝度の均一性が十分に得られているものでは
なかった。また、実施例７と比較例７から明らかなよう
に、本発明の実施例７の面光源では、正面輝度を損なう
ことなく光出射面内での均一な輝度分布が得られるもの
であった。As is clear from Table 1, in the surface light source elements of Examples 1 to 6 of the present invention, the variation degree (R%) of luminance in the light emitting surface is 10% or less, which is excellent in uniformity. It was sufficiently practical as a surface light source element for liquid crystal display devices. On the other hand, in the surface light source elements of Comparative Examples 1 to 6, the variation degree (R%) of luminance in the light emitting surface exceeds 20%, and the uniformity of luminance is not sufficiently obtained. It was Further, as is clear from Example 7 and Comparative Example 7, the surface light source of Example 7 of the present invention was able to obtain a uniform brightness distribution in the light emitting surface without impairing the front brightness.
【００３４】[0034]
【発明の効果】本発明は、導光体の光出射面およびそれ
と対向する裏面の少なくとも一方の面を、平均傾斜角
（θａ）が０．５〜７．５゜の凹凸を有する粗面とする
ことによって、高い輝度を有するとともに、斑点パター
ン等の均一化処理を施すことなく光出射面内での均一な
輝度分布が得られ、ノートパソコン、液晶テレビ等に使
用される液晶表示装置用として適した面光源素子を提供
できるものである。According to the present invention, at least one of the light emitting surface of the light guide and the back surface facing the light emitting surface is a rough surface having irregularities having an average inclination angle (θa) of 0.5 to 7.5 °. As a result, it has a high brightness and a uniform brightness distribution in the light emitting surface can be obtained without applying a uniforming treatment such as a spot pattern, and is used for a liquid crystal display device used in a notebook computer, a liquid crystal television, etc. It is possible to provide a suitable surface light source element.
【図１】本発明の導光体の粗面における光の光路を示す
概略図である。FIG. 1 is a schematic view showing an optical path of light on a rough surface of a light guide according to the present invention.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 林 泰子 神奈川県川崎市多摩区登戸3816番地 三菱 レイヨン株式会社東京技術・情報センター 内 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuko Hayashi 3816 Notobe, Tama-ku, Kawasaki City, Kanagawa Prefecture Mitsubishi Rayon Co., Ltd. Tokyo Technology and Information Center
Claims (2)
つの光入射面およびこれと略直交する光出射面を有する
導光体からなり、導光体の光出射面およびその裏面の少
なくとも一方の面が平均傾斜角（θａ）０．５〜７．５
゜の凹凸を有する粗面から構成されており、導光体の光
出射面における輝度のバラツキ度（Ｒ％）が２０％以下
であることを特徴とする液晶表示装置用面光源素子。1. A light source, and a light guide body having at least one light incident surface facing the light source and a light exit surface substantially orthogonal to the light entrance surface. At least one of the light exit surface of the light guide body and the back surface thereof. The surface has an average inclination angle (θa) of 0.5 to 7.5.
A surface light source element for a liquid crystal display device, characterized in that it is composed of a rough surface having an unevenness of 0 ° and has a degree of variation in brightness (R%) of 20% or less on the light emitting surface of the light guide.
る端部までの長さ（Ｌ）と厚さ（ｔ）との比（Ｌ／ｔ）
が１２０以下であることを特徴とする請求項１記載の液
晶表示装置用面光源素子。2. The ratio (L / t) between the length (L) and the thickness (t) of the light guide from the light incident end to the end facing the light incident end.
Is 120 or less, The surface light source element for liquid crystal display devices of Claim 1 characterized by the above-mentioned.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28855295A JP3656967B2 (en) | 1995-11-07 | 1995-11-07 | Surface light source element for liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28855295A JP3656967B2 (en) | 1995-11-07 | 1995-11-07 | Surface light source element for liquid crystal display device |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2005008922A Division JP4170991B2 (en) | 2005-01-17 | 2005-01-17 | Surface light source element for liquid crystal display device and liquid crystal display device using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09133918A true JPH09133918A (en) | 1997-05-20 |
| JP3656967B2 JP3656967B2 (en) | 2005-06-08 |
Family
ID=17731729
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28855295A Expired - Lifetime JP3656967B2 (en) | 1995-11-07 | 1995-11-07 | Surface light source element for liquid crystal display device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3656967B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7736045B2 (en) | 2001-10-04 | 2010-06-15 | Mitsubishi Rayon Co., Ltd. | Area light source and lightguide used therefore |
| WO2013002002A1 (en) | 2011-06-30 | 2013-01-03 | 三菱樹脂株式会社 | Coating film |
-
1995
- 1995-11-07 JP JP28855295A patent/JP3656967B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7736045B2 (en) | 2001-10-04 | 2010-06-15 | Mitsubishi Rayon Co., Ltd. | Area light source and lightguide used therefore |
| WO2013002002A1 (en) | 2011-06-30 | 2013-01-03 | 三菱樹脂株式会社 | Coating film |
| KR20140032442A (en) | 2011-06-30 | 2014-03-14 | 미쓰비시 쥬시 가부시끼가이샤 | Coating film |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3656967B2 (en) | 2005-06-08 |
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