200909941 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種面光源裝置。 【先前技術】 用於液晶顯示裝置等面光源裝置之方式，其係具有··將 光源裝配在導光板稜邊部之稜邊光源（edge light)方式；及 將光源配置在擴散板之正下方，藉由擴散板而使光擴散之 正下方型方式。畫面尺寸較小的液晶顯示裝置之情形，採 用稜邊光源方式已成爲主流。 稜邊光源方式之情形，從已裝配在導光板稜邊部的光源 所發出的光將從導光板之稜邊部射入，以相對於導光板表 面爲臨界角以上射入的光將從導光板之射出面射出。另一 方面，大部分以相對於導光板表面爲臨界角以下之角度行 進的光將在表面重複進行反射，行進於導光板內，幾乎不 會從導光板之射出面射出。爲了使行進於如此導光板內之 光從導光板射出面予以射出，實施向導光板之光散亂劑的 添加，或是將光擴散層賦與在導光板射出面之背面。 液晶顯示裝置之情形，相較於畫面端部，大多注視畫面 之中央部。因此，必須使畫面中央部之亮度與畫面端部之 亮度相等或是較畫面端部更爲提高。 從光源射入導光板內的光之中，以相對於導光板表面爲 臨界角以上射入的光量，亦即從射出面射出的光量將有隨 著遠離光源而遞減、使畫面中央部之亮度變得較畫面端部 爲低之問題。習知其解決手段係在射出面之背面上設置不 連續之光擴散層。具體而言，根據佔有光擴散層的每單位 200909941 面積之面積率，其係隨著遠離光源而連續性增大，所謂作 成明暗層次圖案（grad ation pattern)，一般而言，使亮度控 制於所期望之分布。設置此光擴散層之方法，可舉出：網 版印刷法所代表之各種印刷法；使用.壓模之射出成型法、 壓縮成型法所代表之形狀轉印法；或是預先賦與光擴散層 之片狀物貼合法等。基於量產性及經濟性之觀點，此等方 法之中’大多使用在導光板射出面之背面的網版印刷所代 表之各種印刷法。 液晶顯示裝置係朝向數位高視覺之因應等，影像高精細 顯示之需求強烈。爲了高精細顯示影像，將有縮小液晶面 板之開口度的必要。然而，由於開口度之降低將使液晶面 板之光透過率降低、畫面變暗，更高亮度之面光源裝置已 設爲必要。 爲了達成高亮度化，已有人提案一種使光散亂劑分散於 導光板中，盡可能增加射入導光板之光的射出的方法（參 照專利文獻1 )。 此方法係藉由使光散亂劑分散於導光板中，雖然面光源 裝置之亮度將提高，但是仍未達滿足之水準，正要求更進 一步之筒亮度化。 專利文獻1:日本專利特開2002-148443號公報 【發明內容】 發明所欲解決之課題 本發明之目的係有鑑於如上所述之高亮度的要求，在於 提供一種適合於液晶顯示裝置用之高亮度的面光源裝置。 解決課題之技術手段 200909941 本發明人等爲了解決上述課題而鑽硏探討之結果，發現 能夠提供一種適合於液晶顯示裝置用之高亮度的面光源裝 置。 本發明係一種面光源裝置，其係具備：具有光射出面與 一面以上之光射入面的導光板；將光供給至該射入面的光 源；在該導光板之光射出面的背面上所形成的光擴散層； 與在該背面側所配設的反射板；該光擴散層係隨著遠離光 源，而使該光擴散層面積佔有該背面之每單位面積的比率 得以增大之方式來加以分散，該光擴散層表面之十點平均 粗糙度爲8μιη〜25μιη，該光擴散層表面凹凸之平均間隔爲 20μηι 〜150μιη。 發明之效果 若根據本發明，能夠提供一種適合於液晶顯示裝置用之 高亮度的面光源裝置。 【實施方式】 用以實施發明之最佳形態 以下，針對本發明之較佳形態而具體加以說明，但是本 發明並非僅受此等之形態所限定。 用於本發明之導光板係具有一面以上之光射入面。 構成導光板之基材例子，可舉出：甲基丙烯酸樹脂、聚 碳酸酯樹脂、苯乙烯系樹脂、環狀烯烴系樹脂、非結晶性 聚酯樹脂等之透明有機材料，或無機玻璃等之透明無機材 料。此等樹脂之中，較佳爲甲基丙烯酸樹脂、聚碳酸酯樹 脂、環狀烯烴系樹脂，其中更佳爲甲基丙烯酸樹脂。 導光板之成形方法並未予以特別限定，能夠使用習知之 200909941 方法。例如，可舉出：因應於必要時，在含有成 有機透明材料的原料單體或是原料單體之部分 漿液中，添加各種添加劑之後，經澆鑄聚合後而 成形物，其後切斷成既定之尺寸，硏磨切斷面而 法；或是因應於必要時，將由所添加的各種添加 基材之樹脂所構成的樹脂組成物，經由片材濟出 壓縮成型機以得到片材成形物，其後切斷成既定 硏磨切斷面而得到的方法等。於此時，能夠添加 材與塑模之剝離性得以提高之剝離劑，或是使因 造成之劣化得以延遲之紫外線吸收劑等習知之名 導光板之形狀係具有：板厚爲一定之平板型、 著遠離光源而變薄之楔形，較佳爲平板型。 另外，能夠添加具有與構成導光板之基材折射 射率的光散亂劑。藉由將該光散亂劑添加於本發 導光板中，能夠更進一步達成高亮度化。 光散亂劑之形狀可以爲正球形、球形、鱗片形 等，並未予以特別限定。例如，光散亂劑可舉出 矽、碳酸鈣、硫酸鋇、氧化鈦、氧化鋁、氫氧化 機系微粒；或胺基甲酸酯珠、矽酮珠、PMMA珠 苯乙烯珠等之有機系微粒。此等光散亂劑之數目 較佳爲〇 . 1 μιη以上、5 0 μπι以下。不定形之情形’ 較佳爲Ο.ίμιη以上、50μπι以下。若光散亂劑之數 徑（不定形之情形爲長徑長度）過小時，光散亂 關性將變大，射出的光將帶有顏色。另外，若光 數目平均粒徑過大時，因散亂光所造成之偏異 爲基材之 聚合物的 得到片材 得到的方 劑與構成 成形機或 :之尺寸， 爲了使基 紫外線所 民加劑。 或板厚隨 率不同折 明使用之 、不定形 :二氧化 鋁等之無 、MS 珠、 平均粒徑 長徑長度 目平均粒 之波長相 散亂劑之 亮度不均 200909941 將可能發生。作爲導光板中之光散亂劑，前述導光板與前 述光散亂劑之折射率差X於0.0 1 ^ X < 0 . 1範圍內之情形， 光散亂劑的含量y(ppm)較佳爲lOOSy^lOOO範圍； 於Ο.Κχ< 0.5範圍內之情形，較佳爲l〇<y^5 00範圍； 於0.5 S X範圍內之情形，較佳爲1 ^ y ^ 1 〇範圍。 與導光板基材之折射率差爲小的光散亂劑之情形，將增 多添加量；與導光板基材之折射率差爲大的光散亂劑之情 形，將減少添加量。 對應於上述折射率差X之光散亂劑量y過低之情形下， 所得的亮度將降低。另外，若對應於上述折射率差X之光 散亂劑量y過高時，即使在光源附近部與中央部，作成改 變光擴散層面積率之明暗層次圖案，將有射出光之均句性 或發光圖案之調整也爲困難的，畫面中央部之亮度較畫面 端部變得更低之問題。還有，所謂「ppm」係表示相對於 含有光散亂劑的導光板之重量百萬分率。 在導光板射出面之背面上具有光擴散層。該光擴散層係 一種隨著遠離光源而使佔有該導光板射出面背面的每單位 面積之該光擴散層面積比率予以增大的方式來加以分散之 物。針對該光擴散層之分散形狀並無特別之限制，也可以 爲點狀、正方形點（dot)狀、多角形、條紋狀、格子狀等， 無論任一種形狀皆可以。光擴散層佔有該面之每單位面積 之面積比率係隨著遠離光源而增大。藉由作成所謂的明暗 層次圖案，能夠使亮度控制於所期望之分布。該光擴散層 之面積比率隨著遠離光源而無法變大之情形下，相較於光 源附近，畫面中央部之亮度將有變低之傾向，實用上無法 200909941 作爲光源裝置使用。該擴散層表面之形狀，其十點平均粗 糙度（Rz)爲8μιη〜25μιη，較佳爲8μπι〜15μιη。該擴散層 表面凹凸之平均間隔（Sm)爲20μιη〜150μιη，較佳爲40μιη 〜140μηι。於此，十點平均粗糙度（Rz)與凹凸之平均間 隔（Sm)係遵照JIS B 060 1 - 1 994所測出之値。還有，凹凸 之平均間隔（S m )係指規定於JI S B 0 6 0 1 - 1 9 9 4之「輪廓曲 線要件的平均長度」。 十點平均粗糙度（Rz )低於8 μηι之情形下，行進於導光 板內部的光之中，由於照射至光擴散層之光變角效果將變 小，超過臨界角而從射出面射出的光之比例將變少、亮度 將變低。另外，十點平均粗糙度（Rz )超過2 5 μηι之情形 下，表面之凹凸變得容易刮傷，另外，局部之亮度將變高， 成爲所謂偏異之原因。 凹凸之平均間隔（S m )低於2 0 μ m之情形下，表面之凹 凸變得容易刮傷，局部之亮度不均將變得容易發生。凹凸 之平均間隔（S m )超過1 5 0 μ m之情形下，由於照射在該光 擴散層之擴散效果將變小’因而相對於導光板表面，將超 過臨界角而從射出面射出的光之比例將變少、亮度將降低。 該光擴散層之形成方法’可舉出：網版印刷法所代表之 各種印刷法；使用壓模之射出成型法或壓縮成型法所代表 之形狀轉印法；或是預先賦與光擴散層之片材狀物貼合法 等。於此等方法之中，基於高量產性及低成本性之觀點， 較佳爲使用印刷法。於印刷法之中，基於調整該光擴散層 面積比率之容易性的觀點，較佳爲使用網版印刷法。網版 印刷法之情形’在由聚酯或耐綸等之篩網所構成的版上， -10- 200909941 實施使微粒分散於黏結劑樹脂中的墨水得以通過，使所期 望之印刷圖案轉印至導光板上，十點平均粗糙度（Rz )超 過如2 5 μπι之情形下，必須使大粒徑之粒子添加於墨水中， 於如此之情形下，由於成爲使構成版之篩網阻塞的原因而 不佳。爲了不引起篩網之阻塞而得到安定之印刷性，較佳 爲更進一步縮小微粒之粒徑，使十點平均粗糙度（Rz )成 爲1 5 μιη以下。 於網版印刷法中，爲了印刷所期望之光擴散層，構成版 之篩網係具有藉由乳劑限制墨水通過之未開口部，與爲了 使墨水通過而使所期望之印刷圖案轉印至導光板上之開口 部。以下’將佔有導光板表面之射出面背面的每單位面積 之該光擴散層面積比率稱爲「面積率」。例如，在導光板 表面2mmx2mm之面內，形成1個光擴散層lmmxlmm之情 形，光擴散層佔有之面積率成爲25%。還有，歸納未連續 之許多光擴散層群而稱爲「光擴散層」。調整光擴散層面 積率之方法’一般進行改變構成該版之篩網的未開口部與 開口部之面積比率。爲了提高光擴散層之面積率，例如因 而擴大佔有構成該版之篩網每單位面積的該開口部面積， 窄化該未開口部面積。爲了減低光擴散層之面積率，因而 窄化佔有構成該版之篩網每單位面積的該開口部面積，擴 大該未開口部之面積。相對於導光板表面3mm2之面積， 較佳爲形成1個以上之光擴散層而加以分散，相對於導光 板表面1mm2之面積，較佳爲形成丨個以上之光擴散層而 加以分散。於印刷法中’墨水能夠使用各種型式之墨水。 於熱硬化型墨水中，一般使用將無機系微粒或有機系微粒 -11- 200909941 添加於利用溶劑所稀釋之黏結劑樹脂的墨水中。 調整十點平均粗糙度（Rz )或凹凸之平均間隔（Snl )之 方法，可舉出：變更墨水中之溶劑與黏結劑樹脂及微粒的 比率，或是變更微粒之粒徑。例如，網版印刷之情形，爲 了增大十點平均粗糙度（Rz )，因而提高佔有墨水中之溶 劑比例，另外擴大微粒之粒徑。另外，也藉由縮小構成篩 網之絲線直徑’或是藉由降低表示篩網網眼之篩孔數，能 夠增加墨水之透過體積’並藉由增厚附著於導光板表面之 墨水厚度，也能夠擴大十點平均粗糙度（Rz )。另外相反 的，爲了縮小十點平均粗糙度（Rz )，因而降低佔有墨水 中之溶劑比例、縮小微粒之粒徑。另外，藉由增大構成篩 網之絲線直徑或提高篩孔數，能夠減少墨水之透過體積， 藉由薄化附著於導光板表面之墨水厚度，也能夠縮小十點 平均粗糙度（Rz )。 添加於擴散層中的無機系微粒或有機系微粒，能夠使用 作爲添加於導光板中之光散亂劑所例示之微粒。另外，也 能夠使用習知之褪光劑等。 溶劑適宜爲充分溶解黏結劑樹脂，並且蒸發速度慢的溶 劑。使用黏結劑樹脂之溶解性爲低的溶劑之情形下，於墨 水之貯藏時或印刷中，黏結劑之析出將發生，將成爲印刷 不良發生之原因。另外，使用蒸發速度快的溶劑之情形下’ 於印刷時，篩網之網眼阻塞容易發生，將成爲量產性降低 之原因。 此外，也能夠使用光硬化型墨水。光硬化型墨水之情 形，爲了增大十點平均粗糙度（Rz )，可舉出：增大墨水 -12- 200909941 中微粒之粒徑，或增大光硬化時之收縮量。光硬化型墨水 係藉由使單體成分予以聚合而進行硬化，但是經由此聚合 將伴隨收縮。因而，針對增大光硬化時之收縮量，具有增 多墨水中之單體成分的方法。另外’爲了縮小十點平均粗 糙度（R z )，可舉出：縮小墨水中微粒之粒徑，或減少墨 水中之單體成分而縮小光硬化時之收縮量。 爲了擴大凹凸之平均間隔（Sm )，可舉出：減低墨水中 微粒之比率；相反的’爲了窄化凹凸之平均間隔（S m )-可舉出：提高墨水中微粒之比率。 爲了擴大十點平均粗糙度（Rz )’因而增大微粒粒徑之 情形，若是佔有墨水中之微粒的重量或體積比率爲相同的 話，由於微粒之個數將減少’凹凸之平均間隔（Sm)將變 大。因而，爲了增大十點平均粗糙度（Rz) ’並且使凹凸 之平均間隔（S m )予以相同或縮小，必須增大微粒之粒徑， 並且提高佔有墨水中之微粒的重量或體積比率。隨著增加 佔有墨水中之微粒的重量或體積比率’相對之下’由於溶 劑與黏結劑樹脂之比例降低’因而將有墨水之流動性降 低、印刷性降低之傾向。一旦使用過度增加佔有墨水中之 微粒的比率，亦即使用流動性大幅降低之墨水以進行網版 印刷時，於轉印至導光板之墨水透過體積中將產生不均’ 得到均勻之光擴散層將變得困難。光擴散層不均勻之情 形，若將光源配置在導光板之邊緣而使光源點亮時，導光 板射出面之亮度將變得局部不均而不適合實用。因而’十 點平均粗糙度（R z )過大且凹凸之平均間隔（S m )過小的 光擴散層便將因印刷而造成良率降低。 -13- 200909941 爲了得到均勻的光擴散層，於墨水1 ο 0重量份中，佔有 墨水中之黏結劑樹脂量較佳爲超過5重量份，更佳爲超過 1 0重量份。 爲了提高亮度，較佳爲使大多數光在光擴散層之空氣界 面予以擴散。因此’構成光擴散層之黏結劑樹脂適合使用 與導光板本身之折射率差爲〇 . 2以內者。若黏結劑樹脂與 導光板之折射率差過大時，由於在光擴散層與導光板之界 面進行正反射之光將增加，在光擴散層所擴散之光的比例 將變少，從射出面進行射出之光的比例將減少，將有亮度 降低之傾向而不佳。另外，適合使用黏結劑樹脂與微粒之 折射率差爲1 . 0以內者。若黏結劑樹脂與微粒之折射率差 過大時，光擴散層之透過率將變低，光之損失將變大，將 有亮度降低之傾向而不佳。 墨水固化後的光擴散層厚度較佳爲0 . 1〜5 Ο μιη，更佳爲 0.5 〜4 Ο μ m 〇 導光板之板厚較佳爲0.1〜15 μιη，更佳爲0.2〜12 mm。 針對射出面之形狀，無論是平面或予以粗面化皆可以，另 外，也可以形成柱狀三角稜鏡所代表之透鏡狀物等。 在導光板之射出面側，也可以配置用以調整散亂射出光 強度之角度特性的擴散膜及稜鏡片或透鏡片，另外，在擴 散膜之射出側也可以配置稜鏡片或透鏡片。還有，在擴散 膜之射出面側也能夠配置稜鏡片，更進一步能夠在其射出 面側配置擴散膜，此等膜之構造係一個例子，並不受此例 所限定。擴散膜也可以與黏結劑一倂塗布丙烯酸或二氧化 矽珠，兼具擴散機能與光之偏光機能。另外，稜鏡片係並 -14- 200909941 列在表面之狀態下連續形成許多柱狀三角稜鏡的 此稜鏡片能夠在稜鏡脊部相對於導光板之射入面 之方向上配置一片，也能夠在垂直於彼此稜鏡脊 上配置二片。透鏡片係在表面形成複數個具有凹 透鏡狀物，也能夠配設一片或數片之此透鏡片。 光源能夠在一面以上之射入面配置冷陰極管 管等之線狀光源。此情形下，能夠相對於一面之 置一根或數根之光源。除了線狀光源之外，也能夠 或雷射等之點狀光源。 在導光板射出面之背面側配置反射板。該反射 將從射出面之背面發出的光反射至導光板側，能 之利用效率。反射板並未予以特別限制，例如能 色反射片等。 藉由作成如上所述之構造，能夠作成適合於各 尤其適用於液晶顯不裝置’作成筒亮度之面光源 實施例 以下，使用實施例及比較例以進一步說明本發 本發明係根據此等例子，並未予以特別限定。 〔實施例1〜7及比較例1〜6〕 (1 )導光板之製作 利用表1揭示之添加濃度，使作爲光散亂劑之_ 射率2.52)分散於由20重量％之聚甲基丙烯酸| 重量％之甲基丙烯酸甲酯所構成的漿液中。接著， 重量份之作爲聚合起始劑的2,2’-偶氮雙（2,4-腈）’更進一步添加0.0 0 5重量份之作爲紫外線 透明片。 成爲並行 部之方向 凸曲面之 或熱陰極 射入面配 使用LED 板係藉由 夠提高光 夠使用白 種用途， 裝置。 明，但是 民化鈦（折 甲酯與8 0 添加0.0 3 二甲基戊 吸收劑的 -15- 200909941 2-(5 -甲基-2_羥苯基）苯并三唑，攪拌30分鐘而作成聚合 性原料獎液。於縱6 5 0 m m、橫4 5 0 m m、厚6 m m之2片強化 玻璃板周圍’透過聚氯乙烯製之無端管子以將聚合性原料 漿液注入已配置的鑄型中，將強化玻璃板調整至既定間隔 之後，浸於7 0 °C之溫水中，予以2小時聚合，接著，於1 3 0 °C之空氣浴中予以1小時聚合。利用嵌板鋸（panel saw ) (SHINX製之商品名SZIVG-4000)以切斷所得的600mmx 400mm x 6mm之壓克力板，利用磨削硏磨機（M e g a r ο Technica製之商品名PU-Beauty )以進行周邊4個側面之 硏磨加工而得到388mmx291mmx6mm之導光板。 (2)光擴散層之形成 利用網版印刷法，在導光板射出面之背面進行光擴散層 之形成。 在作成大小 3 8 8mmx291mmx6mm之導光板射出面的背 面，爲了使黏結劑樹脂得以形成，利用日本帝國墨水製之 VAR-00 0介質，將胺基甲酸酯珠A、胺基甲酸酯珠B、褪 光劑K (以上，任一種皆爲Seiko Advance製）、氫氧化銘 (日本昭和電工製之H320)作爲微粒使用，及將異佛酮作 爲稀釋溶劑使用，利用表1揭示之添加量加以混合後，使 用刮勺以進行1 〇分鐘之手動攪拌，均勻攪拌而得到混合墨 水，還有，日本帝國墨水製之VAR-0 0 0介質的黏結劑樹脂 含率係進行如下方式而算出。將預先稱量之VAR-000介質 塗布在30cmx30cm之強化板玻璃上，於80°C之熱風循環乾 燥爐中予以乾燥4 8小時後而製作厚度5 0 μ m之黏結劑樹脂 膜，計算黏結劑樹脂膜重量佔有乾燥前墨水重量之比率。 -16- 200909941 其結果，VAR-000介質中之黏結劑樹脂成分爲37重量％。 另外，於實施例6中，使用已使聚碳酸酯樹脂（日本出光 興產製之Tafuron FN1700A) 22重量份溶解於三氯乙烷78 重量份中的聚碳酸酯黏結劑（溶液）以取代該VAR-0 0 0介 質。與使用該VAR-000介質之情形相同，將微粒與稀釋溶 劑添加於此聚碳酸酯黏結劑中，攪拌而得到混合墨水。此 時之黏結劑樹脂、微粒與稀釋溶劑（三氯乙烷）之添加量 係揭示於表1。使用網版印刷機（Newlong精密工業製之 LS-560)與膜厚 ΙΟμιη、355篩網之耐綸製之網版（Mesh 股份公司製），將攪拌後之混合墨水印刷在導光板射出面 之背面。此時，將導光板之3 8 8mmx6mm面作爲光之射入 面，使用導光板中央部之亮度較光源附近部之亮度爲高的 明暗層次圖案之網版。針對實施例1〜3及6、7與比較例 1、2、4〜6,使光源附近部之光擴散層之面積率成爲22%、 距離兩端光源部最遠的中央部光擴散層之面積率成爲6 8 % 之方式，來作成隨著線性移向中央部而使光擴散層之面積 率變大的圖案。針對實施例4、5與比較例3，使光源附近 部之光擴散層之面積率成爲32%、距離兩端光源部最遠的 中央部光擴散層之面積率成爲 68%之方式，在導光板 2 9 1 m m長度之方向，以作成隨著線性移向中央部而使光擴 散層之面積率變大的圖案。此時，光擴散層係在導光板表 面之1 m m X 1 m m的大小中，以各種大小印刷1個正方形形 狀之點。於印刷後，室溫下放置1 2小時以進行乾燥，得到 遍及整面已實施印刷之附有3 8 8 mmx291mmx6mm光擴散層 的導光板。 -17- 200909941 (3 )黏結劑樹脂及導光板之折射率測定 將用以形成黏結劑樹脂而使用之日本帝國墨水製之 VAR-000介質或聚碳酸酯黏結劑塗布於30cmx3〇cm之強化 板玻璃上’於8(TC之熱風循環乾燥爐中予以乾燥48小時 後’從強化板坡璃予以剝離，作成厚度5 〇 μ m之黏結劑樹 脂膜。將此黏結劑樹脂膜切割成寬8mmx長20mm。遵照JIS K7 1 42 A法’進行切割後之黏結劑樹脂膜的折射率測定。 此時’ Abbe折射率計係使用Atag0股份公司製之Abbe折 射率計1 · 4型，浸液係使用二碘甲烷，於2 3艽之溫度測 定折射率後’日本帝國墨水製之VAR-000介質的黏結劑樹 脂膜之折射率爲1 · 5 1 8，聚碳酸酯黏結劑樹脂膜之折射率爲 1.585。 另外’將用於實施例及比較例之導光板切割成寬8mmx 長2 0 m m X厚5 m m。針對整個橫剖面，使用日本三共理化學 製之耐水硏磨紙# 2 0 0 0，硏磨鏡面而得到導光板折射率測 定用試樣。針對導光板折射率測定用試樣之折射率，遵照 JIS K7142 A法’於23°C之溫度，使用Atago股份公司製 之Abbe折射率計1 . 4型加以測定。此時，浸液係使用二 碘甲烷。用於實施例1〜3、6、7與比較例1、2、4〜6之 導光板的折射率爲1.4 8 6。另外，用於實施例4、5與比較 例3之導光板的折射率爲1.48 5。 (4 )微粒之折射率測定 針對Seiko Advance製之胺基甲酸酯珠b微粒，遵照jis K 7 1 4 2 B法以進行折射率之測定。此時，將檸檬酸三正丁 酯與1 -溴萘之混合液作爲浸液。將浸液置於玻璃製之薄片 -18- 200909941 上，使微粒分散於浸液上，再於其上放置玻璃蓋片而作成 單元組。使用光學顯微鏡OLYMPUS製之MX61L，以倍率 2 00倍觀察此單元組中之微粒，即使偏離焦距，也將浸液 調整成貝克（Becke )線變成不動之混合比率。此時，將 Ushio Spec公司製之電源裝置型號BA-X500、光源裝置型 號SX-UID501XAMQ作爲光源使用，使用INSTRUMENTS 公司製之單色器H20VIS型式中的589nm波長。其後，遵 照JIS K7 1 42 A法，測定貝克線變成不動之混合比率的浸 液之折射率後，折射率爲1 . 5 2 5。將此浸液之折射率設爲微 粒之折射率。 針對Seiko Advance製之胺基甲酸酯珠A、褪光劑K與 曰本昭和電工製之氫氧化鋁H3 20，也同樣進行折射率之測 定。胺基甲酸酯珠A之折射率爲1 .5 2 5、褪光劑K之折射 率爲1.459、氫氧化鋁H320之折射率爲1.562。 (5 )亮度及亮度不均之測定 將如上述作成的附有光擴散層之導光板作成顯示於第1 圖之面光源裝置。 亦即，除了將光之射入端面（長度388mm邊之兩端面）、 射出面、及賦與光擴散層的表面之外，也將附有黏著劑之 反射膜（T s u j i d e η製之S U -1 1 9 ( W ))貼附於二個端面。 將白色反射板3 ( Tsujiden製之RF1 88 )配置在導光板1 之賦與有光擴散層8的面側，並將擴散膜6( Tsujiden製之 D 1 22 )配置在導光板1之射出面側，接著，將一片稜鏡片 7(日本住友3M製之BEFII )配置在稜鏡透鏡形成面與導 光板成爲相反側、稜鏡透鏡列之脊部成爲平行於射入端面 -19- 200909941 之方向上，接著，依序配置擴散膜6’（ Tsujiden製之D122 )。 光源係在其各自之射入端面，在射入光面之端面板厚方 向的中央位置上，與導光板1之射入端面的距離隔開lmm 設置各一根直徑 3mm'長度 419mm之冷陰極管 2、2’ (Harison東芝製之冷陰極螢光燈）。還有，在冷陰極管中 係使用反向器（inverter) ( Harison 東芝製之 HIU-766 52K )，燈反射器5、5 ’係利用反射片（日本麗光製之 Luiremirror 150W05)以覆蓋冷陰極管之方式來成形爲「门」 字而加以配置，於是形成了面光源裝置。反射片與導光板 1之相重疊的長度係作成〇 . 5 m m。 將電壓12V、管電流7mA通電於冷陰極管中，約20分 鐘直到安定爲止而予以放置，測定面光源裝置之亮度。 亮度之測定係在導光板面之法線方向上，將亮度計 (Konica Minolta製之CA1500W)設置在距離導光板面中 央67 0mm之位置。亮度測定領域係作成除了從各自之4端 面起10mm以外的內側368mmx271mm，將此領域之平均亮 度設爲亮度而顯示於表1。 另外，亮度不均之測定係以目視確認整面亮度有無局部 不均。使用印刷性不佳的混合墨水之情形下，整面之亮度 均勻性將受損，局部不均將發生而變得不適合實用。另一 方面，若使用印刷性佳的混合墨水時，將無局部不均而變 得適合實用。 (6 )亮度分布之測定 亮度測定領域係作成除了從各自之4端面起1 0 m m以外 的內側 3 6 8 m m X 2 7 1 m m，將此領域之長邊、短邊分別予以 -20- 200909941 19等分，將19.37mmx 14.26mm之大小設爲1區劃。於長邊 之中央部且最接近於一側冷陰極管的區劃設爲位置1，以 下，隨著遠離冷陰極管而依序賦與位置2、位置3…之編 號，將領域之中心部設爲位置1 〇，隨著接近另一側之冷陰 極管而賦與位置η、位置12…位置1 9。所謂位置1 9係最 接近於另一側之冷陰極管的區劃。分別測定在與冷陰極管 平行方向19.37mm、2根冷陰極管間方向14.26mm的19個 位置之平均亮度，中央部之亮度係取自位置10之平均亮度 値，端部亮度係取自位置1或位置19中較低者之平均亮度 値。除此以外，進行相同於亮度測定之方式。其結果，針 對實施例1〜7與比較例1〜5，相較於位置1與位置1 9， 位置1 〇之亮度皆變得較高，適合作爲面光源裝置的亮度分 布。針對比較例6，由於亮度不均已經確認，故未測定亮 度分布與平均亮度。 (7 )光擴散層表面之十點平均粗糙度及凹凸平均間隔之測 定 使用表面粗糙度測定機（日本東京精密製之Surfcom 1500DX)以測定戶斤得的附有388mmx291mmx6mm光擴散層 之導光板光擴散層表面之十點平均粗糙度（Rz)與凹凸之 平均間隔（S m )。在點佔有面積率6 8 %之點上，測定5次 正方形形狀之對角方向以作爲其平均値。除了將測定長度 設爲0.5 mm，並將截止波長設爲0.25 mm之外，遵照JIS B060 1 - 1 994加以測定。將所得的十點平均粗糙度（Rz)與 凹凸之平均間隔（S m )顯示於表1。 相較於比較例1、2、4、5，實施例1〜3與6、7之亮度 -21- 200909941 變得較高。相較於比較例3，實施例4、5之亮度變得較高。 另外，於比較例6之情形，印刷性變差，亮度形成局部不 均。還有，無論是實施例、比較例，中央部亮度皆較周邊 部亮度爲高。 因而，得知藉由利用本發明之方法，能夠提供一種最適 合之面光源裝置，其適合於液晶顯示裝置用之高亮度且亮 度分布良好、無亮度之局部不均。 -22- 200909941200909941 IX. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to a surface light source device. [Prior Art] A method for a surface light source device such as a liquid crystal display device includes an edge light method in which a light source is mounted on an edge portion of a light guide plate, and a light source is disposed directly under the diffusion plate A direct-down type of light that diffuses light by a diffusing plate. In the case of a liquid crystal display device having a small screen size, the use of an edge light source method has become mainstream. In the case of the edge light source method, light emitted from a light source that has been mounted on the edge portion of the light guide plate is incident from the edge portion of the light guide plate, and light that is incident above a critical angle with respect to the surface of the light guide plate will be guided. The exit surface of the light plate is emitted. On the other hand, most of the light that travels at an angle lower than the critical angle of the surface of the light guide plate is repeatedly reflected on the surface, travels in the light guide plate, and hardly emits from the exit surface of the light guide plate. In order to allow the light traveling in the light guide plate to be emitted from the light-emitting plate emitting surface, the light-scattering agent of the light guide plate may be added, or the light-diffusing layer may be applied to the back surface of the light-emitting plate emitting surface. In the case of a liquid crystal display device, most of the screen is viewed from the center of the screen. Therefore, it is necessary to make the brightness of the center of the picture equal to the brightness of the end of the picture or to the end of the picture. Among the light incident on the light guide plate from the light source, the amount of light incident on the surface of the light guide plate at a critical angle or more, that is, the amount of light emitted from the exit surface will decrease as the distance from the light source decreases, and the brightness of the central portion of the screen It becomes a problem that it is lower than the end of the screen. It is known that the solution is to provide a discontinuous light diffusion layer on the back side of the exit surface. Specifically, according to the area ratio of the area of 200,909,941 per unit of the light-diffusing layer, the continuity increases as the distance from the light source increases, so that a gradation pattern is formed, and in general, the brightness is controlled by the The distribution of expectations. The method of providing the light diffusion layer includes various printing methods represented by the screen printing method; the shape transfer method represented by the injection molding method of the stamper or the compression molding method; or the light diffusion in advance. The layer of the layer is legally attached. From the viewpoints of mass productivity and economy, among these methods, most of the printing methods represented by screen printing on the back surface of the light-emitting plate exit surface are used. The liquid crystal display device is oriented toward digital high-vision, and the demand for high-definition display of images is strong. In order to display images with high definition, it is necessary to reduce the opening degree of the liquid crystal panel. However, since the decrease in the degree of opening causes the light transmittance of the liquid crystal panel to decrease and the screen to become dark, a higher-luminance surface light source device is necessary. In order to achieve high brightness, a method of dispersing a light-scattering agent in a light guide plate and increasing the emission of light incident on the light guide plate has been proposed (refer to Patent Document 1). This method is achieved by dispersing the light-scattering agent in the light guide plate. Although the brightness of the surface light source device will be improved, it has not yet reached a satisfactory level, and further brightness of the tube is required. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION The object of the present invention is to provide a high liquid crystal display device in view of the above requirements for high brightness. Brightness surface light source device. MEANS TO SOLVE THE PROBLEM 200909941 The inventors of the present invention have found that it is possible to provide a high-intensity surface light source device suitable for a liquid crystal display device. The present invention relates to a surface light source device comprising: a light guide plate having a light exit surface and one or more light incident surfaces; a light source that supplies light to the incident surface; and a back surface of the light exit surface of the light guide plate a light diffusing layer formed; and a reflecting plate disposed on the back side; the light diffusing layer is configured to increase a ratio of the area of the light diffusing layer to the area per unit area of the back surface as the distance from the light source is increased To be dispersed, the ten-point average roughness of the surface of the light-diffusing layer is 8 μm to 25 μm, and the average interval of the surface unevenness of the light-diffusing layer is 20 μm to 150 μm. Advantageous Effects of Invention According to the present invention, it is possible to provide a high-intensity surface light source device suitable for a liquid crystal display device. [Embodiment] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the preferred embodiments of the present invention will be specifically described, but the present invention is not limited by the embodiments. The light guide plate used in the present invention has one or more light incident surfaces. Examples of the substrate constituting the light guide plate include transparent organic materials such as methacrylic resin, polycarbonate resin, styrene resin, cyclic olefin resin, and amorphous polyester resin, or inorganic glass. Transparent inorganic material. Among these resins, a methacrylic resin, a polycarbonate resin, and a cyclic olefin resin are preferable, and among them, a methacrylic resin is more preferable. The method of forming the light guide plate is not particularly limited, and the conventional method of 200909941 can be used. For example, when a certain amount of additives are added to a slurry containing a raw material monomer or a raw material monomer which is an organic transparent material, the molded product is cast and polymerized, and then cut into a predetermined shape. The size of the cut surface is honed; or, if necessary, the resin composition composed of the various added substrate-added resins is passed through a sheet-forming compression molding machine to obtain a sheet-formed product. Thereafter, the method is obtained by cutting into a predetermined honing cut surface. At this time, a release agent capable of improving the releasability of a material and a mold, or a shape of a known light guide plate such as an ultraviolet absorber which is delayed by deterioration is provided as a flat plate having a constant thickness. The wedge shape which is thinned away from the light source is preferably a flat plate type. Further, it is possible to add a light scattering agent having a refractive index to the substrate constituting the light guide plate. By adding the light-scattering agent to the light-transmitting sheet of the present invention, it is possible to further increase the luminance. The shape of the light scattering agent may be a true spherical shape, a spherical shape, a scale shape or the like, and is not particularly limited. For example, the light scattering agent may be exemplified by cerium, calcium carbonate, barium sulfate, titanium oxide, aluminum oxide, or oxidizer-based fine particles; or organic systems such as urethane beads, fluorenone beads, and PMMA beads styrene beads. particle. The number of such light scattering agents is preferably 〇 1 μmη or more and 50 μππ or less. The case of the amorphous shape is preferably Ο.ίμιη or more, 50 μπι or less. If the number of the light-scattering agent (the length of the amorphous shape is too long) is too small, the light-scattering property will become large, and the emitted light will be colored. In addition, when the average number of light particles is too large, the deviation of the light caused by the scattered light is the formula obtained by obtaining the sheet of the polymer of the substrate and the size of the forming machine or the like, in order to make the ultraviolet ray additive . Or the thickness of the plate varies with the use of amorphous, amorphous, such as aluminum oxide, MS beads, average particle size, long diameter, and average wavelength of the particles. Uneven brightness of the dispersing agent 200909941 will occur. As a light scattering agent in the light guide plate, the refractive index difference X between the light guide plate and the light scattering agent is in the range of 0.01 μL × 0.1, and the content of the light scattering agent y (ppm) is higher. Preferably, it is in the range of Ο.Κχ < 0.5, preferably l〇<y^5 00 range; in the case of 0.5 SX, preferably 1 ^ y ^ 1 〇 range. In the case of a light-scattering agent having a small difference in refractive index from the substrate of the light guide plate, the amount of addition is increased, and the amount of the light-scattering agent having a large difference in refractive index from the substrate of the light-guide plate is reduced. In the case where the light scattering dose y corresponding to the above refractive index difference X is too low, the obtained luminance will be lowered. Further, when the light-scattering dose y corresponding to the refractive index difference X is excessively high, even in the vicinity of the light source and the central portion, a light-dark layer pattern which changes the area ratio of the light-diffusing layer is formed, and there is a uniformity of the emitted light or The adjustment of the illuminating pattern is also difficult, and the brightness at the center of the screen is lower than that at the end of the screen. Further, "ppm" means a parts per million by weight of the light guide plate containing the light scattering agent. A light diffusion layer is provided on the back surface of the light guide plate exit surface. The light diffusion layer is dispersed in such a manner that the ratio of the area of the light diffusion layer per unit area occupying the back surface of the light exit surface of the light guide plate is increased as it is away from the light source. The shape of the dispersion of the light-diffusing layer is not particularly limited, and may be a dot shape, a dot shape, a polygonal shape, a striped shape, a lattice shape, or the like, and may be any shape. The ratio of the area per unit area occupied by the light diffusion layer to the surface increases as it moves away from the light source. By forming a so-called light and dark layer pattern, it is possible to control the brightness to a desired distribution. When the area ratio of the light-diffusing layer does not become large as it goes away from the light source, the brightness in the central portion of the screen tends to be lower than in the vicinity of the light source, and it is practically impossible to use it as a light source device in 200909941. The surface of the diffusion layer has a ten-point average roughness (Rz) of from 8 μm to 25 μm, preferably from 8 μm to 15 μm. The average interval (Sm) of the unevenness of the surface of the diffusion layer is 20 μm to 150 μm, preferably 40 μm to 140 μm. Here, the average interval (Sm) of the ten-point average roughness (Rz) and the unevenness is measured in accordance with JIS B 060 1 - 994. Further, the average interval (S m ) of the concavities and convexities refers to the "average length of the contour curve elements" defined in JI S B 0 6 0 1 - 1 9 9 4 . When the ten-point average roughness (Rz) is less than 8 μηι, among the light traveling inside the light guide plate, the light-angle effect of the light-diffusing layer becomes small, and the light exits from the exit surface beyond the critical angle. The proportion of light will decrease and the brightness will become lower. Further, when the ten-point average roughness (Rz) exceeds 25 μm, the unevenness of the surface is likely to be scratched, and the local brightness is increased, which is a cause of the so-called deviation. When the average interval (S m ) of the concavities and convexities is less than 20 μm, the convexities on the surface become easily scratched, and local unevenness in brightness tends to occur easily. When the average interval (S m ) of the concavities and convexities exceeds 150 μm, the diffusion effect on the light diffusion layer becomes small, and thus the light emitted from the exit surface exceeds the critical angle with respect to the surface of the light guide plate. The ratio will decrease and the brightness will decrease. The method for forming the light-diffusing layer may be exemplified by various printing methods represented by a screen printing method, a shape transfer method represented by an injection molding method using a stamper or a compression molding method, or a light diffusion layer previously provided. The sheet is legally attached. Among these methods, a printing method is preferably used from the viewpoint of high mass productivity and low cost. Among the printing methods, it is preferable to use a screen printing method from the viewpoint of easiness of adjusting the area ratio of the light diffusion layer. In the case of the screen printing method, 'on a plate composed of a screen of polyester or nylon, -10-200909941, the ink which disperses the fine particles in the binder resin is passed, and the desired printing pattern is transferred. On the light guide plate, if the ten-point average roughness (Rz) exceeds 25 μm, it is necessary to add particles of a large particle size to the ink, in which case it becomes a blockage of the screen constituting the plate. The reason is not good. In order to obtain stable printability without causing clogging of the screen, it is preferable to further reduce the particle diameter of the fine particles so that the ten-point average roughness (Rz) is 15 μm or less. In the screen printing method, in order to print a desired light diffusion layer, the screen constituting the plate has an unopened portion through which the ink is restricted by the emulsion, and a desired printing pattern is transferred to the light guide plate for the passage of the ink. The opening on the top. Hereinafter, the ratio of the area of the light diffusion layer per unit area of the back surface of the exit surface of the surface of the light guide plate is referred to as "area ratio". For example, in the surface of the surface of the light guide plate of 2 mm x 2 mm, a light diffusion layer of 1 mm x 1 mm is formed, and the area ratio of the light diffusion layer is 25%. Further, a plurality of groups of light diffusion layers which are not continuous are referred to as "light diffusion layers". The method of adjusting the light diffusion level is generally performed by changing the area ratio of the unopened portion to the opening portion of the screen constituting the plate. In order to increase the area ratio of the light-diffusing layer, for example, the area of the opening portion per unit area of the screen constituting the plate is enlarged, and the area of the unopened portion is narrowed. In order to reduce the area ratio of the light diffusion layer, the area of the opening portion per unit area of the screen constituting the plate is narrowed, and the area of the unopened portion is enlarged. It is preferable that one or more light-diffusing layers are formed and dispersed with respect to an area of 3 mm 2 of the surface of the light guide plate, and it is preferable to form one or more light-diffusing layers to be dispersed with respect to an area of 1 mm 2 of the surface of the light guide plate. In the printing method, 'ink can use various types of ink. In the thermosetting ink, inorganic fine particles or organic fine particles -11 to 200909941 are generally used in an ink which is added to a binder resin diluted with a solvent. The method of adjusting the ten-point average roughness (Rz) or the average interval (Snl) of the irregularities may be to change the ratio of the solvent to the binder resin and the fine particles in the ink, or to change the particle diameter of the particles. For example, in the case of screen printing, in order to increase the ten-point average roughness (Rz), the proportion of the solvent in the ink is increased, and the particle size of the particles is additionally increased. In addition, by reducing the diameter of the wire constituting the screen or by reducing the number of meshes indicating the mesh of the mesh, it is possible to increase the transmission volume of the ink and to thicken the thickness of the ink attached to the surface of the light guide plate. Can increase the ten point average roughness (Rz). On the contrary, in order to reduce the ten-point average roughness (Rz), the proportion of the solvent in the ink is reduced, and the particle diameter of the particles is reduced. Further, by increasing the diameter of the wire constituting the screen or increasing the number of the mesh holes, the transmission volume of the ink can be reduced, and the ten-point average roughness (Rz) can be reduced by thinning the thickness of the ink adhering to the surface of the light guide plate. The inorganic fine particles or the organic fine particles added to the diffusion layer can be used as the fine particles exemplified as the light scattering agent added to the light guide plate. Further, a conventional matting agent or the like can also be used. The solvent is preferably a solvent which sufficiently dissolves the binder resin and has a slow evaporation rate. In the case where a solvent having a low solubility of the binder resin is used, precipitation of the binder occurs during storage or during printing of the ink, which may cause printing defects. Further, in the case of using a solvent having a high evaporation rate, the mesh clogging of the screen tends to occur at the time of printing, which causes a decrease in mass productivity. Further, a photocurable ink can also be used. In order to increase the ten-point average roughness (Rz), it is possible to increase the particle diameter of the particles in the ink -12-200909941 or increase the amount of shrinkage during photohardening. The photocurable ink is cured by polymerizing a monomer component, but shrinkage is accompanied by the polymerization. Therefore, there is a method of increasing the monomer component in the ink for increasing the amount of shrinkage at the time of photohardening. Further, in order to reduce the ten-point average roughness (R z ), the particle diameter of the fine particles in the ink may be reduced, or the monomer component in the ink may be reduced to reduce the amount of shrinkage when the photocuring is reduced. In order to increase the average interval (Sm) of the concavities and convexities, the ratio of the particles in the ink is reduced, and the opposite is to narrow the average interval (S m ) of the concavities and convexities - the ratio of the particles in the ink is increased. In order to increase the ten-point average roughness (Rz)' and thus increase the particle size, if the weight or volume ratio of the particles in the ink is the same, the number of particles will decrease by the average interval (Sm) of the unevenness. Will become bigger. Therefore, in order to increase the ten point average roughness (Rz)' and to make the average interval (S m ) of the concavities and convexities equal or smaller, it is necessary to increase the particle diameter of the particles and increase the weight or volume ratio of the particles occupying the ink. As the weight or volume ratio of the particles in the occupied ink is increased, the ratio of the solvent to the binder resin is lowered, so that the fluidity of the ink is lowered and the printability is lowered. Once the use increases the ratio of the particles in the ink, that is, when the ink having a greatly reduced fluidity is used for screen printing, unevenness is generated in the ink permeation volume transferred to the light guide plate to obtain a uniform light diffusion layer. Will become difficult. If the light diffusion layer is uneven, if the light source is disposed at the edge of the light guide plate to illuminate the light source, the brightness of the light exit surface of the light guide plate becomes locally uneven and is not suitable for practical use. Therefore, the light diffusion layer in which the ten point average roughness (R z ) is too large and the average interval (S m ) of the unevenness is too small will cause a decrease in yield due to printing. -13- 200909941 In order to obtain a uniform light-diffusing layer, the amount of the binder resin in the ink is preferably more than 5 parts by weight, more preferably more than 10 parts by weight, based on 1 part by weight of the ink. In order to increase the brightness, it is preferred that most of the light is diffused on the air interface of the light diffusion layer. Therefore, the binder resin constituting the light-diffusing layer is preferably used in a refractive index difference of less than or equal to 2 to the light guide plate itself. If the difference in refractive index between the binder resin and the light guide plate is too large, since the light that is regularly reflected at the interface between the light diffusion layer and the light guide plate increases, the proportion of light diffused in the light diffusion layer decreases, and the light exits from the exit surface. The proportion of light that is emitted will decrease, and the tendency to reduce brightness will be poor. Further, it is suitable to use a difference in refractive index between the binder resin and the particles of 1.0 or less. When the difference in refractive index between the binder resin and the fine particles is too large, the transmittance of the light diffusion layer becomes low, and the loss of light becomes large, which tends to lower the brightness. The thickness of the light-diffusing layer after the ink is cured is preferably 0.1 to 5 Ο μιη, more preferably 0.5 to 4 Ο μ m 〇 The thickness of the light guide plate is preferably 0.1 to 15 μm, more preferably 0.2 to 12 mm. The shape of the exit surface may be either flat or roughened, or a lens such as a columnar triangular ridge may be formed. On the exit surface side of the light guide plate, a diffusion film and a cymbal or a lens sheet for adjusting the angular characteristics of the scattered light intensity may be disposed, and a ruthenium or a lens sheet may be disposed on the emission side of the diffusion film. Further, the ruthenium sheet can be disposed on the side of the exit surface of the diffusion film, and the diffusion film can be further disposed on the side of the emission surface. The structure of these films is not limited to this example. The diffusion film can also be coated with acrylic or ruthenium dioxide beads together with the binder, and has both a diffusion function and a light polarization function. In addition, the cymbal system can be formed by arranging a plurality of columnar triangular ridges in a state in which the ridges are continuously formed in the state of the surface of the ridges, and can be disposed in the direction of the entrance surface of the ridges with respect to the light guide plate. Two pieces are placed on the ridges perpendicular to each other. The lens sheet is formed with a plurality of concave lenses on the surface, and one or a plurality of the lens sheets can be disposed. The light source can be used to arrange a linear light source such as a cold cathode tube on one or more incident surfaces. In this case, one or several light sources can be placed relative to one side. In addition to the linear light source, it is also possible to use a point light source such as a laser. A reflector is disposed on the back side of the light guide plate exit surface. This reflection reflects the light emitted from the back surface of the emitting surface to the side of the light guide plate, and the utilization efficiency can be utilized. The reflecting plate is not particularly limited, such as a color reflective sheet. By making the above-described structure, it is possible to create a surface light source which is suitable for each of the liquid crystal display devices, which is particularly suitable for forming a tube brightness. The embodiments and comparative examples are used to further explain the present invention. It is not specifically limited. [Examples 1 to 7 and Comparative Examples 1 to 6] (1) Production of a light guide plate The dispersion concentration as disclosed in Table 1 was used to disperse the photo-scattering agent at a rate of 2.52) in a polymethyl group of 20% by weight. Acrylic acid | A weight percent of methyl methacrylate in a slurry. Next, 0.02 parts by weight of 2,2'-azobis(2,4-carbonitrile) as a polymerization initiator was further added as an ultraviolet transparent sheet. The direction of the parallel part is convex or curved. The surface of the hot cathode is used. The LED board is used to increase the light. Ming, but the mineralized titanium (folding methyl ester with 80 added 0.0 3 dimethyl pentyl absorbent -15- 200909941 2-(5-methyl-2-hydroxyphenyl) benzotriazole, stirred for 30 minutes As a polymerized raw material prize liquid, it is passed through an endless tube made of polyvinyl chloride on two sheets of tempered glass sheets with a length of 65 mm, a width of 450 mm, and a thickness of 6 mm to inject a polymerizable raw material slurry into the cast. In the model, the tempered glass plate was adjusted to a predetermined interval, immersed in warm water of 70 ° C, polymerized for 2 hours, and then polymerized in an air bath at 130 ° C for 1 hour. The panel saw ) (trade name SZIVG-4000 manufactured by SHINE) is cut off using a 600 mm x 400 mm x 6 mm acrylic sheet, and a grinding honing machine (trade name PU-Beauty, manufactured by Megaro Technica) is used for the periphery. The light guide plate of 388 mm x 291 mm x 6 mm was obtained by honing four sides. (2) Formation of light diffusion layer The light diffusion layer was formed on the back surface of the light exit surface of the light guide plate by screen printing. The guide was formed in a size of 3 8 8 mm x 291 mm x 6 mm. The back side of the exit surface of the light plate is used for the formation of the binder resin. VAR-00 0 medium made by Japan Imperial Ink, urethane bead A, urethane bead B, matting agent K (above, any of which is made by Seiko Advance), Hydroxide (Japan Showa) H320, manufactured by Electrician, used as a fine particle, and used isophorone as a diluent solvent. After mixing with the addition amount disclosed in Table 1, the hand was stirred for 1 minute using a spatula, and the mixture was uniformly stirred to obtain a mixed ink. Yes, the adhesive resin content of the VAR-0 0 0 medium made by the Japanese Imperial Ink was calculated as follows. The pre-weighed VAR-000 medium was coated on a 30 cm x 30 cm tempered glass, and the hot air at 80 ° C was applied. After drying in a circulating drying oven for 48 hours, a binder resin film having a thickness of 50 μm was prepared, and the ratio of the weight of the binder resin film to the weight of the ink before drying was calculated. -16- 200909941 The result is VAR-000 medium. The binder resin component was 37% by weight. In addition, in Example 6, 22 parts by weight of polycarbonate resin (Tafuron FN1700A, manufactured by Nippon Izumi Co., Ltd.) was dissolved in 78 parts by weight of trichloroethane. Ester adhesive A solution (solution) is substituted for the VAR-0 0. In the same manner as in the case of using the VAR-000 medium, fine particles and a dilution solvent are added to the polycarbonate binder, and stirred to obtain a mixed ink. The amounts of the binder resin, the fine particles and the diluent solvent (trichloroethane) are shown in Table 1. A screen printing machine (LS-560 manufactured by Newlong Precision Industries Co., Ltd.) and a screen made of nylon (Mesh Co., Ltd.) having a film thickness of ΙΟμιη and 355 mesh were used, and the mixed ink after the mixing was printed on the exit surface of the light guide plate. back. At this time, the 38 8 mm x 6 mm surface of the light guide plate was used as the light incident surface, and the screen of the light and dark layer pattern in which the brightness of the central portion of the light guide plate was higher than that of the vicinity of the light source was used. With respect to Examples 1 to 3 and 6, 7 and Comparative Examples 1, 2, and 4 to 6, the area ratio of the light diffusion layer in the vicinity of the light source was 22%, and the light diffusion layer in the center portion which is the farthest from the light source portions at both ends In the case where the area ratio is 68%, a pattern in which the area ratio of the light diffusion layer is increased as the linear portion is moved toward the center portion is formed. In the fourth and fifth embodiments and the comparative example 3, the area ratio of the light diffusion layer in the vicinity of the light source is 32%, and the area ratio of the central portion light diffusion layer farthest from the light source portion at both ends is 68%. In the direction of the length of the light plate 2 9 1 mm, a pattern in which the area ratio of the light diffusion layer is increased as the linear movement toward the center portion is made. At this time, the light diffusion layer is printed in a square shape of various sizes in a size of 1 m m X 1 m m on the surface of the light guide plate. After printing, it was allowed to stand at room temperature for 12 hours to be dried, and a light guide plate having a light diffusion layer of 3 8 8 mm x 291 mm x 6 mm which had been printed on the entire surface was obtained. -17- 200909941 (3) Refractive index of adhesive resin and light guide plate VAR-000 medium or polycarbonate adhesive made of Japanese Imperial ink used to form a binder resin is applied to a 30cmx3〇cm reinforcing plate. The glass was peeled off from the reinforced plate glass after drying in a hot air circulating drying oven of TC for 48 hours to form a binder resin film having a thickness of 5 μm. The adhesive resin film was cut into a width of 8 mm× 20 mm. The refractive index of the adhesive resin film after cutting was carried out in accordance with JIS K7 1 42 A. At this time, the Abbe refractometer was an Abbe refractometer type 1-4 manufactured by Atag0 Co., Ltd., and the immersion liquid was used. Diiodomethane, after measuring the refractive index at a temperature of 23 ', the refractive index of the resin film of the VAR-000 medium made by Nippon Empire ink is 1 · 5 1 8, and the refractive index of the polycarbonate resin film is 1.585. In addition, the light guide plates used in the examples and comparative examples were cut into a width of 8 mm x a length of 20 mm and a thickness of 5 mm. For the entire cross section, a water-resistant honing paper #3 0 0 0 made by Japan Sankyo Chemical Co., Ltd. was used. Honing the mirror surface to get the light guide plate refraction The sample for measurement is measured for the refractive index of the sample for measuring the refractive index of the light guide plate according to JIS K7142 A method at a temperature of 23 ° C using an Abbe refractometer type 1.4 manufactured by Atago Co., Ltd. The immersion liquid used diiodomethane. The refractive index of the light guide plates used in Examples 1 to 3, 6, 7 and Comparative Examples 1, 2, and 4 to 6 was 1.48 6. Further, used in Examples 4 and 5. The refractive index of the light guide plate of Comparative Example 3 was 1.48 5. (4) The refractive index of the fine particles was measured for the urethane bead b fine particles of Seiko Advance, and the refractive index was carried out in accordance with the jis K 7 1 4 2 B method. In this case, a mixture of tri-n-butyl citrate and 1-bromo-naphthalene is used as an immersion liquid. The immersion liquid is placed on a glass sheet -18-200909941 to disperse the particles on the immersion liquid, and then A glass cover sheet was placed thereon to form a unit group. The MX61L manufactured by an optical microscope OLYMPUS was used to observe the particles in the unit group at a magnification of 200 times, and the immersion liquid was adjusted to a Becke line to become a stationary mixture even if the focal length was deviated. Ratio. At this time, Ushio Spec's power supply unit model BA-X500, light source The model SX-UID501XAMQ was used as the light source, and the wavelength of 589 nm in the monochromator H20VIS type manufactured by INSTRUMENTS was used. Then, according to the JIS K7 1 42 A method, the refractive index of the immersion liquid in which the Becker line became immovable was measured. The refractive index is 1. 5 2 5. The refractive index of the immersion liquid is set to the refractive index of the particles. The refractive index was measured in the same manner for the urethane beads A and the matting agent K manufactured by Seiko Advance and the aluminum hydroxide H3 20 manufactured by Sakamoto Showa Electric Co., Ltd. The refractive index of the urethane bead A was 1.52, the refractive index of the matting agent K was 1.459, and the refractive index of the aluminum hydroxide H320 was 1.562. (5) Measurement of luminance and luminance unevenness The light guide plate with the light diffusion layer prepared as described above was formed as the surface light source device shown in Fig. 1. That is, in addition to the light incident on the end surface (the end faces of the 388 mm side), the exit surface, and the surface to which the light diffusion layer is applied, a reflective film with an adhesive (T sujide η SU - 1 1 9 ( W )) attached to the two end faces. The white reflecting plate 3 (RF1 88 manufactured by Tsujiden) is disposed on the surface side of the light guiding plate 1 to which the light diffusing layer 8 is provided, and the diffusion film 6 (D 1 22 manufactured by Tsujiden) is disposed on the emitting surface of the light guiding plate 1. On the side, a piece of cymbal 7 (BEFII manufactured by Sumitomo 3M, Japan) is placed on the opposite side of the 稜鏡 lens forming surface and the light guide plate, and the ridge portion of the 稜鏡 lens column is parallel to the injection end surface -19-200909941. Then, the diffusion film 6' (D122 manufactured by Tsujiden) is sequentially disposed. The light sources are disposed at their respective injection end faces, and are disposed at a central position in the thickness direction of the end face of the incident light surface, and are spaced apart from the entrance end faces of the light guide plate 1 by a distance of 1 mm, and each of the cold cathodes having a diameter of 3 mm and a length of 419 mm is disposed. Tube 2, 2' (Haryong Toshiba cold cathode fluorescent lamp). In addition, an inverter (HIU-766 52K manufactured by Harmonic Toshiba) was used in the cold cathode tube, and the lamp reflectors 5, 5' were covered with a reflection sheet (Luiremirror 150W05, manufactured by Liguang, Japan) to cover the cold. The cathode tube is formed into a "door" and arranged to form a surface light source device. The length of the reflection sheet overlapping the light guide plate 1 is 〇 5 m m. A voltage of 12 V and a tube current of 7 mA were supplied to the cold cathode tube, and were left for about 20 minutes until the stability was set, and the brightness of the surface light source device was measured. The brightness was measured in the normal direction of the surface of the light guide plate, and a luminance meter (CA1500W manufactured by Konica Minolta) was placed at a position of 67 mm from the center of the surface of the light guide plate. In the field of the measurement of brightness, the average brightness of the field was set to be the brightness, and the average brightness of the field was 368 mm x 271 mm, which is 10 mm from the respective four end faces, and is shown in Table 1. Further, the measurement of the unevenness in brightness was visually confirmed whether or not the brightness of the entire surface was partially uneven. In the case of using a mixed ink having poor printability, the uniformity of brightness of the entire surface is impaired, and local unevenness is caused to become unsuitable for practical use. On the other hand, when a mixed ink excellent in printability is used, it will be suitable for practical use without local unevenness. (6) Measurement of luminance distribution The field of luminance measurement is created by the inner side of 3 8 8 mm X 2 7 1 mm other than 10 mm from the respective 4 end faces, and the long side and the short side of this field are respectively given -20-200909941 19 divisions, the size of 19.37mmx 14.26mm is set to 1 division. The division in the central portion of the long side and closest to one side of the cold cathode tube is set to position 1. Hereinafter, the position of the position 2, the position 3, etc. is sequentially assigned as it is away from the cold cathode tube, and the center portion of the field is set. For position 1 〇, position η, position 12... position 19 is assigned as it approaches the cold cathode tube on the other side. The position 1 9 is the zone of the cold cathode tube closest to the other side. The average brightness at 19 positions in the direction parallel to the cold cathode tube of 19.37 mm and the direction between the two cold cathode tubes of 14.26 mm was measured, and the brightness of the central portion was taken from the average brightness of the position 10, and the end brightness was taken from the position. The average brightness of 1 or the lower of position 19 is 値. Except for this, the same method as the brightness measurement is performed. As a result, in Examples 1 to 7 and Comparative Examples 1 to 5, the luminance at the position 1 〇 was higher than that at the position 1 and the position 19, and it was suitable as the luminance distribution of the surface light source device. With respect to Comparative Example 6, since luminance unevenness was confirmed, the luminance distribution and the average luminance were not measured. (7) Measurement of the ten-point average roughness and the average interval of the unevenness on the surface of the light-diffusing layer The surface roughness measuring machine (Surfcom 1500DX manufactured by Tokyo Fine Industries, Japan) was used to measure the light guide plate light of the 388 mm x 291 mm x 6 mm light diffusion layer. The ten-point average roughness (Rz) of the surface of the diffusion layer and the average interval (S m ) of the irregularities. At the point where the dot occupied area ratio was 68%, the diagonal direction of the square shape was measured 5 times as its average enthalpy. Except that the measurement length was set to 0.5 mm and the cutoff wavelength was set to 0.25 mm, it was measured in accordance with JIS B060 1 - 1 994. The obtained ten point average roughness (Rz) and the average interval (S m ) of the unevenness are shown in Table 1. The luminances -21 to 200909941 of Examples 1 to 3 and 6, 7 became higher than those of Comparative Examples 1, 2, 4, and 5. The brightness of Examples 4 and 5 became higher as compared with Comparative Example 3. Further, in the case of Comparative Example 6, the printability was deteriorated, and the luminance was locally uneven. Further, in the examples and comparative examples, the brightness in the central portion was higher than that in the peripheral portion. Therefore, it has been found that by using the method of the present invention, it is possible to provide an optimum surface light source device which is suitable for high luminance of a liquid crystal display device and has a good luminance distribution and no local unevenness in luminance. -22- 200909941
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CO 200909941 【產業上利用之可能性】 本發明之高亮度且亮度分布最爲適合之面光源裝置，係 適合於液晶顯示裝置用等。 【圖式簡單說明】 第1圖係顯示面光源裝置一例之槪略圖。 【主要元件符號說明】 1 導 光 板 2、 2， 冷 陰 極 管 3 反 射 板 5、 5， 燈 反 射 器 6、 6， 擴 散 膜 7 稜 Δ^£. m 片 8 光 擴 散 層 -24-CO 200909941 [Problem for industrial use] The surface light source device of the present invention which is most suitable for high brightness and brightness distribution is suitable for liquid crystal display devices and the like. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing an example of a surface light source device. [Main component symbol description] 1 light guide plate 2, 2, cold cathode tube 3 reflector plate 5, 5, lamp reflector 6, 6, diffused film 7 edge Δ^£. m piece 8 light diffusion layer -24-