201248211 六、發明說明： 【發明所屬之技術領域】 本發明關於光擴散片、包含 含光學單元的背光單元以及包;^f的光學單元、包 置。 早70的液晶顯示裴 【先前技術】 液晶顯示裝置有效地利用薄型 徵，並作為平板顯示器被廇泛應用，工里和低耗電等特 例如用作手機、可携式資雜端晋途逐年擴大， 等的顯示裝置。近年來，液晶_ 腦和電視機 列舉高輝度化、廣視角化、節能 的特性可以 是對高輝度化的要求較高。 ，1輕I化等，特別 —通的液晶顯示裝置具有液晶 專利文獻！：曰本專利公的背面側（例如參照 曰n β 開報特開細5]_59號）。液 m'/、有將液晶單元夾持在表面側偏光板和背面側 =先=: 桃结構’並且以各種顯示模式驅動液晶顯示」 件。貪光早7L從背面側照射液晶顯示元件，並且廣泛普及 的是邊緣光型和直下型的背光單元。這些以往的背光單元 具有♦光源’導光板，將來自光源的光線導向液晶顯示元 件側’以及光學單元，配置在導光板的液晶顯示元件一 側的表面上。光學單元用於有效且均勻地使來自導光板的 光線射入液晶顯示元件背面側的整個表面上，例如包括： 光擴散片’使來自導光板的光線擴散；以及棱鏡片’使透 射光線向法線方向側折射。 3/23 201248211 雖然以往的液晶顯示裝置由於具有如上所述的光擴散 片和棱鏡片等，所以實現了一定程度的高輝度化，但是現 在進一步要求液晶顯示裝置高輝度化。基於提高液晶顯示 裝置的輝度等目的，開發出了高增益棱鏡片。例如，（株） 住友3M公司制的產品名稱為“BEF2-G2-MR-155”的高增 益棱鏡片已經商品化。上述高增益棱鏡片是高折射率材料 構成的棱鏡片。雖然高增益棱鏡片已經商品化，但是並未 開發出與南增盈棱鏡片配合的光擴散片’也沒有發揮出由 高增益棱鏡片產生的提高輝度的效果。此外，現在還進一 步要求液晶顯不裝置薄型化。 【發明内容】 本發明的目的在於提供用於進一步實現液晶顯示裝置 的高輝度化和薄型化的光擴散片、包含該光擴散片的光學 單元、包含該光學單元的背光單元、以及進一步實現了高 輝度化和薄型化的液晶顯示裝置。 本發明提供一種光擴散片’其包括：透明的基體材料 層；以及光擴散層，層疊於所述基體材料層的表面，旅 在黏結劑中具有樹脂珠，所述光擴散片的特徵在於，所述 樹脂珠的折射率在1.5〇以上。 由於5亥光擴散片的樹脂珠的折射率大於以往光擴散片 的樹脂珠的折射率，所以由樹脂珠產生的光線的反射和折 射比以往大。因此，如果將該光擴散片組裝到液晶顯示裝 置上，則與以往相比可以提高液晶顯示裝置的輝度。其結 果，可以使背光單元薄型化，進而可以實現液晶顯示裝置 的薄型化。此外，通過分別調整該光擴散片的黏結劑和樹 4/23 201248211 曰朱的折射率，不論具有什麼樣的折射率的高增益棱鏡 片，都可以實現利用高增益棱鏡片使光線朝向垂直方向直 立。 上述黏結劑的折射率可以在1.49以上且在1.51以下， 上述樹脂珠的折射率可以在152以上且在1 59以下。在這 種，況下，由於該光擴散片的樹脂珠的折射率大於以往光 擴散片的樹脂珠的折射率，所以由樹脂珠產生的光線的反 射和折射比以往大，從而提高了液晶顯示裝置的輝度。 在該光擴散片中，從樹脂珠的折射率減去黏結劑的折 射率後的值可以在〇.〇6以上且在_以下。在這種情況 下，由樹脂珠產生的光線的反射和折射進一步變大，從而 進一步提高了液晶顯示裝置的輝度。 上述樹脂珠的主體聚合物可以是（甲基）丙歸酸類單 體和笨乙烯類單體的共聚物。在這種情況下，可以容易地 使樹脂珠的折射率在h52以上且在159以下，或者是使從 樹脂珠的折射率減去黏結劑的折射率後的值在_以上且 在0.08以下。 上述樹脂珠相對於100質量份黏結劑的配入量可以在 4〇質量份以上且在230質量份以下。在這種情況下，由樹 f珠產生的光線的反射和折射進—步變大，從而進一步提 尚了液晶顯示裝置的輝度。 該光擴散>；的霧度值可以在78%以±且在93%以下。 在這種情況下，由樹脂珠產生的光線的反射和折射進一步 變大，從而進一步提高了液晶顯示裝置的輝度。 ^ 上述樹脂珠的平均粒子直徑可以在2阿以上且在^陣 以下。在這種情況下，由樹脂珠產生的光線的反射和折射 5/23 201248211 進一步變大，從而進-步提高了液晶顯示裝置的輝度。 上述樹脂珠可以是多分紐的珠。在這種情況下由 樹脂珠產生的光線的反射和折射進―步敎，從而進一步 提高了液晶顯示裝置的輝度。 為了進一步實現液晶顯示裝置的高輝度化和薄型化， 可以將如下光學單元用作液晶顯示裝置的一個結構要素， 即，該光學單^包括：上述光擴散片；以及—個棱鏡片， 層叠於上述錢散#的表關’上述棱鏡Η的折射率在15〇 以上。同樣，為了進一步實現液晶顯示裝置的高輝度化和 溥型化，可以將如下光學單元用作液晶顯示裝置的一個結 構^素’即，該光學單元包括：上述光擴散片；以及兩個 棱叙片，層疊於上述光擴散片的表面側，兩個上述棱鏡片 配置成棱線相互交叉，兩個上述棱鏡片的折射率在1 5〇以 上。在這種情況下，如果各棱鏡片的折射率在1·55以上且 在1.70以下，則可以進一步提高液晶顯示裝置的輝度。此 外’可以實現液晶顯示裝置的薄型化。 此外，為了進一步實現液晶顯示裝置的高輝度化和薄 型化，可以將如下背光單元用作液晶顯示襞置的一個結構 要素即，5亥奇光單元包括.光源；導光板，入射有來自 該光源的光線’並且使入射的光線射出；以及上述光學單 元，層疊於上述導光板的上側。 此外’本發明還提供一種液晶顯示裝置，該液晶顯示 名置包括.上述背光單元；以及液晶顯示元件，配置在上 述背光早元的棱鏡片的上方。 本發明可以提供用於進一步實現液晶顯示裝置的高輝 度化和薄型化的光擴散片、包含該光擴散片的光學單元、 6/23 201248211 包含該光學單元的背光單元、以及進一梦實現了高輝度化 和薄型化的液晶顯示裝置。 【實施方式】 下面參照附圖，對本發明的實施方式進行說明。 (液晶顯示裝置的結構） 圖1的液晶顯示裝置丨具有液晶顯示元件]〇和背光單 元20。液晶顯示元件1〇利用光來顯示資訊，並且具有將液 晶單元12夾持在表面側偏光板丨丨和背面側反射偏光板13 之間的結構。背面側反射偏光板13使光一個方向的偏振光 成分透射’並反射剩餘的偏振光成分。 背光單兀20配置在液晶顯示元件1〇的背面側，是從 背面側照射液晶顯示元件】〇的邊緣光型背光單元，並且背 光單元20具有光源21、導光板22和光學單元23。 光源21在直線上排列多個發光二極體。導光板22為 楔形，從液晶顯示裝置1的表面觀察時具有長方形的平面， 其長方形的一邊配置成與整個光源21相對。雖然未圖示， 但在導光板22的未與光源21相對的側面上設置有反射光 線的構件。雖然未圖示，但在導光板22的背面也設置有反 射光線的構件。導光板22利用上述的反射紐的構件，使 從光源21入射的光線向光學單元23射出。 光學單元23配置在導光板22職晶顯示元件1〇 一側 的表面上，並且以使光線垂直射人液晶顯料件ig背面整 個表面的方式，使從導光板22人射㈣線擴散並向液晶顯 示元件1G射^具體地說’光學料^具有：光擴散片 31，使從導光板22入射的光線擴散；以及第一棱鏡片％ 7/23 201248211 和第二棱鏡片33 ’使被光擴散片31擴散後的光線折射，並 實質上垂直於液晶顯示元件〗0前進。如圖】所示，光擴散 片3】、第一棱鏡片32和第二棱鏡月33分別從液晶顯示裝 置1的背面側朝向表面側依次層疊。 光擴散片31以使光線射入液晶顯示元件1〇背面整個 表面的方式’使從導光板22入射的光線擴散並向第—棱鏡 片32射出。光擴散片31具有：基體材料層4丨；光擴散層 42 ’層疊於基體材料層41的表面側；黏附防止層43，層疊 於基體材料層41的背面側。將在後面對光擴散片3丨的结 構進行詳細敘述。 第一棱鏡片32是高增益棱鏡片，使從光擴散片3ι入 射的光線折射並向第二棱鏡片33射出。第二棱鏡片33是 尚增益棱鏡片，以使射出的光線相對於液晶顯示元件1〇背 面大體垂直前進的方式，使從第一棱鏡片32入射的光線折 射並向液晶顯示元件〗〇射出。第一棱鏡片32和第二棱鏡 片33包括.基體材料層；以及突起列，由層疊在該基體材 料層表面的多個突條棱鏡部構成。 第一棱鏡片32和第二棱鏡片33的厚度（從背面到突 條棱1¾部的頂點的高度）較佳為5〇〖im以上且在2〇〇μΓη以 下’更佳為]〇〇μηι以上且在〗8〇μηι以下。此外，第一棱鏡 片32和第二棱鏡片33中的突條棱鏡部間的間隔（節距） 較佳為3〇μΐΏ以上且在1〇〇μηι以下，更佳為4〇μηι以上且 在6〇μΠ1以下。此外’突條棱鏡部的頂角較佳為85。以上且 在95以下。第一棱鏡片32和第二棱鏡片33的折射率在 】.50以上，較佳為1.55以上且在1.70以下。另外，棱鏡片 的折射率是指棱鏡部的折射率。通過組合使用這種結構的 8/23 201248211 棱鏡片32、33和該光擴散片3卜可以進一步實現高輝度化。 此外’第一棱鏡片32和第二棱鏡片33都在背面側使來自 與基板法線成33〜34。左右角度方向的光線向法線的表面 側折射。以往的棱鏡片使來自與基板法線成3〇〜31。左右角 度方向的光線向法線的表面側折射。即，關於使相對於基 板的背面傾斜入射的光線垂直地直立的功能，第一棱鏡片 32和第二棱鏡片33比以往的棱鏡片具有更高的能力。第一 棱鏡片32和第二棱鏡片33例如分別是（株）住友3M公司 制的產品名稱為BEF2-G2-MR-155”的高增益棱鏡片。 (光擴散片的結構） 光擴散片31是使入射的光線擴散並射出的光學片，如 上所述具有：基體材料層41 ;光擴散層42，層疊於基體材 料層41的表面側；以及黏附防止層43，層疊於基體材料層 41的背面側。 基體材料層41是能夠使光線透射的透明層，由樹脂形 成。該樹脂例如是丙稀酸樹脂 '聚對苯二曱酸乙二醇酯、 聚萘二甲酸乙二醇酯、聚碳酸酯、聚苯乙烯、聚烯烴、醋 酸纖維素或耐候性氯乙烯等。基體材料層41的平均厚度較 佳為ΙΟμιη以上且在400μηι以下，更佳為20μιη以上且在 130μηι以下。通過使平均厚度在]〇μηι以上，可以使基體材 料層41具有不會產生彎曲的強度。此外，通過使平均厚度 在400μηι以下，可以實現液晶顯示裝置1的薄型化，並且 可以充分確保液晶顯示裝置1的輝度。 光擴散層42包括：具有高折射率的樹脂珠51 ;以及黏 結劑52，用於以分散狀態固定樹脂珠51。樹脂珠51也分 散配置在光擴散層42的表面上，由此，在光擴散層42的 9/23 201248211 201248211 的凹凸形狀。利用該凹凸 的介面，進一步得到了使 表面上設置有微小且無秩序狀態 形狀以及樹脂珠51和黏結劑& 光線擴散的功能。 樹脂珠Μ的折射率在K50以上，較佳為]52以 在1.59以下t佳為1.55以上且在157以下。由 光擴散片中的樹脂珠的折射率為149卢亡， _的 式的樹脂珠51的折射率大於以往的樹二珠’。以本實施方 形成樹脂珠51的主體聚合物沒有特別限定，可以扩 丙烯酸樹脂、丙烯腈樹脂、聚氨酯、聚氣乙烯、聚苯乙 聚丙稀腈、聚醯胺等’但較佳採用（甲基）丙烯酸類單谱 和笨乙烯類單體的共聚物，更佳採用從（甲基）丙烯酸海 單體、苯乙烯類單體和交聯性單體得到的交聯（曱基^声 烯酸-苯乙烯類共聚物。通過採用將苯乙烯骨架導入（甲笑 丙烯酸骨架的主體聚合物，可以提高樹脂珠51的折射率， 並且通過進一步使其成為交聯結構，可以進一步提高折射 率。此外，當在黏結劑52中使用丙烯酸類樹脂（丙稀酸多 元醇等）時，由於具有相同的丙烯酸骨架，所以樹脂珠5】 在黏結劑52中均勻分散’從而可以進一步提高正面輝度。 上述（甲基）丙烯酸類單體可以列舉：丙烯酸；丙烯 酸的衍生物，例如丙烯酸曱醋'丙稀酸乙醋、丙稀酸丙酿、 丙稀酸丁酯、丙烯酸戊酯、丙稀酸己酯、丙稀酸庚酯、丙 烯酸辛酯、丙烯酸壬酯、丙烯酸癸醋、丙晞酸十一院基醋、 丙晞酸十二炫基酯、丙婦酸縮水甘油酯、丙烯酸曱氧基乙 酯、丙烯酸丙氧基乙酯、丙稀酸丁氧基乙_、丙稀酸甲氧 基二甘醇酯、丙烯酸乙氧基二甘醇酯、丙烯酸甲氧基乙二 醇酯、丙烯酸丁氧基三甘醇酯、丙烯酸甲氧基二丙二醇酯、 10/23 201248211 丙烯酸笨氧基乙酯、丙烯酸苯氧基二甘醇酯、丙烯酸苯氧 基四甘醇酯、丙烯酸苄酯、丙烯酸環己酯、丙烯酸四氫糖 基醋、丙烯酸二環戊烯基酯、丙烯酸二環戊烯基氧基乙酯、 丙烯酸N-乙烯基-2-吡咯烷酮基酯、丙烯酸羥乙酯、丙烯酸 羥丙酯、丙烯酸羥丁酯、丙烯酸2-羥基-3-苯氧基丙酯、丙 烯酸縮水甘油酯、丙烯腈、丙烯醯胺、N-羥甲基丙烯醯胺、 二丙S同丙烯醯胺；或者是曱基丙烯酸；甲基丙烯酸的衍生 物，例如甲基丙烯酸甲酯、曱基丙烯酸乙酯、曱基丙烯酸 丙酯、曱基丙烯酸丁酯、曱基丙烯酸戊酯、曱基丙烯酸己 酯、曱基丙烯酸庚酯、曱基丙烯酸辛酯、甲基丙烯酸壬酯、 曱基丙烯酸癸酯、甲基丙烯酸十一烷基酯、曱基丙烯酸十 二统基酯、曱基丙烯酸縮水甘油酯、曱基丙烯酸曱氧基乙 酯、甲基丙烯酸丙氧基乙酯、甲基丙烯酸丁氧基乙酯、曱 基丙烯酸曱氧基二甘醇酯、甲基丙烯酸乙氧基二甘醇酯、 甲基丙稀酸曱氧基乙一醇酿、甲基丙稀酸丁氧基三甘醇 酯、曱基丙嫦酸甲氧基二丙二醇酯、甲基丙烯酸苯氧基乙 酯、曱基丙烯酸苯氧基二甘醇酯、曱基丙烯酸苯氧基四甘 醇酯、曱基丙烯酸苄酯、甲基丙烯酸環己酯、曱基丙烯酸 四氬糖基醋、甲基丙烯酸一環戊埽基醋、甲基丙浠酸二環 戊烯基氧基乙酯、甲基丙烯酸N-乙烯基-2-吼咯烷酮基酯、 異丁烯腈、曱基丙烯醯胺、N-羥曱基曱基丙烯醯胺、甲基 丙烯酸2-羥乙酯、甲基丙烯酸羥丙酯、甲基丙烯酸羥丁酯、 甲基丙烯酸2-輕基_3_苯氧基两醋等。可以使用上述一種或 多種的組合。 上述苯乙烯類單體可以列舉笨乙烯、基苯乙稀、乙 烯基甲基苯、對叔T基苯乙鱗笨乙烯衍生物。可以使用 Π/23 201248211 上述一種或多種的組合。 交聯性單體可以列舉二乙稀基苯、乙二醇二甲基_ 酸酯、1，3-丁一知—甲基丙烯酸酯、1 , 4_丁二醇二甲基丙 烯酸酯、1，5_戊二醇二曱基丙烯酸酯、丨，6•己二^二^基 丙稀酸酷、新戊二醇二曱基丙稀酸g旨、二甘醇二甲基心 酸醋、三甘醇二曱基丙稀義、聚乙二醇二甲基丙烤酸醋、 三丙二醇二曱基丙稀_等。可以使用上述—種或多種的 組合。 在上述主體聚合物中，除了包含（甲基）丙稀酸類單 體、苯乙烯鮮體和交聯性單體以外，還可以包含豆他單 體。其他單體可以列舉乙酸乙職、氣乙稀、順丁稀二酸 針、順丁稀二酸、順丁蝉二酸醋、富馬酸、富馬酸醋、三 烯丙基異氰脲酸酯等。 把上述共聚物作為主體聚合物的樹脂珠例如通過使各 單體的混合物在存在聚合引發劑的狀態下懸浮聚合而得 到《亥懸浮t合通常可以在水或水與乙醇的混合物等水性 介質中進行。 上述樹脂珠51的形狀沒有特別限定，可以列舉球狀、 ，方狀、針狀、棒狀、紡錘形狀、板狀、鱗片狀、纖維狀 等，其中較佳為光擴散性優良的球狀。 上述樹脂珠51的平均粒子直徑較佳為 2μπι以上且在 5μΠΊ以下，更佳為2·5μιπ以上且在4μΓη以下。通過使用這 種平均粒子直徑的粒子，可以提高光擴散性等。另外，本 發明中的平均粒子直徑是指倍率1〇〇〇倍的電子顯微鏡所觀 測的粒子中隨機抽取的30個粒子的平均粒子直徑。此外， 粒子直徑由費雷特徑（由一定方向的平行線夾著投影圖像 12/23 201248211 時的間隔）定義。 樹脂珠51較佳為多分散性的珠，粒子直徑的變動係數 較佳為20%以上且在40%以下。通過使用這種多分散性的 珠，可以提高光擴散性，進而可以提高正面輝度等。 此外，光擴散層42中所含的樹脂珠51相對於1⑻質 量份黏結劑52的配入量較佳為4〇質量份以上且在23〇質 量份以下，更佳為45質量份以上且在1〇〇質量份以下，^ 佳為60質量份以T。獅珠51的配人量以進—步發揮光 擴散性的方式，根據平均粒子直徑的大小來確定。 上述黏結劑5 2通常由固化劑對基體材料聚合物進行固 化而得到。上述黏結劑52中還可以適#配人增塑劑、分散 劑、各種均化劑、料線吸㈣、抗氧化劑、減改性劑、 潤滑劑和光穩定鮮。姉結劑52 _作為主要結構要素 的基體材料聚合物，將樹脂珠Η大體等密度地固定配置在 基體材料層41的整個表面。 上述基體材料聚合物沒有特別限定，可以列舉丙稀酸 類樹脂、聚氨_、聚醋、氟類樹脂、石夕類樹脂、聚酿胺邊 亞胺、裱氧樹脂、紫外線固化型樹脂等，可以使用上述聚 合物的-種或兩種以上的組合。_是上述基體材料聚ς 物較佳衫元醇，其加玉性高，可以_塗敷等方式容易 地形成光擴散層42。此外，由於黏結劑52使用的基體材料 聚合物需要透射光線，所以為透明，特佳為無色透明。 〜上述多元醇較佳為聚醋多元醇或（甲基）丙稀酸多元 醇’更佳4(甲基）丙烯酸多元醇。將這些聚醋多元醇或 丙烯元醇作為基體材料聚合物的黏結劑52的耐候性 高’可以抑制光擴散層42變黃等。此外，在樹脂珠51使 13/23 201248211 用含有上述（甲基）丙稀酸類單體的共聚物的情況下，.通 過使用（甲基）丙稀酸多元醇，可以提高分散性，並且可 以提高正面輝度等。另外’可以使用該聚酿多元醇和丙稀 酸多元醇中的任意一方，也可以使用雙方。 上述聚酿多元醇和（甲基）丙稀酸多元醇令的經基的 個數只要是每-分子具有兩個以上就沒有㈣的限定，但 ^果固體成分+ _值在】〇以下，則交聯數減少，存在对 溶劑性、耐雜、耐熱性、表面硬度等伽的物性下降的 傾向。 如上所述，在基體材料聚合物採用多元醇的情況下， 固化劑較佳為六亞甲基二異氰酸醋、異佛_二異氯酸醋 和二甲笨二異氰酸酯，更佳為六亞曱基二異氰酸酯，特佳 為加成型的’、亞甲基二異氰酸g旨。如果使用這些固化劑， 貝^合物組合物_化反應速度變大。_化反應速度的 提尚有助於樹脂珠在黏結劑中的均勻分散性。 進-步提高均句分散性等’更佳組合使用（甲基）丙婦酸 多元醇和六亞甲基二異氰酸酯。 黏結劑52的折射率較佳為丨49以上且在15ι以下。 此外，彳<上述樹脂珠51的折射率減去上述黏結劑S2的折 射率後的值較佳為0.06以上且在〇 以下。 黏附防止層43由黏結劑和分散在該黏結劑中的珠構 成。该黏結繼成分也可以與上述光紐層42雜結劑52 相同。此外，珠的材料可以列舉無機珠和有機珠。另外， 該黏附防止層43的厚度（除珠以外的黏結劑部分的厚度） 沒有特別限定，例如可以在1μηι以上且在1〇μηι以下。 該黏附防止層43中的珠的配入量為較少量，珠相互分 14/23 201248211 喊地分政在黏結劑中’大部分的珠是其下端從黏結劑極少 量突出。因此，如果將該光擴散片31層叠於導光板22，則 突出的珠的下端抵接於導光板22的表面，光擴散片31背 面的整個表面不會與導光板22抵接。由此，防止了光擴散 片31和導光板22的黏附，可以抑制液晶顯示裝置畫面的 輝度不均。 以下說明光擴散片3〗的製造方法。該光擴散片31的 製造方法例如包括以下工序：（a)通過在構成黏結劑52的 組合物（基體材料聚合物和固化劑等）中混合樹脂珠， 而製造光擴散層用塗敷液；（b)通過將該光擴散層用塗敷 液塗敷於基體材料層41的表面，而層疊光擴散層42 ;⑷ 通過在構成黏結劑的聚合物組合物中混合珠，而製造黏附 防止層用塗敷液；⑷通過將該黏附防止層用塗敷液塗敷 於基體材料層41的背面，而層疊黏附防止層43。 (光線的前進） 接著，說明本實施方式的液晶顯示裝置i中光線的前 進。光線由光源21發光來產生，如圖2所示，來自光源21 的光線A被導光板22向光學單元23引導，並且被光學單 兀23的光擴散片31散射而從第一棱鏡片32背面的整個表 面射入第-棱鏡片32。射人第—棱鏡片32的光線a被第 一棱銃片32折射，由此，朝向與液晶顯示元件ι〇背面垂 直的方向直立，並前進至第二棱鏡片33。前進至第二棱鏡 片33的光線A被第一棱鏡片折射而進一步直立，實質 上垂直地射入液晶顯示元件1〇的背面。由此，來自背光單 元20的光線A射入液晶顯示元件1〇。 由於在液晶顯示元件1〇的背面側設置有背面側反射偏 15/23 201248211 光板13，所以射入液晶顯示元件的光線a的—部分透 射背面側反射偏光板13，而剩餘部分被反射到背光單元2〇 一側。透射背面側反射偏光板13後的光線A依次透射液晶 單元12和表面側偏光板U並向液晶顯示裝置1的表面側 射出。向背光單元20 —側反射的光線A被導光板22的反 射構件反射，如上所述，透射光學單元23並再次射入液晶 顯示元件10。 (效果） 如上所述，本實施方式的光擴散片31具有光擴散層 42，該光擴散層42包括：具有高折射率的樹脂珠51 ;以及 折射率較佳為1.49以上且在〗·51以下的黏結劑52。由於以 往的光擴散片中的樹脂珠的折射率如上所述為〗.49左右， 所以本貫施方式的樹脂珠51的折射率大於以往的樹脂珠。 因此’由本實施方式的樹脂珠5〗產生的光線的反射或折射 比以往大。其結果，本實施方式的光擴散片31能夠與作為 高增益棱鏡片的第一棱鏡片32和第二棱鏡片33配合，發 揮由第一棱鏡片32和第二棱鏡片33產生的提高輝度的致 果。因此，本實施方式的液晶顯示裝置1的輝度比以往高， 從而實現了所需要的高輝度化。 此外’由於第一棱鏡片32和第二棱鏡片33是由高折 射率材料構成的高增益棱鏡片，所以向該棱鏡片背面前進 的光線中、被反射的光的比例變高。但是，按照該光擴散 片31，由於樹脂珠51產生的光線的反射或折射較大，所以 被棱鏡片向光擴散層42 —側反射的光線被光擴散層42再 次反射到第一棱鏡片32和第二棱鏡片33 —側。因此，與 以往相比提高了光線的利用效率，並且進一步實現了液晶 16/23 201248211 顯不裳置1的南輝度化。 並且，由於實現了液晶顯示裝置的高輝度化，所以可 以使背光單元20薄型化，進而可以實現液晶顯示裝置的薄 型化。此外，利用本實施方式的光擴散片31，使本實施方 式的液晶顯示裝置1的輝度以保持較高的狀態在畫面内均 勻化。因此’可以從表面側遮擋背光單元2〇。此外，通過 分別調整光擴散片31的黏結劑和樹脂珠的折射率，不論具 有什麼樣的折射率的高增益棱鏡片’都可以實現利用高增 盈棱鏡片使光線朝向垂直方向直立。 该光擴散片的霧度值較佳為78%以上且在93%以下， 更佳為80%以上且在90%以下，通過具有這種較高的霧度 值’進一步提高了液晶顯示裝置1的正面輝度。另外，霧 度值是以JIS-K-7105為基準而測量的值。 如上所述，由於本實施方式的液晶顯示装置丨具有光 擴散片31，該光擴散片31包含比以往樹脂珠的折射率大的 向折射率的樹脂珠51，所以進一步實現了所需要的高輝度 化。因此，本實施方式的液晶顯示裝置1可以用作包含例 如從2英寸到22英寸各種大小的高輝度顯示裝置。即，本 實施方式的液晶顯示裝置1可以用作手機、智慧手機、車 载機、遊戲機、平板電腦、可檇式個人電腦、筆記型電腦 以及監視器等的顯示裝置。 (變形例） 另外，在上述實施方式中，光學單元23具有第—棱鏡 片32和第二棱鏡片33。但是光學單元23也可以僅具有第 —棱鏡片32作為棱鏡片。此外，該光擴散片也可以不具有 黏附防止層。 17/23 201248211 此外’在上述實施方式中，背光單元20是邊緣光型的 背光單元。但是，背光單元20也可以是直下型的背光單元。 在背光單元20是直下型的背光單元的情況下，即使光學單 元23僅具有第一棱鏡片32作為棱鏡片，也可以使光線非 常大地擴散。其結果’可以實現所需要的液晶顯示裝置的 高輝度化。 此外’在上述實施方式中，光源21在直線上排列多個 發光二極體’但是光源21也可以是棒狀的冷陰極管。此外， 在上述實施方式中，導光板22為楔形，但是導光板22也 可以是平板型。由此，包含光源21和導光板22的背光單 元20的形態不限於上述形態。 此外’在上述實施方式中，液晶顯示元件〗0具有背面 側反射偏光板13 ’但是液晶顯示元件〗〇也可以採用不具備 反射功能的偏光板來替代背面側反射偏光板13。 (實施例） 以下基於實施例對本發明進行詳細說明，但該實施例 的記載並不用於限定本發明。 [實施例1] 基體材料層採用厚度為〗〇0μΓη的透明聚對苯二甲酸乙 二醇酯制薄膜。光擴散層用聚合物組合物採用黏結劑（丙 烯酸多元醇和加成型的六亞曱基二異氰酸酯類固化劑）1㈨ 份、樹脂制ί朱50份和溶劑構成的聚合物組合物。表示各組 分的配入量的份數是固含量換算的f量比。通過利用凹版 塗敷法在絲歸料層表面以5g/m2 (时量換算）層叠光 擴散層用聚合物組合物，得到實施例丨的光擴散4。上述 黏結劑的折群為〗·49，上述樹脂制珠以懸浮聚合而得到 18/23 201248211 (甲基）丙烯酸-苯乙_共聚物為主體聚合物。該 柄·知珠的折射率為156、平均粒子直秤 ° 3〇〇/N 丁 ；祖于Ik為3.0_ (變動係數 [實施例2〜10] 除了採用表】所示折射率的黏結劑，以及表丨所示折 =率,、平均粒子直徑和份數的麵珠以外，與實施例！同 樣地％•到實施例2〜1 〇的光擴散片。 [比較例1] 除了樹脂珠採㈣浮聚合形成的㊅烯酸類樹脂珠（折 射率為1.49) α外，與上述實施例t同樣地得到比較例i 的光擴散片。 [比較例2] 除了樹脂珠的配入量為〗00質量份以外，與上述比較 例1同樣地得到比較例2的光擴散片。 [比較例3] 除了採用折射率為1.42的黏結劑以外，與上述比較例 1同樣地得到比較例3的光擴散片。 [特性評價] 採用上述實施例1〜10的光擴散片和比較例1〜3的光擴 散片’測量這些光擴散片的霧度值。此外，將這些光擴散 片實際組裝到邊緣光型背光單元上，並測量了正面輝度。 結果如下述表1所示。另外，該背光單元在上述光擴散片 的表面側層疊兩個棱鏡片，兩個棱鏡片配置成棱線相互交 又。另外’上述棱鏡片使用（株）住友3M公司制的 BEF2-G2-MR-155” 。評價結果如表1所示。另外，正面 輝度表示將實施例1作為100.0%的相對值。 19/23 201248211 表1 黏結劑折 射率 珠折射率 珠粒子 直徑(μηι) 珠配入量 (質量份） 霧度值 (%) 正面輝度 (相對值） 實施例1 1.49 1.56 3.0 50 85 100.0 實施例2 1.49 1.57 3.0 50 87 99.58 實施例3 1.49 1.59 3.0 . 50 88 98.6 f施例4 1.49 1.53 3.0 50 80 96.3 實施例5 1.52 1.56 3.0 50 83 96.5 實施例6 1.49 1.56 6.0 50 86 98.2 實施例7 1.49 1.56 1.0 50 80 94.0 實施例8 1.49 1.56 3.0 40 79 96.0 實施例9 1.49 1.56 3.0 80 88 99.4 實施例10 1.49 1.56 3.0 100 90 98.2 比較例1 1.49 1.49 3.0 50 77 91.8 比較例2 1.49 1.49 3.0 100 84 88.2 比較例3 1.42 1.49 3.0 50 82 89.5 如上述表1所示，實施例〗〜〗〇的光擴散片與採用以往 珠的比較例的光擴散片相比，顯示了高霧度值和正面輝 度，具有優良的光學特性。 (工業實用性） 本發明的光擴散片、光學單元和背光單元可以用作液 晶顯示裝置的結構構件。此外，本發明的液晶顯示裝置可 以用作手機和個人電腦等的顯示裝置。 【圖式簡單說明】 圖1示意性表示本發明實施方式的液晶顯示裝置斷面 的圖。 圖2是用於說明圖〗的液晶顯示裝置的光線前進的圖。 【主要元件符號說明】 1 液晶顯不裝置 10 液晶顯示元件 20/23 11 201248211 12 13 20 21 22 23 31 32 33 41 42 43 51 52 表面側偏光板 液晶早元 背面側反射偏光板 背光單元 光源 導光板 光學單元 光擴散片 第一棱鏡片 第二棱鏡片 基體材料層 光擴散層 黏附防止層 樹脂珠 黏結劑 21 /23201248211 VI. Description of the Invention: [Technical Field] The present invention relates to a light diffusing sheet, a backlight unit including the optical unit, and an optical unit and a package. LCD display of the early 70 先前 [Prior Art] The liquid crystal display device effectively utilizes the thin type, and is widely used as a flat panel display. The utility model and the low power consumption are used, for example, as a mobile phone, and the portable type is used for the next year. Expanded, etc. display devices. In recent years, liquid crystal _ brains and televisions have been characterized by high luminance, wide viewing angle, and energy saving, which may require high luminance. , 1 light, etc., special - through liquid crystal display device with liquid crystal patent literature! : The back side of this patent (for example, refer to 曰n β opening special 5]_59). The liquid m'/ has a liquid crystal cell sandwiched between the surface side polarizing plate and the back side = first =: peach structure 'and drives the liquid crystal display in various display modes". The greedy light illuminates the liquid crystal display element from the back side as early as 7L, and is widely used as an edge light type and a direct type backlight unit. These conventional backlight units have a light source 'light guide plate, and direct light from the light source to the liquid crystal display element side' and the optical unit, and are disposed on the surface of the liquid crystal display element side of the light guide plate. The optical unit is configured to efficiently and uniformly cause light from the light guide plate to be incident on the entire surface of the back side of the liquid crystal display element, for example, including: a light diffusion sheet that diffuses light from the light guide plate; and a prism sheet that transmits transmitted light to the method The line direction side is refracted. 3/23 201248211 In the conventional liquid crystal display device, since the light diffusion sheet, the prism sheet, and the like described above are provided, a certain degree of high luminance is achieved. However, the liquid crystal display device is further required to have high luminance. A high-gain prism sheet has been developed for the purpose of improving the luminance of the liquid crystal display device and the like. For example, a high-enhancement prism sheet manufactured by Sumitomo 3M Co., Ltd. under the product name "BEF2-G2-MR-155" has been commercialized. The above high-gain prism sheet is a prism sheet made of a high refractive index material. Although the high-gain prism sheet has been commercialized, the light-diffusing sheet y which has not been developed in cooperation with the south-enhanced prism sheet has not been developed to exhibit the effect of increasing the luminance produced by the high-gain prism sheet. In addition, there is still a further demand for thinning of the liquid crystal display device. SUMMARY OF THE INVENTION An object of the present invention is to provide a light diffusion sheet for further realizing high luminance and thinning of a liquid crystal display device, an optical unit including the light diffusion sheet, a backlight unit including the optical unit, and further realized Highly brightened and thinned liquid crystal display device. The present invention provides a light diffusing sheet comprising: a transparent base material layer; and a light diffusing layer laminated on a surface of the base material layer, having a resin bead in the binder, the light diffusing sheet being characterized by The resin beads have a refractive index of 1.5 Å or more. Since the refractive index of the resin beads of the 5 ray light diffusion sheet is larger than that of the resin beads of the conventional light diffusion sheet, the reflection and the ray of light generated by the resin beads are larger than in the past. Therefore, when the light diffusion sheet is assembled to the liquid crystal display device, the luminance of the liquid crystal display device can be improved as compared with the related art. As a result, the backlight unit can be made thinner, and the liquid crystal display device can be made thinner. In addition, by adjusting the refractive index of the light diffusing sheet and the refractive index of the tree 4/23 201248211, respectively, the high-gain prism sheet can be made to stand upright in the vertical direction regardless of the refractive index of the high-gain prism sheet. . The refractive index of the above-mentioned binder may be 1.49 or more and 1.51 or less, and the refractive index of the above resin beads may be 152 or more and 159 or less. In this case, since the refractive index of the resin beads of the light-diffusing sheet is larger than that of the resin beads of the conventional light-diffusing sheet, the reflection and refraction of the light generated by the resin beads is larger than in the past, thereby improving the liquid crystal display. The brightness of the device. In the light-diffusing sheet, the value obtained by subtracting the refractive index of the binder from the refractive index of the resin beads may be 〇6 or more and _ or less. In this case, the reflection and refraction of the light generated by the resin beads are further increased, thereby further improving the luminance of the liquid crystal display device. The host polymer of the above resin beads may be a copolymer of a (meth)propionic acid monomer and a stupid vinyl monomer. In this case, the refractive index of the resin beads can be easily made h52 or more and 159 or less, or the value obtained by subtracting the refractive index of the binder from the refractive index of the resin beads is _ or more and 0.08 or less. The amount of the resin beads to be added to 100 parts by mass of the binder may be 4 parts by mass or more and 230 parts by mass or less. In this case, the reflection and refraction of the light generated by the tree f beads become larger, thereby further enhancing the luminance of the liquid crystal display device. The haze value of the light diffusion >; may be 78% or less and 93% or less. In this case, the reflection and refraction of the light generated by the resin beads are further increased, thereby further improving the luminance of the liquid crystal display device. ^ The average particle diameter of the above resin beads may be 2 Å or more and below the array. In this case, the reflection and refraction of the light generated by the resin beads 5/23 201248211 is further increased, thereby further increasing the luminance of the liquid crystal display device. The above resin beads may be beads of multi-minutes. In this case, the reflection and refraction of the light generated by the resin beads are further advanced, thereby further improving the luminance of the liquid crystal display device. In order to further achieve high luminance and thinning of the liquid crystal display device, the following optical unit can be used as one structural element of the liquid crystal display device, that is, the optical unit includes: the light diffusion sheet; and a prism sheet laminated on The above-mentioned money scattered #'s representation 'the prism Η has a refractive index of 15 〇 or more. Similarly, in order to further achieve high luminance and stenosis of the liquid crystal display device, the following optical unit can be used as a structure of the liquid crystal display device, that is, the optical unit includes: the above-mentioned light diffusion sheet; The sheet is laminated on the surface side of the light-diffusing sheet, and the two prism sheets are arranged such that the ridge lines intersect each other, and the refractive indices of the two prism sheets are 15 or more. In this case, if the refractive index of each of the prism sheets is 1.55 or more and 1.70 or less, the luminance of the liquid crystal display device can be further improved. Further, the thickness of the liquid crystal display device can be reduced. In addition, in order to further achieve high luminance and thinning of the liquid crystal display device, the following backlight unit can be used as one structural element of the liquid crystal display device, that is, the 5-Hyun light unit includes a light source; the light guide plate is incident from the light source The light ray 'and emits incident light rays; and the optical unit is laminated on the upper side of the light guide plate. Further, the present invention provides a liquid crystal display device comprising: the backlight unit; and a liquid crystal display element disposed above the prism sheet of the backlight unit. The present invention can provide a light diffusing sheet for further realizing high luminance and thinning of a liquid crystal display device, an optical unit including the light diffusing sheet, a backlight unit including the optical unit, 6/23 201248211, and a dream realization high A brightening and thinning liquid crystal display device. [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. (Structure of Liquid Crystal Display Device) The liquid crystal display device of Fig. 1 has a liquid crystal display element 〇 and a backlight unit 20. The liquid crystal display element 1 显示 uses light to display information, and has a structure in which the liquid crystal cell 12 is sandwiched between the front side polarizing plate 丨丨 and the back side reflecting polarizing plate 13. The back side reflection polarizing plate 13 transmits the polarized light component in one direction of light and reflects the remaining polarized light component. The backlight unit 20 is disposed on the back side of the liquid crystal display element 1A, and is an edge light type backlight unit that illuminates the liquid crystal display element from the back side, and the backlight unit 20 has a light source 21, a light guide plate 22, and an optical unit 23. The light source 21 has a plurality of light emitting diodes arranged in a line. The light guide plate 22 has a wedge shape and has a rectangular flat surface when viewed from the surface of the liquid crystal display device 1, and a rectangular side thereof is disposed to face the entire light source 21. Although not shown, a member that reflects light is provided on a side surface of the light guide plate 22 that is not opposed to the light source 21. Although not shown, a member that reflects light is also provided on the back surface of the light guide plate 22. The light guide plate 22 emits light incident from the light source 21 to the optical unit 23 by the above-described member of the reflection button. The optical unit 23 is disposed on the surface of the light guide plate 22 on the side of the LED display element 1 and diffuses and directs the light from the light guide plate 22 to the human (four) line in such a manner that the light is directed perpendicularly to the entire surface of the back surface of the liquid crystal display member ig. The liquid crystal display element 1G specifically has an optical diffuser 31 for diffusing light incident from the light guide plate 22, and a first prism sheet of % 7/23 201248211 and a second prism sheet 33' to be lighted. The light diffused by the diffusion sheet 31 is refracted and proceeds substantially perpendicular to the liquid crystal display element "0". As shown in the figure, the light diffusion sheet 3, the first prism sheet 32, and the second prism sheet 33 are laminated in this order from the back side to the front side of the liquid crystal display device 1, respectively. The light-diffusing sheet 31 diffuses the light incident from the light guide plate 22 so as to emit light into the entire surface of the back surface of the liquid crystal display element 1 to be emitted toward the first prism sheet 32. The light diffusion sheet 31 has a base material layer 4A; the light diffusion layer 42' is laminated on the surface side of the base material layer 41; and the adhesion preventing layer 43 is laminated on the back side of the base material layer 41. The structure of the light diffusion sheet 3A will be described in detail later. The first prism sheet 32 is a high-gain prism sheet, and refracts light incident from the light diffusion sheet 3 ι and emits it toward the second prism sheet 33. The second prism sheet 33 is a gain prism sheet, and the light incident from the first prism sheet 32 is refracted and emitted toward the liquid crystal display element so that the emitted light beam advances substantially perpendicularly to the back surface of the liquid crystal display element 1. The first prism sheet 32 and the second prism sheet 33 include a base material layer, and a protrusion row composed of a plurality of protruding prism portions laminated on the surface of the base material layer. The thickness of the first prism sheet 32 and the second prism sheet 33 (the height from the back surface to the apex of the ridge rib portion) is preferably 5 〇 〖im or more and 2 〇〇 μ Γ or less 'better' 〇〇 μ η ι Above and below 〖8〇μηι. Further, the interval (pitch) between the ridge prism portions in the first prism sheet 32 and the second prism sheet 33 is preferably 3 〇 μ ΐΏ or more and 1 μ μηι or less, more preferably 4 〇 μηι or more and 6〇μΠ1 or less. Further, the apex angle of the ridge prism portion is preferably 85. Above and below 95. The refractive index of the first prism sheet 32 and the second prism sheet 33 is 0.45 or more, preferably 1.55 or more and 1.70 or less. Further, the refractive index of the prism sheet means the refractive index of the prism portion. High luminance can be further achieved by using the 8/23 201248211 prism sheets 32, 33 and the light diffusion sheet 3 of such a structure in combination. Further, both the first prism sheet 32 and the second prism sheet 33 are formed 33 to 34 from the normal to the substrate on the back side. The light in the left and right angular directions is refracted toward the surface side of the normal. The conventional prism sheet is made from the normal to the substrate at 3 〇 to 31. The light in the left and right angles is refracted toward the surface side of the normal. That is, the first prism sheet 32 and the second prism sheet 33 have higher capabilities than the conventional prism sheet in that the light obliquely incident on the back surface of the substrate is vertically erected. The first prism sheet 32 and the second prism sheet 33 are, for example, high-gain prism sheets manufactured by Sumitomo 3M Co., Ltd. under the product name of BEF2-G2-MR-155. (Structure of Light-Diffusing Sheet) Light-Diffusing Sheet 31 An optical sheet that diffuses and emits incident light, has a base material layer 41 as described above, a light diffusion layer 42 laminated on the surface side of the base material layer 41, and an adhesion preventing layer 43 laminated on the base material layer 41. The back side The base material layer 41 is a transparent layer capable of transmitting light, and is formed of a resin such as acrylic acid resin 'polyethylene terephthalate, polyethylene naphthalate, poly. Carbonate, polystyrene, polyolefin, cellulose acetate or weather resistant vinyl chloride, etc. The average thickness of the base material layer 41 is preferably ΙΟμηη or more and 400 μηη or less, more preferably 20 μm or more and 130 μηη or less. When the thickness is 〇μηι or more, the base material layer 41 can have a strength that does not cause bending. Further, by making the average thickness to be 400 μm or less, the thickness of the liquid crystal display device 1 can be reduced, and The brightness of the liquid crystal display device 1 can be sufficiently ensured. The light diffusion layer 42 includes: a resin bead 51 having a high refractive index; and a binder 52 for fixing the resin beads 51 in a dispersed state. The resin beads 51 are also dispersedly disposed in the light diffusion layer. On the surface of 42, thus, the uneven shape of 9/23 201248211 201248211 of the light diffusion layer 42. With the interface of the unevenness, it is further obtained that the surface is provided with a minute and disorderly shape and the resin beads 51 and the binder & The function of light diffusion. The refractive index of the resin bead is above K50, preferably 52, preferably less than 1.55 or less and 1.55 or more and less than 157. The refractive index of the resin beads in the light diffusion sheet is 149. The refractive index of the resin bead 51 of the formula is larger than that of the conventional tree beads. The main polymer which forms the resin bead 51 in the present embodiment is not particularly limited, and an acrylic resin, an acrylonitrile resin, a polyurethane, a polyethylene gas, or the like may be used. Polystyrene polyacrylonitrile, polyamide, etc. 'but preferably a copolymer of a (meth)acrylic monolithic and stupid vinyl monomer, preferably a monomer derived from (meth)acrylic acid Crosslinking of a styrene monomer and a crosslinkable monomer (a fluorenyl olefinic styrene-styrene copolymer) can be improved by introducing a styrene skeleton (a base polymer of a acetonyl acrylic skeleton) The refractive index of 51 can further increase the refractive index by further making it into a crosslinked structure. Further, when an acrylic resin (acrylic acid polyol or the like) is used in the binder 52, since it has the same acrylic skeleton, Therefore, the resin beads 5] are uniformly dispersed in the binder 52 to further improve the front luminance. The above (meth)acrylic monomer may, for example, be acrylic acid; a derivative of acrylic acid such as acrylic acid vinegar vinegar acetoacetate, Acrylic acid propyl, butyl acrylate, amyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, decyl acrylate, acrylic acid vinegar, propionic acid eleven vinegar, propylene Twelfthyl decanoate, glycidyl acrylate, methoxyethyl acrylate, propoxyethyl acrylate, butyl ethoxylate, methoxy diglycol acrylate, acrylic acid Ethoxydiethylene glycol ester, methoxyethylene glycol acrylate, butylene triethylene glycol acrylate, methoxy dipropylene glycol acrylate, 10/23 201248211 phenyloxyethyl acrylate, phenoxy acrylate Glycol ester, phenoxytetraethylene glycol acrylate, benzyl acrylate, cyclohexyl acrylate, tetrahydro sugar vinegar, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, acrylic acid N -vinyl-2-pyrrolidone, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, glycidyl acrylate, acrylonitrile, acrylamide, N-methylol acrylamide, dipropyl S and acrylamide; or methacrylic acid; derivatives of methacrylic acid, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, hydrazine Butyl acrylate, amyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, decyl methacrylate, decyl methacrylate, undecyl methacrylate, Hydryl decyl acrylate Glycidyl methacrylate, methoxyethyl methacrylate, propoxyethyl methacrylate, butoxyethyl methacrylate, decyl decyl acrylate, ethoxy methacrylate Diethylene glycol ester, methoxyethyl methoxyacetate, methyl propylene glycol butoxide, methoxy propylene glycol methacrylate, phenoxy methacrylate Ester, phenoxy diglycol methacrylate, phenoxytetraethylene glycol methacrylate, benzyl methacrylate, cyclohexyl methacrylate, tetrahydroglucosyl methacrylate, methacrylic acid Pentamidine vinegar, dicyclopentenyloxyethyl methacrylate, N-vinyl-2-pyrrolidone methacrylate, methacrylonitrile, decyl acrylamide, N-oxindole Alkyl acrylamide, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, 2-light methoxy-3-phenyloxy acetonate, and the like. A combination of one or more of the above may be used. The styrene monomer may, for example, be stupid ethylene, styrenethiylene, vinylmethylbenzene or p-tert-t-phenylphenidene ethylene derivative. You can use Π/23 201248211 one or more of the above combinations. Examples of the crosslinkable monomer include diethyl benzene, ethylene glycol dimethyl ester, 1,3-butyl ketone, methacrylate, 1,4-butanediol dimethacrylate, and 1 , 5_ pentanediol dimercapto acrylate, hydrazine, 6• hexanediyl acrylate acid, neopentyl glycol dimercapto acrylate acid, diethylene glycol dimethyl vinegar, three Glycol dimercaptopropane, polyethylene glycol dimethyl propylene vinegar, tripropylene glycol dimercapto propylene _ and the like. A combination of one or more of the above may be used. The above host polymer may contain, in addition to the (meth)acrylic acid monomer, the styrene fresh material, and the crosslinkable monomer, a sodar monomer. Other monomers may be listed as acetic acid, ethylene ethylene, cis-butane diacid needle, cis-butyl diacid, cis-butane vinegar, fumaric acid, fumaric acid, triallyl isocyanuric acid Ester and the like. The resin beads in which the above copolymer is used as a host polymer can be obtained, for example, by suspension polymerization of a mixture of monomers in the presence of a polymerization initiator, usually in an aqueous medium such as water or a mixture of water and ethanol. get on. The shape of the resin bead 51 is not particularly limited, and examples thereof include a spherical shape, a square shape, a needle shape, a rod shape, a spindle shape, a plate shape, a scaly shape, and a fiber shape. Among them, a spherical shape excellent in light diffusibility is preferable. The average particle diameter of the resin beads 51 is preferably 2 μm or more and 5 μΠΊ or less, more preferably 2·5 μm or more and 4 μΓη or less. By using such particles having an average particle diameter, light diffusibility and the like can be improved. Further, the average particle diameter in the present invention means an average particle diameter of 30 particles randomly selected from particles observed by an electron microscope having a magnification of 1 〇〇〇. In addition, the particle diameter is defined by the Ferret diameter (the interval between the parallel lines of a certain direction sandwiching the projected image 12/23 201248211). The resin beads 51 are preferably polydisperse beads, and the coefficient of variation of the particle diameter is preferably 20% or more and 40% or less. By using such a polydisperse bead, the light diffusibility can be improved, and the front luminance and the like can be improved. In addition, the amount of the resin beads 51 contained in the light-diffusing layer 42 to be added to the (1) parts by mass of the binder 52 is preferably 4 parts by mass or more and 23 parts by mass or less, more preferably 45 parts by mass or more. 1 part by mass or less, ^ is preferably 60 parts by mass to T. The amount of the lion's bead 51 is determined by the way the light diffuses in a stepwise manner, based on the average particle diameter. The above-mentioned binder 52 is usually obtained by curing a base material polymer with a curing agent. The above-mentioned adhesive agent 52 can also be formulated with a plasticizer, a dispersant, various leveling agents, a wire suction (four), an antioxidant, a modifier, a lubricant, and a light stable fresh. The binder 52 is a base material polymer as a main structural element, and the resin beads are fixedly disposed on the entire surface of the base material layer 41 at substantially equal density. The base material polymer is not particularly limited, and examples thereof include an acrylic resin, a polyurethane, a polyester, a fluorine resin, a stone resin, a polyamine amine, a silicone resin, and an ultraviolet curable resin. One type or a combination of two or more types of the above polymers is used. The above-mentioned base material is preferably a mercaptan, which has a high jade property, and the light-diffusing layer 42 can be easily formed by coating or the like. Further, since the base material polymer used for the binder 52 needs to transmit light, it is transparent, and particularly preferably colorless and transparent. The above polyol is preferably a polyhydric polyol or a (meth)acrylic polyol, and more preferably a (meth)acrylic polyol. The weather resistance of the binder 52 which uses these polyester polyols or propylene glycol as a base material polymer is high, and it is possible to suppress yellowing of the light diffusion layer 42 and the like. Further, in the case where the resin bead 51 is used in the case of using a copolymer containing the above (meth)acrylic monomer, 13/23 201248211, by using a (meth)acrylic acid polyol, the dispersibility can be improved and Improve positive brightness and so on. Further, either one of the polystyrene polyol and the acrylic acid polyol may be used, or both of them may be used. The number of the base groups of the above-mentioned polystyrene polyol and (meth)acrylic acid polyol is not limited to (four) as long as it is two or more per molecule, but the solid component + _ value is below 〇 The number of cross-linking decreases, and the physical properties such as solvent resistance, miscellaneous resistance, heat resistance, and surface hardness tend to decrease. As described above, in the case where the base material polymer is a polyol, the curing agent is preferably hexamethylene diisocyanate, isophora diisochloric acid vinegar, and dimethyl diisocyanate, more preferably six. The mercapto diisocyanate is particularly preferably an addition molded 'methylene diisocyanate g. If these curing agents are used, the reaction rate of the shell composition becomes large. The improvement of the reaction rate contributes to the uniform dispersion of the resin beads in the binder. Further, it is preferable to use (meth)propionic acid polyol and hexamethylene diisocyanate in combination. The refractive index of the binder 52 is preferably 丨49 or more and 15 MPa or less. Further, the value of 彳<the refractive index of the resin bead 51 minus the refractive index of the above-mentioned binder S2 is preferably 0.06 or more and 〇 or less. The adhesion preventing layer 43 is composed of a binder and beads dispersed in the binder. The bonding component may also be the same as the bonding layer 52 of the phototone layer 42 described above. Further, the material of the beads may be exemplified by inorganic beads and organic beads. Further, the thickness of the adhesion preventing layer 43 (the thickness of the binder portion other than the beads) is not particularly limited, and may be, for example, 1 μm or more and 1 μm or less. The amount of beads incorporated in the adhesion preventing layer 43 is a small amount, and the beads are separated from each other by 14/23 201248211. In the binder, most of the beads are protruded from the binder at a low end. Therefore, when the light diffusion sheet 31 is laminated on the light guide plate 22, the lower end of the protruding beads abuts against the surface of the light guide plate 22, and the entire surface of the back surface of the light diffusion sheet 31 does not abut against the light guide plate 22. Thereby, adhesion of the light diffusion sheet 31 and the light guide plate 22 is prevented, and unevenness in luminance of the screen of the liquid crystal display device can be suppressed. Hereinafter, a method of manufacturing the light diffusion sheet 3 will be described. The method for producing the light-diffusing sheet 31 includes, for example, the following steps: (a) producing a coating liquid for a light-diffusing layer by mixing resin beads in a composition (base material polymer, curing agent, etc.) constituting the binder 52; (b) The light diffusion layer 42 is laminated by applying the coating liquid for a light diffusion layer to the surface of the base material layer 41; (4) an adhesion preventing layer is produced by mixing beads in a polymer composition constituting the bonding agent. (4) The adhesion preventing layer 43 is laminated by applying the coating liquid for the adhesion preventing layer to the back surface of the base material layer 41. (Advance of Light) Next, the advancement of light in the liquid crystal display device i of the present embodiment will be described. The light is generated by the light source 21, and as shown in FIG. 2, the light A from the light source 21 is guided by the light guide plate 22 to the optical unit 23, and is scattered by the light diffusion sheet 31 of the optical unit 23 from the back of the first prism sheet 32. The entire surface is incident on the first prism sheet 32. The light ray a of the incident first prism sheet 32 is refracted by the first rib sheet 32, thereby standing upright in the direction perpendicular to the back surface of the liquid crystal display element ι, and proceeds to the second prism sheet 33. The light ray A advanced to the second prism sheet 33 is refracted by the first prism sheet and further erected, and is incident substantially perpendicularly on the back surface of the liquid crystal display element 1A. Thereby, the light A from the backlight unit 20 is incident on the liquid crystal display element 1A. Since the back side side reflection bias 15/23 201248211 light plate 13 is provided on the back side of the liquid crystal display element 1A, the portion of the light ray a incident on the liquid crystal display element is partially transmitted through the back side reflection polarizing plate 13, and the remaining portion is reflected to the backlight. Unit 2 is on one side. The light A transmitted through the back side reflecting the polarizing plate 13 is sequentially transmitted through the liquid crystal cell 12 and the front side polarizing plate U, and is emitted toward the surface side of the liquid crystal display device 1. The light A reflected toward the side of the backlight unit 20 is reflected by the reflecting member of the light guide plate 22, and as described above, passes through the optical unit 23 and is incident on the liquid crystal display element 10 again. (Effect) As described above, the light diffusion sheet 31 of the present embodiment has the light diffusion layer 42 including: the resin beads 51 having a high refractive index; and the refractive index is preferably 1.49 or more and at 〖·51 The following adhesive 52. Since the refractive index of the resin beads in the conventional light-diffusing sheet is about .49 as described above, the refractive index of the resin beads 51 of the present embodiment is larger than that of the conventional resin beads. Therefore, the reflection or refraction of the light generated by the resin beads 5 of the present embodiment is larger than in the past. As a result, the light-diffusing sheet 31 of the present embodiment can be combined with the first prism sheet 32 and the second prism sheet 33 as the high-gain prism sheet, and exhibits enhanced brightness generated by the first prism sheet 32 and the second prism sheet 33. Resulting in fruit. Therefore, the luminance of the liquid crystal display device 1 of the present embodiment is higher than that of the related art, and the required high luminance is achieved. Further, since the first prism sheet 32 and the second prism sheet 33 are high-gain prism sheets made of a high refractive index material, the proportion of the light reflected toward the back surface of the prism sheet becomes high. However, according to the light diffusion sheet 31, since the light or the reflection of the light generated by the resin beads 51 is large, the light reflected by the prism sheet toward the light diffusion layer 42 is again reflected by the light diffusion layer 42 to the first prism sheet 32. And the second prism sheet 33 is on the side. Therefore, the utilization efficiency of light is improved as compared with the prior art, and the south luminance of the liquid crystal 16/23 201248211 is further realized. In addition, since the high luminance of the liquid crystal display device is achieved, the backlight unit 20 can be made thinner, and the liquid crystal display device can be made thinner. Further, with the light-diffusing sheet 31 of the present embodiment, the luminance of the liquid crystal display device 1 of the present embodiment is uniformized in the screen while maintaining a high state. Therefore, the backlight unit 2 can be blocked from the surface side. Further, by adjusting the refractive indices of the binder and the resin beads of the light-diffusing sheet 31, respectively, the high-gain prism sheet ′ regardless of the refractive index can be made to stand upright in the vertical direction by using the high-enhancement prism sheet. The haze value of the light-diffusing sheet is preferably 78% or more and 93% or less, more preferably 80% or more and 90% or less, and the liquid crystal display device 1 is further improved by having such a high haze value. Positive brightness. Further, the haze value is a value measured based on JIS-K-7105. As described above, the liquid crystal display device of the present embodiment has the light diffusion sheet 31, and the light diffusion sheet 31 includes the resin beads 51 having a refractive index larger than that of the conventional resin beads, so that the required height is further achieved. Brightness. Therefore, the liquid crystal display device 1 of the present embodiment can be used as a high-intensity display device including various sizes such as from 2 inches to 22 inches. That is, the liquid crystal display device 1 of the present embodiment can be used as a display device of a mobile phone, a smart phone, a car carrier, a game machine, a tablet computer, a portable personal computer, a notebook computer, and a monitor. (Modification) Further, in the above embodiment, the optical unit 23 has the first prism sheet 32 and the second prism sheet 33. However, the optical unit 23 may have only the first prism sheet 32 as a prism sheet. Further, the light diffusion sheet may not have an adhesion preventing layer. 17/23 201248211 Further In the above embodiment, the backlight unit 20 is an edge light type backlight unit. However, the backlight unit 20 may also be a direct type backlight unit. In the case where the backlight unit 20 is a direct type backlight unit, even if the optical unit 23 has only the first prism sheet 32 as a prism sheet, the light can be greatly diffused. As a result, the high luminance of the liquid crystal display device required can be achieved. Further, in the above embodiment, the light source 21 has a plurality of light emitting diodes arranged in a line, but the light source 21 may be a rod-shaped cold cathode tube. Further, in the above embodiment, the light guide plate 22 has a wedge shape, but the light guide plate 22 may be a flat plate type. Therefore, the form of the backlight unit 20 including the light source 21 and the light guide plate 22 is not limited to the above embodiment. Further, in the above-described embodiment, the liquid crystal display element "0" has the back side reflection polarizing plate 13'. However, the liquid crystal display element may be replaced by a polarizing plate having no reflection function instead of the back side reflection polarizing plate 13. (Examples) Hereinafter, the present invention will be described in detail based on examples, but the description of the examples is not intended to limit the present invention. [Example 1] A base material layer was made of a transparent polyethylene terephthalate film having a thickness of 〇0 μΓη. The polymer composition for a light-diffusing layer is a polymer composition comprising a binder (acrylic acid polyol and an addition of a hexamethylene diisocyanate curing agent) of 1 (nine) parts, a resin resin of 50 parts, and a solvent. The number of parts indicating the amount of the components to be dispensed is the ratio of the amount of the solid content converted. The light diffusion 4 of Example 得到 was obtained by laminating the polymer composition for a light diffusion layer at 5 g/m 2 (time conversion) on the surface of the silk retort layer by a gravure coating method. The above-mentioned binder is a group of 49, and the above resin beads are obtained by suspension polymerization to obtain 18/23 201248211 (meth)acrylic acid-phenethyl copolymer as a main polymer. The refractive index of the handle and the bead is 156, the average particle diameter is 3 〇〇/N butyl; the ancestor is Ik is 3.0 _ (variation coefficient [Examples 2 to 10] except the refractive index of the adhesive shown in Table] In addition to the bead=rate, the average particle diameter and the number of parts shown in the table, the light diffusion sheet of Example 2 to 1 is the same as in the example! [Comparative Example 1] In addition to the resin beads A light-diffusing sheet of Comparative Example i was obtained in the same manner as in Example t except that the hexaenoic acid-based resin beads (refractive index: 1.49) α formed by floating polymerization were used. [Comparative Example 2] The amount of the resin beads was calculated. The light-diffusing sheet of Comparative Example 2 was obtained in the same manner as in Comparative Example 1 except for the above-mentioned Comparative Example 1. [Comparative Example 3] Light of Comparative Example 3 was obtained in the same manner as in Comparative Example 1 except that a binder having a refractive index of 1.42 was used. Diffusion sheet. [Characteristic evaluation] The haze values of these light diffusion sheets were measured using the light diffusion sheets of the above Examples 1 to 10 and the light diffusion sheets of Comparative Examples 1 to 3. Further, these light diffusion sheets were actually assembled to the edges. The front luminance was measured on the light type backlight unit. The results are shown in Table 1 below. In addition, the backlight unit has two prism sheets stacked on the surface side of the light-diffusing sheet, and the two prism sheets are arranged such that the ridge lines intersect each other. In addition, the above-mentioned prism sheet is BEF2-G2- manufactured by Sumitomo 3M Co., Ltd. MR-155". The evaluation results are shown in Table 1. In addition, the front luminance indicates that Example 1 is a relative value of 100.0%. 19/23 201248211 Table 1 Refractive index of the binder Bead refractive index Bead particle diameter (μηι) Beads Intake (parts by mass) Haze value (%) Positive luminance (relative value) Example 1 1.49 1.56 3.0 50 85 100.0 Example 2 1.49 1.57 3.0 50 87 99.58 Example 3 1.49 1.59 3.0 . 50 88 98.6 f Example 4 1.49 1.53 3.0 50 80 96.3 Example 5 1.52 1.56 3.0 50 83 96.5 Example 6 1.49 1.56 6.0 50 86 98.2 Example 7 1.49 1.56 1.0 50 80 94.0 Example 8 1.49 1.56 3.0 40 79 96.0 Example 9 1.49 1.56 3.0 80 88 99.4 Example 10 1.49 1.56 3.0 100 90 98.2 Comparative Example 1 1.49 1.49 3.0 50 77 91.8 Comparative Example 2 1.49 1.49 3.0 100 84 88.2 Comparative Example 3 1.42 1.49 3.0 50 82 89.5 As shown in Table 1 above, Example 〖~〗 Light expansion Sheet compared to the use of a conventional light diffusion sheet of Comparative Example beads showed a high haze value and the front luminance, has excellent optical properties. (Industrial Applicability) The light-diffusing sheet, optical unit and backlight unit of the present invention can be used as structural members of a liquid crystal display device. Further, the liquid crystal display device of the present invention can be used as a display device for mobile phones, personal computers, and the like. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view schematically showing a cross section of a liquid crystal display device according to an embodiment of the present invention. Fig. 2 is a view for explaining the advancement of light rays of the liquid crystal display device of the drawing. [Main component symbol description] 1 Liquid crystal display device 10 Liquid crystal display device 20/23 11 201248211 12 13 20 21 22 23 31 32 33 41 42 43 51 52 Surface side polarizing plate liquid crystal early side back side reflective polarizing plate backlight unit light source guide Light plate optical unit light diffusing sheet first prism sheet second prism sheet base material layer light diffusing layer adhesion preventing layer resin bead bonding agent 21 / 23