200905274 九、發明說明： 【發明所屬之技術領蜮】 本發明關於—種用於液晶顯示器（LCD)之背光單元 的導光板。 【先前技術】 習知的邊緣照明型或楔型導光板包含一用於從一光源 接收光線的光入射側、一用於使光線射往外界的前侧、及 一用於使光線朝該前側反射的後側，其中該光源被定位在 该导側之一者附近。 此外’在邊緣照明型或楔型導光板中，二個稜鏡薄片、 一漫射片及一保護片可被堆疊在該前侧上當作發光側，且 一譬如由點狀稜鏡和類似物組成之圖案可被印在該後侧 上。 其中’漫射片設置在導光板之頂上且用來使已通過導 光板之光線均勻化。 棱鏡薄片用來藉由折射並集中傾向於因在通過漫射片 夺於兩方向（亦即水平方向和錯直方向）中漫射而經歷 冗度快速減低之光線的方式使亮度提高。一般而言會使用 二個稜鏡薄片。 ◊ 蒦片设置在稜鏡薄片頂上，且用來保護棱鏡薄片不 又^ S如刮傷的傷害’並且避免當使用兩層堆疊之稜鏡薄 、在K平和錯直方向中發生的莫瑞效應（M〇jre )。 111此*’邊緣照明型或楔型導光板的用途是支援一在前 200905274 侧上有一均勻咼凴度的平面光源，使僅透過一側已進入導 光板的光線朝對向側偏移。 ' 儘管如上所述建構之邊緣照明型或楔型導光板比起在 兩側都有光源之邊緣照明型平面導光板的亮度較低，此— 5 邊緣照明型或楔型導光板通常被用在因為邊框狹小而僅在 一侧有光源的情況，譬如筆記型電腦。 因此，需要一種能夠用少量光線最大化光效率的邊緣 照明型或楔型導光板。 10 【發明内容】 技術性問題 本發明係鑑於上述問題做出，且本發明之一觀點是提 出一種用於LCD背光單元的導光板，其包含一後側，該後 侧具有一雙重階狀結構，該雙重階狀結構與階狀物及幾何 15 反射器結合以使光線朝一前側反射；或者該後側具有一全 然由階狀物組成的單一階狀結構，其中該等階狀物平行於 該前側且隨著從該等階狀物到該導光板之一光入射側之距 離增加而靠近該前侧。 20 技術性解決方荦 依據本發明之一第一觀點，一種用於LCD背光單元的 導光板包含一用於從一光源接收光線的光入射側，一用於 使光線射往外界的前侧，及一具有階狀物與幾何反射器結 合之一橫截面形狀用於使光線朝該前側反射的後側，其中 6 200905274 ，等階狀物每-者平行於該前側且隨著從鮮階狀物到該 光入射側之距離增加而靠近該前側。 、曾、，依據本發明之—第二觀點，-種用於LCD背光單元的 5 =光板包含-用於從—光源接收光線的光人射侧，一用於 ^光、=往外界的前側，及—具有階狀物錢何反射器結 ^ ^截面形狀用於使光線朝該前侧反射的後侧，其中 二’、狀物著從•等p#狀物到該光人射侧之距離增加而 罪近該前側。 iMjLM. 依據本U ,帛於LCD背光單元的導光板確保在LG]) *反之整體表面上有〶亮度、優異的光均勻度和可視度， =允4免除習知導光板所用之—漫射片和—稜鏡薄片其 —者或二者，從而降低背光單元之製造成本。 【實施方式】 本务明之以上和其他目的、特徵及其他優點將在搭配 4附圖式提出的以下詳細說明中更清楚顯露。 以下簽照隨附圖式說明本發明之範例實施例。 、圖1疋一依據本發明一第一實施例用於lCe^^光單元 之導光板的立體圖。 依據本發明第一實施例，導光板包含一用於從一光源 7 200905274 接收光線的光入射側，一用於使光線射往外界的前侧，及 一具有階狀物與幾何反射器結合之一橫截面形狀用於使光· 線朝S亥如側反射的後側’其中該等階狀物每一者平行於該 前側且隨著從該等階狀物到該光入射側之距離增加而靠近 該前侧。 參照圖1 ’第一實施例之導光板被建構為允許光線僅 透過鄰近於一光源140之一側（以下稱為、、光入射侧21〇β ) 進入該導光板，同時防止光線透過對向側（以下稱為、、對 向光入射侧215")進入該導光板。 一前侧230垂直於光入射側210連接且當作一發光 侧，已透過光入射侧210進入該導光板的光線會穿過該前 侧射往該導光板以外。前侧230對於液晶顯示器之面板來 說是最鄰近之侧。 依據第一實施例之導光板是一具有形成於一後側220 上之特徵圖案的楔型導光板。 圖2和3是例示圖1所示依據第一實施例之導光板之 後側上的圖案的後視立體圖。 參照圖2和3，在依據第一實施例之導光板中，後侧 220具有配置成一階狀結構的複數個平面1、2、3、4、5、 6 ’使得從平面1至6到前側23〇的距離di〜d“參見圖3) Ik著從光入射側210到對向光入射侧215而減小。 就此而論’應理解到儘管圖2和圖3中僅示出六個平 面’平面之數量將是取決於導光板之大小及平面間之距 離、亦即平面間距（P )。 8 200905274 複數個平面1至6較佳被製作為平行於前侧23〇。 如果後側220對水平面傾斜，則該導光板無法獲得具 有全内反射之理論導光效果且經歷~大角度發射光分量之 產生，這造成光損失。 其中，平面1至6係配置為在±〇 5度公差以内面向前 側23〇，此公差係考慮製程之誤差決定。 後側220相對於前側230之總基礎斜率係由光入射側 210、對向光入射側215、及導光板之長度決定。 此外’假設平面1至6每一者具有固定長度Lx，每一 平面之長度Lx對上導光板之總長度l〇的比較佳在 1:100〜1:1,〇〇〇的範圍内。 光源之數量是一主要決定參數。舉例來說，隨著光源 之數增加，光入射侧和對向光入射側之長度加大，故後 侧之基礎斜率亦加大。在此實施例中，後側以0.42度的角 度傾斜。 參照圖3，後侧220包含設置在二個相鄰平面之間（例 如位於圖3之平面1和2之間）的階狀物211及幾何反射 裔212和213，其中幾何反射器212和213係由一具有一 内角θ2之凹刻稜鏡212與一具有一内角Θ3之凸起稜鏡213 的組合構成。 其中’凹刻稜鏡212之左侧（在圖3觀看）與階狀物 211之右側共用，且凹刻稜鏡212之右側與凸起稜鏡213 之左侧共用。 較佳來說，階狀物211具有一在110〜160度範圍内的 200905274 内角Θ1，且凹刻棱鏡212和凸起稜鏡213二者具有在 60〜100度範圍内的内角Θ2或Θ3。 將階狀物211設定為具有110〜160度範圍内之内角Θ1 的理由在於藉由反射光線使光線在鉛直方向中偏移的主要 功能係加諸於凸起稜鏡213之右側（在圖3觀看），且階 狀物211之右側（在圖2觀看）具有在鉛直方向中反射光 線的主要功能及將光線導往凸起稜鏡213的次要功能。 也就是說，當階狀物之内角Θ1係在110〜160度之範圍 内時’階狀物211之右側變成以與凸起棱鏡213之右側大 致相同的角度歪斜，故凸起稜鏡213可在階狀物211發揮 上述一個功能的同時有效地使光線在錯直方向中朝前側偏 移。 將凸起稜鏡213設定為具有60〜100度範圍内之内角 Θ3的理由在於使進入的光線盡可能多地在鉛直方向中朝 15 前側偏移，如同階狀物211中之情況。當光線以一約82.5 度的角度進入凸起稜鏡213時，光線之錯直向反射和折射 作用藉此最有效率地發生。 又’較佳來說’凸起稜鏡213具有一比階狀物211離 别側230更退的尖端。為了允許光線依錯直方向行進，已 20 通過階狀物211右側的光線應當被折射到凸起稜鏡213之 左側内然後被凸起稜鏡213之右側反射。就此而論，為允 許已通過階狀物211右侧的光線以一較大量進入凸起稜鏡 213之左側而不朝前側離開，最好凸起稜鏡213之尖端比 階狀物211離前侧230更遠。 200905274 較佳來說，光入射側對上對向光入射側之寬度比在9:1 至1:1範圍内。 此外’較佳來說，凹刻稜鏡212對上凸起稜鏡213之 咼度比在1:2〜2:1範圍内。 又’較佳來說，導光板後側上之幾何反射器對上階狀 物的面積比在1:100〜1:10,000範圍内。 在具有如上所述配置成階狀結構之複數個平面1至6 之導光板後侧上，相鄰平面間之距離或相鄰凸起稜鏡213 間之距離、亦即間距P (參見圖2 )較佳為〇.3〜2麵，但其 係取決於從該導光板之一平面光源發出的光強度及光源種 類。 再次參照圖3，複數個平面1〜6每一者可更進一步具 備複數個點狀稜鏡222，該等點狀稜鏡具有特定形狀例如 圓形、橢圓形、菱形、矩形、或以上之組合’藉以獲得使 15 通過光入射侧21〇進入之光線更有效地朝前侧230反射的 作用。 其中’形成於點狀稜鏡222上的每一稜鏡較佳具有一 垂直於一光進入方向設置的縱向方向。 參照圖2 ’可形成一條紋圖案310取代點狀稜鏡222、 2〇 連同點狀稜鏡222、或視需要形成在複數個平面丨至6之 表面上。條紋圖案230之寬度從光入射侧21〇往對向光入 射侧215加大且有複數個稜鏡形成於其表面上。其中，條 紋圖案310之衩數個稜鏡具有一垂直於光進入方向設置的 縱向方向。 11 200905274 此時，條紋圖案310之每一稜鏡較佳具有一 70〜85度 的内角，因為此範圍内之棱鏡内角確保鉛直向發射光之比 提高且藉此實現一高亮度LCD。 參照圖3，前側230可被形成為具備前稜鏡315，每一 5 前稜鏡具有一預定橫截面形狀且用來使通過導光板之光線 均勻折射和漫射。 前稜鏡315係形成於前侧230之整個表面上且具有一 平行於光進入方向設置的縱向方向。 另一方面，儘管前稜鏡315在圖3之鉛直方向中具有 ίο 三角形橫截面，應理解到前稜鏡315可具有不受限於三角 形橫截面的多樣修改。舉例來說，前棱鏡315可具有梯形 形狀或是在侧向侧具有一預定曲率半徑的倒溝形狀。 為提升光線之均勻度和可視度，前稜鏡315較佳以固 定間距（d)配置，如圖3所示。 is 換句話說，當彼此相隔固定間距（d)的前稜鏡315 使來自導光板依一相對於面向導光板之LCD面板（圖中未 示）為傾斜之方向發射的光線折射並漫射時，光線透過一 由此一固定間距（d)界定之分離平面（亦即前棱鏡間之一 空間）被導向為垂直於LCD面板（圖中未示），藉此更進 2〇 一步提升抵達LCD面板之光線均勻度。 前稜鏡315對上由前側230上前稜鏡315間之固定間 距（d)界定之分離平面的面積比較佳在1:0.5〜1:10範圍内。 此外，每一前棱鏡315較佳具有在0.3〜0.6範圍内之 高度（h2):寬度（W2)比。若高度/寬度比小於0.3，液晶 12 200905274 =器會有-過高水平視角，導致亮度降低。若此比值大 ；LCD會有一太低水平視角，無法滿足光學特質。 —圖4和5是依據本發明—第二實施例用於LCD背光單 元之導光板的平面圖。 在圖4和圖5中，與圖2和圖3所示相 標以相畔考財。 因此，在理解圖4和圖5之第二實施例時，與圖2和 圖3相同的參考數字可參照圖2和圖3進行理解。 10 15 20 以下針對不同於圖2和圖3之第一實施例的特徵參照 圖4和圖5說明依據第二實施例之導光板，且將省略與第 一實施例相同之組件的說明。 參照圖4和圖5,設置在成階狀結構配置之平面丨至6 間的幾何反射器每一者僅由單一個階狀物和一凹刻稜鏡 212建構而非如圖2和圖3所示之複數個稜鏡。 其中’階狀物211和凹刻稜鏡212之内角01和Q2分 別與前文所述第一實施例相同。 圖6是一依據本發明一第三實施例用kLCD背光單元 之導光板的平面圖。 在圖6中，與圖2所不相同的組件會被標以相同灸考 數字，且應參照圖2進行理解。 依據第三實施例，導光板有二個光入射側21〇。也就 疋説，第三實施例之導光板係建構為在其對向兩側接收入 射光。 因此，依據第三實施例，條紋圖案之寬度從側面往導 13 200905274 光板中心加大，且從構成階狀結構之平面之每一者到前侧 的距離從侧面往導光板中心減小。 圖7是一依據本發明一第四實施例用於LCD背光單元 之導光板的平面圖。 5 在圖7中，與圖4所示相同的組件會被標以相同參考 數字，且應參照圖4進行理解。 依據第四實施例，導光板有二個光入射侧210。也就 是說，第三實施例之導光板係建構為在其對向兩侧接收入 射光。 ίο 因此，依據第四實施例，條紋圖案之寬度從侧面往導 光板中心加大，且從構成階狀結構之平面之每一者到前側 的距離從侧面往導光板中心減小。 以下將參照剖面圖說明依據前述幾個實施例之導光板 之主要部分藉以更進一步理解本發明。 15 在下列剖面圖中，與前述圖式所示相同的參考數字將 應參照圖2、圖4、圖6和圖7進行理解。 圖8是一沿圖2之線A-B取得的剖面圖。 參照圖8，單元棱鏡311形成於條紋圖案310之表面 上。 2〇 圖9是一沿圖2之線C-D取得的剖面圖。 參照圖9，導光板之後侧具有如同圖2第一實施例所 述配置成階狀結構的複數個平面1至6。 此外，圖10是一沿圖4之線A-B取得的剖面圖，且 圖11是一沿圖4之線C-D取得的剖面圖。 14 200905274 圖12是一沿圖6之線A-B取得的剖面圖，且圖13是 一沿圖6之線C-D取得的剖面圖。 如圖12和13所示，在圖6所示導光板之後側上，設 置有複數個平面建構階狀結構致使從該等平面每一者到前 5 側的距離從側面往導光板中心減小。 圖14是一沿圖7之線A-B取得的剖面圖，且圖15是 一沿圖7之線C-D取得的剖面圖。 圖16是一例示具有階狀圖案之導光板後侧220之一基 礎斜率的圖。 ίο 如圖16所示，依據本發明之導光板具有形成於後側上 的幾何反射器和階狀圖案，該後侧之基礎斜率係依據導光 板之光入射侧210與對向光入射侧215間之一厚度距離、 及導光板之總長決定。 15 發明模式 以下參照各實例說明本發明。 1.實例和比較實例 實例1-1 在一寬度（W)x長度（L)x厚度（T)為 288.8x217.7x2.4 2〇 (光入射侧）x〇_8麵（對向光入射側）的楔型導光板中， 後侧對前侧之基礎斜率是0.42度，此係藉由導光板之光入 射侧與對向光入射側間之厚度差、且藉由導光板之全長決 定。在此實例中，本發明之圖案係僅形成於導光板之後侧 上以提供一包括階狀稜鏡的單一階狀結構。此時，該單一 15 200905274 階狀結構之圖案係以1，〇〇〇μηι之固定間距配置，其中每一 階狀稜鏡具有130.33度之内角Θ1且以0,42度之角度傾斜 以便平行於前侧。在此例中，階狀稜鏡間之鉛直方向高度 差為約7.33 μπι。此外，導光板被形成為具備一有815度 夾角的條紋稜鏡圖案。 實例1-2 在一寬度（W)x長度（L)x厚度（Τ)為 288.8x217.7x2.4 (光入射側）χ〇.8腿（對向光入射側）的楔型導光板中， 後側對前側之基礎斜率是0.42度，此係藉由導光板之光入 射側與對向光入射側間之厚度差、且藉由導光板之全長決 定。其中，本發明之圖案係僅形成於導光板之後側上以建 構—包括具有130.33度内角Θ1之階狀棱鏡及具有815度 内角之幾何反射器的雙重階狀結構。此時，該雙重階狀結 構之圖案係以1，000 μπι之固定間距配置，其中每一階狀棱 鏡以0.42度之角度傾斜以便平行於前側。在此例中，階狀 稜鏡間之鉛直方向高度差為約7.33 μιη。此外，導光板被 形成為具備一有81 ·5度夾角的條紋稜鏡圖案。 比較實例1-1 在一寬度（W)x長度（L)x厚度（τ)為 288.8x217.7x2.4 (光入射侧）χ〇·8麵（對向光入射侧）的楔型導光板中， 後側對前侧之基礎斜率是0.42度’此係藉由導光板之光入 射侧與對向光入射側間之厚度差、且藉由導光板之全長決 16 200905274 定。在此實例中，本發明之圖案係僅形成於導光板之後侧 上以提供一包括階狀稜鏡的單一階狀結構。此時，該單一 階狀結構之圖案係以1，〇〇〇 μπι之固定間距配置，其中每一 階狀稜鏡具有130.33度之内角Θ1且以0.42度之角度傾斜 以便平行於前側。在此例中，階狀稜鏡間之鉛直方向高度 差為約7·33 μιη。 比較實例1-2 10 15 20 (二:if(W)x長度⑴χ厚度⑺為28δ·8侧χ2·4 (先入射側）Χ0.8 mm (對向光入射側） 後侧對前狀麵斜率是G.42度，此 射側與對向光人射側間之厚度差、且 ^歧之先入 上以建構之圖/係僅形戍於導光_^^ 81.5度内角之角θ1、狀棱鏡及具有 μιη 階狀結構之圖案係以以—之固定間：。此時，該雙重 階狀稜鏡以Q·42度1度傾斜以便平彳^f，其中每一 中，階狀稜鏡間之絡直方向高度差為約7丁 =側。在此例 實例2-1 在一寬度（w)x長度（L)x厚度（τ) (光入射側）Χ〇.δ _ (對向光入射側）的和 7Χ2.4 各自具有90度頂角的多個前稜鏡以5广，先板中’ 於前側上以偾平杆., 之固定間距配置 叫上以使十仃於從一燈發出之光 、展之行進方向。此 17 200905274 外，後側對前侧之基礎斜率是0.42度，此係藉由導光板之 光入射侧與對向光入射侧間之厚度差、且藉由導光板之全 長決定。其中，本發明之圖案係僅形成於導光板之後側上 以建構一包括階狀棱鏡的單一階狀結構。此時，該單一階 狀結構之圖案係以1,000 μπι之固定間距配置，其中每一階 狀稜鏡具有130.33度之内角Θ1且以0.42度之角度傾斜以 便平行於前側。在此例中，階狀稜鏡間之鉛直方向高度差 為約7.33 μηι。此外’導光板被形成為具備一有81.5度夾 角的條紋棱鏡圖案。 實例2-2 在一寬度（W)x長度（L)x厚度（τ)為 288.8x217.7x2.4 (光入射側）χ〇·8腿（對向光入射侧）的楔型導光板中， 各自具有90度頂角的多個前稜鏡以5〇 μιη之固定間距配置 於兩側上以便平行於從一燈發出之光線之行進方向。此 外’後側對前侧之基礎斜率是〇·42度，此係藉由導光板之 光入射側與對向光入射側間之厚度差、且藉由導光板之全 長決定。其中’本發明之圖案係僅形成於導光板之後側上 以建構一包括具有130.33度内角Θ1之階狀稜鏡及具有 81.5度内角之幾何反射器的雙重階狀結構。此時，該雙重 階狀結構之圖案係以1，〇〇〇 之固定間距配置，其中每一 階狀稜鏡以0.42度之角度傾斜以便平行於前側。在此例 中，階狀稜鏡間之高度方向差為約7.33 μπι。此外，導光 板被形成為具備一有81.5度夾角的條紋稜鏡圖案。 18 200905274 比較實例2-1 在一寬度（W)x長度（L)x厚度（T)為 288.8x217.7x2.4 (光入射側）x〇.8 mm (對向光入射側）的楔型導光板中， 各自具有90度頂角的多個前稜鏡以50 μιη之固定間距配置 5 於前侧上以便平行於從一燈發出之光線之行進方向。此 外，後侧對前侧之基礎斜率是0.42度，此係藉由導光板之 光入射側與對向光入射側間之厚度差、且藉由導光板之全 長決定。其中，本發明之圖案係僅形成於導光板之後侧上 以建構一包括階狀稜鏡的單一階狀結構。此時，該單一階 ίο 狀結構之圖案係以1，000 μπι之固定間距配置，其中每一階 狀稜鏡具有130.33度之内角Θ1且以0.42度之角度傾斜以 便平行於前側。在此例中，階狀稜鏡間之錯直方向高度差 為約 7.33 μιη。 is 比較實例2-2 在一寬度（W)x長度（L)x厚度（Τ)為 288.8x217.7x2.4 (光入射側）x〇.8腿（對向光入射側）的楔型導光板中， 各自具有90度頂角的多個前稜鏡以50 μηι之固定間距配置 於前側上以便平行於從一燈發出之光線之行進方向。此 2〇 外，後侧對前侧之基礎斜率是0.42度，此係藉由導光板之 光入射侧與對向光入射側間之厚度差、且藉由導光板之全 長決定。其中，本發明之圖案係僅形成於導光板之後侧上 以建構一包括具有130.33度内角Θ1之階狀稜鏡及具有 81.5度内角之幾何反射器的雙重階狀結構。此時，該雙重 19 200905274 階狀結構之圖案係以1,000 μιη之固定間距配置，其中每一 階狀稜鏡以0.42度之角度傾斜以便平行於前侧。在此例 中，階狀稜鏡間之高度方向差為約7.33 μιη。 2.結果分析 表1200905274 IX. Description of the Invention: The present invention relates to a light guide plate for a backlight unit of a liquid crystal display (LCD). [Prior Art] A conventional edge-illuminated or wedge-shaped light guide plate includes a light incident side for receiving light from a light source, a front side for directing light to the outside, and a light for directing the front side The back side of the reflection, wherein the light source is positioned adjacent one of the conduction sides. Further, in the edge-illuminated or wedge-shaped light guide plate, two enamel sheets, a diffusion sheet and a protective sheet may be stacked on the front side as a light-emitting side, and one such as a dot-like cymbal and the like A pattern of composition can be printed on the back side. Wherein the 'diffuse sheet is disposed on top of the light guide plate and is used to homogenize the light that has passed through the light guide plate. The prism sheet is used to enhance the brightness by refracting and concentrating in such a manner that it undergoes light that is rapidly reduced in redundancy by being diffused in two directions (i.e., horizontal direction and straight direction) by the diffusion sheet. In general, two enamel sheets are used.蒦 The cymbal is placed on top of the enamel sheet and is used to protect the prism sheet from damage such as scratches and avoids the Murray effect that occurs when the two layers are thin and in the K-flat and misaligned directions. (M〇jre). The purpose of this *' edge-lit or wedge-shaped light guide is to support a flat light source with a uniform twist on the side of the front 200905274, so that light that has entered the light guide only through one side is offset toward the opposite side. 'Although the edge-illuminated or wedge-shaped light guide constructed as described above has lower brightness than the edge-illuminated planar light guide plate with light sources on both sides, this edge-illuminated or wedge-shaped light guide is usually used in Because the frame is small and there is only a light source on one side, such as a notebook computer. Therefore, there is a need for an edge illumination or wedge type light guide that is capable of maximizing light efficiency with a small amount of light. [Disclosure] [Technical Problem] The present invention has been made in view of the above problems, and an aspect of the present invention is to provide a light guide plate for an LCD backlight unit including a rear side having a double stepped structure The double stepped structure is combined with the step and the geometric 15 reflector to reflect the light toward a front side; or the back side has a single stepped structure consisting entirely of steps, wherein the steps are parallel to the The front side is adjacent to the front side as the distance from the order to the light incident side of the light guide plate increases. 20 Technical Solution According to a first aspect of the present invention, a light guide plate for an LCD backlight unit includes a light incident side for receiving light from a light source, and a front side for directing light to the outside. And a rear side having a cross-sectional shape combined with a geometric reflector for reflecting light toward the front side, wherein 6 200905274, the equal-order is parallel to the front side and follows from the fresh step The distance from the object to the incident side of the light increases toward the front side. According to the second aspect of the present invention, a light panel for an LCD backlight unit includes a light-emitting side for receiving light from the light source, and a front side for the light and the outside. , and - have a step of the money and the reflector junction ^ ^ cross-sectional shape is used to make the light reflected toward the front side of the front side, where the two ', the shape from the • p# to the light side of the light The distance increases and the sin is near the front side. iMjLM. According to this U, the light guide plate of the LCD backlight unit ensures LG]) * Conversely, there is 〒 brightness, excellent light uniformity and visibility on the whole surface, and = 4 is free from the conventional light guide plate - diffuse The sheet and the sheet are either or both, thereby reducing the manufacturing cost of the backlight unit. [Embodiment] The above and other objects, features and other advantages of the present invention will become more apparent from the description of the appended claims. Exemplary embodiments of the present invention are described with reference to the accompanying drawings. 1 is a perspective view of a light guide plate for a light unit according to a first embodiment of the present invention. According to a first embodiment of the present invention, the light guide plate includes a light incident side for receiving light from a light source 7 200905274, a front side for directing light to the outside, and a step having a step combined with the geometric reflector. A cross-sectional shape is used to cause the light-line to be reflected toward the side of the S-black side, wherein each of the steps is parallel to the front side and increases in distance from the level to the light incident side Close to the front side. Referring to Fig. 1, the light guide plate of the first embodiment is constructed to allow light to enter the light guide plate only through a side adjacent to a light source 140 (hereinafter referred to as a light incident side 21?β) while preventing light from passing through. The side (hereinafter referred to as the opposite light incident side 215") enters the light guide plate. A front side 230 is connected perpendicular to the light incident side 210 and acts as a light emitting side. Light that has entered the light guide plate through the light incident side 210 passes through the front side and exits the light guide plate. The front side 230 is the most adjacent side of the panel of the liquid crystal display. The light guide plate according to the first embodiment is a wedge type light guide plate having a characteristic pattern formed on a rear side 220. 2 and 3 are rear perspective views illustrating a pattern on the rear side of the light guide plate according to the first embodiment shown in Fig. 1. Referring to Figures 2 and 3, in the light guide plate according to the first embodiment, the rear side 220 has a plurality of planes 1, 2, 3, 4, 5, 6' configured in a stepped configuration such that from the planes 1 to 6 to the front side The distance di of d to d "d" (see Fig. 3) Ik decreases from the light incident side 210 to the opposite light incident side 215. In this case, it should be understood that although only six planes are shown in Figs. 2 and The number of planes will depend on the size of the light guide and the distance between the planes, ie the plane spacing (P). 8 200905274 The plurality of planes 1 to 6 are preferably made parallel to the front side 23〇. If the rear side 220 When tilting the horizontal plane, the light guide plate cannot obtain the theoretical light guiding effect with total internal reflection and undergoes the generation of a large-angle emitted light component, which causes light loss. Among them, the planes 1 to 6 are configured to have a tolerance of ±〇5 degrees. The tolerance is determined by the error of the process. The total base slope of the rear side 220 relative to the front side 230 is determined by the light incident side 210, the opposite light incident side 215, and the length of the light guide plate. Plane 1 to 6 each have a fixed length Lx, each flat The length of the face Lx is better than the total length l〇 of the upper light guide plate in the range of 1:100 to 1:1, 〇〇〇. The number of light sources is a major determining parameter. For example, with the number of light sources Increasing, the length of the light incident side and the opposite light incident side is increased, so that the base slope of the rear side is also increased. In this embodiment, the rear side is inclined at an angle of 0.42 degrees. Referring to Fig. 3, the rear side 220 includes the setting Steps 211 and geometric reflectors 212 and 213 between two adjacent planes (e.g., between planes 1 and 2 of Figure 3), wherein geometric reflectors 212 and 213 are recessed by a recess having an internal angle θ2 The engraving 212 is combined with a projection 213 having an inner corner Θ3. The left side of the concave engraving 212 (viewed in FIG. 3) is shared with the right side of the step 211, and the concave engraving is performed. The right side of 212 is shared with the left side of the protrusion 213. Preferably, the step 211 has a 200905274 inner angle Θ1 in the range of 110 to 160 degrees, and both the intaglio prism 212 and the protrusion 213 It has an internal angle Θ2 or Θ3 in the range of 60 to 100 degrees. The step 211 is set to have a range of 110 to 160 degrees. The reason for the inner angle Θ1 is that the main function of shifting the light in the vertical direction by reflecting light is applied to the right side of the convex 稜鏡213 (viewed in Fig. 3), and the right side of the step 211 (viewed in Fig. 2) ) has the main function of reflecting light in the vertical direction and the secondary function of guiding light to the convex 稜鏡 213. That is, when the inner angle Θ 1 of the step is in the range of 110 to 160 degrees, the step is The right side of the object 211 is inclined at substantially the same angle as the right side of the convex prism 213, so that the protrusion 213 can effectively shift the light toward the front side in the wrong direction while the step 211 performs the above-described one function. . The reason why the boss 213 is set to have an inner angle Θ3 in the range of 60 to 100 degrees is to cause the incoming light to be offset as much as possible in the vertical direction toward the front side of the 15 as in the case of the step 211. When light enters the ridge 213 at an angle of about 82.5 degrees, the direct reflection and refraction of the light occurs most efficiently. Further, the projection 213 has a tip that is more retracted than the side 230 of the step 211. In order to allow the light to travel in the wrong direction, the light that has passed through the right side of the step 211 should be refracted into the left side of the ridge 213 and then reflected by the right side of the ridge 213. In this connection, in order to allow the light that has passed through the right side of the step 211 to enter the left side of the protrusion 213 by a relatively large amount without leaving toward the front side, it is preferable that the tip of the protrusion 213 is farther from the front than the step 211. Side 230 is further away. 200905274 Preferably, the width ratio of the light incident side to the upper opposite light incident side is in the range of 9:1 to 1:1. Further, preferably, the ratio of the entanglement of the concave ridge 212 to the upper ridge 213 is in the range of 1:2 to 2:1. Further, preferably, the area ratio of the geometric reflector on the rear side of the light guide plate to the upper step is in the range of 1:100 to 1:10,000. On the rear side of the light guide plate having a plurality of planes 1 to 6 configured as a stepped structure as described above, the distance between adjacent planes or the distance between adjacent projections 213, that is, the pitch P (see FIG. 2) It is preferably 〇.3~2 faces, but it depends on the intensity of light emitted from a planar light source of the light guide plate and the type of light source. Referring again to FIG. 3, each of the plurality of planes 1 to 6 may further include a plurality of dot-like turns 222 having a specific shape such as a circle, an ellipse, a diamond, a rectangle, or a combination thereof. 'By the effect of getting the light entering through the light incident side 21〇 more efficiently toward the front side 230. Wherein each of the turns formed on the spot-like turns 222 preferably has a longitudinal direction disposed perpendicular to a direction of light entry. Referring to Fig. 2', a stripe pattern 310 may be formed instead of the dot 稜鏡222, 2〇 together with the dot 稜鏡222, or formed on the surface of the plurality of planes 丨6 as needed. The width of the stripe pattern 230 is increased from the light incident side 21 to the opposite light incident side 215 and a plurality of turns are formed on the surface thereof. The plurality of turns of the strip pattern 310 have a longitudinal direction perpendicular to the direction in which the light enters. 11 200905274 At this time, each of the stripe patterns 310 preferably has an internal angle of 70 to 85 degrees because the prism inner angle in this range ensures an increase in the ratio of the direct-to-light emission and thereby realizes a high-brightness LCD. Referring to Fig. 3, the front side 230 may be formed to have a front beak 315, each of which has a predetermined cross-sectional shape and is used to uniformly refract and diffuse light passing through the light guide plate. The front weir 315 is formed on the entire surface of the front side 230 and has a longitudinal direction disposed parallel to the light entering direction. On the other hand, although the front weir 315 has a ίο triangular cross section in the vertical direction of Fig. 3, it should be understood that the front weir 315 may have various modifications that are not limited to the triangular cross section. For example, the front prism 315 may have a trapezoidal shape or an inverted groove shape having a predetermined radius of curvature on the lateral side. In order to improve the uniformity and visibility of the light, the front 稜鏡 315 is preferably arranged at a fixed pitch (d), as shown in FIG. In other words, when the front 稜鏡 315 spaced apart from each other by a fixed pitch (d) refracts and diffuses light from the light guide plate in a direction oblique to the LCD panel (not shown) of the face light guide plate. The light is guided through a separation plane defined by a fixed distance (d) (ie, a space between the front prisms) to be perpendicular to the LCD panel (not shown), thereby further increasing the arrival. Light uniformity of the LCD panel. The area of the separation plane defined by the front weir 315 to the upper fixed distance (d) between the front sills 315 on the front side 230 is preferably in the range of 1:0.5 to 1:10. Further, each of the front prisms 315 preferably has a height (h2):width (W2) ratio in the range of 0.3 to 0.6. If the height/width ratio is less than 0.3, the liquid crystal 12 200905274 = the device will have an excessively high horizontal viewing angle, resulting in a decrease in brightness. If the ratio is large, the LCD will have a too low horizontal viewing angle to meet the optical characteristics. - Figures 4 and 5 are plan views of a light guide plate for an LCD backlight unit in accordance with the present invention - a second embodiment. In Fig. 4 and Fig. 5, the same as shown in Fig. 2 and Fig. 3 is used to check the money. Therefore, in understanding the second embodiment of Figs. 4 and 5, the same reference numerals as in Figs. 2 and 3 can be understood with reference to Figs. 2 and 3. 10 15 20 The light guide plate according to the second embodiment will be described below with reference to the features of the first embodiment different from those of Figs. 2 and 3, and the description of the same components as those of the first embodiment will be omitted. Referring to Figures 4 and 5, geometric reflectors disposed between planes 66 of the stepped configuration are each constructed by only a single step and a recess 212 instead of Figures 2 and 3. The plurals shown. The inner corners 01 and Q2 of the 'step 211 and the concave cut 212 are the same as the first embodiment described above. Figure 6 is a plan view of a light guide plate using a kLCD backlight unit in accordance with a third embodiment of the present invention. In Fig. 6, components different from those of Fig. 2 will be labeled with the same moxibustion number and should be understood with reference to Fig. 2. According to the third embodiment, the light guide plate has two light incident sides 21A. That is to say, the light guide plate of the third embodiment is constructed to receive the incident light on both sides thereof. Therefore, according to the third embodiment, the width of the stripe pattern is increased from the side toward the center of the light guide plate, and the distance from each of the planes constituting the stepped structure to the front side is reduced from the side toward the center of the light guide plate. Figure 7 is a plan view of a light guide plate for an LCD backlight unit in accordance with a fourth embodiment of the present invention. 5 In Fig. 7, the same components as those shown in Fig. 4 will be denoted by the same reference numerals and will be understood with reference to Fig. 4. According to the fourth embodiment, the light guide plate has two light incident sides 210. That is, the light guide plate of the third embodiment is constructed to receive the incident light on both sides thereof. Therefore, according to the fourth embodiment, the width of the stripe pattern is increased from the side toward the center of the light guide plate, and the distance from each of the planes constituting the stepped structure to the front side is reduced from the side toward the center of the light guide plate. The present invention will be further understood by referring to the cross-sectional views of the main portions of the light guide plate according to the foregoing several embodiments. In the following cross-sectional views, the same reference numerals as those shown in the foregoing drawings will be understood with reference to Figs. 2, 4, 6, and 7. Figure 8 is a cross-sectional view taken along line A-B of Figure 2 . Referring to Fig. 8, a unit prism 311 is formed on the surface of the stripe pattern 310. 2〇 Fig. 9 is a cross-sectional view taken along line C-D of Fig. 2. Referring to Fig. 9, the rear side of the light guide plate has a plurality of planes 1 to 6 arranged in a stepped configuration as in the first embodiment of Fig. 2. Further, Fig. 10 is a cross-sectional view taken along line A-B of Fig. 4, and Fig. 11 is a cross-sectional view taken along line C-D of Fig. 4. 14 200905274 Fig. 12 is a cross-sectional view taken along line A-B of Fig. 6, and Fig. 13 is a cross-sectional view taken along line C-D of Fig. 6. As shown in FIGS. 12 and 13, on the rear side of the light guide plate shown in FIG. 6, a plurality of plane-constructed stepped structures are disposed such that the distance from each of the planes to the front 5 side decreases from the side toward the center of the light guide plate. . Figure 14 is a cross-sectional view taken along line A-B of Figure 7, and Figure 15 is a cross-sectional view taken along line C-D of Figure 7. Fig. 16 is a view showing an example of a basic slope of the rear side 220 of the light guide plate having a step pattern. As shown in FIG. 16, the light guide plate according to the present invention has a geometric reflector and a stepped pattern formed on the rear side, and the base slope of the rear side is based on the light incident side 210 and the opposite light incident side 215 of the light guide plate. The thickness distance between one and the total length of the light guide plate is determined. 15 Mode for Invention The present invention will be described below with reference to examples. 1. Examples and Comparative Examples Example 1-1 at a width (W) x length (L) x thickness (T) is 288.8 x 217.7 x 2.4 2 〇 (light incident side) x 〇 _ 8 plane (optical light incident In the wedge-shaped light guide plate of the side, the slope of the base of the rear side to the front side is 0.42 degrees, which is determined by the difference in thickness between the light incident side of the light guide plate and the incident side of the opposite light, and is determined by the total length of the light guide plate. . In this example, the pattern of the present invention is formed only on the rear side of the light guide plate to provide a single stepped structure including stepped turns. At this time, the pattern of the single 15 200905274 stepped structure is arranged at a fixed pitch of 1, 〇〇〇μηι, wherein each stepped 稜鏡 has an inner angle 1301 of 130.33 degrees and is inclined at an angle of 0,42 degrees so as to be parallel to Front side. In this example, the height difference in the vertical direction between the stepped turns is about 7.33 μπι. Further, the light guide plate is formed to have a stripe pattern having an angle of 815 degrees. Example 1-2 in a wedge-shaped light guide plate having a width (W) x length (L) x thickness (Τ) of 288.8 x 217.7 x 2.4 (light incident side) χ〇.8 leg (opposite light incident side) The base slope of the rear side to the front side is 0.42 degrees, which is determined by the difference in thickness between the light incident side of the light guide plate and the incident light incident side, and is determined by the total length of the light guide plate. Here, the pattern of the present invention is formed only on the rear side of the light guide plate to be constructed - including a stepped prism having an inner angle of 1301 of 130.33 degrees and a double stepped structure having a geometrical reflector having an inner angle of 815 degrees. At this time, the pattern of the double-stepped structure was arranged at a fixed pitch of 1,000 μm, wherein each of the stepped prisms was inclined at an angle of 0.42 degrees so as to be parallel to the front side. In this example, the height difference in the vertical direction between the stepped turns is about 7.33 μm. Further, the light guide plate is formed to have a stripe pattern having an angle of 81 · 5 degrees. Comparative Example 1-1 A wedge-shaped light guide plate having a width (W) x length (L) x thickness (τ) of 288.8 x 217.7 x 2.4 (light incident side) χ〇 · 8 faces (opposite light incident side) The base slope of the rear side to the front side is 0.42 degrees. This is determined by the difference in thickness between the light incident side of the light guide plate and the incident light incident side, and is determined by the total length of the light guide plate. In this example, the pattern of the present invention is formed only on the rear side of the light guide plate to provide a single stepped structure including stepped turns. At this time, the pattern of the single stepped structure is arranged at a fixed pitch of 1, 〇〇〇 μπι, wherein each of the stepped turns has an inner angle 1301 of 130.33 degrees and is inclined at an angle of 0.42 degrees so as to be parallel to the front side. In this example, the height difference in the vertical direction between the stepped turns is about 7.33 μm. Comparative example 1-2 10 15 20 (2: if (W) x length (1) χ thickness (7) is 28 δ · 8 side χ 2 · 4 (first incident side) Χ 0.8 mm (opposite light incident side) rear side to front surface The slope is G.42 degrees, and the difference between the thickness of the incident side and the opposite side of the incident light, and the first difference of the image is constructed to form a map/line of the internal angle of the light guide _^^ 81.5 degrees. The prism and the pattern having the step structure of μιη are fixed to each other: at this time, the double stepped 稜鏡 is inclined at a degree of Q·42 degrees to 1 degree, in which each step is stepped. The height difference in the straight direction between the mirrors is about 7 deg = side. In this example, Example 2-1 is in a width (w) x length (L) x thickness (τ) (light incident side) Χ〇.δ _ (right The front side of the light incident side) and the 7 Χ 2.4 each having a 90 degree apex angle are 5 wide, and the first plate is placed on the front side with a fixed pitch. The fixed pitch is called to make the ten 仃From the light emitted by a lamp, the direction of travel of the exhibition. The base slope of the rear side to the front side is 0.42 degrees, which is the thickness difference between the light incident side of the light guide plate and the incident side of the opposite light. And by the full length of the light guide Wherein, the pattern of the present invention is formed only on the rear side of the light guide plate to construct a single stepped structure including the stepped prism. At this time, the pattern of the single stepped structure is arranged at a fixed pitch of 1,000 μm, wherein each The first-order crucible has an inner angle 1301 of 130.33 degrees and is inclined at an angle of 0.42 degrees so as to be parallel to the front side. In this example, the vertical height difference between the stepped turns is about 7.33 μηι. Further, the 'light guide plate is formed as It has a stripe prism pattern with an angle of 81.5 degrees. Example 2-2 at a width (W) x length (L) x thickness (τ) is 288.8x217.7x2.4 (light incident side) χ〇 · 8 legs (pair In the wedge-shaped light guide plate to the light incident side, a plurality of front ridges each having a 90-degree apex angle are disposed on both sides at a fixed pitch of 5 〇 μη so as to be parallel to the traveling direction of the light emitted from a lamp. 'The base slope of the back side to the front side is 〇·42 degrees, which is determined by the difference in thickness between the light incident side of the light guide plate and the incident light incident side, and is determined by the total length of the light guide plate. The pattern is formed only on the rear side of the light guide plate to be built A double stepped structure comprising a stepped crucible having an inner angle of 130.33 degrees and a geometrical reflector having an inner angle of 81.5 degrees. At this time, the pattern of the double stepped structure is arranged at a fixed pitch of 1, 〇〇〇, wherein Each stepped 稜鏡 is inclined at an angle of 0.42 degrees so as to be parallel to the front side. In this example, the height difference between the stepped turns is about 7.33 μπι. Further, the light guide plate is formed to have an angle of 81.5 degrees. Stripe 稜鏡 pattern 18 200905274 Comparative Example 2-1 at a width (W) x length (L) x thickness (T) is 288.8x217.7x2.4 (light incident side) x 〇.8 mm (optical light incident In the wedge-shaped light guide plate of the side, a plurality of front sills each having a 90-degree apex angle are disposed at a fixed pitch of 50 μm on the front side so as to be parallel to the traveling direction of the light emitted from a lamp. Further, the base slope of the rear side to the front side is 0.42 degrees, which is determined by the difference in thickness between the light incident side of the light guide plate and the incident light incident side, and by the total length of the light guide plate. Wherein, the pattern of the present invention is formed only on the rear side of the light guide plate to construct a single stepped structure including stepped turns. At this time, the pattern of the single-order structure is arranged at a fixed pitch of 1,000 μm, wherein each of the stepped turns has an inner angle 1301 of 130.33 degrees and is inclined at an angle of 0.42 degrees so as to be parallel to the front side. In this example, the height difference between the stepped turns is about 7.33 μιη. Is a comparison example 2-2 in a width (W) x length (L) x thickness (Τ) is 288.8x217.7x2.4 (light incident side) x 〇. 8 leg (opposite light incident side) wedge guide In the light panel, a plurality of front sills each having a 90 degree apex angle are disposed on the front side at a fixed pitch of 50 μm to be parallel to the traveling direction of the light emitted from a lamp. In addition, the base slope of the rear side to the front side is 0.42 degrees, which is determined by the difference in thickness between the light incident side of the light guide plate and the incident light incident side, and is determined by the total length of the light guide plate. Wherein, the pattern of the present invention is formed only on the rear side of the light guide plate to construct a double stepped structure including a stepped crucible having an inner angle of 1301 of 130.33 degrees and a geometrical reflector having an inner angle of 81.5 degrees. At this time, the pattern of the double 19 200905274 stepped structure is arranged at a fixed pitch of 1,000 μm, wherein each stepped 稜鏡 is inclined at an angle of 0.42 degrees so as to be parallel to the front side. In this example, the height difference between the stepped turns is about 7.33 μm. 2. Analysis of results Table 1
導光板之組態 表2 分類 實例1-1 實例1-2 比較實例1-1 比較實例1-1 亮度(cd) 〜204 〜207 〜55 〜90 外觀 良好 良好 角落陰暗 角落陰暗 表1示出與實例1-1和1-2及比較實例1-1和1-2有關 的亮度測量結果。表2示出用這些實例和比較實例製造之 導光板的亮度值和外觀。 20 200905274 從表1和2可理解到實例相較於比較實例具有較高亮 度和較好外觀。 表3Light guide plate configuration table 2 classification example 1-1 example 1-2 comparison example 1-1 comparison example 1-1 brightness (cd) ~ 204 ~ 207 ~ 55 ~ 90 appearance good good corner dark corner dark table 1 shown with Brightness measurement results relating to Examples 1-1 and 1-2 and Comparative Examples 1-1 and 1-2. Table 2 shows the brightness values and appearance of the light guide plates manufactured by these examples and comparative examples. 20 200905274 It can be understood from Tables 1 and 2 that the examples have higher brightness and better appearance than the comparative examples. table 3
導光板之組態 表4 分類 實例2-1 實例2-2 比較實例2-1 比較實例2-1 亮度(cd) 〜236 〜254 〜73 〜101 外觀 良好 良好 角落陰暗 角落陰暗 表3示出與實例2-1和2-2及比較實例2-1和2-2有關 ίο 的亮度測量結果。表4示出用這些實例和比較實例製造之 導光板的亮度值和外觀。 從表3和4可理解到實例相較於比較實例具有較高亮 度和較好外觀。 21 200905274 儘管已參照實施例和隨附圖式說明本發明，本發明並 不侷限於這些實施例和圖式。應理解到熟習此技藝者可不 脫離由隨附申請專利範圍項界定之發明精神和範圍作出許 多修改和變化。 5 【圖式簡單說明】 圖1是一依據本發明一第一實施例用於LCD背光單元 之導光板的立體圖； 圖2和3是例示形成於圖1所示依據第一實施例之導 ίο 光板之後側上的圖案的後視立體圖； 圖4和5是依據本發明一第二實施例用於LCD背光單 元之導光板的平面圖； 圖6是一依據本發明一第三實施例用於LCD背光單元 之導光板的平面圖； is 圖7是一依據本發明一第四實施例用於LCD背光單元 之導光板的平面圖； 圖8是一沿圖2之線A-B取得的剖面圖； 圖9是一沿圖2之線C-D取得的剖面圖； 圖10是一沿圖4之線A-B取得的剖面圖； 2〇 圖11是一沿圖4之線C-D取得的剖面圖； 圖12是一沿圖6之線A-B取得的剖面圖； 圖13是一沿圖6之線C-D取得的剖面圖； 圖14疋 一沿圖7之線A-B取得的剖面圖， 圖15是一沿圖7之線C-D取得的剖面圖；且 22 200905274 圖16是一例示具有階狀圖案之導光板後侧之一基礎 斜率的圖。 【主要元件符號說明】 5 1、2、3、4、5、6 階狀結構平面 140 光源 210 光入射侧 211 階狀物 212 幾何反射器、凹刻稜鏡 10 213 幾何反射器、凸起棱鏡 215 對向光入射側 220 後侧 222 點狀稜鏡 230 前侧 15 310 條紋圖案 311 單元棱鏡 \ 315 前稜鏡 23Light guide plate configuration table 4 classification example 2-1 example 2-2 comparison example 2-1 comparison example 2-1 brightness (cd) ~ 236 ~ 254 ~ 73 ~ 101 Appearance good good corner dark corners dark table 3 shows with Examples 2-1 and 2-2 and Comparative Examples 2-1 and 2-2 relate to the luminance measurement results of ίο. Table 4 shows the brightness values and appearance of the light guide plates manufactured by these examples and comparative examples. As can be understood from Tables 3 and 4, the examples have higher brightness and better appearance than the comparative examples. 21 200905274 Although the invention has been described with reference to the embodiments and the accompanying drawings, the invention is not limited to these embodiments and drawings. It is to be understood that many modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a light guide plate for an LCD backlight unit according to a first embodiment of the present invention; FIGS. 2 and 3 are diagrams showing the guide according to the first embodiment shown in FIG. 4 is a plan view of a light guide plate for an LCD backlight unit according to a second embodiment of the present invention; FIG. 6 is a third embodiment of the present invention for an LCD according to a third embodiment of the present invention; A plan view of a light guide plate of a backlight unit; FIG. 7 is a plan view of a light guide plate for an LCD backlight unit according to a fourth embodiment of the present invention; FIG. 8 is a cross-sectional view taken along line AB of FIG. A cross-sectional view taken along line CD of Fig. 2; Fig. 10 is a cross-sectional view taken along line AB of Fig. 4; Fig. 11 is a cross-sectional view taken along line CD of Fig. 4; Figure 6 is a cross-sectional view taken along line CD of Figure 6; Figure 14 is a cross-sectional view taken along line AB of Figure 7, and Figure 15 is taken along line CD of Figure 7 Sectional view; and 22 200905274 Figure 16 is an example of the base of the rear side of a light guide plate having a stepped pattern Rate chart. [Main component symbol description] 5 1, 2, 3, 4, 5, 6 Step structure plane 140 Light source 210 Light incident side 211 Step 212 Geometric reflector, concave engraving 10 213 Geometric reflector, convex prism 215 Opposite light incident side 220 Rear side 222 Point 稜鏡 230 Front side 15 310 Stripe pattern 311 Unit prism \ 315 Front 稜鏡 23