1360672 九、發明說明· 【發明所屬之技術領域】 本發明關於一種用於液晶顯示器（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—狀從一光源1360672 IX. Description of the Invention [Technical Field] 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 shape from a light source
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20 接收光線的光人射側、—用於使光線射往外界的前側、及 -用於使光線朝該前側反射的後側，其中該光源被定位在 該等側之一者附近。 、/匕外，在邊緣照明型或楔型導光板中，二個稜鏡薄片、 -漫射片及-保護片可被堆疊在該前側上當作發光侧，且 -譬如由點狀稜鏡和類似物組成之圖案可被印在該後側 上。 八中/又射片5曼置在導光板之頂上且用來使已通過導 光板之光線均勻化。 士稜鏡薄片用來藉由折射並集中傾向於因在通過漫射片 =於兩方向（亦即水平方向和錯直方向）巾漫射而經歷 讀t速減低之光線的方式使亮度提高。-般而言會使用 二個稜鏡薄片。 為在稜鏡薄片頂上，且用來保護稜鏡薄片不 顺的傷害，並且避免#使用兩層堆疊之棱鏡薄 1水平和敍直方向中發生的莫碟效應（M〇ireeffec〇。 此’邊緣照明型或楔型導光板的用途是支援一在前 5 1360672 側上有一均勻高亮度的平面光源，使僅透過一侧已進入導 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 一側有光源的情況，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 鲁照明型或楔型導光板。 10 【發明内容] - 技術性 • 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 反射為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 離增加而靠近該前側。 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側，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 該等階狀㈣-者平行於轉散隨著從料階狀物到該 光入射側之距離增加而靠近該前側。 依據本發明之H點’ _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侧，一用於 使光線射往外界的前側’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侧反射的後側，其中 該等階狀物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》 有益效應 依據本發明’用於LCD背光單元的導光板確保在LCD 面板之整體表面上有高亮度、優異的光均勻度和可視度， 藉以允許免除習知導光板制之—漫射片和—稜鏡薄片其 中一者或二者，從而降低背光單元之製造成本。 【實施方式】 本發明之以上和其他目的、特徵及其他優點將在搭配 隨附圖式提出的以下詳細說明中更清楚顯露。 最佳模式 以下參照隨附圖式說明本發明之範例實施例。 圖1是一依據本發明一第一實施例用於L c D背光單元 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 1360672 接收光線的光入射側，一用於使光線射往外界的前側，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 線朝該前侧反射的後侧，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 5 該前側。 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") . 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。 0 —前側230垂直於光入射側210連接且當作一發光 側’已透過光入射側210進入該導光板的光線會穿過該前 側射往該導光板以外。前側230對於液晶顯示器之面板來 說是最鄰近之側。 依據第一實施例之導光板是一具有形成於一後側220 5 上之特徵圖案的楔型導光板。 货圖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，後側 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230的距離山〜(16 (參見圖3 ) 隨著從光入射側210到對向光入射側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 1360672 複數個平面1至6較佳被製作為平行於前側23〇。 如果後側220對水平面傾斜’則該導光板無法赛彳曰且 有全内反射之理論導光效果且經歷一大角度發射光分量〃 產生，這造成光損失。 其中，平面1至6係配置為在±0.5度公差以内面向^ 側230，此公差係考慮製程之誤差決定。 _ 後側220相對於前侧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_ 平面之長度Lx對上導光板之總長度L0的比較佳在 1:100〜1:1，000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 之數量增加，光入射側和對向光入射側之長度加大，故後 側之基礎斜率亦加大。在此實施例中，後側以0 42度的角 度傾斜。 參照圖3 ’後側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 器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之左側（在圖3觀看）與階狀物 211之右側共用，且凹刻棱鏡212之右側與凸起棱鏡213 之左側共用。 較佳來說，階狀物211具有一在110〜160度範圍内的 9 1360672 内角Θ1，且凹刻稜鏡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11〇〜160度範圍内之内角μ 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 5 功能係加諸於凸起棱鏡213之右側（在圖3觀看），且階 狀物211之右侧（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稜鏡213之右側大 ίο 致相同的角度歪斜，故凸起稜鏡213可在階狀物211發揮 上述二個功能的同時有效地使光線在鉛直方向中朝前側偏 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 is 前侧偏移，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，光線之鉛直向反射和折射 _ 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 前侧230更遠的尖端。為了允許光線依鉛直方向行進，已 2〇 通過階狀物211右側的光線應當被折射到凸起棱鏡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右側的光線以一較大量進入凸起棱鏡 213之左侧而不朝前側離開，最好凸起稜鏡213之尖端比 階狀物211離前側230更遠。 10 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 高度比在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0.3〜2 mm，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，該等點狀棱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 通過光入射側210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、 連同點狀稜鏡222、或視需要形成在複數個平面1至6之 表面上。條紋圖案230之寬度從光入射側210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之複數個稜鏡具有一垂直於光進入方向設置的 縱向方向。 1360672 此*時’條紋圖案310之每一棱鏡較佳具有一 70〜85度 角’因為此範圍内之稜鏡内角確保鉛直向發射光之比 提同且藉此實現〜高亮度LCD。 ^參照圖3 ’前側230可被形成為具備前稜鏡315，每一 刖棱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。 月’J棱鏡315係形成於前側230之整個表面上且具有一 平行於光進人方向設置的縱向方向。 二另:方面’儘管前稜鏡315在圖3之鉛直方向中具有 y ^應理解到前稜鏡315可具有不受限於三角 形横截面的容;# b ^ 夕樣修改。舉例來說’前棱鏡315可具有梯形 夕在側向侧具有一預定曲率半徑的倒溝形狀。 :提升光線之均勻度和可視度，前稜鏡315較佳以固 :L(d?配置，如圖3所示。 20 示. 由此 使來f句遺說’當彼此相隔固定間距（d)的前棱鏡315 導光板依—相對於面向導光板之LCD面板（圖中未 二傾，之方向發射的光線折射並漫射時，光線透過一 办n 1 口定間距界定之分離平面（亦即前稜鏡間之一 =破導向為垂直於LCD面板（圖中未示），藉此更進 升抵達LCD面板之光線均勻度。 距315對上由前側230上前棱鏡315間之固定間 |定之分離平面的面積比較佳在LOU:1〇範圍内。 高声此外，每一前稜鏡315較佳具有在0.3〜0.6範圍内之 & (h2):寬度（W2)比。若高度/寬度比小於〇.3，液晶 12 1360672 顯示器會有一過高水平視角，導致亮度降低。若此比值大 於0.6，LCD會有一太低水平視角，無法滿足光學特質。 圖4和5是依據本發明一第二實施例用於LCD背光單 元之導光板的平面圖。 5 在圖4和圖5中，與圖2和圖3所示相同的組件會被 標以相同參考數字。 因此，在理解圖4和圖5之第二實施例時，與圖2和 B 圖3相同的參考數字可參照圖2和圖3進行理解。 以下針對不同於圖2和圖3之第一實施例的特徵參照 ίο 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1至6 間的幾何反射器每一者僅由單一個階狀物和一凹刻棱鏡 212建構而非如圖2和圖3所示之複數個稜鏡。 is 其中，階狀物211和凹刻稜鏡212之内角Θ1和Θ2分 別與前文所述第一實施例相同。 B 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。 在圖6中，與圖2所示相同的組件會被標以相同參考 20 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210.。也就 是說，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 1360672 光板中心加大，且從構成階狀結構之平面之每一者到前側 的距離從側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側210。也就 g 是說，第三實施例之導光板係建構為在其對向兩側接收入 射光。 ίο 因此，依據第四實施例，條紋圖案之寬度從側面往導 光板中心加大，且從構成階狀結構之平面之每一者到前側 的距離從側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。 B 圖8是一沿圖2之線A-B取得的剖面圖。 參照圖8，單元稜鏡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，導光板之後側具有如同圖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 1360672 圖12是一沿圖6之線A-B取得的剖面圖，且圖π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 沿圖7之線C-D取何·的剖面圖。 圖16是一例示具有階狀圖案之導光板後側22〇之一基 • 礎斜率的圖。 10 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，該後側之基礎斜率係依據導光 . 板之光入射側210與對向光入射側215間之一厚度距離、 及導光板之總長決定。 15 &ΜΜΛ. • 以下參照各實例說明本發明。 L實例和比較實例 貫例1 -1 20 、，在一寬度（W)X長度（L)x厚度（T)為 288.8x217.7x2.4 /光入射侧）χ〇.8 _ (對向光入射側）的楔型導光板中， $側對前侧之基礎斜率是〇 42度，此係藉由導光板之光入 ^側與對向光入射側間之厚度差、且藉由導光板之全長決 疋1在此實例中，本發明之圖案係僅形成於導光板之後側 上以提供一包括階狀稜鏡的單一階狀結構。此時，該單一 15 階狀結構之圖案係以1，000 μιη之固定間距配置，其中每一 Ρ白狀棱鏡具有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 μη^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—寬度（W)x長度（l)x厚度（Τ)為 288.8x217.7x2.4 (光入射侧）x〇 8咖（對向光入射側）的楔型導光板中， 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 μιη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 稜鏡間之錯直方向高度差為約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 (光入射側）x〇.8 _ (對向光入射側）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 1360672 定。在此實例中，本發明之圖案係僅形士丄 7成於導光板之後側 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，其每一 階狀棱鏡具有130.33度之内角Θ1且以〇 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。 5 _ 比較實例1-2 在一寬度（W)x 長度（L)x厚度（Τ)為 288.8x217.7x2.4 10 (光入射侧）x〇.8 mm (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。在此實例中，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 is 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 μπι之固定間距配置’其中每一 Β 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 ° 2〇 實例2-1 在一寬度（W)x長度（L)x厚度（T)為 288.8x217.7x2.4 (光入射侧）χ〇·8刪（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5 0 μιη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 17 1360672 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 以建構一包括階狀稜鏡的單一階狀結構。此時，該單一階 5 狀結構之圖案係以i，000 pm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。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。 10 •實例2-2 在一寬度（W)x長度（L)x厚度（τ)為 288.8x217.7x2.4 (光入射侧）x〇.8麵（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5〇 μπι之固定間距配置 15 於前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 以建構一包括具有130.33度内角Θ1之階狀稜鏡及具有 2〇 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1，000 μιη之固定間距配置，其中每一 階狀棱鏡以〇·42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 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。 18 1360672 比較實例2-1 在一寬度（W)x長度（L)x厚度（T)為 288.8x217.7x2.4 (光入射侧）x〇.8麵（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 μπι之固定間距配置 5 於前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 ρ 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 ίο 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。 15 比較實例2-2 在一寬度（W)x長度（L)x厚度（Τ)為 288.8x217.7x2.4 B (光入射侧）χ0.8麵（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 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 1360672 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，階狀稜鏡間之高度方向差為約7.33 μιη。 2.結果分析 表120 a light-emitting side that receives light, a front side for directing light to the outside, and a rear side for reflecting light toward the front side, wherein the light source is positioned adjacent one of the sides. In addition, 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 - for example, by a dot-like 稜鏡A pattern of analog composition can be printed on the back side. The eighth/receiving film 5 is placed on top of the light guide plate and is used to homogenize the light that has passed through the light guide plate. The girdle sheets are used to enhance the brightness by refracting and concentrating in such a manner that the light of the t-speed is reduced by diffusing through the diffusing sheet = the two directions (i.e., the horizontal direction and the straight direction). - Generally speaking, two enamel sheets will be used. For the top of the crucible sheet, and to protect the crucible sheet from damage, and avoid the use of the two-layer stacked prism thin 1 horizontal and straight direction in the m disc effect (M〇ireeffec〇. This 'edge The purpose of the illuminating or wedge-shaped light guide is to support a uniform high-brightness planar light source on the side of the first 5 1360672 so that light that has entered the light guide only through one side is offset toward the opposite side. Edge-illuminated or wedge-shaped light guides have lower brightness than edge-lit planar light guides with light sources on both sides. This edge-edge or wedge-type light guide is usually used because the frame is narrow and only one The case where there is a light source on the side, such as a notebook computer. Therefore, it is required to have a edge-lit or wedge-shaped light guide plate capable of maximizing light efficiency with a small amount of light. 10 [Summary] - Technical Aspects The present invention is made in view of the above problems. And one aspect of the present invention is to provide a light guide plate for an LCD backlight unit, comprising a rear side having a double stepped structure, the double stepped structure and the step And the geometry 15 is reflected as a combination 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 front side and follow the order The distance from the object to the light incident side of the light guide plate increases toward the front side. 20 Technical Solution According to a first aspect of the present invention, a light guide plate for an LCD backlight unit includes a The light source receives the light incident side of the light, a front side for directing light to the outside, and a rear side having a cross-sectional shape combined with the geometric reflector for reflecting the light toward the front side, wherein The step (4)-parallel to the divergence is close to the front side as the distance from the material step to the light incident side increases. The H-point of the present invention for the LCD backlight unit includes a light guide plate. a light incident side for receiving light from a light source, 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 Of which The effect is closer to the front side as the distance from the order to the light incident side increases. Benefits According to the present invention, the light guide plate for the LCD backlight unit ensures high brightness on the entire surface of the LCD panel, Excellent light uniformity and visibility, thereby allowing one or both of the diffusing sheet and the 稜鏡 sheet to be dispensed with by the conventional light guide plate, thereby reducing the manufacturing cost of the backlight unit. And other objects, features and advantages of the invention will be apparent from the accompanying drawings. The first embodiment is a perspective view of a light guide plate for an L c D backlight unit. According to the first embodiment of the present invention, the light guide plate includes a light incident side for receiving light from a light source 1362672, and one for directing light to the outside. a front side, and a rear side having a cross-sectional shape in combination with a geometric reflector for reflecting light toward the front side, wherein the steps are each parallel to Such as from the front and from the order was to increase the light incident side of and close to the front side 5. Referring to Fig. 1, the light guide plate of the first embodiment is constructed to allow light to pass only through one side adjacent to a light source 140 (hereinafter referred to as "light incident side 21"). Enter the light guide plate while preventing light from passing through. The opposite side (hereinafter referred to as the opposite light incident side 215") enters the light guide plate. 0 — The front side 230 is 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 5 . Figs. 2 and 3 are rear perspective views illustrating the 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 from the mountain 230 (see Fig. 3) decreases as it goes from the light incident side 210 to the opposite light incident side 215. In this connection, it should be understood that although only six planes are shown in Figs. 2 and 3. The number of planes will depend on the size of the light guide plate and the distance between the planes, that is, the plane spacing (P). 8 1360672 The plurality of planes 1 to 6 are preferably made parallel to the front side 23〇. If the water level is tilted, the light guide plate cannot be played and has the theoretical light guiding effect of total internal reflection and is generated by a large angle of emitted light component ,, which causes light loss. Among them, the planes 1 to 6 are configured to be ±0.5 degrees. The tolerance is within the tolerance side 230, which 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 length of the light incident side 210, the opposite light incident side 215, and the light guide. In addition, 'assuming planes 1 to 6 each have a fixed length Lx, per _ level The length Lx is preferably in the range of 1:100 to 1:1,000 for the total length L0 of the upper light guide plate. The number of light sources is a main determining parameter. For example, as the number of light sources increases, light incidence The length of the side of the side and the opposite side of the incident light is increased, so that the slope of the base of the rear side is also increased. In this embodiment, the rear side is inclined at an angle of 0 to 42 degrees. Referring to Fig. 3, the rear side 220 is provided in two Steps 211 and geometric reflectors 212 and 213 between 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 inner corner Θ2 212 is combined with a protrusion 213 having an inner corner Θ3. The left side of the concave ridge 212 (viewed in FIG. 3) is shared with the right side of the step 211, and the right side and the convex portion of the concave prism 212 are convex. Preferably, the step 211 has an internal angle Θ1 of 1 1360672 in the range of 110 to 160 degrees, and both the concave engraving 212 and the protrusion 213 have a ratio of 60 to 100. The inner angle Θ2. or Θ3 in the range of degrees. The step 211 is set to have a range of 11 〇 to 160 degrees. The reason for the internal angle μ is that the main 5 function system that shifts the light in the vertical direction by reflecting the light is applied to the right side of the convex prism 213 (viewed in FIG. 3), and the right side of the step 211 (in FIG. 2) View) 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 Θ1 of the step is in the range of 110 to 160 degrees, The right side of the step 211 becomes inclined at the same angle as the right side of the protrusion 213, so that the protrusion 213 can effectively make the light in the vertical direction while the step 211 performs the above two functions. The front side of the middle is offset. The reason why the projection 稜鏡213 is set to have an inner angle Θ3 in the range of 60 to 100 degrees is to cause the incoming ray to be offset as much as possible in the vertical direction toward the front side of the is, 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 ray acts most efficiently. Also, preferably, the raised jaw 213 has a tip that is further from the front side 230 than the step 211. In order to allow the light to travel in the vertical direction, the light passing through the right side of the step 211 should be refracted into the left side of the convex prism 213 and then reflected by the right side of the convex 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 convex prism 213 by a relatively large amount without leaving toward the front side, it is preferable that the tip end of the protrusion 213 is away from the front side 230 from the step 211. farther. 10 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 height ratio 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 0.3 to 2 mm, 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-shaped prisms 222 having a specific shape such as a circle, an ellipse, a diamond, a rectangle, or a combination thereof. The effect of making the light entering through the light incident side 210 more efficiently reflected toward the front side 230 is obtained. Preferably, each of the turns formed on the dot-like turns 222 has a longitudinal direction disposed perpendicular to a direction of light entry. Referring to Fig. 2, a stripe pattern 310 may be formed in place of the dot-like turns 222, together with the dot-like turns 222, or as desired on the surfaces of the plurality of planes 1 to 6. The width of the stripe pattern 230 is increased from the light incident side 210 toward the opposite light incident side 215 and a plurality of turns are formed on the surface thereof. Wherein, the plurality of turns of the strip pattern 310 have a longitudinal direction perpendicular to the direction in which the light enters. 1360672 Each of the prisms of the stripe pattern 310 preferably has an angle of 70 to 85 degrees because the inner corners within this range ensure the ratio of the vertical to the emitted light and thereby achieve 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 month 'J prism 315 is formed on the entire surface of the front side 230 and has a longitudinal direction disposed parallel to the light entering direction. Two other aspects: Although the front sill 315 has y in the vertical direction of Fig. 3, it should be understood that the front sill 315 may have a volume that is not limited to the triangular cross section; #b^ 夕样改改. For example, the front prism 315 may have an inverted groove shape having a trapezoidal shape with a predetermined radius of curvature on the lateral side. : to improve the uniformity and visibility of the light, the front 稜鏡 315 is preferably solid: L (d? configuration, as shown in Figure 3. 20 shows. This makes the sentence say 'when separated from each other by a fixed distance (d The front prism 315 light guide plate is separated from the LCD panel of the surface light guide plate (the light emitted from the direction of the light is refracted and diffused, and the light is transmitted through a separation plane defined by the interval of n 1 ) That is, one of the front turns = the break guide is perpendicular to the LCD panel (not shown), thereby increasing the uniformity of the light reaching the LCD panel. The distance between the front side prisms 315 and the front side prisms 315 is fixed. The area of the separation plane is preferably in the range of LOU: 1 。. In addition, each front 稜鏡 315 preferably has a & (h2): width (W2) ratio in the range of 0.3 to 0.6. /width ratio is less than 〇.3, liquid crystal 12 1360672 The display will have an excessively high horizontal viewing angle, resulting in a decrease in brightness. If the ratio is greater than 0.6, the LCD will have a too low horizontal viewing angle to meet optical characteristics. Figures 4 and 5 are in accordance with the present invention. A second embodiment is a plan view of a light guide plate for an LCD backlight unit. In Fig. 5, the same components as those shown in Fig. 2 and Fig. 3 will be denoted by the same reference numerals. Therefore, in understanding the second embodiment of Figs. 4 and 5, the same reference as in Figs. 2 and B The numbers can be understood with reference to Fig. 2 and Fig. 3. The following is a description of the light guide plate according to the second embodiment with reference to the features of the first embodiment different from Fig. 2 and Fig. 3, and the first light guide plate will be omitted. Description of the same components of the embodiment. Referring to Figures 4 and 5, the geometric reflectors disposed between the planes 1 through 6 of the stepped configuration are each constructed from a single step and an intaglio prism 212. It is not the plural 稜鏡 shown in Fig. 2 and Fig. 3. Here, the inner corners Θ1 and Θ2 of the step 211 and the concave ridge 212 are respectively the same as the first embodiment described above. B Fig. 6 is a basis A plan view of a light guide plate for an LCD backlight unit according to a third embodiment of the present invention. In Fig. 6, the same components as those shown in Fig. 2 will be denoted by the same reference numerals, and will be understood with reference to Fig. 2. In a third embodiment, the light guide plate has two light incident sides 210. That is, the light guide of the third embodiment The system is configured to receive incident light on opposite 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 13 1360672, and from each of the planes constituting the stepped structure to the front side 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 Figure 7, the same components as those shown in Figure 4 are The same reference numerals are used, and should 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 be opposite thereto. The incident light is received on both sides. 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. B Figure 8 is a cross-sectional view taken along line A-B of Figure 2. Referring to Fig. 8, a unit 稜鏡 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 1360672 Fig. 12 is a cross-sectional view taken along line A-B of Fig. 6, and Fig. π 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 base slope of the rear side 22 of the light guide plate having a step pattern. 10, 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 of the light guide plate. The thickness distance between one of the incident sides 215 and the total length of the light guide plate are determined. 15 &ΜΜΛ. • The present invention will be described below with reference to examples. L example and comparative example Example 1 -1 20 ,, in a width (W) X length (L) x thickness (T) is 288.8x217.7x2.4 / light incident side) χ〇.8 _ (opposite light In the wedge-shaped light guide plate on the incident side, the base slope of the side to the front side is 〇42 degrees, which is caused by the difference in thickness between the light entrance side of the light guide plate and the incident side of the opposite light, and by the light guide plate Full Length Rule 1 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 stepped structure was arranged at a fixed pitch of 1,000 μm, wherein each of the white prisms had an internal angle 1301 of 130.33 degrees and 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 μη. Further, the light guide plate is formed to have a striped 稜鏡 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) x 〇 8 coffee (opposite light incident side), The slope of the base of the rear 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. 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 internal angle of 1301 of 130.33 degrees and a geometrical reflector having an internal 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 μηη, wherein each stepped prism 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. Further, the light guide plate is formed to have a striped enamel 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) x 〇 .8 _ (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. In this example, the pattern of the present invention is only shaped on the back side of the light guide 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, each of which has an internal angle 1301 of 130.33 degrees and is inclined at an angle of 〇42 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. 5 _ Comparative Example 1-2 Wedge at a width (W) x length (L) x thickness (Τ) of 288.8x217.7x2.4 10 (light incident side) x 〇.8 mm (opposite light incident side) In the type of light guide plate, 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. In this example, 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 internal angle of 1301 of 130.33 degrees and a geometrical reflector having an internal 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 μπι, where each of the 阶 stepped prisms 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 ° 2 〇 Example 2-1 at a width (W) x length (L) x thickness (T) is 288.8 x 217.7 x 2.4 (on the light incident side) χ〇·8 (·8 (the opposite light incident side) of the wedge-shaped light guide plate ′′ each of the plurality of front ridges having a 90-degree apex angle is disposed on the front side at a fixed pitch of 50 μm so as to be parallel to The direction of travel of light from a light. In addition to the 17 1360672, 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. 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 5-shaped structure is arranged at a fixed pitch of i,000 pm, 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 "steps" is about 7.33 μιη. Further, the light guide plate is formed to have a stripe prism pattern having an angle of 81.5 degrees. 10 • Example 2-2 Wedge guide at a width (W) x length (L) x thickness (τ) of 288.8x217.7x2.4 (light incident side) x 〇 .8 plane (opposite light incident side) In the light panel, a plurality of front sills each having a 90 degree apex angle are disposed at a fixed pitch of 5 〇 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 thickness difference 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 2〇81.5 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 〇 42 degrees so as to be parallel to the front side. In this example, the difference in height direction between the "steps" is about 7.33 μιη. Further, the light guide plate is formed to have a striped enamel pattern having an angle of 81.5 degrees. 18 1360672 Comparative Example 2-1 Wedge type at a width (W) x length (L) x thickness (T) of 288.8x217.7x2.4 (light incident side) x 〇 8 plane (opposite light incident side) In the light guide plate, 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 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 light incident side, and is determined by the total ρ 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 prisms. At this time, the pattern of the single-step 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 in the vertical direction between the stepped turns is about 7.33 μιη. 15 Comparative Example 2-2 Wedge guide at a width (W) x length (L) x thickness (Τ) of 288.8x217.7x2.4 B (light incident side) χ 0.8 plane (opposite light incident side) 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 so as 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 1360672 stepped structure is arranged at a fixed pitch of 1, 〇〇〇 μπι, wherein each stepped prism 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
導光板之组癌 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 1360672 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3 300 250 Q200 wl50 噌100 50 0 OQC： OQ 254.32 101,28 T3.3 t 1 議丨丨丨...,.,-,,1.................... 實例2-1 實例2-2 比較實例2-1 導光板之組態 比較實例2-2Light guide plate group cancer 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 1360672 It can be understood from Tables 1 and 2 that the examples have higher brightness and better appearance than the comparative examples. Table 3 300 250 Q200 wl50 噌100 50 0 OQC: OQ 254.32 101,28 T3.3 t 1 Discussion...,.,-,,1.............. ...... Example 2-1 Example 2-2 Comparative Example 2-1 Configuration of Light Guide Plate Example 2-2
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Table 4 Classification Example 2-1 Example 2-2 Comparative Example 2-1 Comparative Example 2-1 Brightness (cd) ~ 236 ~ 254 ~ 73 ~ 101 Appearance Good Good Corner dark Corner dark
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 1360672 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 I 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 光板之後侧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 元之導光扳的平面圖； 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， 15 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， B 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是一沿圖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 1360672 圖16是一例示具有階狀圖案之導光板後側之一基礎 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 光入射側 211 階狀物 W 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 後側 222 點狀稜鏡 230 前側 15 310 條紋圖案 311 單元稜鏡 • 315 前稜鏡 23Table 3 shows the luminance measurement results relating to Examples 2-1 and 2-2 and Comparative Examples 2-1 and 2-2. 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 1360672 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 1 according to a first embodiment of the present invention, and FIGS. 2 and 3 are exemplified in the guide according to the first embodiment shown in FIG. 3 is a rear perspective view of a pattern on the rear side of the light panel; FIGS. 4 and 5 are plan views 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. Figure 7 is a plan view of a light guide plate for an LCD backlight unit according to a fourth embodiment of the present invention, and Figure 8 is a cross-sectional view taken along line AB of Figure 2; Figure 9 is a cross-sectional view taken along line CD of Figure 2; Figure 10 is a cross-sectional view taken along line AB of Figure 4; Figure 2 is a cross-sectional view taken along line CD of Figure 4; A cross-sectional view taken along line AB of Fig. 6; Fig. 13 is a cross-sectional view taken along line CD of Fig. 6; Fig. 14 is a cross-sectional view taken along line AB of Fig. 7; Fig. 15 is a cross-sectional view taken along line 7 of Fig. 7. A cross-sectional view taken by line CD; and 22 1360672 FIG. 16 is an example of a base of the rear side of a light guide plate having a stepped pattern A map of the slope. [Main component symbol description] 5 1, 2, 3, 4, 5, 6 Step structure plane 140 Light source 210 Light incident side 211 Step W 212 Geometric reflector, concave engraving 10 213 Geometric reflector, bulge Prism - 215 Opposite light incident side 220 Rear side 222 Point 稜鏡 230 Front side 15 310 Stripe pattern 311 Unit 稜鏡 • 315 Front 稜鏡 23