200907438 九、發明說明： 【發明所屬之技術領域】 本發明涉及一種背光模組及其光學板，尤其沣一 用於液晶顯示之背光模組及其光學板。 及種 【先前技術】 ''面光源裝 示器面板供 由於液晶顯示器面板之液晶本身不具發光 爲達到顯示效果需給液晶顯示器面板提供、’，因而 置，如背光模組。背光模組之作用係向液晶顯 應亮度充分且分佈均勻之面光源。 請參見圖1 ,所示爲一種習知之背光模叙1〇〇，苴 括框架101、反射板102、擴散板103、稜鏡片1〇4 ^ = 一發光二極體105。框架101包括一底板1〇11及複數彳 底板1011邊緣向其同一侧垂直延伸之側壁1〇13。底板& = 與複數側壁1013共同形成一腔體1017。發光二極體1〇5 包括出光部1051與基部1053，基部1053與電路板（未才# 示）相連並固定於底板1011。擴散板1〇3與稜鏡片1〇4依 次没置於极數侧壁1 〇 13頂部。反射板1 〇2爲一小框體結 構，其可配置於框架101内部。反射板102之底部開設有 與發光二極體105相對應之通孔（未標示），發光二極體 105之出光部1051穿過相應通孔。發光二極體1〇5之基部 1053頂持該反射板102。 工作時，發光二極體105産生之光線被反射板102反 射進入擴散板103，於擴散板103中被均勻擴散後光線繼 續進入稜鏡片104，於稜鏡片104之作用下，出射光線發 生一定程度之聚集，使得背光模組於特定視角範圍内之亮 度提高。 然而，由於發光二極體105爲點光源，其到達擴散板 5 200907438 103上各處之距離大小不相等，位於發光二極體105正上 方之擴散板103單位區域所接受光較多，位於發光二極體 105四周之擴散板103單位區域所接受光較少，故容易於 發光二極體105正上方之區域形成亮區，而於其上方之四 周區域形成暗區，影響背光模組100之出光均勻性。爲此， 通常需於發光二極體105之上方設置反射片106，以控制 發光二極體105正上方之出光量。發光二極體105與反射 片106之搭配設計，可一定程度上減弱發光二極體105正 上方之亮區，惟，背光模組100仍有出光不均之缺點。 【發明内容】 鑒於上述狀況，有必要提供一種出光均勻之背光模組 及其光學板。 一種光學板，其包括至少一光學板單元，該光學板單 元包括出光面、與該出光面相對之底面及形成於該出光面 之散射層，該底面形成有複數長條狀V型凸起*且該底面 開設有至少一光源容納部。 一種背光模組，其包括框架、至少一點光源及光學 板；該框架包括底板及複數從該底板邊緣延伸之相互連接 之側壁，該複數側壁與該底板形成一腔體；該至少一具有 出光部之點光源設於該底板；該光學板設置於該腔體内， 該光學板包括至少一光學板單元，該光學板單元包括出光 面及與該出光面相對之底面，該底面形成有複數長條狀V 型凸起，且該底面開設有至少一光源容納部，該光學板還 包括一形成於該出光面之散射層；該點光源之出光部相應 設置于該光源容納部内。 上述背光模組之光學板之光學板單元包括光源容納 部、形成於底面之複數長條狀V型凸起以及形成於出光面 6 200907438 . 之散射層，點光源之出光部容納於光源容納部内。從點光 源發出之光線藉由光源容納部之内側壁直接進入光學板 • 内部。由於光學板底面設置之長條狀v型凸起具有變化之 ^ 表面結構，使得光線於光學板内傳輸至長條狀V型凸起 時，長條狀V型凸起可將部分原來於未設有長條狀V型凸 起之光學板内全反射傳播之光線調節後從底面出射，於框 架之反射作用下，此部分光線經多次折射後進入散射層， 並經散射層均勻擴散後從腔體開口均勻出射，故背光模組 之光學利用率與出光均勻性得以提高。更進一步地，點光 源所發射之光線大部分於光學板内向四周傳播，點光源被 轉變成面光源，從而使得採用該光學板之背光模組不會因 爲點光源至擴散板之距離過小而於點光源上方之區域産 生亮點，故，背光模組可進行降低燈箱高度之設計；另， 採用此具有散射層之光學板之背光模組可省略擴散板之 使用，從而使背光模組之成本減少、厚度降低。 【實施方式】 下面將結合附圖及實施例對本發明之背光模組及其 光學板作進一步之詳細說明。 請參見圖2,所示爲本發明較佳實施例一之背光模組 200，其包括一框架21、一反射板22、一側光式點光源25 及一光學板20。框架21包括一長方形底板211及從底板 211邊緣向其同一侧垂直延伸並相互連接之四侧壁213。 四側壁213與底板211共同形成一腔體217，用於收容點 光源25、反射板22及光學板20等元件。 請參見圖3，光學板20爲矩形板，其包括一出光面 202、一與該出光面202相對之底面203。底面203中央開 設有一光源容納部204，光源容納部204爲從底面203貫 7 200907438 穿至出光面202之通孔。出光面202形成一均勻厚度之散 射層205，底面203形成複數長條狀V型凸起206。 散射層205包括透明樹脂2052與均勻摻雜於透明樹 脂2052中之散射粒子2054。透明樹脂2052優選丙烯酸樹 脂或環氧樹脂。散射粒子2054摻入透明樹脂2052中，其 可選自以下之一種或多種粒子：二氧化矽顆粒、聚曱基丙 烯酸甲酯顆粒與玻璃微珠等。 本實施例中，該複數長條狀V型凸起206沿X軸方向 延伸，且相鄰長條狀V型凸起206緊密連接。請參見圖4， 每一長條狀V型凸起206之頂角Θ之較佳取值範圍爲60 至120度。相鄰長條狀V型凸起206之間距D優選0.025 毫米至2毫米。 可以理解，長條狀V型凸起206之延伸方向亦可爲Y 軸方向或與光學板20之側邊形成一銳角夾角，此設計可 進一步控制出射光之出射角度。 請再參閱圖2，點光源25優選爲侧光式發光二極體， 其包括一基部253、一固定於基部253上方之出光部251 與一反射片255。點光源25藉由電路板（未標示）固定於 底板211。光學板20設置於腔體217内，其出光面202面 向腔體217之開口。點光源25之出光部251容納於光學 板20之光源容納部204内。反射片255設置於對應點光 源25正上方之位置，用於覆蓋點光源25之頂部。反射片 255之面積等於或略大於出光部251之投影面積。反射板 22開設有一對應於點光源25之出光部251之通孔（未標 示）。反射板22設置於光學板20底面203之下方，點光 源25之出光部251穿過該通孔。 點光源25從出光部251發出之光線藉由光源容納部 204之内側壁直接進入光學板20内部。由於光學板20之 8 200907438 底面203設置有長條狀V型凸起206,長條狀V型凸起206 可將4刀原來於未設有長條狀V型凸起2〇6之光學板 内全反射傳播之光線調節後從底面203出射，於反射板22 之輔助作用下’此部分光線多次折射後進入散射層205， 並經散射層205均勻擴散後從腔體開口均勻出射，故背光 模組之光學利用率與出光均勻性得以提高。更進-步地， Ϊ於採：侧光式點光源25，點光源25所發射之光線大部 刀於光·^板20内向四周傳播，點光源被轉變成面光源， 從而使得採用該光學板之背光模組不會因爲點光源至擴 散板之距離過小而於點光源上方之區域產生亮點，故，背 光模組可進行降低燈箱高度之設計；卩，採用此具有散射 層mi學板之背光模組可省略擴散板ig3之使用，從 而使月光杈組之成本減少、厚度降低。 24 J = 還可於四側壁213頂部增加一稜鏡片 择^該背光模組200於特定之視角範圍内之均勻 板束於㈣㈣勻混光與提高光線利用率，該 f射板可進一步包括複數反射側壁223。可以理解：本 板22可省略’尤其當框架21爲高反射材料 咬板211及側壁213内側塗覆高反射塗層時。 30 圖5 斤示爲本發明較佳實施例二之光學板 η在：ί: 佳實施例一之光學板20相似，其不 之長條狀¥型凸起306之頂角以及相鄰 長^ i凸起306形成之底部夾 成咖與R2，RUR2之圓角之取 於0且t於或等於u毫米。被圓角化之長條 學板如之背域組1t步料。可先 亦可於長條狀¥型凸起遍之頂角以及相鄰長條狀νί凸 9 200907438 起306形成之底部夾角之其中之一單獨進行上述圓角化設 計。 請參見圖6,所示爲本發明較佳實施例三之光學板 40。該光學板40與較佳實施例一之光學板20相似，其不 同在於光學板40之光源容納部404爲開設於底面403之 盲孔。採用光學板40之背光模組可搭配一未設反射元件 之側光式點光源，或者於盲孔底部直接塗覆高反射層。 請參見圖7,所示爲本發明較佳實施例四之光學板 50。該光學板50與較佳實施例一之光學板20相似，其不 同在於光學板50之散射層505爲不連續分佈。本實施例 中，散射層505爲網點狀中心對稱分佈。 上述實施例中，光學板20、30、40、50均爲一整體 結構。本發明之大尺寸之光學板可由複數上述整體結構之 光學板單元組合而成，或者每一光學板單元開設複數光源 容納部。光學板20、30、40、50之形狀除矩形外，還可 爲多邊形或圓形等。 本發明之光學板單元或組合光學板可設置複數光源 容納部，配合該複數光源容納部，可採用不同顏色之側光 式發光二極體製成白光混光背光模組，或者採用相同顏色 之侧光式發光二極體製成特定顏色之背光模組。 上述各實施例中光學板之間隔之散射層之分佈還可 以有以下變換設計。 如圖8所示，散射層605於出光面602之分佈爲：以 光源容納部604爲中心，複數矩形狀之封閉式散射層605 間隔分佈，且越遠離光源容納部604，矩形狀之封閉式散 射層605之寬度越大，此設計有利於提高光學板之出光均 勻性。 如圖9所示，散射層705於出光面702之分佈爲：以 200907438 . 光源容納部704爲圓心，複數網點狀散射層705沿著圓環 形執道間隔分佈，且越遠離光源容納部704，網點狀之散 - 射層705之面積越大，此設計有利於提高光學板之出光均 . 勻性。 如圖10所示，散射層805於出光面802之分佈爲： 以光源容納部804爲圓心，複數相同大小之網點狀之散射 層805沿著圓環形執道間隔分佈，且越遠離光源容納部 804，網點狀之散射層805之分佈密度越大，此設計有利 於提高光學板之出光均勻性。 綜上所述，本發明確已符合發明專利要件，爰依法提 出專利申請。惟，以上所述者僅為本發明之較佳實施例， 舉凡熟悉本案技藝之人士，於援依本案發明精神所作之等 效修飾或變化，皆應包含於以下之申請專利範圍内。 【圖式簡單說明】 圖1係一種習知之背光模組之剖視圖。 圖2係本發明較佳實施例一之背光模組之剖視圖。 圖3係圖2所示背光模組之光學板之立體圖。 圖4係圖3所示光學板沿III-III線之剖視圖。 圖5係本發明較佳實施例二之光學板之剖視圖。 圖6係本發明較佳實施例三之光學板之剖視圖。 圖7係本發明較佳實施例四之光學板之剖視圖。 圖8至圖10係本發明之光學板之散射層之各種分佈示意 圖。 11 200907438 . 【主要元件符號說明】 背光模組 200 • 光學板 20 > 30 ' 40 ' 50 框架 21 反射板 22 棱鏡片 24 點光源 25 出光面 202、602、702、802 底面 203 ' 403 光源容納部 204 、 404 、 604 、 704 、 804 散射層 205 、 505 、 605 、 705 、 805 透明樹脂 2052 散射粒子 2054 長條狀V型凸起 206 ' 306 底板 211 側壁 213 腔體 217 反射側壁 223 出光部 251 基部 253 反射片 255 12200907438 IX. Description of the Invention: [Technical Field] The present invention relates to a backlight module and an optical plate thereof, and more particularly to a backlight module for liquid crystal display and an optical plate thereof. [Prior Art] ''The surface light source panel is provided. The liquid crystal display panel itself does not have a light. In order to achieve the display effect, the liquid crystal display panel is required to be provided, such as a backlight module. The function of the backlight module is to display a surface light source with sufficient brightness and uniform distribution to the liquid crystal. Referring to Fig. 1, there is shown a conventional backlight module, including a frame 101, a reflecting plate 102, a diffusing plate 103, and a cymbal 1 〇 4 ^ = a light emitting diode 105. The frame 101 includes a bottom plate 1〇11 and a plurality of side walls 1〇13 extending perpendicularly to the same side of the bottom plate 1011. The bottom plate & = forms a cavity 1017 with the plurality of side walls 1013. The light-emitting diode 1〇5 includes a light-emitting portion 1051 and a base portion 1053, and the base portion 1053 is connected to the circuit board (not shown) and fixed to the bottom plate 1011. The diffusion plate 1〇3 and the cymbal plate 1〇4 are not placed on the top of the pole side wall 1 〇13. The reflecting plate 1 〇 2 is a small frame structure which can be disposed inside the frame 101. A through hole (not shown) corresponding to the light emitting diode 105 is opened at the bottom of the reflecting plate 102, and the light exiting portion 1051 of the light emitting diode 105 passes through the corresponding through hole. The base 1053 of the light-emitting diode 1〇5 holds the reflector 102. During operation, the light generated by the LEDs 105 is reflected by the reflector 102 into the diffuser 103. After being uniformly diffused in the diffuser 103, the light continues to enter the cymbal 104. Under the action of the cymbal 104, the emitted light is generated to a certain extent. The aggregation causes the brightness of the backlight module to be increased within a specific viewing angle range. However, since the light-emitting diode 105 is a point light source, the distances reaching the diffusion plate 5 200907438 103 are not equal, and the unit area of the diffusion plate 103 located directly above the light-emitting diode 105 receives more light and is located in the light. The unit area of the diffusion plate 103 around the diode 105 receives less light, so that a bright area is easily formed in the area directly above the light-emitting diode 105, and a dark area is formed in the upper area of the diode 105, which affects the backlight module 100. Light uniformity. For this reason, it is usually necessary to provide a reflection sheet 106 above the light-emitting diode 105 to control the amount of light emitted directly above the light-emitting diode 105. The design of the light-emitting diode 105 and the reflective sheet 106 can weaken the bright area directly above the light-emitting diode 105 to a certain extent. However, the backlight module 100 still has the disadvantage of uneven light emission. SUMMARY OF THE INVENTION In view of the above circumstances, it is necessary to provide a backlight module having uniform light emission and an optical plate thereof. An optical plate comprising at least one optical plate unit, the optical plate unit comprising a light emitting surface, a bottom surface opposite to the light emitting surface, and a scattering layer formed on the light emitting surface, wherein the bottom surface is formed with a plurality of strip-shaped V-shaped protrusions* And the bottom surface is provided with at least one light source receiving portion. A backlight module includes a frame, at least one light source, and an optical plate; the frame includes a bottom plate and a plurality of interconnecting sidewalls extending from an edge of the bottom plate, the plurality of sidewalls and the bottom plate forming a cavity; the at least one having a light exiting portion The light source is disposed on the bottom plate; the optical plate is disposed in the cavity, the optical plate includes at least one optical plate unit, and the optical plate unit includes a light emitting surface and a bottom surface opposite to the light emitting surface, wherein the bottom surface is formed with a plurality of lengths The strip-shaped V-shaped projections are provided with at least one light source receiving portion, and the optical plate further includes a scattering layer formed on the light-emitting surface; the light-emitting portion of the point light source is correspondingly disposed in the light source receiving portion. The optical plate unit of the optical plate of the backlight module includes a light source receiving portion, a plurality of elongated V-shaped protrusions formed on the bottom surface, and a scattering layer formed on the light emitting surface 6 200907438. The light emitting portion of the point light source is received in the light source receiving portion. . Light from the point source directly enters the optical panel • inside by the inner side wall of the light source housing. Since the long v-shaped protrusions provided on the bottom surface of the optical plate have a varying surface structure, when the light is transmitted to the long V-shaped protrusions in the optical plate, the long V-shaped protrusions may partially be in the original The light of the total reflection in the optical plate with the long V-shaped protrusion is adjusted and then emitted from the bottom surface. Under the reflection of the frame, the part of the light is refracted multiple times and enters the scattering layer, and is uniformly diffused by the scattering layer. The uniformity of the light source utilization and the light output uniformity of the backlight module is improved by uniformly emitting from the cavity opening. Further, most of the light emitted by the point source propagates around the optical plate, and the point source is converted into a surface light source, so that the backlight module using the optical plate is not too small because the distance from the point source to the diffusion plate is too small. The area above the point source generates a bright spot. Therefore, the backlight module can reduce the height of the light box. In addition, the backlight module using the scattering layer can omit the use of the diffusion plate, thereby reducing the cost of the backlight module. The thickness is reduced. [Embodiment] Hereinafter, a backlight module and an optical plate thereof according to the present invention will be further described in detail with reference to the accompanying drawings and embodiments. Referring to FIG. 2, a backlight module 200 according to a preferred embodiment of the present invention includes a frame 21, a reflector 22, a side light source 25, and an optical panel 20. The frame 21 includes a rectangular bottom plate 211 and four side walls 213 extending perpendicularly from the edge of the bottom plate 211 toward the same side and connected to each other. The four side walls 213 and the bottom plate 211 together form a cavity 217 for accommodating elements such as the point source 25, the reflection plate 22, and the optical plate 20. Referring to FIG. 3, the optical plate 20 is a rectangular plate, and includes a light emitting surface 202 and a bottom surface 203 opposite to the light emitting surface 202. A light source accommodating portion 204 is formed in the center of the bottom surface 203. The light source accommodating portion 204 is a through hole extending from the bottom surface 203 to the light exiting surface 202. The light exiting surface 202 forms a uniform thickness of the scattering layer 205, and the bottom surface 203 forms a plurality of elongated V-shaped projections 206. The scattering layer 205 includes a transparent resin 2052 and scattering particles 2054 uniformly doped in the transparent resin 2052. The transparent resin 2052 is preferably an acrylic resin or an epoxy resin. The scattering particles 2054 are incorporated into the transparent resin 2052, which may be selected from one or more of the following particles: cerium oxide particles, polymethyl methacrylate particles, glass beads, and the like. In this embodiment, the plurality of elongated V-shaped projections 206 extend in the X-axis direction, and the adjacent elongated V-shaped projections 206 are closely connected. Referring to FIG. 4, the apex angle Θ of each elongated V-shaped projection 206 preferably ranges from 60 to 120 degrees. The distance D between adjacent elongated V-shaped projections 206 is preferably 0.025 mm to 2 mm. It can be understood that the extending direction of the elongated V-shaped projections 206 can also be in the Y-axis direction or form an acute angle with the side edges of the optical plate 20. This design can further control the exit angle of the outgoing light. Referring to FIG. 2 , the point source 25 is preferably an edge-lit LED, and includes a base 253 , a light-emitting portion 251 fixed to the base 253 , and a reflective sheet 255 . The point source 25 is fixed to the bottom plate 211 by a circuit board (not shown). The optical plate 20 is disposed in the cavity 217 with its light exiting surface 202 facing the opening of the cavity 217. The light exit portion 251 of the point light source 25 is housed in the light source housing portion 204 of the optical plate 20. The reflection sheet 255 is disposed at a position directly above the corresponding point light source 25 for covering the top of the point light source 25. The area of the reflection sheet 255 is equal to or slightly larger than the projected area of the light exit portion 251. The reflection plate 22 has a through hole (not shown) corresponding to the light exit portion 251 of the point light source 25. The reflecting plate 22 is disposed below the bottom surface 203 of the optical plate 20, and the light exiting portion 251 of the spot light source 25 passes through the through hole. The light emitted from the light exit portion 251 by the point light source 25 directly enters the inside of the optical plate 20 through the inner side wall of the light source accommodating portion 204. Since the bottom surface 203 of the optical plate 20 is 200907438, the long V-shaped protrusion 206 is provided, and the long V-shaped protrusion 206 can be used to form an optical plate which is not provided with the long V-shaped protrusion 2〇6. The light of the total total reflection propagation is emitted from the bottom surface 203, and under the auxiliary action of the reflecting plate 22, the light is repeatedly refracted into the scattering layer 205, and uniformly diffused through the scattering layer 205, and then uniformly emitted from the cavity opening, so The optical utilization and light uniformity of the backlight module are improved. Further, step by step, the edge light source 25, the light emitted by the point source 25 is mostly propagated in the light plate 20, and the point source is converted into a surface light source, thereby making the optical The backlight module of the board does not generate a bright spot in the area above the point source because the distance from the point source to the diffuser is too small. Therefore, the backlight module can reduce the height of the light box; 卩, the scattering layer is used. The backlight module can omit the use of the diffusion plate ig3, thereby reducing the cost and thickness of the moonlight group. 24 J = can also add a cymbal on the top of the four side walls 213 to select a uniform plate bundle of the backlight module 200 in a specific viewing angle range to (4) (four) to mix light and improve light utilization, the f-plate can further include a plurality of Reflecting sidewalls 223. It will be understood that the present plate 22 may be omitted 'especially when the frame 21 is a highly reflective material bite plate 211 and the inside of the side wall 213 is coated with a highly reflective coating. 30 shows that the optical plate η of the preferred embodiment 2 of the present invention is similar to the optical plate 20 of the preferred embodiment 1, and the apex angle of the long strip-shaped protrusion 306 and the adjacent length are The bottom of the i-shaped protrusion 306 is sandwiched between R2 and R2, and the rounded corner of RUR2 is taken at 0 and t is equal to or equal to u mm. The long strips that are rounded off are like the 1t step of the back domain group. The above-described fillet design may be separately performed on one of the apex angles of the long strip-shaped protrusions and the bottom corner formed by the adjacent strip-shaped νί convex 9 200907438. Referring to Figure 6, there is shown an optical panel 40 of a preferred embodiment of the present invention. The optical plate 40 is similar to the optical plate 20 of the first embodiment except that the light source receiving portion 404 of the optical plate 40 is a blind hole formed in the bottom surface 403. The backlight module using the optical plate 40 can be combined with an edge-light point source without a reflective element or directly coated with a highly reflective layer at the bottom of the blind hole. Referring to Figure 7, there is shown an optical plate 50 of a preferred embodiment 4 of the present invention. The optical plate 50 is similar to the optical plate 20 of the preferred embodiment 1 except that the scattering layer 505 of the optical plate 50 is discontinuously distributed. In this embodiment, the scattering layer 505 is symmetrically distributed in the center of the dot. In the above embodiment, the optical plates 20, 30, 40, 50 are all of a unitary structure. The large-sized optical plate of the present invention may be composed of a plurality of optical plate units of the above-described overall structure, or a plurality of light source accommodating portions may be provided for each of the optical plate units. The shape of the optical plates 20, 30, 40, 50 may be polygonal or circular, etc. in addition to the rectangular shape. The optical plate unit or the combined optical plate of the present invention may be provided with a plurality of light source accommodating portions, and the light source illuminating diodes of different colors may be used to form the white light mixed light backlight module, or the same color may be used. The edge-lit LEDs are made into a backlight module of a specific color. The distribution of the scattering layers at intervals of the optical plates in the above embodiments may also have the following conversion design. As shown in FIG. 8 , the distribution of the scattering layer 605 on the light-emitting surface 602 is such that a plurality of rectangular closed-type scattering layers 605 are spaced apart from each other around the light source accommodating portion 604 , and the rectangular shape is closed away from the light source accommodating portion 604 . The larger the width of the scattering layer 605, the better the uniformity of the light output of the optical plate. As shown in FIG. 9 , the distribution of the scattering layer 705 on the light-emitting surface 702 is: 200907438 . The light source housing portion 704 is centered, and the plurality of dot-like scattering layers 705 are distributed along the circular path and away from the light source housing portion 704 . , the dot-like dispersion - the larger the area of the shot layer 705, this design is conducive to improve the uniformity of the light output of the optical plate. As shown in FIG. 10, the distribution of the scattering layer 805 on the light-emitting surface 802 is: centered on the light source receiving portion 804, and a plurality of dot-like scattering layers 805 of the same size are distributed along the circular path, and are further away from the light source. In section 804, the greater the distribution density of the dot-like scattering layer 805, the design is advantageous for improving the light uniformity of the optical plate. In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above-mentioned embodiments are merely preferred embodiments of the present invention, and equivalent modifications or variations made by those skilled in the art of the present invention should be included in the following claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a conventional backlight module. 2 is a cross-sectional view of a backlight module in accordance with a preferred embodiment of the present invention. 3 is a perspective view of an optical plate of the backlight module shown in FIG. 2. Figure 4 is a cross-sectional view of the optical plate of Figure 3 taken along line III-III. Figure 5 is a cross-sectional view showing an optical plate of a preferred embodiment 2 of the present invention. Figure 6 is a cross-sectional view showing an optical plate according to a third preferred embodiment of the present invention. Figure 7 is a cross-sectional view showing an optical plate of a preferred embodiment 4 of the present invention. 8 to 10 are schematic views showing various distributions of scattering layers of the optical sheets of the present invention. 11 200907438 . [Main component symbol description] Backlight module 200 • Optical plate 20 > 30 ' 40 ' 50 Frame 21 Reflector 22 Prism sheet 24 Point source 25 Light exit surface 202, 602, 702, 802 Bottom surface 203 ' 403 Light source housing Portion 204, 404, 604, 704, 804 scattering layer 205, 505, 605, 705, 805 transparent resin 2052 scattering particles 2054 elongated V-shaped protrusion 206' 306 bottom plate 211 side wall 213 cavity 217 reflection side wall 223 light exit portion 251 Base 253 reflector 255 12