201007295 、 九、發明說明： '【發明所屬之技術領域】 ' 本發明涉及一種直下式背光模組，尤其涉及一種應用 於液晶顯示之直下式背光模組。 【先前技術】 液晶顯示裝置被廣泛應用於個人數位助理、筆記型電 腦、數位相機、移動電話、液晶電視等電子產品中。但由 於液晶顯示裝置本身不能發光，因此其需要借助背光模組 ❿才能產生顯示功能。 請參見圖1，一種背光模組100，其包括框架10，一反 射板12、複數LED(發光二極體）點光源14、一擴散板16 及複數光學片18。該複數LED點光源14設置於框架10之 底板上，複數光學片18蓋設於框架10之開口處。擴散板 16間隔設置於LED點光源14及複數光學片18之間，從而 將框架10内分割成第一和第二擴散空間19、20。擴散板 16由含有散射粒子之樹脂材料製成。該複數光學片18包括 ®稜鏡片、擴散片或折射偏振膜。 使用時，由複數LED點光源14產生之光線經過第一 擴散空間19後進入擴散板16，經過擴散板16擴散後，光 線進入第二擴散空間20進行擴散，最後經過複數光學片18 之擴散或聚集作用後，於特定視角範圍内均勻出射。 然而從LED點光源14發出之光線雖經過多次擴散， 但仍很難避免點光源14光源殘影之產生，即形成中心亮度 高而周圍較暗之區域。為了儘量減少光源殘影之產生，業 6 201007295 :界通常會增大框架Η)之深度，即增 之高度。惟，增加框架之深度將減：，間 並1致背光模組100之厚度較大，難以滿足薄型 之要求。假如相應增加點光源之話， 认计 【發明内容】 耗功率。 鑒於上述狀況，有必要提供一 且厚度較薄之背光模組。 種出射先線均勾性較佳 ❷ -直下式背光模組’其包括框架、設置於框架底邻之 複=光二極體:依次間隔設置於該複數發光二極體上方 之第一光學板及第二光學板。第一光 為-透明本體。第一光學板包括形成於第一光; 之複數相互平行之長條狀弧形凹槽及形成於第—光學= 光面之複數相互平行之長條狀弧形凸起。第二 形成於第二光學板入光面之複數 ^ ❿ :=該第二光學板-一平:= 上述之直下式背光模組令之發光二極體發射出之光線 、、生過空間擴散後進人第-光學板，由於第—光學板之 面形成有複數孤形凹槽，出光面形成有複數弧形凸起，且 可將點光源擴散成面光源並使光線向特定視角範圍内聚 j ’提升背錢組之正面出光率和^均勻性；接著從第 一光學板iii射之光線再經過空間擴散後進人第二光學板， 由於第一光學板入光面形成有弧形凹槽，出光面形成有弧 形凸起’使從第二光學板出射之光線發生特定之折射、散 201007295 射、反射與繞射等光學作用，從而將光線進一步面光源化 之同時將光線擴散均勻，避免了光源殘影之產生。同時， 光線自發光二極體射出到入射至第二光學板之過程中，經 過了二次空間擴散作用且由於光學板之微結構增加擴散光 程，從而達到較好擴散效果，進而可實現該直下式背光模 組之薄型化設計。 【實施方式】 下面將結合附圖及實施例對本發明之直下式背光模組 ❿200作進一步詳細說明。 請參見圖2,所示為本發明實施例一之直下式背光模組 200，其包括框架21、複數發光二極體23、第一光學板24、 第二光學板25及複數光學片26。其中複數發光二極體23 設置於框架21底部，第一光學板24和第二光學板25依次 間隔設置於發光二極體23上方，從而將框架21分割成第 一和第二擴散空間27、28,複數光學片26設置於第二光學 秦板25上方。 框架21可由具有高反射率之金屬或塑膠製成，或塗佈 有高反射率塗層之金屬或塑膠製成。 請參閱圖3至圖5,第一光學板24由一透明本體構成， 其包括入光面241及形成於入光面241之複數相互平行之 長條狀弧形凹槽242，與入光面241相對之出光面243及形 成於出光面243上之複數交替排佈且相互平行之長條狀V 形凸起244及長條狀弧形凸起245。複數長條狀V形凸起 244和長條狀弧形凸起245之延伸方向與複數長條狀弧形 201007295 ：22=伸方向相交。本實施例中，複數長條狀v形 二It形凸起245之延伸方向與複數長條狀 Γ之延伸方向相互垂直，長條狀弧形凸起244 =直截面為半圓弧形，長條狀弧形凹槽24 為半圓弧形。 生旦戳® 高声^記為h’頂角記為θ， ^<1 -卓卜1 Dl、0、Hl滿足如下關係式：0.〇25毫米 …=1笔未，80度梅1〇〇度’ 〇〇 起2〇5之寬度叫半徑記二 ^ 2, Ll、Rl、H2滿足如下關係式：〇.〇25毫米叫幻5 :米;W4舶―1毫米崎。藉由調節Di:e、 1 ! &、及h2之數值，可調整長條狀乂形凸起μ及 長條狀弧形凸起245之形狀，從而調節第 光率及出光視角。 I曰 將，鄰二長條狀藏形凹槽如之間距記為I，半徑計 ❹臺己為h，則匕”1及hl滿足如下關係式：0·025 Π 毫米’ ΡΐΜ&^2Ρΐ，〇.01毫米。藉 矣：1Γ、Γι及hl之數值，可調整長條狀弧形凹槽242之 表面曲率及間距’從而調節對複數長條狀弧形凹槽24 入射光之擴散效果。 請參見圖6與圖7,第二井擧拓山 备 九予板25由一透明本體構成， 其包括入先面251及形成於入光面251之複數長條狀 凹『252,與入光面251相對之出光面⑸及形成於出光面 之複數長條狀弧形凸起254。出光面253上之複數長條 9 201007295201007295, IX, invention description: '[Technical field of invention] The present invention relates to a direct type backlight module, and more particularly to a direct type backlight module applied to liquid crystal display. [Prior Art] Liquid crystal display devices are widely used in electronic products such as personal digital assistants, notebook computers, digital cameras, mobile phones, and LCD TVs. However, since the liquid crystal display device itself cannot emit light, it is required to use the backlight module to generate a display function. Referring to FIG. 1, a backlight module 100 includes a frame 10, a reflective plate 12, a plurality of LED (light emitting diode) point light sources 14, a diffusing plate 16, and a plurality of optical sheets 18. The plurality of LED point light sources 14 are disposed on the bottom plate of the frame 10, and the plurality of optical sheets 18 are disposed at the opening of the frame 10. The diffusion plate 16 is spaced apart between the LED point light source 14 and the plurality of optical sheets 18 to divide the inside of the frame 10 into the first and second diffusion spaces 19, 20. The diffusion plate 16 is made of a resin material containing scattering particles. The plurality of optical sheets 18 include a bismuth sheet, a diffusion sheet or a refractive polarizing film. In use, the light generated by the plurality of LED point light sources 14 passes through the first diffusion space 19 and enters the diffusion plate 16. After being diffused by the diffusion plate 16, the light enters the second diffusion space 20 for diffusion, and finally passes through the diffusion of the plurality of optical sheets 18. After aggregating, it is uniformly emitted within a specific viewing angle range. However, although the light emitted from the LED point light source 14 is diffused a plurality of times, it is still difficult to avoid the generation of the residual light of the light source of the point source 14, that is, an area having a high center luminance and a dark surrounding area. In order to minimize the generation of residual light source, industry 6 201007295: the boundary usually increases the depth of the frame ,), that is, the height. However, increasing the depth of the frame will reduce: the thickness of the backlight module 100 is large, and it is difficult to meet the requirements of the thin type. If the point source is added correspondingly, it is recognized. [Summary of the invention] Power consumption. In view of the above, it is necessary to provide a thinner backlight module. The direct-emitting backlight module is preferably ❷ - the direct-lit backlight module includes a frame, a complex photodiode disposed at the bottom of the frame, and a first optical plate sequentially disposed above the plurality of light-emitting diodes and Second optical plate. The first light is a transparent body. The first optical plate includes a plurality of elongated arc-shaped grooves formed parallel to each other and a plurality of elongated arc-shaped protrusions formed on the first optical-light surface. The second plurality formed on the light-incident surface of the second optical plate: ???: the second optical plate-one flat: = the above-mentioned direct-type backlight module causes the light emitted by the light-emitting diode to diffuse into the space In the human-optical plate, since the surface of the first optical plate is formed with a plurality of orphaned grooves, the light-emitting surface is formed with a plurality of curved protrusions, and the point light source can be diffused into a surface light source and the light is concentrated to a specific viewing angle range. 'Improve the front light output rate and uniformity of the back money group; then the light emitted from the first optical plate iii is spatially diffused and then enters the second optical plate, since the first optical plate is formed with an arcuate groove on the light incident surface, The light-emitting surface is formed with an arc-shaped protrusion' to cause a specific refraction of the light emitted from the second optical plate, and the optical effect of the 201007295 radiation, reflection and diffraction, thereby further diffusing the light while illuminating the light to avoid uniform diffusion of the light. The generation of the residual light source. At the same time, the light is emitted from the light-emitting diode to the second optical plate, and the secondary space is diffused and the diffusion path is increased due to the microstructure of the optical plate, thereby achieving a better diffusion effect, thereby achieving the The thin design of the direct type backlight module. [Embodiment] Hereinafter, the direct type backlight module ❿200 of the present invention will be further described in detail with reference to the accompanying drawings and embodiments. Referring to FIG. 2, a direct type backlight module 200 according to a first embodiment of the present invention includes a frame 21, a plurality of light emitting diodes 23, a first optical plate 24, a second optical plate 25, and a plurality of optical sheets 26. The plurality of light-emitting diodes 23 are disposed at the bottom of the frame 21, and the first optical plate 24 and the second optical plate 25 are sequentially disposed above the light-emitting diode 23, thereby dividing the frame 21 into the first and second diffusion spaces 27, 28, the plurality of optical sheets 26 are disposed above the second optical Qin plate 25. The frame 21 may be made of metal or plastic having high reflectivity or metal or plastic coated with a high reflectivity coating. Referring to FIG. 3 to FIG. 5 , the first optical plate 24 is formed by a transparent body, and includes a light incident surface 241 and a plurality of long curved arcuate grooves 242 formed on the light incident surface 241 , and the light incident surface. 241 is opposite to the light-emitting surface 243 and a plurality of strip-shaped V-shaped protrusions 244 and elongated arc-shaped protrusions 245 which are alternately arranged and parallel to each other and formed on the light-emitting surface 243. The extending direction of the plurality of elongated V-shaped projections 244 and the elongated arcuate projections 245 is intersected with a plurality of elongated arcs 201007295 : 22 = intersecting directions. In this embodiment, the extending direction of the plurality of long v-shaped two It-shaped protrusions 245 and the extending direction of the plurality of long strip-shaped ridges are perpendicular to each other, and the elongated arc-shaped protrusions 244=the straight sections are semi-arc-shaped, long strips The arcuate groove 24 has a semicircular arc shape. Sheng Dan Piao® High sound ^ is recorded as h' vertex angle as θ, ^<1 - Zhuobu 1 Dl, 0, Hl satisfy the following relationship: 0. 〇 25 mm... = 1 pen not, 80 degrees plum 1 〇〇度' The width of 2〇5 is called radius 2^2, Ll, Rl, H2 satisfy the following relationship: 〇.〇25mm is called illusion 5:m; W4 ——1mm. By adjusting the values of Di:e, 1 ! &, and h2, the shape of the long strip-shaped protrusions μ and the elongated strip-shaped protrusions 245 can be adjusted to adjust the first light rate and the light-emitting angle of view. I曰, the adjacent two long strip-shaped recesses, if the distance between them is I, and the radius is already h, then 匕"1 and hl satisfy the following relationship: 0·025 Π mm ' ΡΐΜ & ^2Ρΐ, 〇.01 mm. By means of the values of 1Γ, Γι and hl, the surface curvature and spacing of the elongated arcuate grooves 242 can be adjusted to adjust the diffusion effect of incident light on the plurality of elongated arcuate grooves 24. Referring to FIG. 6 and FIG. 7 , the second well-lifting extension mountain preparation plate 25 is composed of a transparent body, and includes a first surface 251 and a plurality of long concaves 252 formed on the light-incident surface 251, and the light entering the light. The surface 251 is opposite to the light-emitting surface (5) and the plurality of elongated arc-shaped protrusions 254 formed on the light-emitting surface. The plurality of strips on the light-emitting surface 253 9 201007295
=形凸起254之延伸方向與發光二極體糊之轴向方 σ平行且其與入光面251上之彳I 之延伸方向正交。可以理解，出之:面數2=:凹槽252 形凸起⑽之延伸方向Ζ光面=53 =數長條狀弧 29夕π庙士人 先 上之複數長條狀凹槽 2之延伸方向相交也能達到近似之效果。 入光面251之複數長條狀弧形凹槽252之間相互平 t °、每:長條狀弧形凹槽252之豐直戴面為圓弧形。將長The extending direction of the =-shaped projection 254 is parallel to the axial direction σ of the light-emitting diode paste and is orthogonal to the extending direction of the 彳I on the light-incident surface 251. It can be understood that: face number 2 =: groove 252 shape protrusion (10) extension direction Ζ light surface = 53 = number of long strips of arc 29 π 庙 士 士 人 人 人 人 人 人 人The intersection of directions can also achieve an approximate effect. The plurality of long arcuate grooves 252 of the light incident surface 251 are flat with each other, and each of the straight curved grooves 252 has a circular arc shape. Will grow
!52中圓孤之半徑記為r2,相鄰長條狀弧形 =深度〈記為h2,則匕、uh2滿足以下關係式， 〆 ，ρ2/4$Γ2$2ρ2，〇 〇1咖^私；即 虽相鄰二長條狀弧形凹槽252之間之中心間距Pa為奶咖 時’每-長條狀弧形凹槽252之半徑。為m.5um，每一 長條狀弧形凹槽252之最大深度匕為ii〇um。 出光面253之複數長條狀弧形凸起254之間相互平 行。每-長條狀弧形凸起254之登直截面為圓弧形。將長 條狀弧形凸起254中圓弧之半徑記為&，相鄰長條狀弧形 :起54之中心間距s己為，每一長條狀弧形凸起之 最大深度。己為H3 ’則r2、l2及H3滿足以下關係式： 〇.〇25mm^L2^l.5mm » L2/4^R2^2L2 ^ 0.01mm^H3^ R2 〇 同樣之，當相鄰兩長條狀弧形凸起254之間之中心間距l2 為275um時，每一長條狀弧形凸起254之半徑&為 137*5um，每—長條狀弧形凸起254之最大深度H3為110um。 第一光學板24和第二光學板25之總體厚度Τι、丁2可 201007295 .為0.4毫米至4毫米。第一光學板24和第二光學板25可由 .聚甲基丙烯酸甲酿、聚碳酸醋、聚苯乙烯、苯乙烯-曱基丙 烯酸甲酯共聚物中之一種或一種以上之材質注塑成型而The radius of the circle in !52 is denoted by r2, and the adjacent strip-shaped arc=depth <denoted as h2, then 匕 and uh2 satisfy the following relationship, 〆, ρ2/4$Γ2$2ρ2, 〇〇1咖^私That is, although the center-to-center spacing Pa between adjacent two long strip-shaped curved grooves 252 is the radius of the 'per-long strip-shaped curved groove 252'. For m. 5um, the maximum depth 匕 of each elongated arcuate groove 252 is ii〇um. The plurality of elongated arcuate projections 254 of the light exiting surface 253 are parallel to each other. The straight section of each-long strip-shaped convex protrusion 254 has a circular arc shape. The radius of the arc in the long arcuate projection 254 is referred to as & adjacent to the elongated arc: the center-to-center spacing s of 54 is the maximum depth of each elongated arcuate projection. H3' is then r2, l2 and H3 satisfy the following relationship: 〇.〇25mm^L2^l.5mm » L2/4^R2^2L2 ^ 0.01mm^H3^ R2 〇 Similarly, when two adjacent strips When the center-to-center distance l2 between the arcuate protrusions 254 is 275 um, the radius & amp of each strip-shaped arcuate protrusion 254 is 137*5 um, and the maximum depth H3 of each of the strip-shaped arcuate protrusions 254 is 110um. The total thickness of the first optical plate 24 and the second optical plate 25 may be 0.4 mm to 4 mm. The first optical plate 24 and the second optical plate 25 may be injection molded from one or more of polymethyl methacrylate, polycarbonate, polystyrene, and styrene-mercapto acrylate copolymer.
成。製備第-光學板24過程中需於模具上設置與長條狀V I凸起244和長條狀孤形凸起245相應之凹陷結構，以及 與長條狀弧形凹槽242相應之凸起結構，以便使第一光學 板24可於單次注塑過程巾成型。製備第二光學板μ過程 _中需於模具上設置與長條狀弧形凹槽252以及長條狀弧形 凸起254相應之結構，以便使第二光學板乃可於單次注塑 過程中成型。 第光學板24採用注塑成型之方式一體成型，其上之 長條狀v形凸起244及長條狀弧形凸起245和第一光學板 24之其他部分一起形成，因此可使得長條狀V形凸起244 及長條狀弧形凸起245具有較高之結構強度，同時還能提 升長條狀V形凸起244及長條狀弧形凸起245和第一光學 ❷板24其他部分之結合力，從而可避免或減少長條狀v形凸 起244及長條狀弧形凸起245於使用中被損壞之危險。同 理，第二光學板25之製備方法和第一光學板24之製備方 法一樣。 複數光學片26可為擴散片、增光片或反射式偏光片。 本實施例背光模組200中，第一光學板24位於框架21 中部並可由支撐架支撐或藉由黏接之方式固定於框架21之 内側壁上，第二光學板25蓋設於框架21之開口處。當然， 二者間之距離可視實際情況作調整，一般地，於出光均勻 11 201007295 度相同之情況下，框架21之深度與發光二極體23之數量 成反平方，當發光二極體23之數量較多時，框架21之深 度較小，第一光學板24與第二光學板25間隔之距離可設 置得小一些，當發光二極體23之數量較少時，框架21之 深度較大，第一光學板24與第二光學板25間隔之距離相 應地設置得大一些。 使用時，發光二極體23發射出之光線經過第一空間27 擴散作用後進入第一光學板24,由於第一光學板24之入光 ®面241形成有相互平行之長條狀弧形凹槽242，出光面243 形成有特定排佈之長條狀V形凸起244和長條狀弧形凸起 245之傾斜表面結構，使光線於第一光學板24内發生了特 定之折射、散射、反射與繞射等光學作用，將光線擴散成 複數面積較大之面光源之同時使光線向特定視角範圍内聚 集；該複數被擴散成較大面積之面光源經過第二空間28擴 散後進入第二光學扳25，由於第二光學板25之入光面251 _形成有複數長條狀弧形凹槽252,出光面253形成有複數長 條狀弧形凸起254之傾斜表面結構，使該複數被擴散之面 光源進一步擴散成更大面積之面光源之同時將光線擴散均 勻，從而於背光模組200之出光面形成均勻之發光面。 複數光學片26蓋設於第二光學板25上，可使出射光 線更為柔和、平緩。當然，當發光二極體23之間之間距較 小時，複數光學片26可省略。 由此可見，本發明實施例一之背光模組200之第一光 學板24和第二光學板25之間隔設置，使光線得到較佳之 12 201007295 •少框架21之深度;第一光學板Μ和 • ,出光面特殊之表面結構，使光線發 錄 折射、政射、反射與繞射等光學作用，從而將光 面光源化和擴散並向料視角範圍内聚集，從而於 ^先模組200之出光面形成亮度均勻之光亮面。如是二光 學板24、25於背光模組遍中之相互搭配，便可減弱甚至 避免光源殘影，提高背光模组之出光均句性同時可 實現背光模組200之薄型化設計。 〃請參閱圖8,所示為本發明實施例二之第二光學板… 第二光學板35與實施例—之第二光學板25相似，其不同 在於第一光學板35進一步包括形成於出光面扣之複數 相互平行之長條狀弧形凸起354及複數相互平行之長條狀 V形凸起355’且該複數相互平行之長條狀弧形凸起與 馥數相互平行之長條狀ν形凸起355相交，從而將長條狀 弧形凸起354分割成複數半圓柱狀凸起，入光面351上形 ❹成有複數相互平行之長條狀弧形凹槽352，且長條弧形凹槽 352與出光面353上之長條狀弧形凸起354延伸方向相同。 本實施例中，該複數長條狀ν形凸起355或長條狀弧形凸 起355之延伸方向與複數長條狀弧形凹槽352之延伸方向 相互垂直；該長條狀弧形凸起354之垂直截面為半圓弧形， 該長條狀弧形凹槽352之垂直截面為半圓弧形。可以理解， 長條狀弧形凸起354與長條狀弧形凹槽352之垂直截面還 可為橢圓弧形。當然，實施例二中之第二光學板35可採用 實施例一 20〇中之第一光學板24來代替。 13 201007295 . 可以理解，本發明之直下式背光模組中之第一光學板 之出光面之表面結構和第二光學板出光面之表面結構=相 同。另，第一光學板可設置於第二光學板之位置，第二光 學板可設置於第一光學板之位置。 θ综上所述，本發明確已符合發明專利之要件，遂依法 提出專利申請。惟，以上所述者僅為本發明之較佳實施方 式，自不能以此限制本案之申請專利範圍。舉凡熟悉本案 _技藝之人士援依本發明之精神所作之等效修飾或變化，皆 應涵蓋於以下申請專利範圍内。 【圖式簡單說明】 圖1係一種直下式背光模組之刮面示意圖。 圖2係本發明實施例一之直下式背光模組之剖面示意 圖。 圖3係圖2所示直下式背光模組之第一光學板之立體 圖〇 G 圖4係圖3所示第一光學板沿IV_IV方向之剖面示意 圖。 圖5係圖3所示第一光學板沿ν_ν方向之剖面示意圖。 圖6係圖3所示第一光學板之立體圖。 圖7係圖6所示第二光學板之沿VII-νΐΙ方向之剖面示 思_ 0 圖8係本發明實施例二之第二光學板之立體圖。 【主要元件符號說明】 2〇〇 背光模組 201007295 框架 21 發光二極體 23 第一光學板 24 第二光學板 25、35 入光面 241 ' 251 出光面 243 、 253 長條狀弧形凹槽 242、252 長條狀V形凸起 244 、 355 長條狀弧形凸起 245 、 254 光學片 26 第一擴散空間 27 第二擴散空間 28 351 353 352 354to make. In the process of preparing the first optical plate 24, a concave structure corresponding to the elongated VI protrusion 244 and the elongated shape-shaped protrusion 245 is disposed on the mold, and a convex structure corresponding to the long curved concave groove 242 is provided on the mold. In order to allow the first optical plate 24 to be formed in a single injection molding process. In the process of preparing the second optical plate, a structure corresponding to the long arc-shaped groove 252 and the long arc-shaped protrusion 254 is disposed on the mold, so that the second optical plate can be used in a single injection molding process. forming. The first optical plate 24 is integrally formed by injection molding, and the long v-shaped protrusions 244 and the elongated arc-shaped protrusions 245 are formed together with other portions of the first optical plate 24, thereby making the strips long The V-shaped protrusions 244 and the elongated arc-shaped protrusions 245 have higher structural strength, and can also lift the elongated V-shaped protrusions 244 and the elongated curved protrusions 245 and the first optical rafts 24 Part of the bonding force, thereby avoiding or reducing the risk of the long v-shaped projections 244 and the elongated arcuate projections 245 being damaged during use. Similarly, the second optical plate 25 is prepared in the same manner as the first optical plate 24. The plurality of optical sheets 26 may be a diffusion sheet, a brightness enhancement sheet or a reflective polarizer. In the backlight module 200 of the present embodiment, the first optical plate 24 is located in the middle of the frame 21 and can be supported by the support frame or fixed on the inner side wall of the frame 21 by adhesion, and the second optical plate 25 is disposed on the frame 21 At the opening. Of course, the distance between the two can be adjusted according to the actual situation. Generally, in the case that the uniformity of the light is 11 201007295 degrees, the depth of the frame 21 and the number of the light-emitting diodes 23 are inversely squared, when the light-emitting diode 23 When the number is large, the depth of the frame 21 is small, and the distance between the first optical plate 24 and the second optical plate 25 can be set smaller. When the number of the light-emitting diodes 23 is small, the depth of the frame 21 is large. The distance between the first optical plate 24 and the second optical plate 25 is correspondingly set larger. In use, the light emitted from the LED 23 enters the first optical plate 24 after being diffused through the first space 27, and the light-incident surface 241 of the first optical plate 24 is formed with a long arc-shaped concave parallel to each other. The groove 242, the light-emitting surface 243 is formed with a slanted surface structure of the elongated strip-shaped V-shaped protrusion 244 and the elongated arc-shaped protrusion 245, so that the light is specifically refracted and scattered in the first optical plate 24. Optical effects such as reflection and diffraction, the light is diffused into a plurality of large-area surface light sources while the light is concentrated to a specific viewing angle range; the complex light is diffused into a larger area and the surface light source is diffused through the second space 28 to enter The second optical plate 25 is formed with a plurality of elongated arcuate grooves 252 formed by the light incident surface 251 of the second optical plate 25, and the light emitting surface 253 is formed with an inclined surface structure of a plurality of elongated arcuate protrusions 254. The plurality of diffused surface light sources are further diffused into a larger area of the surface light source while diffusing the light uniformly, thereby forming a uniform light emitting surface on the light emitting surface of the backlight module 200. The plurality of optical sheets 26 are covered on the second optical plate 25 to make the outgoing light line softer and gentler. Of course, when the distance between the light-emitting diodes 23 is small, the plurality of optical sheets 26 can be omitted. Therefore, the first optical plate 24 and the second optical plate 25 of the backlight module 200 of the first embodiment of the present invention are spaced apart to provide a better light. 12 201007295 • The depth of the frame 21 is less; the first optical plate is • The special surface structure of the illuminating surface allows the light to refract optically, refraction, reflection, and diffraction, thereby illuminating and diffusing the illuminating light and concentrating it within the viewing angle of the material, thereby The light-emitting surface forms a bright surface with uniform brightness. If the two optical boards 24 and 25 are matched with each other in the backlight module, the light source residual image can be weakened or even avoided, and the light-emitting uniformity of the backlight module can be improved, and the thinning design of the backlight module 200 can be realized. Referring to FIG. 8, a second optical plate is shown in the second embodiment of the present invention. The second optical plate 35 is similar to the second optical plate 25 of the embodiment, except that the first optical plate 35 further includes a light-emitting plate. a plurality of strip-shaped arcuate protrusions 354 parallel to each other and a plurality of strip-shaped V-shaped protrusions 355' parallel to each other, and the plurality of strip-shaped arc-shaped protrusions parallel to each other and the strips parallel to each other The v-shaped protrusions 355 intersect to divide the elongated arc-shaped protrusions 354 into a plurality of semi-cylindrical protrusions, and the light-incident surface 351 is shaped into a plurality of long-shaped arcuate grooves 352 which are parallel to each other, and The elongated arcuate groove 352 extends in the same direction as the elongated arcuate projection 354 on the light exiting surface 353. In this embodiment, the extending direction of the plurality of elongated v-shaped protrusions 355 or the elongated arc-shaped protrusions 355 and the extending direction of the plurality of elongated arc-shaped grooves 352 are perpendicular to each other; the elongated arc-shaped convex The vertical section of 354 is a semi-circular arc shape, and the vertical section of the elongated arcuate groove 352 has a semicircular arc shape. It can be understood that the vertical cross section of the elongated arcuate projection 354 and the elongated arcuate recess 352 can also be an elliptical arc. Of course, the second optical plate 35 of the second embodiment can be replaced with the first optical plate 24 of the first embodiment. 13 201007295. It can be understood that the surface structure of the light-emitting surface of the first optical plate and the surface structure of the light-emitting surface of the second optical plate in the direct-type backlight module of the present invention are the same. Alternatively, the first optical plate may be disposed at a position of the second optical plate, and the second optical plate may be disposed at a position of the first optical plate. In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application in accordance with the law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by those skilled in the art of the present invention in light of the spirit of the present invention are intended to be included in the scope of the following claims. [Simple description of the drawing] Fig. 1 is a schematic view of a scraping surface of a direct type backlight module. 2 is a schematic cross-sectional view of a direct type backlight module according to Embodiment 1 of the present invention. 3 is a perspective view of the first optical plate of the direct type backlight module shown in FIG. 2. FIG. 4 is a cross-sectional view of the first optical plate shown in FIG. 3 taken along the line IV_IV. Figure 5 is a schematic cross-sectional view of the first optical plate shown in Figure 3 taken along the direction of ν_ν. Figure 6 is a perspective view of the first optical plate shown in Figure 3. Figure 7 is a cross-sectional view of the second optical plate shown in Figure 6 taken along the line VII-νΐΙ. Figure 8 is a perspective view of the second optical plate of the second embodiment of the present invention. [Main component symbol description] 2〇〇Backlight module 201007295 Frame 21 Light-emitting diode 23 First optical plate 24 Second optical plate 25, 35 Light-incident surface 241 ' 251 Light-emitting surface 243, 253 Strip-shaped curved groove 242, 252 elongated V-shaped projections 244, 355 elongated arcuate projections 245, 254 optical sheet 26 first diffusion space 27 second diffusion space 28 351 353 352 354
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