200819858 九、發明說明： . 【發明所屬之技術領域】 . 本發明係關於一種用於液晶顯示裝置之背光模組，特別 係關於一種採用發光二極體光源之直下式背光模組。 【先前技術】 發光二極體（Light Emitting Diode，LED)具有體積小、 重量輕、壽命長、耗能少與無輻射等特點。採用LED作為 光源之背光模組也具有相應之優良特性。惟，在LED之發 光過程中，也會產較多之熱量，以高功率GaN型LED為例， 當該種LED開啟後，其僅將10%之電能轉化為光能，而其 餘之90%則轉化為熱能散發出來。因此，LED之散熱問題便 成為LED應用之重要問題之一，特別是對於使用複數LED 作為光源系統之直下式背光模組顯得尤為重要。 請參閱圖1，一種習知之直下式背光模組10，其包括一 燈箱11、複數發光二極體12、一電路板13、一反射板14、 兩散熱鰭片單元15、一擴散板16、一擴散片17及一稜鏡片 18。該燈箱11包括一基板111及由該基板111之四側邊垂 直延伸形成之四侧壁112，該基板111及四侧壁112形成一 收容腔113。該電路板13置於燈箱11之基板111内表面。 該複數發光二極體12排佈於該電路板13。反射板14相對發 光二極體12開設有複數安裝孔（未標示），電路板13上之 發光二極體12穿過該安裝孔，可使反射板14定位於該電路 板13之上方。基板111之外表面設置有兩個散熱鰭片單元 15，其通過複數螺絲（圖未示）鎖固於該基板111。而且， 6 200819858 該散熱鰭片單元15與基板111之間設有導熱介質層19，用 於增加熱傳導率。擴散板16、擴散片17及棱鏡片18依次疊 合於燈箱11之收容腔113開口處。 然，該直下式背光模組10為使發光二極體12較好地散 熱，需用複數螺絲將散熱鰭片單元15螺合於該燈箱11上， 組裝較為複雜。而且，散熱鰭片單元15與基板111之間設 置有一導熱介質層19,使得整個背光模組之製作成本增加。 【發明内容】 有鑒於此，提供一種組裝較為簡單、製作成本較低之 直下式背光模組實為必要。 一種直下式背光模組，其包括一燈箱、複數發光二極體 及一電路板，該燈箱包括一基板及由該基板侧邊延伸形成之 複數侧壁，該基板及複數側壁形成一收容腔，該電路板設置 於上述收容腔内鄰近基板處，該複數發光二極體排佈於該電 路板，該燈箱至少部分外表面一體成型設置複數散熱鰭片。 相較於習知技術，該直下式背光模組之散熱鰭片與燈箱 一體成型，故無需在散熱鰭片與燈箱之間設置導熱介質層即 可達到較高之熱傳導效率，且可減少該直下式背光模組之製 作成本，另，該直下式背光模組之組裝過程可省去習知技術 中將複數散熱鰭片單元用螺絲鎖合於燈箱表面之步驟。 【實施方式】 下面將結合附圖和複數實施例對本發明之直下式背光 模組作進一步之詳細說明。 請參閱圖2及圖3，本發明第一實施例提供一種直下式 7 200819858 ’背光模組20，其包括一燈箱21、複數發光二極體22及一電 . 路板23。該燈箱21包括一基板211及由該基板211四侧邊 . 延伸形成之四侧壁212，該基板211及四側壁212形成一收 容腔213,該燈箱21之至少部分外表面還一體成型設置複數 散熱鰭片24,本實施例中散熱鰭片24 —體成型於基板211 外表面之兩端。該複數散熱鰭片24由高導熱性材料通過擠 壓成型或壓鑄成型製成，該高導熱性材料包括銘合金、鎂合 金及鋁鎂合金。該電路板23設置於收容腔213内鄰近基板 211處，該複數發光二極體22排佈於該電路板23上。可以 理解，該基板211也可包括多條侧邊，其由該多條侧邊延伸 形成有複數侧壁。 散熱鰭片24與燈箱21之基板211為一體成型，故無需 於散熱鰭片24與燈箱21之間設置導熱介質層即能達到較高 之熱傳導率，且可減少該直下式背光模組20之製作成本， 另，該直下式背光模組20之組裝過程可省去習知技術中將 複數散熱鰭片單元用螺絲鎖合於燈箱表面之步驟。 該燈箱21之四侧壁212之内表面上塗佈有一反射層 214，該反射層214可反射從發光二極體22射出之光線。 該直下式背光模組20還包括一反射板25，其相對電路 板23上之發光二極體22設置有複數穿孔251。組裝時，該 反射板25將被置入燈箱21之收容腔213内，發光二極體22 將穿過該反射板25上之穿孔251使其定位於電路板23上方。 該直下式背光模組20還包括一擴散板26、一擴散片27 及一稜鏡片28，其依次疊合於燈箱21之收容腔213之開口 8 200819858 •處。擴散板26用於將從發光二極體22出射之光線發散，並 • 具有支撐其他光學膜片之功能；擴散片27將光線進一步散 . 射，從而提高該直下式背光模組20之出光均勻性；稜鏡片 28使原本散亂之光線集中至正前方約70度之範圍内出射， 可提升該直下式背光模組20特定視角範圍内之亮度。 請參閱圖4，本發明第二實施例提供一種直下式背光模 組30，其與第一實施例中之直下式背光模組20具有相似之 結構，其不同在於複數散熱鰭片34佈滿基板311之外表面。 請參閱圖5，本發明第三實施例提供一種直下式背光模 組40，其與第一實施例中之直下式背光模組20具有相似之 結構，其不同在於複數散熱鰭片44佈滿基板411外表面之 兩端及侧壁412之外表面。 請參閱圖6，本發明第四實施例提供一種直下式背光模 組50，其與第一實施例中之直下式背光模組20具有相似之 結構，其不同在於複數散熱鰭片54佈滿燈箱51之外表面。 請參閱圖7，本發明第五實施例提供一種直下式背光模 組60，其與第一實施例之直下式背光模組20具有相似之結 構，其不同在於該直下式背光模組60於燈箱61之基板611 之外表面對應散熱鰭片64還設置有複數散熱風扇69，該散 熱風扇69可加速散熱鰭片64周圍之空氣流動，使散熱鰭片 64上熱量更快地散發到空氣中，從而進一步提升該直下式背 光模組60之散熱性能。 請參閱圖8，本發明第六實施例提供一種直下式背光模 組70，其與第一實施例之直下式背光模組20具有相似之結 9 200819858 •構，其不同在於該直下式背光模組70之燈箱71由第一殼體 • 711及第二殼體712接合而成。該第一殼體711包括一底板 ,7111及由該底板7111之三侧邊延伸形成之三側壁7112，該 底板7111之外表面一體成型有複數散熱鰭片7113，且於未 設置侧壁7112之侧邊延伸形成一彎折部7114。該第二殼體 712包括一底板7121及由該底板7121之三侧邊延伸形成之 三侧壁7122，該底板7121之外表面一體成型有複數散熱鰭 片7123,且於未設置侧壁7122之一端延伸形成一平板部 7124。組合時，將第二殼體712之平板部7124置放於第一 殼體711之彎折部7114中，再用螺絲79穿過該彎折部7111 及平板部7124上之安裝孔（未標示），即可將該第一殼體711 與第二殼體712鎖固。這種燈箱設計主要應用於大尺寸之直 下式背光模組，因為成型設備或許不能實現對整個燈箱進行 一體成型，故需分別一體成型兩個設置有散熱鰭片之殼體 後，再進行組合。 可以理解，燈箱也可由複數殼體組成，例如，再設置一 第三殼體，該第三殼體包括一底板，以及由該底板兩相對之 側邊延伸形成之兩侧壁，該底板於未設置侧壁之一側邊延伸 形成一彎折部，相對之另一側邊延伸形成一平板部，通過將 上述第一殼體、第二殼體置於兩侧，第三殼體置於中間，再 將一殼體之平板部置放於相鄰另一殼體之彎折部上，並用螺 絲分別進行鎖固，可使該複數殼體組合形成一燈箱。可以理 解，該複數殼體也可通過焊接接合、鉚釘鉚合等方式進行鎖 200819858 請參閱圖9，本發明第七實施例提供一種直下式背光模 • 組80，其與第一實施例之直下式背光模組20具有相似之結 .構，其不同在於該直下式背光模組80之燈箱81之基板811 上退等間距設置有複數與基板811相垂直之隔板8 9 ’該隔板 89之表面塗佈有反射介質層（圖未示），可對發光二極體82 出射之光線進行反射。電路板83被該複數隔板89間隔為複 數子電路板，每塊子電路板上規則排佈有複數紅色、綠色或 藍色之發光二極體82。隔板89之設置可使從發光二極體82 發出之光線經過多次反射後再進入燈箱81上方之擴散板 86,從而使各種不同顏色之發光二極體82發出之光在進入 擴散板86前充分混合，另，隔板89之設置還可使該直下式 背光模組80形成複數獨立之發光區域，且每個發光區域之 亮度與色彩均可單獨控制。 綜上所述，本發明符合發明專利要件，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方式，本發明 之範圍並不以上述實施例為限，舉凡熟習本案技藝之人士援 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 請專利範圍第内。 【圖式簡單說明】 圖1是習知之直下式背光模組之剖面示意圖。 圖2是本發明第一實施例之直下式背光模組立體分解 不意圖。 圖3是圖2所示直下式背光模組組合後沿III-III線剖面 示意圖。 11 200819858 圖4是本發明第二實施例之直下式背光模組剖面示意 圖。 圖5是本發明第三實施例之直下式背光模組剖面示意 圖。 圖6是本發明第四實施例之直下式背光模組剖面示意 圖。 圖7是本發明第五實施例之直下式背光模組剖面示意 圖。 圖8是本發明第六實施例之直下式背光模組剖面示意 圖。 圖9是本發明第七實施例之直下式背光模組剖面示意 圖0 【主要元件符號說明】 (本發明） 直下式背光模組 20 燈箱 21 發光二極管 22 電路板 23 散熱鰭片 24 反射板 25 30 、 40 、 50 、 60 、 70 、 80 61、81 82 34、44、54、64、74、7113、7123 擴散板 26、86 擴散片 27 稜鏡片 28 散熱風扇 69 12 89 200819858 隔板 基板 側壁 收容腔 反射層 穿孔 第一殼體 第二殼體 底板 彎折部 平板部 習知） 直下式背光模組 燈箱 發光二極管 電路板 反射板 散熱鰭片單元 擴散板 擴散片 稜鏡片 導熱介質層 基板 側壁 211 、 311 、 411 、 212 、 412 、 7112 213 214 251 711 712 7111 、 7121 7114 7124 10 11 12 13 14 15 16 17 18 19 111 112 611 、 811 、7122 13 113 200819858 收容腔 14200819858 IX. INSTRUCTIONS: [Technical Field] The present invention relates to a backlight module for a liquid crystal display device, and more particularly to a direct type backlight module using a light emitting diode light source. [Prior Art] Light Emitting Diode (LED) has the characteristics of small size, light weight, long life, low energy consumption and no radiation. A backlight module using an LED as a light source also has corresponding excellent characteristics. However, in the process of LED illumination, more heat is generated. Taking high-power GaN-type LEDs as an example, when the LED is turned on, it converts only 10% of the electrical energy into light energy, and the remaining 90%. Then it is converted into heat and emitted. Therefore, the heat dissipation problem of LEDs has become one of the important issues in LED applications, especially for direct-lit backlight modules that use multiple LEDs as the light source system. Referring to FIG. 1 , a conventional direct type backlight module 10 includes a light box 11 , a plurality of light emitting diodes 12 , a circuit board 13 , a reflector 14 , two heat sink fin units 15 , and a diffusion plate 16 . A diffusion sheet 17 and a cymbal sheet 18. The light box 11 includes a substrate 111 and four side walls 112 extending vertically from four sides of the substrate 111. The substrate 111 and the four side walls 112 form a receiving cavity 113. The circuit board 13 is placed on the inner surface of the substrate 111 of the light box 11. The plurality of light emitting diodes 12 are arranged on the circuit board 13. The reflector 14 is provided with a plurality of mounting holes (not shown) opposite to the light-emitting diode 12, and the light-emitting diode 12 on the circuit board 13 passes through the mounting hole to position the reflector 14 above the circuit board 13. The outer surface of the substrate 111 is provided with two heat dissipating fin units 15 which are locked to the substrate 111 by a plurality of screws (not shown). Further, 6 200819858, a heat transfer medium layer 19 is provided between the heat sink fin unit 15 and the substrate 111 for increasing the thermal conductivity. The diffusion plate 16, the diffusion sheet 17, and the prism sheet 18 are sequentially laminated on the opening of the housing cavity 113 of the light box 11. However, in the direct-type backlight module 10, the light-emitting diode 12 is preferably heat-dissipated, and the heat-dissipating fin unit 15 is screwed onto the light box 11 by a plurality of screws, which is complicated to assemble. Moreover, a heat conductive medium layer 19 is disposed between the heat dissipation fin unit 15 and the substrate 111, so that the manufacturing cost of the entire backlight module is increased. SUMMARY OF THE INVENTION In view of the above, it is necessary to provide a direct type backlight module that is relatively simple to assemble and has a low manufacturing cost. A direct-lit backlight module includes a light box, a plurality of light-emitting diodes, and a circuit board. The light box includes a substrate and a plurality of sidewalls extending from a side of the substrate, the substrate and the plurality of sidewalls forming a receiving cavity. The circuit board is disposed in the receiving cavity adjacent to the substrate, and the plurality of light emitting diodes are arranged on the circuit board, and at least part of the outer surface of the light box is integrally formed with a plurality of heat dissipating fins. Compared with the prior art, the heat dissipation fin of the direct type backlight module is integrally formed with the light box, so that a heat conduction medium layer is not required between the heat dissipation fin and the light box to achieve high heat conduction efficiency, and the direct reduction can be reduced. The manufacturing cost of the backlight module, in addition, the assembly process of the direct-type backlight module can eliminate the step of screwing the plurality of heat-dissipating fin units to the surface of the light box in the prior art. [Embodiment] Hereinafter, the direct type backlight module of the present invention will be further described in detail with reference to the accompanying drawings and the embodiments. Referring to FIG. 2 and FIG. 3, a first embodiment of the present invention provides a direct-lit type 7 200819858 backlight module 20, which includes a light box 21, a plurality of light-emitting diodes 22, and an electric circuit board 23. The light box 21 includes a substrate 211 and four side walls 212 extending from the four sides of the substrate 211. The substrate 211 and the four side walls 212 form a receiving cavity 213. At least part of the outer surface of the light box 21 is integrally formed. The heat dissipation fins 24 are integrally formed on both ends of the outer surface of the substrate 211 in this embodiment. The plurality of heat radiating fins 24 are formed of a high thermal conductive material by extrusion molding or die casting, and the high thermal conductive material includes an ingot alloy, a magnesium alloy, and an aluminum magnesium alloy. The circuit board 23 is disposed in the receiving cavity 213 adjacent to the substrate 211, and the plurality of LEDs 22 are arranged on the circuit board 23. It can be understood that the substrate 211 can also include a plurality of side edges extending from the plurality of side edges to form a plurality of side walls. The heat dissipating fins 24 are integrally formed with the substrate 211 of the light box 21, so that a heat transfer medium layer is not required between the heat dissipating fins 24 and the light box 21 to achieve a high thermal conductivity, and the direct type backlight module 20 can be reduced. The manufacturing cost of the direct-type backlight module 20 can eliminate the step of screwing the plurality of heat-dissipating fin units to the surface of the light box in the prior art. The inner surface of the four side walls 212 of the light box 21 is coated with a reflective layer 214 which reflects the light emitted from the light emitting diode 22. The direct type backlight module 20 further includes a reflecting plate 25 disposed with a plurality of through holes 251 opposite to the light emitting diodes 22 on the circuit board 23. When assembled, the reflector 25 will be placed into the receiving cavity 213 of the light box 21, and the LED 22 will pass through the through hole 251 of the reflector 25 to be positioned above the circuit board 23. The direct type backlight module 20 further includes a diffusion plate 26, a diffusion sheet 27 and a cymbal sheet 28 which are sequentially superposed on the opening 8 200819858 of the light box 21 . The diffuser plate 26 is used for diverging the light emitted from the light-emitting diode 22, and has a function of supporting other optical films; the diffuser 27 further diffuses the light, thereby improving the uniform light emission of the direct-type backlight module 20. The cymbal sheet 28 causes the originally scattered light to be concentrated to a range of about 70 degrees in front of it, which can enhance the brightness of the direct-type backlight module 20 within a specific viewing angle range. Referring to FIG. 4 , a second embodiment of the present invention provides a direct type backlight module 30 , which has a similar structure to the direct type backlight module 20 of the first embodiment, except that the plurality of heat dissipation fins 34 are covered with a substrate. 311 outside the surface. Referring to FIG. 5, a third embodiment of the present invention provides a direct type backlight module 40 having a similar structure to the direct type backlight module 20 of the first embodiment, except that the plurality of heat dissipation fins 44 are covered with a substrate. Both ends of the outer surface of 411 and the outer surface of side wall 412. Referring to FIG. 6 , a fourth embodiment of the present invention provides a direct type backlight module 50 , which has a similar structure to the direct type backlight module 20 of the first embodiment, except that the plurality of heat dissipation fins 54 are covered with light boxes. 51 outer surface. Referring to FIG. 7 , a fifth embodiment of the present invention provides a direct type backlight module 60 , which has a similar structure to the direct type backlight module 20 of the first embodiment, and the difference is that the direct type backlight module 60 is in the light box. The outer surface of the substrate 611 of the 61 is further provided with a plurality of heat dissipation fins 69. The heat dissipation fan 69 accelerates the air flow around the heat dissipation fins 64, so that heat on the heat dissipation fins 64 is dissipated into the air more quickly. Thereby, the heat dissipation performance of the direct type backlight module 60 is further improved. Referring to FIG. 8, a sixth embodiment of the present invention provides a direct type backlight module 70, which has a similar structure to the direct type backlight module 20 of the first embodiment. The structure is different from the direct type backlight module. The light box 71 of the group 70 is joined by the first housing 711 and the second housing 712. The first housing 711 includes a bottom plate, 7111, and three side walls 7112 extending from three sides of the bottom plate 7111. The outer surface of the bottom plate 7111 is integrally formed with a plurality of heat dissipation fins 7113, and the side walls 7112 are not disposed. The side edges extend to form a bent portion 7114. The second housing 712 includes a bottom plate 7121 and three side walls 7122 extending from three sides of the bottom plate 7121. The outer surface of the bottom plate 7121 is integrally formed with a plurality of heat dissipation fins 7123, and the side wall 7122 is not disposed. One end extends to form a flat portion 7124. When assembled, the flat portion 7124 of the second housing 712 is placed in the bent portion 7114 of the first housing 711, and the screw 79 is passed through the mounting portion of the bent portion 7111 and the flat portion 7124 (not labeled) The first housing 711 and the second housing 712 can be locked. This light box design is mainly applied to a large-sized direct-lit backlight module. Since the molding equipment may not be able to integrally form the entire light box, it is necessary to integrally form two housings with heat-dissipating fins and then combine them. It can be understood that the light box can also be composed of a plurality of housings, for example, a third housing, the third housing includes a bottom plate, and two side walls extending from opposite sides of the bottom plate, the bottom plate is not One side of the side wall is extended to form a bent portion, and the other side is extended to form a flat portion. The first casing and the second casing are placed on both sides, and the third casing is placed in the middle. Then, the flat plate portion of one casing is placed on the bent portion of the adjacent other casing, and is respectively locked by screws, so that the plurality of casings can be combined to form a light box. It can be understood that the plurality of housings can also be locked by welding, rivet riveting, etc. 200819858. Referring to FIG. 9, a seventh embodiment of the present invention provides a direct type backlight module 80, which is directly down from the first embodiment. The backlight module 20 has a similar structure, and the difference is that the substrate 811 of the light box 81 of the direct type backlight module 80 is provided with a plurality of spacers 8 9 ' perpendicular to the substrate 811. The surface is coated with a reflective medium layer (not shown) to reflect the light emitted from the LEDs 82. The circuit board 83 is divided by the plurality of spacers 89 into a plurality of sub-boards, and each of the sub-boards is regularly arranged with a plurality of red, green or blue light-emitting diodes 82. The partition 89 is disposed such that the light emitted from the LED 82 is reflected by the plurality of times and then enters the diffuser 86 above the light box 81, so that the light emitted by the LEDs 82 of different colors enters the diffuser 86. The front portion is fully mixed. In addition, the partition 89 can also be configured to form the plurality of independent light-emitting regions, and the brightness and color of each of the light-emitting regions can be individually controlled. In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and those skilled in the art will be able to make equivalent modifications or variations in accordance with the spirit of the present invention. It should be covered in the scope of the following patent application. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view of a conventional direct type backlight module. Fig. 2 is a perspective exploded view of the direct type backlight module of the first embodiment of the present invention. 3 is a schematic cross-sectional view taken along line III-III of the rear-type backlight module of FIG. 2 . 11 200819858 Fig. 4 is a schematic cross-sectional view showing a direct type backlight module according to a second embodiment of the present invention. Fig. 5 is a schematic cross-sectional view showing a direct type backlight module according to a third embodiment of the present invention. Fig. 6 is a schematic cross-sectional view showing a direct type backlight module according to a fourth embodiment of the present invention. Fig. 7 is a schematic cross-sectional view showing a direct type backlight module according to a fifth embodiment of the present invention. Figure 8 is a cross-sectional view showing a direct type backlight module of a sixth embodiment of the present invention. 9 is a cross-sectional view of a direct-type backlight module according to a seventh embodiment of the present invention. [Main component symbol description] (Invention) Direct-lit backlight module 20 Light box 21 Light-emitting diode 22 Circuit board 23 Heat-dissipating fins 24 Reflecting plate 25 30 , 40 , 50 , 60 , 70 , 80 61 , 81 82 34 , 44 , 54 , 64 , 74 , 7113 , 7123 diffusion plate 26 , 86 diffusion sheet 27 diaphragm 28 cooling fan 69 12 89 200819858 spacer substrate sidewall receiving cavity Reflective layer perforation first housing second housing bottom plate bending portion flat portion conventionally) direct type backlight module light box light emitting diode circuit board reflector heat dissipation fin unit diffusion plate diffusion sheet 导热 piece heat conduction medium layer substrate sidewall 211, 311 , 411 , 212 , 412 , 7112 213 214 251 711 712 7111 , 7121 7114 7124 10 11 12 13 14 15 16 17 18 19 111 112 611 , 811 , 7122 13 113 200819858 Containment chamber 14