1281070 九、發明說明： 【發明所屬之技術領域】 ^本發明係關於一種背光模組，尤指一種出光均句度較 高之採用燈管之直下式背光模組。 【先前技術】 ,由於液晶顯示器具輕、薄、耗電小等優點，廣泛應用 於筆記本電腦、行動電話、個人數位助理等現代化資訊設 ，。因為液晶顯示器中的液晶本身不具發光特性，需為其 提供月光杈組以實現顯示功能。背光模組可按結構分為側 ，式背光模組及直下式背光模組二種。其中，直下式背光 模組主要應用在LCD監視器或液晶電視等領域。 眾所週知，直下式背光模組需具有較高之出光輝度， 二出光均句度要達到預定需求，從而提昇液晶顯示器的色 =對比度、全屏區域亮度效果及整機的可視角度。其耗電 量及成本需盡可能降低，另外，為適應液晶顯示器輕、薄 的要求，其結構設計不能太過複雜。 先刖技術之直下式背光模組一般包括複數發光二極體 :成的光源陣列與置於光源陣列出光面—側的散射面板。 ，，採用發光二極體之直下式背光模組具有缺陷··發光二 格高，增加直下式背光模組之成本；其光場分佈 轉對稱狀’出光均勻度難以達到液晶顯示器之需求. ^為匹配散射面板’需㈣複數發光二極體之設計，使得 光源陣列體積大、結構複雜且耗電量大，並且當某—發先 極體出現故障時會影響整體出光均勻度。 1281070 因此，業界發展出採用燈管作為光源之直下式背光模 組。一種先前技術直下式背光模組可參閱公告於1995年12 月26日之美國專利第5,479,328號（第一圖參照）。該直下 式月光模組10為液晶顯示面板2〇提供照明，包括螺旋形燈 管（Serpentine Tube) 12、反射框體14、玻璃基板15、設 置於玻璃基板15之上的擴散板17及增亮片18，該螺旋形燈 官12嵌套於反射框體14之複數通道（未標示）中。該增亮 片18藉由空氣間隙19與液晶顯示面板2〇相對。 惟，由於該直下式背光模組1〇單純採用擴散板口來均 勻出射之光束，即其出光均句度依賴於擴散板17之品質， 其控制較為困難，出光均勻度不夠理想。請一併表閱第二 圖，因為燈管U發出之光線之輝度分佈與㈣平方成反 比’該直下式背光模組出射1G之光束於擴散板17表面依光 線傳輸距離之不同而形成明暗不均之分佈。 另，該先前技術直下式背光模組10還具有以下缺陷： t盡可能提高出光均勾度’該反射框體14之設計殊為不 牦加直下式月光模組10結構之複雜度；該螺旋形燈管 12之外形複雜，製作較為困難，且價格及耗電量較高。 有鑑於此，提供—種出光均勾度高、機構設計簡單之 直下式背光模組實為必要。 【發明内容】 本發明之目的在於提供 簡單之直下式背光模組。 一種出光均勻度高、機構設計 1281070 本發明直下式背光模組包括至少一燈管、部分圍繞燈 管之燈罩、擴散板及反射元件。該至少一燈管及燈罩係位 於反射元件與擴散板所界定之區域内，該燈罩包括基材及 設置於基材之複數擴散點，該複數擴散點係印刷於基材表 面之光學透明粒子，且燈罩位於燈管與擴散板之間，燈管 發出之光線經燈罩作用後傳輸至擴散板並轉換成均勻之平 面光。 與先前技術單純採用擴散板來均勻出射之光束相比， 本發明直下式背光模組由於採用位於燈管與擴散板之間的 燈罩，燈管發出之光線經燈罩進行透射及折射作用進行均 化後再傳輸至擴散板，可有效提昇直下式背光模組之出光 均勻度；並且本發明相對先前技術之具複數通道之反射框 體而言還具有機構設計簡單的優點。 【實施方式】 請參閱第三圖，本發明直下式背光模組100包括複數 燈管101、部分圍繞燈管101之燈罩102、擴散板103及反 射元件104。該燈管101及燈罩102係位於反射元件104 與擴散板103所界定之區域内，且燈罩102位於燈管101 與擴散板103之間，燈管101發出之光線經燈罩102作用 後傳輸至擴散板103並轉換成均勻之平面光。 該燈管101可為冷陰極螢光燈，其相較於其他光源技 術具有輝度較高且發光效率高、管徑細、壽命長等優點。 該燈管101之管徑約為10mm，功率約為8-29w，壽命長 達lOOOOhrs，光通量約為35-901m。 1281070 該燈管101之發光原理與日光燈管相似，依靠燈管101 内氣體原子的能態轉換成輻射發光。最常用的放電介質為 汞蒸氣，燈管101内會填充惰性氣體如Ar、Kr、Ne等輔 助啟動，燈管101内的遊離電子被電場加速而激發Ar原 子，受激的Ar再使汞原子遊離而放出輻射能，主要產生 253.7nm 與 185nm 兩種紫外光（UV-Radiation)，其中 235.7 nm之輻射效率最大，經激發管壁之螢光體後發光，藉由調 整螢光體之配方，可發出不同色溫的光線，如偏紅或偏藍 以符合不同顯示器之要求。 請參閱第四圖，該燈罩102係採用光學透光材質製 成，可選用光學級丙烯酸類聚合物、高分子聚合物、高分 子碳化物、玻璃或石英其中之一。該燈罩102大致呈圓弧 柱狀，包括基材121及其上設置之複數擴散點122，該複 數擴散點122係微透鏡，依據光線輝度與距離平方成反比 之原理分佈於基材121表面，即對應光線傳輸距離較遠處 之擴散點122較大，且對應光線傳輸距離較遠處之擴散點 122亦可分佈較密，從而使光線經其折射及透射後均勻化 分佈，進而提昇直下式背光模組100之出光均勻度。惟， 該複數擴散點122亦可係印刷於基材121表面之光學透明 粒子，其可為圓球狀、橢圓球狀或矩形狀其中之一。 請復參閱第三圖，該擴散板103呈平板狀，其功用在 於使燈管101發出之光束及經燈罩102傳輸之光束透過其 内部時產生充分散射，從而使光均勻化。該擴散板103 — 般包括基片及形成於基片之擴散層，基片採用光透過率較 1281070 同之材料製成，其用以充當擴散層之載體。該擴散層採 一般導光塑料如 PMMA ( P〇lymethyl Methacrylate，聚甲美 丙烯酸曱酯）或PC ( P〇lyCarbonate，聚碳酸酯）等製 同時混雜散射粒子。.准，該擴散層亦可係藉由印刷^理方 法於基片之表面形成之複數凸出散射點，散射點所採 材料為高發散光物質，其形狀可為柱狀、球狀或四面體， 可均勻分佈於基片之表面，其使入射之光束發生散射及折 射，使光束由擴散板103之表面均勻出射，進而得到平面 光。 該反射元件104用於收容燈管1〇1與燈罩1〇2，並於 表面鑛覆反射膜以使投射於其上之光線反射，防止光線自 反射元件104之表面逸出’從而提高光能利㈣，增加直 下式背光模組100之出光輝度。 請-併參閱第五圖，工作時，燈管101發出光線，部 分光線直接入射至燈罩搬，其餘光線經反射元件104反 射，入射至燈罩102及擴散板103,該燈罩102部分包圍 燈管101，使投射於其上之光線經擴散點122進行透射與 折射㈣輸至㈣板1()3’擴散板⑽散射其接收之光線: 使其均句分佈於出光區域，形成所需之平面光。 綜上所述，本發明確已符合發明專利要件，疫依法提 出專利申請。惟，以上所述者僅為本發明之較佳實施方式， 舉凡U案技藝之人士’在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】 1281070 第一圖係先前技術直下式背光模組之剖視圖。 第二圖係第一圖所示直下式背光模組之部分光路圖。 第三圖係本發明直下式背光模組之立體圖。 第四圖係第三圖所示燈罩之立體圖。 第五圖係本發明直下式背光模組之光路示意圖。 【主要元件符號說明】 背光模組 100 燈管 101 燈罩 102 擴散板 103 反射元件 104 基材 121 散射點 122 111281070 IX. Description of the invention: [Technical field to which the invention pertains] The present invention relates to a backlight module, and more particularly to a direct-lit backlight module using a lamp with a high degree of uniformity of light output. [Prior Art] Because of its advantages of lightness, thinness, and low power consumption, liquid crystal display devices are widely used in modern information devices such as notebook computers, mobile phones, and personal digital assistants. Since the liquid crystal in the liquid crystal display itself does not have a luminescent property, it is required to provide a moonlight 杈 group to realize the display function. The backlight module can be divided into two types according to the structure: a side backlight module and a direct backlight module. Among them, the direct type backlight module is mainly used in the fields of LCD monitors or LCD TVs. As is known, the direct-lit backlight module needs to have a high light-emitting brightness, and the second light-emitting uniformity should reach a predetermined requirement, thereby improving the color contrast of the liquid crystal display, the brightness effect of the full-screen area, and the viewing angle of the whole machine. The power consumption and cost should be reduced as much as possible. In addition, in order to meet the requirements of light and thin liquid crystal displays, the structural design cannot be too complicated. The direct-lit backlight module of the prior art generally includes a plurality of light-emitting diodes: an array of light sources and a scattering panel disposed on the side of the light-emitting surface of the light source array. The direct-lit backlight module using the light-emitting diode has the defects of high light-emitting height and the cost of the direct-type backlight module; the light field distribution is symmetrical, and the uniformity of light output is difficult to meet the demand of the liquid crystal display. In order to match the scattering panel, the design of the (four) complex light-emitting diodes is required to make the light source array bulky, complicated in structure and large in power consumption, and affect the overall light uniformity when a certain first-pole body fails. 1281070 Therefore, the industry has developed a direct-lit backlight module that uses a lamp as a light source. A prior art direct-lit backlight module can be found in U.S. Patent No. 5,479,328, the entire disclosure of which is incorporated herein by reference. The direct-type moonlight module 10 provides illumination for the liquid crystal display panel 2, including a spiral tube (Serpentine Tube) 12, a reflective frame 14, a glass substrate 15, a diffusion plate 17 disposed on the glass substrate 15, and a brightness enhancement sheet. 18, the spiral lamp 12 is nested in a plurality of channels (not labeled) of the reflection frame 14. The brightness enhancing sheet 18 is opposed to the liquid crystal display panel 2 by an air gap 19. However, since the direct-lit backlight module 1 simply uses the diffuser plate to uniformly emit the light beam, that is, the uniformity of the light output depends on the quality of the diffuser plate 17, and the control thereof is difficult, and the uniformity of light emission is not ideal. Please read the second picture together, because the brightness distribution of the light emitted by the lamp U is inversely proportional to the square of the square. The beam of the 1G beam emitted by the direct-type backlight module is formed on the surface of the diffuser plate according to the difference in light transmission distance. The distribution of the average. In addition, the prior art direct-lit backlight module 10 has the following defects: t improving the light-emitting uniformity as much as possible. The design of the reflective frame 14 is not complicated by the complexity of the structure of the direct-type moonlight module 10; The shape of the shaped tube 12 is complicated, the production is difficult, and the price and power consumption are high. In view of this, it is necessary to provide a direct-lit backlight module with a high light-emitting hook and a simple mechanism design. SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple direct type backlight module. A light-emitting uniformity and mechanism design 1281070 The direct-lit backlight module of the present invention comprises at least one lamp tube, a lamp cover partially surrounding the lamp tube, a diffusion plate and a reflective element. The at least one tube and the lamp cover are located in a region defined by the reflective element and the diffuser plate, and the lamp cover comprises a substrate and a plurality of diffusion points disposed on the substrate, the plurality of diffusion points being optically transparent particles printed on the surface of the substrate, The lampshade is located between the lamp tube and the diffuser plate, and the light emitted by the lamp tube is transmitted to the diffuser plate through the lampshade and converted into uniform planar light. Compared with the light beam which is uniformly emitted by the prior art by using the diffusion plate, the direct type backlight module of the present invention uses the lamp cover between the lamp tube and the diffusion plate, and the light emitted by the lamp tube is homogenized by transmission and refraction of the lamp cover. After being transmitted to the diffusion plate, the light uniformity of the direct type backlight module can be effectively improved; and the invention has the advantages of simple mechanism design compared with the reflection frame of the prior art with multiple channels. [Embodiment] Referring to the third figure, the direct type backlight module 100 of the present invention includes a plurality of lamps 101, a lamp cover 102 partially surrounding the lamp tube 101, a diffusion plate 103, and a reflection member 104. The lamp tube 101 and the lamp cover 102 are located in the area defined by the reflective element 104 and the diffuser plate 103, and the lamp cover 102 is located between the lamp tube 101 and the diffuser plate 103. The light emitted by the lamp tube 101 is transmitted to the diffusion through the lamp cover 102. The plate 103 is converted into uniform planar light. The lamp tube 101 can be a cold cathode fluorescent lamp, which has the advantages of high luminance, high luminous efficiency, thin tube diameter, long life, and the like compared with other light source technologies. The tube 101 has a diameter of about 10 mm, a power of about 8-29 W, a life of up to 100 hrs, and a luminous flux of about 35-901 m. 1281070 The light-emitting principle of the lamp 101 is similar to that of a fluorescent tube, and the energy state of the gas atoms in the lamp 101 is converted into radiation. The most commonly used discharge medium is mercury vapor. The lamp 101 is filled with an inert gas such as Ar, Kr, Ne, etc., and the free electrons in the lamp 101 are accelerated by the electric field to excite the Ar atom, and the stimulated Ar causes the mercury atom. Free and emit radiant energy, mainly producing 253.7nm and 185nm UV-Radiation, of which 235.7 nm has the highest radiation efficiency, and after emitting the phosphor of the excitation tube wall, by adjusting the formula of the phosphor, Lights of different color temperatures, such as reddish or bluish, can be emitted to meet the requirements of different displays. Referring to the fourth figure, the lampshade 102 is made of an optically transparent material, and one of optical grade acrylic polymer, high molecular polymer, high molecular weight carbide, glass or quartz can be selected. The lampshade 102 is substantially in the shape of a circular arc, and includes a substrate 121 and a plurality of diffusion points 122 disposed thereon. The plurality of diffusion points 122 are microlenses, and are distributed on the surface of the substrate 121 according to the principle that the light luminance is inversely proportional to the square of the distance. That is, the diffusion point 122 corresponding to the distance of the light transmission distance is larger, and the diffusion point 122 corresponding to the distance of the light transmission distance can also be densely distributed, so that the light is evenly distributed after being refracted and transmitted through the light, thereby improving the direct type. The light uniformity of the backlight module 100. However, the plurality of diffusion dots 122 may be optically transparent particles printed on the surface of the substrate 121, and may be one of a spherical shape, an elliptical shape, or a rectangular shape. Referring to the third drawing, the diffusing plate 103 has a flat shape, and its function is to make the light beam emitted from the lamp tube 101 and the light beam transmitted through the lamp cover 102 pass through the inside thereof to sufficiently scatter, thereby homogenizing the light. The diffusion plate 103 generally comprises a substrate and a diffusion layer formed on the substrate. The substrate is made of a material having a light transmittance higher than that of 1281070, and serves to serve as a carrier for the diffusion layer. The diffusion layer is made of a common light-guiding plastic such as PMMA (P〇lymethyl Methacrylate) or PC (P〇ly Carbonate, polycarbonate). The diffusion layer may also be a plurality of convex scattering dots formed on the surface of the substrate by a printing method. The material of the scattering point is a high divergent material, and the shape may be a columnar shape, a spherical shape or a tetrahedron. It can be evenly distributed on the surface of the substrate, which scatters and refracts the incident light beam, so that the light beam is uniformly emitted from the surface of the diffusion plate 103, thereby obtaining planar light. The reflective element 104 is configured to receive the lamp tube 1〇1 and the lamp cover 1〇2, and to cover the surface of the reflective film to reflect the light projected thereon to prevent light from escaping from the surface of the reflective element 104 to improve light energy. (4), increasing the brightness of the direct-lit backlight module 100. Please refer to the fifth figure. During operation, the lamp 101 emits light, part of the light is directly incident on the lamp cover, and the remaining light is reflected by the reflective element 104, and is incident on the lamp cover 102 and the diffusion plate 103. The lamp cover 102 partially surrounds the lamp tube 101. The light projected thereon is transmitted and refracted by the diffusion point 122. (4) The (4) plate 1 () 3' diffuser plate (10) scatters the light it receives: distributes the average sentence in the light exiting area to form the desired planar light. . In summary, the present invention has indeed met the requirements of the invention patent, and the patent application is filed in accordance with the 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 in the spirit of the present invention should be included in the following claims. [Simple description of the diagram] 1281070 The first figure is a cross-sectional view of a prior art direct type backlight module. The second figure is a partial optical path diagram of the direct type backlight module shown in the first figure. The third figure is a perspective view of the direct type backlight module of the present invention. The fourth figure is a perspective view of the lampshade shown in the third figure. The fifth figure is a schematic diagram of the optical path of the direct type backlight module of the present invention. [Main component symbol description] Backlight module 100 Lamp 101 Lamp cover 102 Diffuser plate 103 Reflecting element 104 Substrate 121 Scattering point 122 11