1241440 玫、發明說明 【發明所屬之技術領域】 本發明與一種液晶顯示器有關，特別是與一種可改善 液晶顯示斋之直下式背光源均勻性之結構有關。 【先前技術】 液晶顯示 (LCD:Liquid Crystal Display)本身不會發 光因此必需借助外部光源，尤其是穿透式TFT(Thin FUm Transistor)彩色液晶顯示器通常會使用背光板丨丨眇丈) 作為照明光源。而背光照明模組的光線來源則為具有三波 長的冷陰極燈管（CCFL:Cold Cathode Fluorescernt Lamp) 或疋叙光一極體（LED:Light Emitting Diode)等。其中冷陰 極燈官具有咼輝度、高效率、壽命長、高演色性等特性， 加上圓柱狀外形因此很容易與光反射元件組合成薄板狀 照明器’廣被應用於平面顯示器（FpD:Flat panel Display)。 光源杈組可分為背光式（back type )與前光式听⑽t t^e)兩種；其中背光式可依照光線入射位置的不同分成 端緣^光（edge lighting)與直下式入光（direct Ughting)兩 ^。端緣入光式背光模組的照明輝度非常均勻，模組外形 二又也很銓薄，光使用效率大約在5左右，適合可攜式 心 使用。而直下式背光模組的光源效率大約在6 0 % 1241440 左右，由於模組外形厚度較厚重，因此常用於桌置型lcd 顯示器（monitor)或是液晶電視等非可攜式產品。如果lcd 超過1 7彳以上日^ ’直下式背光板的重量&而比端緣式背 光板模組輕巧。因此，對於未來大尺寸之液晶電視使用直 下式％光模組將是一種趨勢。 參閱第1A圖所示為傳統直下式背光模組概略上視 圖’複數條冷陰極燈管1〇〇以平行排列之方式提供背光给 液晶面板（圖巾未展示出），參閱第1B圖所示為由第1A 圖AA線看入之傳統直下式背光模組概略剖視圖，光源由 冷陰極燈f 1〇〇射出後，經由反射片1〇2反射後，向上經 擴散板UM均句分散後於正面射出，其中擴散板_主要 功能是將經由反射4 1()2反射後的光線做散射處理。由於 直下式背光模組複數燈管依序排列於液晶面板正下方，因 此燈管的輪廓極易纟LCD畫面上造成輝度不均與陰影。 因此，極需有一種背光模組結構來解決上述之問題'和 【發明内容】 敕要目的在提供一種背光模組結構，藉由調 整月光杈組中燈管高度來提高發射光線之均勻度。 本發明的另一目的即是提供一種可產生均勻意产之 背光方法，改善因為不均勻之背光亮度所 :=之 影鄕。 取旦面品質之 1241440 切明之提升背光結構，將最接近背板 之兩根冷陰極燈瞢撼田 Ά用不^度之排列，讓其更接近擴散 產生輝度不均與陰影 特疋處 實施方式 、第圖所不為根據本發明較佳實施例所形成之直下 式背光模組概略分解圖。其中，在一背板2〇6上，排列有 多條冷陰極燈管（CCFL) 2〇〇,作為背光源，其中此背光 源亦可使用發光：極體（LED )、有機發光二極體 ED )鹵鎢燈、電致發光（ELD )、陰極發射燈（) 和金屬鹵化物燈來提供；一擴散板2〇4位於冷陰極燈管 2〇〇的上方，其主要功能是在於提高正面的亮度，並且讓 冷陰極燈管200發射的光線分佈更加均勻。 、第2B圖所示為由第2A圖AA，線看入之本發明直下 式月光模組概略剖視圖，光源由冷陰極燈管2⑽射出後， 經由反射片202反射後，向上經擴散板2〇4均勻分散後於 正面射出。由於本發明之直下式被光模組除了使用傳統之 反射片202外，另將最接近背板2〇6兩側之兩根冷陰極燈 管200採用不同高度之排列，讓發射出之光線更加趨近於 擴散板204，並避免於液晶面板之週邊產生輝度不均與陰 影之情況。 參閱第3圖所示為根據本發明較佳實施例可提升背 1241440 光均勻性之背光模組剖面放大圖。光源由冷陰極燈管2〇〇 射出後，經由反射片202反射，向上經擴散板2〇4均勻分 散後於正面射出，其中最接近背板2〇6兩側之兩根冷陰極 燈管200a與200b，和中間之冷陰極燈管2⑽係採用不同 南度排列，其中冷陰極燈管2〇〇a與擴散板2〇4間之距離 為a，冷陰極燈管2〇〇b與擴散板2〇4間之距離為b，而中 間之冷陰極燈管200與擴散板2〇4間之距離則為c。由於 一般面板輝度之分佈，於最外側處通常低於中心位置，因 此本發明將兩側之兩根冷陰極燈管2〇(^與2〇〇b之擺放位 置高度向上提升，使其更接近擴散板2〇4，藉以增加面板 兩側之輝度，如苐4圖所示，利用本發明之結構，可使得 側邊之輝度值約為中心位置輝度值之86%至96%。 第5圖描繪了利用本發明之結構進行改善前後之輝 度分佈比較圖，由圖中可明顯看出，未經改善之背光模 組’其輝度分佈於面板兩侧會形成急遽之下降，而再經過 本發明之結構改善後，其輝度值於面板兩側將獲得提升， 而約為中心位置輝度值之86%至96%，明顯改善傳統結構 所造成輝度分佈不均之缺點。 根據本發明之較佳實施例，冷陰極燈管200a提升之 巧度係高於冷陰極燈管200約1至5毫米（mm)，而冷陰 極燈官200b提升之高度則高於冷陰極燈管2〇〇約0.5至2 笔米（mm )，而各冷陰極燈管相對於擴散板間之距離關係 則為c>b>a。 綜合上述所言，本發明之背光模組，其燈源除了使用 1241440 傳統之反射片進行反射外，另將最接近背板兩側之兩根冷 陰極燈管採用不同高度之排列，讓其更接近擴散板，藉以 曰加面板兩側之輝度，避免於液晶面板之週邊產生輝度不 均與陰影之情況。 、=然本發明已以一較佳實施例揭露如上，然其並非用 X限^本毛月，任何熟習此技藝者，在不脫離本發明之精 神和範圍内，當可#欠 田』作各種之更動與潤飾，因此本發明之 護範圍當視後附之申士主直丨a ’、 心甲明專利耗圍所界定者為準。 【圖式簡單說明】 第：：圖所示為傳統直下式背光模組概略 ； 弟1B圖所示為由楚 ^ ^ ^ , 、 圖AA’線看入之傳統直下式 月光杈組概略剖視圖； 飞 第2A圖所示為根據本發明較佳實施 拉組概略分解圖； 卜A月光 第2B圖所示為第2A圖 背光模組概略剖視圖； '、、 鲞明直下式 面放大圖； 第3圖所示為根據本發明較佳實施例之背光模組剖 之輝度值比鉍同甘上 1J ^ 車乂圖，其中側邊之輝度值約為中 之86%至96% ;以及 ^值、、、勺為中 !Λ圖為根據本發明較佳實施例之側邊與中心位置 〇位置輝度值 第5圖描繪了利用本發 明之結構進行改善前後之輝 1241440 度分佈比較圖。 【元件代表符號簡單說明】 100，2 00，2 00a和2 00b冷陰極燈管 102和202反射片 104和204擴散板 206背板 a，b，c冷陰極燈管和擴散板間之距離1241440 Description of the invention [Technical field to which the invention belongs] The present invention relates to a liquid crystal display, and more particularly to a structure that can improve the uniformity of a direct type backlight of a liquid crystal display. [Prior technology] Liquid crystal display (LCD: Liquid Crystal Display) itself does not emit light, so external light sources must be used, especially the transmissive TFT (Thin FUm Transistor) color liquid crystal display usually uses a backlight board 丨. The light source of the backlight module is a three-wavelength cold cathode lamp (CCFL: Cold Cathode Fluorescernt Lamp) or a light emitting diode (LED: Light Emitting Diode). Among them, the cold cathode lamp has the characteristics of high brightness, high efficiency, long life, and high color rendering. In addition to the cylindrical shape, it can be easily combined with light reflecting elements to form a thin plate-shaped illuminator. panel Display). The light source can be divided into two types: backlight type (back type) and front light type (t t ^ e); the backlight type can be divided into edge lighting (edge lighting) and direct light type ( direct Ughting) two ^. The edge-light type backlight module has a very uniform illumination brightness, and the module shape is also very thin. The light use efficiency is about 5, which is suitable for portable use. The light source efficiency of the direct type backlight module is about 60% 1241440. Because the module has a thick profile, it is often used in non-portable products such as desktop LCD monitors and LCD TVs. If the LCD exceeds 17 1 or more, the weight of the direct type backlight panel is lighter than the edge-type backlight module. Therefore, it is a trend to use direct-type% optical modules for future large-size LCD TVs. Refer to FIG. 1A for a schematic top view of a conventional direct-type backlight module. A plurality of cold-cathode lamps 100 provide backlight to the LCD panel in a parallel arrangement (not shown). Refer to FIG. 1B A schematic cross-sectional view of a conventional direct-type backlight module viewed from line AA in FIG. 1A. After the light source is emitted from the cold cathode lamp f 100, it is reflected by the reflective sheet 10, and then dispersed upward by the diffuser plate UM uniform sentence. It is emitted from the front, wherein the main function of the diffuser plate is to scatter the light reflected by the reflection 4 1 () 2. Since the plurality of direct-type backlight modules are sequentially arranged directly below the liquid crystal panel, the outline of the lamps is very likely to cause uneven brightness and shadows on the LCD screen. Therefore, there is a great need for a backlight module structure to solve the above problems' and [Summary of the Invention] [1] The main purpose is to provide a backlight module structure to improve the uniformity of the emitted light by adjusting the height of the lamp tube in the moonlight branch group. Another object of the present invention is to provide a backlight method capable of producing uniform production, and to improve the influence of the == due to the uneven brightness of the backlight. Based on the quality of the 1241440 clear backlight structure, the two cold cathode lamps closest to the back panel are arranged in different degrees, so that they are closer to the diffusion to produce uneven brightness and shadows. The diagram in FIG. 2 is not a schematic exploded view of a direct type backlight module formed according to a preferred embodiment of the present invention. Among them, a plurality of cold cathode fluorescent lamps (CCFLs) 200 are arranged on a back plate 206 as a backlight source, and the backlight source can also use light emission: LEDs, organic light emitting diodes ED) provided by tungsten halogen lamp, electroluminescence (ELD), cathode emission lamp () and metal halide lamp; a diffusion plate 204 is located above the cold cathode lamp tube 200, and its main function is to improve the front Brightness, and make the light emitted by the cold cathode lamp 200 more uniform. Figure 2B is a schematic cross-sectional view of the direct-type moonlight module of the present invention viewed from line AA of Figure 2A. After the light source is emitted from the cold cathode tube 2⑽, it is reflected by the reflection sheet 202 and then passes upward through the diffuser 2. 4 It is ejected on the front side after being evenly dispersed. In addition to the conventional reflecting sheet 202 of the direct type light module of the present invention, the two cold cathode lamp tubes 200 closest to the two sides of the back plate 206 are arranged at different heights to make the emitted light more It approaches the diffuser plate 204 and avoids uneven brightness and shadows around the liquid crystal panel. Referring to FIG. 3, an enlarged cross-sectional view of a backlight module capable of improving light uniformity of the back 1241440 according to a preferred embodiment of the present invention is shown. After the light source is emitted from the cold cathode lamp 200, it is reflected by the reflecting sheet 202, and is evenly dispersed upward by the diffuser plate 204, and then emitted from the front, among which the two cold cathode lamp 200a closest to the two sides of the back plate 206 And 200b, and the middle cold cathode lamp 2 are arranged in different south degrees, where the distance between the cold cathode lamp 200a and the diffuser plate 204 is a, and the cold cathode lamp 200b and the diffuser plate The distance between 204 is b, and the distance between the middle cold cathode tube 200 and the diffuser plate 204 is c. Because the brightness distribution of the general panel is usually lower than the center position at the outermost side, the present invention raises the height of the two cold cathode lamp tubes 20 (^ and 2000b) on both sides to increase the height. Close to the diffuser plate 204 to increase the brightness on both sides of the panel, as shown in Figure 4, using the structure of the present invention, the brightness value at the side can be about 86% to 96% of the brightness value at the center. The figure depicts a comparison of the brightness distribution before and after improvement using the structure of the present invention. It can be clearly seen from the figure that the brightness distribution of the unimproved backlight module's distribution on both sides of the panel will cause a sharp drop, and then pass through this After the structure of the invention is improved, its brightness value will be improved on both sides of the panel, which is about 86% to 96% of the central location brightness value, which obviously improves the disadvantage of uneven brightness distribution caused by the traditional structure. In the embodiment, the degree of promotion of the cold cathode lamp 200a is about 1 to 5 millimeters (mm) higher than that of the cold cathode lamp 200, and the height of the cold cathode lamp 200b is higher than that of the cold cathode lamp 200 by about 0.5. Up to 2 meters (mm) with each cold cathode The distance relationship between the lamp tube and the diffuser plate is c > b > a. In summary, in the backlight module of the present invention, in addition to using the 1241440 traditional reflection sheet for reflection, the light source will be closest to the back plate. The two cold cathode lamp tubes on the two sides are arranged at different heights to make them closer to the diffuser plate, so as to increase the brightness of the two sides of the panel to avoid the occurrence of uneven brightness and shadows around the LCD panel. The invention has been disclosed as above with a preferred embodiment, but it is not limited by X ^ this hair month. Anyone skilled in this art can make various modifications and decorations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims of Zhishi Zhuo 丨 a ′ and Xin Jiaming patent consumption. [Simplified illustration of the figure] Section: The picture shows the outline of a traditional direct-type backlight module Figure 1B shows a schematic cross-sectional view of a traditional straight-down moonlight branch group viewed from the line ^^^^, Figure AA '; Figure 2A shows a schematic exploded view of a pull group according to a preferred embodiment of the present invention; A Moonlight Picture 2B FIG. 2A is a schematic cross-sectional view of a backlight module; FIG. 3 is an enlarged view of a straight-down type surface; FIG. 3 illustrates a backlight module according to a preferred embodiment of the present invention; Figure, where the luminance value of the side is about 86% to 96%; and ^, ,, and spoon are medium! Λ is the fifth position luminance value of the side and the center position according to the preferred embodiment of the present invention. The figure depicts a comparison of the distribution of glow 1241440 degrees before and after improvement using the structure of the present invention. [Simple description of the element representative symbols] 100, 2 00, 2 00a, and 2 00b cold cathode lamp tubes 102 and 202 reflectors 104 and 204 diffuser plates 206 Backplane a, b, c Distance between cold cathode tube and diffuser