1282881 五、發明說明（3) 來使來自該光源之光朝向外部透過；其特徵是：在該透光 構件形成有成爲照明遮屏之遮光圖案，用來對強光範圍進 ί了遮光藉以提尚光之均一性；和該遮光圖案之至少一部份 由導電體形成和被接地。 依照此種第2手段時，因爲照明遮屏兼作防止帶電之導 電體，所以可以避免由於導電體而隨便的阻礙該光。 另外，本發明所採用之第3技術性手段是提供一種照明 裝置，在擴散板之背面側配置有多個線狀光源，被使用作 爲液晶顯示裝置用之正下型背照燈；其特徵是：在該擴散 板設有成爲照明遮屏之遮光圖案，用來對來自線狀光源之 強光範圍進行遮光藉以提高光之均一性；和該遮光圖案之 至少一部份由導電體形成和被接地。 依照此種第3手段時，因爲照明遮屏兼·作防止帶電用之 導電體，所以可以避免由於導電體而隨便的阻礙該光。 另外，該遮光圖案最好在線狀光源之正上附近，沿著線 狀光源之長度方向連續的形成，或是最好使在多個線狀光 源之正上附近沿著線狀光源之長度方向連續形成之多個遮 光圖案，利用被設該擴散板之周緣部之連接部，形成互相 電連接。另外，最好使該連接部設在該擴散板之背面，經 由將該連接部設置成連接在由導電體構成之照明裝置外罩 ，用來使遮光圖案接地。 [發明之實施例] 下面將根據圖面用來說明本發明之實施例。 第1圖表示照明裝置之一實例之成爲面發光裝置之正下 1282881 五、發明說明（4) 型背照燈1。該背照燈作爲液晶顯示裝置用。 正下型背照燈1被構建成爲在照明裝置本體之外罩2(亦 稱爲「底盤」）內，配置多根之線狀光源3，由作爲光源之 細長之陰極放電管構成。 外罩2由金屬之導電性材料形成，從矩形狀之底面2a之 四邊分別立起有側壁2b，形成上方爲開口狀之箱形。在收 納線狀光源3之外罩2之內部形成光之反射層（圖中未顯示） ，具有白色光等之反射率良好之色彩。因此，從光源3發 出之光，直接或被反射層反射的從外罩2之上方開口朝向 外部照射。 多個線狀光源3在該外罩2內被設置成互相平行和隔開 指定之間隔。各個光源3連接到由反相器等構成之電源電 路5。另外，電源電路5之地線部被接地，連接到由導電 性材料構成之外罩2。 在外罩2之上部設置有形成板狀之擴散板6，其材料是 使光擴散性之微粒子散布在丙烯酸樹脂等之透明樹脂。另 外，亦可以依照需要在擴散板6之上設置擴散片等之光片 。擴散板6具有透光性和光之擴散作用，擴散板6之面成 爲來自光源3之光所照射之出光面。另外，擴散板6是具 有透光性之用來使光透過到裝置1之外部之透光構件 如第2圖所示，在擴散板6之背面（光源側之面）6b，形 成有作爲照明遮屏之不透明之遮光圖案8。照明遮屏用來 消除在光源3正上方之光之強亮，和在光源間之位置之光 變成較弱暗之光之明暗之差異，在光源正上之位置使遮光 1282881 五、發明說明（5) 圖案8之面積變大，在光源間使遮光圖案8之面積變小， 用來提高光之均一性。 在第2圖中，擴散板6之背面側之光源3是細長線狀光 源，與此對應的，在各個光源3之正上附近之位置，施加與 線狀光源3平行之成爲照明遮屏之遮光圖案8。另外，線狀光 源3具有多根，與其對應的，形成有多根之遮光圖案8。另外 ，該照明遮屏由鋁等之導電性材料形成。 第3圖是第2圖之箭頭A部份之擴大圖，用來表示照明 遮屏之圖案例。第3(a)圖是第1例，在光源3之正上附近 ，具有大面積之圖案（以下亦稱爲遮光元件）8a，隨著從光 源3之正上附近偏離，成爲光源間之位置，變成爲小面積 之遮光元件8b，8c，8d。 第3(b)圖是第2例，在該第2例中，在光源之正上附近 具有大面積之遮光元件8e，隨著從光源3之正上附近偏離 ，成爲光源間之位置，變成爲小面積之遮光元件8f，8g。 另外，第3(a)，（b)圖之上下方向對應到線狀光源3之長度 方向。 在本發明中，爲著防止由非導電性材料構成之容易帶電 之擴散板6之帶電，所以使導電體接觸在擴散板6，將該 導電體接地，用來使擴散板6所帶之電洩漏到地線。 在利用導電體之接觸用來防止帶電之情況時，假如要有 效的防止帶電，最好是使導電體接觸在擴散板6全體，但 是當導電體意外的接觸在成爲透光構件之擴散板6時，由 於導電體之遮光，會使擴散板6之光之透過率降低。 1282881 五、發明説明（6 ) 在本實施例中，因爲構成照明遮屏之遮光元件8a ’ 8b ，8c，8d，8e，8f，8g使用導電性材料，所以照明遮屏兼 作帶電防止用之導電體，因此不會發生光之透過率之降低 之問題，可以使導電體接觸在擴散板6。換言之’因爲在 強光之光源之正上附近配置導電體，所以被導電體遮光之 問題很少。 在此處亦可以使擴散板6所具有之遮光元件全部接地， 但是在第3(a)，（b)圖之實例中’不是使全部之遮光兀件接 地。在第3(a)圖中，在光源3之正上位置之遮光元件8a， 形成與線狀光源3平行的連續延伸，該遮光元件8a被接 地，成爲接地用遮光元件。其以外之遮光元件8b，8c，8d 分散的存在於擴散板6上，與該接地用遮光元件電分離的 存在，成爲未接地之非接地用遮光元件。 另外，在第3(b.)圖中，光源3之正上位置之分散存在之 多個遮光元件8e，被比該遮光元件8e細之導電體配線型 樣1 〇電連接，成爲與線狀光源3平行連續延伸之接地用 遮光元件。其以外之遮光元件8f，8g分散的存在於擴散 板6上，成爲與接地用遮光元件電分離存在之非接地用遮 光元件。另外，在第3(b)圖中，遮光元件8e之一邊爲 1.2mm，配線型樣10之幅度爲〇.2mm。 與線狀光源3平行延伸所形成之接地用遮光元件8a，8e ，1 0，與多個線狀光源3對應的，存在於多個位置，接地 用遮光元件之長度方向端部，被由導電體構成之連接部1 2 進行互相電連接。連接部1 2被設在擴散板6之周緣部β 1282881 五、發明說明（7) 在背照燈1因爲出光面之周緣部爲非發光部，所以在非發 光部之擴散板6之周緣部，即使具有連接部1 2時，遮光 之問題亦很少。 另外，連接部1 2被設在擴散板6之與線狀光源3正交 之2個邊，但是亦可以在與線狀光源3平行之2個邊具有 導電體1 3。亦即，可以在非發光部之擴散板6之周緣全體 形成導電體12，13，其中遮光圖案8(包含配線圖案10)， 連接部1 2，導電體1 3全部成爲電連接狀態（具有相同之電 位）。 遮光圖案8(包含配線圖案10)，連接部12，導電體13， 經由導電材料之印刷和蒸著被施工在擴散板6成爲薄膜狀 〇 在印刷，特別是絲網印刷之情況時，因爲可大量生產之 遮光元件之最小點直徑爲〇.2mm，所以可以使光源之正上 附近和非發光面以配線連接導電體。 另外，在蒸著之情況時，因爲可以使最小蒸著直徑充分 的變小，所以離開光源正上附近之遮光元件亦可以以細導 電體配線圖案進行連接。 另外，施加遮光圖案8，連接部12，導電體13之方法 並不只限於印刷·蒸著。 具有遮光圖案8之擴散板6被設置在外罩2,使第4圖所示 之具有遮光圖案8之面6b成爲在光源側（下側）。該擴散板6 被設置成使其周緣接合和支持在形成於外罩2之上端緣 之接受部1 5。因此，作爲照明遮屏之遮光圖案8，經 1282881 五、發明説明（9 ) 導電性材料構成之照明裝置。 .第8圖〜第1 1圖表示與正下型背照燈有關之其他技術 。當電視或超大型監視器使用液晶顯示裝置之情況時，要 求該背照燈單位具有廣視野角，高亮度和重量輕。爲著達 成該等要求，所以使用將光源配置在液晶之正下方之正下 型之背照燈。 在正下型背照燈中配置有多個光源3，從該光源射出之 光成爲被反射層（由高反射率之層形成）反射之光和直接光 之合成光’從照光面（出光面）照射。該合成光因爲成爲不 均一之亮度分布，所以爲著均一化，使成爲照光面之擴散 板和反射層之間保持大於一定之幅度。當作爲薄型用途時 ，因爲其間隔變狹，所以在擴散板黏貼作爲照明遮屏之構 件，或施加白色的點印刷，用來形成照明遮屏，藉以控制 亮度之均一性。 但是，照明遮屏之加工要具有高精確度，當黏貼或印刷 有偏移時就會發生不均一之亮度分布。另外，由於加工後 之擴散板之偏移亦會造成亮度分布之劣化。 第8圖〜第1 1圖所示之技術有關於未具有照明遮屏， 可以容易調整亮度之均一性之裝置。 與第1圖同樣的，第8圖之背照燈1在外罩2內配置有 互相平行之多個光源3，分別隔開指定之間隔。在外罩2 之內面，覆蓋有由高反射率之樹脂層或金屬層構成之反射 層（反射板）。在外罩2之上設置有形成板狀之擴散板6， 其材料是使光擴散性之微粒子散布在丙烯酸樹脂等之透明 -11- 1282881 五、發明説明（10 ) 樹脂。另外，擴散板6被從外罩2之底面立起之支持梢25 支持成爲不會彎撓之方式。在擴散板6之背面之光源3之 正上具有照明遮屏8，用來遮斷光源正上之光，藉以使亮 度分布均一化。 但是，在利用照明遮屏8使亮度均一化之對策中，要求 在加工時之位置調正具有高精確度，由於位置之偏移會如 第11(a)圖所示的使亮度分布劣化。另外，由於加工後之 擴散板6之偏移亦會使亮度分布劣化。 在第1 〇圖之背照燈中，經由將多個未具有照明遮屏之 擴散板6重疊的配置，在擴散板6，6之間產生折射率較 低之空氣層26，即使沒有照明遮屏亦可以使亮度均一之範 圍變廣（參照第11(b)圖）。另外，對發光面之任何角度均可 以使亮度分布成爲均一，不必擔心擴散板之偏移。另外， 使一片之擴散板6之厚度變厚時，亮度分布同樣的可以均 一化，但是亮度會降低。使多個擴散板6重疊成爲相同之 厚度時，可以抑制由於空氣層26造成之亮度之降低同時 可以使亮度分布均一化。擴散板6之片數最好爲2片。 第12圖〜第14圖表示正下型背照燈之其他技術。在背 照燈之外罩（筐體）2,當考慮到強度，散熱性，和遮光性等 之時，一般是使用金屬製者，但是使用金屬製之外罩2時 ，（1)會產生電能之洩漏到外罩2，產生電能之損失，（2)由 於洩漏之影響，光源3(燈泡）之點亮狀態會有大的變化， 燈泡壽命會產生差異，隨著時間而變化使亮度提早產生不 均。因此，會使作爲照明裝置和顯示裝置之壽命變短。 -12- 1282881 五、發明説明（11 ) 爲著消除此種問題，在第1 2圖〜第1 4圖所示之背照燈 ，使用塑膠，碳素樹脂，尿烷樹脂等之導電性比金屬低之 材料，用來形成外罩2，藉以達成洩漏之減小，和可以減 小燈泡點亮狀態之變化，藉以延長壽命。另外，因爲塑膠 等之材質之比重比金屬小，所以可以達成重量之減輕。另 外，對於材質，依照熱，可塑性，強度等設計上之要求， 可以進行各種選擇。 另外，如第1 3圖所示，亦可以在外罩2之背面等，形 成用以確保強度之翼助30。 另外，要確保強度時，在洩漏之影響較小，或可容許之 範圍•部位，亦可以使用導電性之材料。例如，如第14(b) 圖所示，亦可以在外罩2之角部安裝如第14(a)圖之金屬 製補強構件32。 [發明之效果] 依照本發明時，在擴散板等之透光構件不容易帶有靜電 ，可以減少灰塵之附著，可以防止隨著時間變化而造成之 發光品質之劣化。 另外，當設在擴散板等之透光構件之導電體兼作照明遮 屏之情況時，即使設有防止帶電用之導電體時，亦可以防 止發光品質之降低。 [圖面之簡單說明] 第1圖是本發明之背照燈之斜視圖。 第2圖是擴散板（透光構件）之光源側之面（背面）之斜視 圖。 -13- 1282881 五、發明說明（12) 第3圖是照明遮屏之遮光圖案。 第4圖是背照燈單位之側面圖。 第5圖是平面圖，用來表示用以確認本發明之效果之 實驗所使用之試料之擴散板，（A)是本發明之試料A，（B) 是比較例之試料B。 第6圖是用以表示實驗狀態之背照燈單位之側面圖。 第7圖是用以表示實驗結果之表。 第8圖是其他揭示例之背照燈單位，（a)是外罩等之斜 視圖，（b )是擴散板之背面圖。 第9圖是第8圖之背照燈單位之剖面圖。 第1 0圖是其他揭示例之背照燈單位之剖面圖。 第11圖（a)是第9圖之背照燈單位之亮度分布圖，（b) 是第1 〇圖之背照燈單位之亮度分布圖。 第1 2圖是其他揭示例之背照燈單位之剖面圖。 第13圖是第12圖之背照燈單位之底面圖。 第14圖（a)表示補強構件，（b)表示安裝有補強構件之 外罩之底面圖。 [符號之說明] 1 正下型背照燈單位 2 外罩 3 線狀光源 6 擴散板 8 遮光圖案（照明遮屏） 12 連接部 -14-1282881 V. INSTRUCTION DESCRIPTION (3) The light from the light source is transmitted to the outside; and the light-transmitting member is formed with a light-shielding pattern serving as an illumination mask for shielding the strong light range. The uniformity of the light; and at least a portion of the light-shielding pattern is formed by the electrical conductor and grounded. According to the second means, since the illumination mask also serves as a conductor for preventing electrification, it is possible to avoid the light from being easily blocked by the conductor. Further, a third technical means for use in the present invention is to provide an illumination device in which a plurality of linear light sources are disposed on the back side of a diffusion plate, and are used as a direct type backlight for a liquid crystal display device; The diffusing plate is provided with a light shielding pattern serving as an illumination mask for shielding a strong light range from the linear light source to improve light uniformity; and at least a portion of the light shielding pattern is formed by an electric conductor and Ground. According to the third means, since the illumination mask is used as the conductor for preventing electrification, it is possible to avoid the light being easily blocked by the conductor. In addition, the light shielding pattern is preferably formed continuously along the longitudinal direction of the linear light source, or preferably along the length of the linear light source in the vicinity of the plurality of linear light sources. The plurality of light-shielding patterns continuously formed are electrically connected to each other by a connection portion provided with a peripheral portion of the diffusion plate. Further, it is preferable that the connecting portion is provided on the back surface of the diffusing plate, and the connecting portion is provided to be connected to an illuminating device cover made of a conductor for grounding the light shielding pattern. [Embodiment of the Invention] Hereinafter, embodiments of the invention will be described based on the drawings. Fig. 1 shows an example of a lighting device which is a face light emitting device. 1282881 V. Inventive description (4) type backlight 1 is used. This backlight is used as a liquid crystal display device. The direct type backlight 1 is constructed such that a plurality of linear light sources 3 are disposed in the outer cover 2 (also referred to as "chassis") of the illuminating device main body, and are constituted by a slender cathode discharge tube as a light source. The outer cover 2 is formed of a metallic conductive material, and has side walls 2b rising from the four sides of the rectangular bottom surface 2a to form a box shape having an open top. A light reflecting layer (not shown) is formed inside the cover 2 of the linear light source 3, and has a color with good reflectance such as white light. Therefore, the light emitted from the light source 3 is directly or outwardly reflected from the upper opening of the outer cover 2, which is reflected by the reflective layer. A plurality of linear light sources 3 are disposed in the outer casing 2 so as to be parallel to each other and spaced apart by a specified interval. Each of the light sources 3 is connected to a power supply circuit 5 constituted by an inverter or the like. Further, the ground portion of the power supply circuit 5 is grounded and connected to the outer cover 2 made of a conductive material. A plate-shaped diffusing plate 6 is provided on the upper portion of the outer cover 2, and the material is a transparent resin in which light diffusing fine particles are dispersed in an acrylic resin or the like. Further, a light sheet such as a diffusion sheet may be provided on the diffusion plate 6 as needed. The diffusing plate 6 has a light transmitting property and a diffusing effect of light, and the surface of the diffusing plate 6 is a light emitting surface irradiated with light from the light source 3. Further, the diffusing plate 6 is a translucent member for transmitting light to the outside of the apparatus 1 as shown in Fig. 2, and is formed on the back surface (surface on the light source side) 6b of the diffusing plate 6 as illumination. The opaque shading pattern of the mask. The illumination mask is used to eliminate the strong light of the light directly above the light source 3, and the difference between the light and the position of the light between the light source becomes the difference between the light and the dark light, and the light is blocked at the position directly above the light source 1282881. 5) The area of the pattern 8 becomes large, and the area of the light-shielding pattern 8 is made small between the light sources to improve the uniformity of light. In Fig. 2, the light source 3 on the back side of the diffusing plate 6 is an elongated linear light source, and correspondingly, a position adjacent to the linear light source 3 is applied in the vicinity of the respective light sources 3 to become an illumination mask. Shading pattern 8. Further, a plurality of linear light sources 3 are provided, and a plurality of light shielding patterns 8 are formed corresponding thereto. Further, the illumination mask is formed of a conductive material such as aluminum. Fig. 3 is an enlarged view of the arrow A portion of Fig. 2, showing an example of the pattern of the illumination mask. The third example (a) is a first example. In the vicinity of the light source 3, a pattern having a large area (hereinafter also referred to as a light-shielding element) 8a is deviated from the vicinity of the light source 3 to become a position between the light sources. It becomes a small-area light-shielding element 8b, 8c, 8d. The second example is a second example. In the second example, the light-shielding element 8e having a large area in the vicinity of the light source is deviated from the vicinity of the light source 3, and becomes a position between the light sources. It is a small area shading element 8f, 8g. Further, the lower direction of the third (a) and (b) map corresponds to the longitudinal direction of the linear light source 3. In the present invention, in order to prevent the charging of the diffusing plate 6 which is easily charged by the non-conductive material, the conductor is brought into contact with the diffusing plate 6, and the conductor is grounded for the electric power of the diffusing plate 6. Leaked to the ground. When the contact of the conductor is used to prevent charging, if it is to be effectively prevented from being charged, it is preferable to make the conductor contact the entire diffusing plate 6, but when the conductor accidentally contacts the diffusing plate 6 which becomes the light transmitting member. At the time, the light transmittance of the diffusing plate 6 is lowered due to the light shielding of the electric conductor. 1282881 V. INSTRUCTION DESCRIPTION (6) In the present embodiment, since the light shielding members 8a' 8b, 8c, 8d, 8e, 8f, and 8g constituting the illumination mask are made of a conductive material, the illumination mask serves as a conductive for preventing electrification. Therefore, the problem of a decrease in the transmittance of light does not occur, and the conductor can be brought into contact with the diffusion plate 6. In other words, since the conductor is disposed in the vicinity of the light source of the strong light, there is little problem that the conductor is shielded from light. Here, it is also possible to ground all of the light-shielding members of the diffusing plate 6, but in the example of Figs. 3(a) and (b), it is not the case that all of the light-shielding members are grounded. In Fig. 3(a), the light-shielding element 8a at the position directly above the light source 3 is formed to extend continuously in parallel with the linear light source 3, and the light-blocking element 8a is grounded to form a grounding light-blocking element. The light-shielding elements 8b, 8c, and 8d other than the light-shielding elements 8b, 8c, and 8d are dispersed on the diffusing plate 6, and are electrically separated from the grounding light-blocking element, and are ungrounded light-shielding elements. Further, in the third (b.) diagram, the plurality of light shielding elements 8e which are dispersed in the upper position of the light source 3 are electrically connected to the conductor wiring pattern 1 细 which is thinner than the light shielding element 8e, and is linearly connected. The light source 3 is a grounding light blocking element that extends continuously in parallel. The light-shielding elements 8f and 8g other than the light-shielding elements 8f and 8g are dispersed on the diffusion plate 6, and become a non-grounding light-shielding element which is electrically separated from the ground-shielding light-shielding element. Further, in the third (b) diagram, one side of the light shielding element 8e is 1.2 mm, and the width of the wiring pattern 10 is 〇.2 mm. The grounding light-shielding elements 8a, 8e, and 10 formed in parallel with the linear light source 3 are present at a plurality of positions corresponding to the plurality of linear light sources 3, and the ends of the grounding light-shielding elements are electrically conductive. The connecting portions 1 2 of the body are electrically connected to each other. The connecting portion 1 2 is provided on the peripheral edge portion β 1282881 of the diffusing plate 6. V. In the backlight (1), since the peripheral portion of the light-emitting surface of the backlight 1 is a non-light-emitting portion, the peripheral portion of the diffusing plate 6 of the non-light-emitting portion is provided. Even when the connecting portion 12 is provided, there is little problem of shading. Further, the connecting portion 12 is provided on two sides of the diffusing plate 6 orthogonal to the linear light source 3, but the conductor 13 may be provided on two sides parallel to the linear light source 3. That is, the conductors 12, 13 can be formed on the entire periphery of the diffusion plate 6 of the non-light-emitting portion, wherein the light-shielding pattern 8 (including the wiring pattern 10), the connection portion 12, and the conductors 1 3 are all electrically connected (having the same Potential). The light-shielding pattern 8 (including the wiring pattern 10), the connecting portion 12, and the conductor 13 are applied by printing and evaporation of a conductive material to form a film in the diffusion plate 6, in the case of printing, particularly screen printing, because The minimum spot diameter of the mass-produced shading element is 〇.2 mm, so that the positively adjacent and non-light-emitting surfaces of the light source can be connected to the conductor by wiring. Further, in the case of steaming, since the minimum evaporation diameter can be sufficiently reduced, the light-shielding elements which are separated from the vicinity of the light source can be connected by the thin conductor wiring pattern. Further, the method of applying the light-shielding pattern 8, the connecting portion 12, and the conductor 13 is not limited to printing and evaporation. The diffusing plate 6 having the light-shielding pattern 8 is provided on the outer cover 2, and the surface 6b having the light-shielding pattern 8 shown in Fig. 4 is on the light source side (lower side). The diffuser plate 6 is disposed such that its peripheral edge is joined and supported by the receiving portion 15 formed at the upper end edge of the outer cover 2. Therefore, as the light-shielding pattern 8 of the illumination mask, an illumination device composed of a conductive material is described in 1282881. Fig. 8 to Fig. 1 1 show other techniques related to a direct type backlight. When a television or a very large monitor uses a liquid crystal display device, the backlight unit is required to have a wide viewing angle, high brightness, and light weight. In order to meet these requirements, a backlight of a direct type in which the light source is disposed directly below the liquid crystal is used. A plurality of light sources 3 are disposed in the direct type backlight, and the light emitted from the light source becomes a reflected light (formed by a layer of high reflectivity) and a combined light of direct light 'from the light emitting surface (light emitting surface) ) Irradiation. Since the synthesized light has a non-uniform luminance distribution, it is uniformized so that the diffusion plate and the reflective layer which are the illuminating surfaces are kept larger than a certain extent. When used as a thin type of use, since the interval is narrowed, the diffusion plate is pasted as a member of the illumination mask, or a white dot is applied to form an illumination mask to control the uniformity of brightness. However, the processing of the illumination mask is highly accurate, and a non-uniform brightness distribution occurs when the paste or the print is offset. In addition, the deviation of the diffusion plate after processing also causes deterioration of the luminance distribution. The technique shown in Fig. 8 to Fig. 1 1 relates to a device which does not have an illumination mask and which can easily adjust the uniformity of brightness. Similarly to Fig. 1, in the backlight 1 of Fig. 8, a plurality of light sources 3 parallel to each other are disposed in the outer cover 2, and are spaced apart from each other by a predetermined interval. The inner surface of the outer cover 2 is covered with a reflective layer (reflecting plate) composed of a resin layer or a metal layer having high reflectance. A plate-shaped diffusing plate 6 is provided on the outer cover 2, and the material is such that the light-diffusing fine particles are dispersed in an acrylic resin or the like. -11-1282881 5. Inventive Note (10) Resin. Further, the diffusion plate 6 is supported by the support tip 25 which is raised from the bottom surface of the outer cover 2 so as not to be bent. An illumination mask 8 is provided on the light source 3 on the back side of the diffuser plate 6 for blocking the light directly above the light source, thereby uniformizing the brightness distribution. However, in the countermeasure of uniformizing the brightness by the illumination mask 8, it is required to have high precision in position adjustment at the time of processing, and the positional shift may deteriorate the luminance distribution as shown in Fig. 11(a). In addition, the luminance distribution is deteriorated due to the offset of the diffusion plate 6 after processing. In the backlight of the first drawing, an air layer 26 having a lower refractive index is generated between the diffusing plates 6, 6 via a configuration in which a plurality of diffusing plates 6 having no illumination mask are overlapped, even if there is no illumination The screen can also widen the uniformity of brightness (refer to Figure 11(b)). Further, the brightness distribution can be made uniform at any angle to the light-emitting surface without worrying about the offset of the diffusion plate. Further, when the thickness of one of the diffusion plates 6 is made thick, the luminance distribution can be made uniform, but the brightness is lowered. When the plurality of diffusion plates 6 are overlapped to the same thickness, the decrease in brightness due to the air layer 26 can be suppressed and the luminance distribution can be made uniform. The number of the diffusion plates 6 is preferably two. Fig. 12 to Fig. 14 show other techniques of the downlight type backlight. In the case of the backlight (housing) 2, in consideration of strength, heat dissipation, light blocking property, etc., metal is generally used, but when a metal cover 2 is used, (1) electricity is generated. Leakage to the cover 2, resulting in loss of electrical energy, (2) due to the impact of the leakage, the lighting state of the light source 3 (bulb) will vary greatly, the life of the lamp will be different, and the brightness will change unevenly with time. . Therefore, the life as a lighting device and a display device can be shortened. -12- 1282881 V. INSTRUCTIONS (11) In order to eliminate such problems, the conductivity ratios of plastic, carbon resin, urethane resin, etc. are used in the backlights shown in Figs. 2 to 14 The low metal material is used to form the outer cover 2, thereby achieving a reduction in leakage, and the change in the lighting state of the light bulb can be reduced, thereby prolonging the life. In addition, since the material of the plastic or the like has a smaller specific gravity than the metal, the weight can be reduced. In addition, for materials, various choices can be made according to the design requirements of heat, plasticity, strength, etc. Further, as shown in Fig. 3, the wing assist 30 for ensuring strength may be formed on the back surface of the outer cover 2 or the like. In addition, when strength is required, a conductive material may be used in a range where the influence of leakage is small or tolerable. For example, as shown in Fig. 14(b), a metal reinforcing member 32 as shown in Fig. 14(a) may be attached to the corner portion of the outer cover 2. [Effect of the Invention] According to the present invention, the light-transmitting member such as the diffusion plate is less likely to be electrostatically charged, and the adhesion of dust can be reduced, and the deterioration of the light-emitting quality with time can be prevented. Further, when the conductor of the light-transmitting member such as the diffusing plate is used as the illumination shield, even when the conductor for preventing electrification is provided, the deterioration of the light-emitting quality can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a backlight of the present invention. Fig. 2 is a perspective view of the surface (back surface) on the light source side of the diffusing plate (light transmitting member). -13- 1282881 V. INSTRUCTIONS (12) Figure 3 is the shading pattern of the illumination mask. Figure 4 is a side view of the unit of the backlight. Fig. 5 is a plan view showing a diffusion plate of a sample used for the experiment for confirming the effects of the present invention. (A) is a sample A of the present invention, and (B) is a sample B of a comparative example. Figure 6 is a side view of a backlight unit for indicating an experimental state. Figure 7 is a table showing the results of the experiment. Fig. 8 is a backlight unit of another disclosure, (a) is a perspective view of a cover or the like, and (b) is a rear view of the diffuser. Figure 9 is a cross-sectional view of the backlight unit of Figure 8. Figure 10 is a cross-sectional view of a backlight unit of another disclosure. Fig. 11(a) is a luminance distribution diagram of the backlight unit of Fig. 9, and (b) is a luminance distribution diagram of the backlight unit of Fig. 1. Figure 12 is a cross-sectional view of a backlight unit of another disclosure. Figure 13 is a bottom plan view of the backlight unit of Figure 12. Fig. 14(a) shows a reinforcing member, and Fig. 14(b) shows a bottom view of the outer cover to which the reinforcing member is attached. [Description of symbols] 1 Direct-down backlight unit 2 Cover 3 Linear light source 6 Diffuser 8 Light-shielding pattern (lighting screen) 12 Connection -14-