507242 A7 B7 五、發明説明（1 ) 發明背景 本發明關於一種具有在電子撞擊時會發光之真空螢光 顯示器。 傳統地，此型式之真空螢光顯示器具有構成顯示表面 之殼層，該顯示表面係至少部分具有透光性質。一磷層藉 由施覆磷至該殼層之顯示表面内側上而被形成。一用以朝 向磷層發射電子之陰極電極、一用以從陰極電極抽取電極 之格柵電極、及一用以加速從陰極電極所抽取之電子的陽 極電極被配置在殼層之真空空間中。從陰極電極中藉由格 柵電極所抽取之電極被陽極電極加速並對著磷層撞擊。因 此，形成磷層之磷藉由衝撞電子而被激發，並且磷層以對 應於經激發之磷的顏色而發出光線。從磷層發出之光線透 過光學膜而從顯示表面顯現出來。 此時，若高電壓被施加至陽極電極時，被加速至高速 度的電子對著磷層撞擊而增加發光度。然而，當電子撞擊 時，磷層的溫度會極速地增加，而發光度會極速地減少。 因為撞擊電子具有高能量，因此由磷層所產生的X射線數 量會不期望地從顯示表®洩漏至外側。 為了抑制此極速的溫度增加與磷層X-射線的產生， 傳統地，欲被施加至陽極電極的電壓被抑制成低電壓。然 而，當欲被施加至陽極之電壓減少時，無法得到高發光度 之光。 在某些投射形陰極射線管中，一以真空殼層來避免X 射線洩漏之干擾與液體冷卻機制來避免磷層過熱之干擾被 本紙張尺度適用中國國家標準（CNS) A4規格（210X297公釐） (請先閲諫背面之注意事項再填寫本頁)507242 A7 B7 V. Description of the invention (1) Background of the invention The present invention relates to a vacuum fluorescent display having a luminescence when an electron strikes. Conventionally, this type of vacuum fluorescent display has a shell layer constituting a display surface, which is at least partially translucent. A phosphorus layer is formed by applying phosphorus to the inside of the display surface of the shell layer. A cathode electrode for emitting electrons toward the phosphorus layer, a grid electrode for extracting the electrode from the cathode electrode, and an anode electrode for accelerating the electrons extracted from the cathode electrode are arranged in the vacuum space of the shell layer. The electrode extracted from the cathode electrode by the grid electrode is accelerated by the anode electrode and strikes the phosphor layer. Therefore, the phosphorus forming the phosphor layer is excited by colliding with electrons, and the phosphor layer emits light in a color corresponding to the excited phosphor. The light emitted from the phosphor layer passes through the optical film and appears from the display surface. At this time, when a high voltage is applied to the anode electrode, electrons accelerated to a high speed collide with the phosphor layer to increase the luminosity. However, when electrons strike, the temperature of the phosphorous layer increases extremely rapidly, and the luminosity decreases extremely rapidly. Due to the high energy of the impinging electrons, the amount of X-rays generated by the phosphorous layer can undesirably leak from the display meter® to the outside. In order to suppress this extremely rapid temperature increase and the generation of X-rays of the phosphor layer, conventionally, the voltage to be applied to the anode electrode is suppressed to a low voltage. However, when the voltage to be applied to the anode is reduced, light with high luminosity cannot be obtained. In some projection-type cathode ray tubes, a vacuum shell is used to avoid the interference of X-ray leaks and a liquid cooling mechanism is used to avoid the interference of overheating of the phosphorus layer. This paper is applicable to China National Standard (CNS) A4 (210X297 mm). ) (Please read the notes on the back of 谏 before filling this page)
4 507242 A7 B7 五、發明説明（2 ) (請先閲讀背面之注意事項再填寫本頁) 分開地採用。在此狀況中，陰極射顯管在尺寸與重量上會 變大，使其無法在小尺寸真空螢光顯示器中被採用。為了 避免X射線漏洩，殼層之顯示表面（磷屏幕板）可以鉛玻璃 製成。然而，在此情況中，變黑現象會因熱而產生。因此， 殼層之顯示表面無法由鉛玻璃製成。 發明之概要說明 本發明之一目的在於提供一真空顯示器，其中X射線 洩漏與磷層過熱被以簡單之結構避免。 本發明之另一目的在於提供一種真空顯示器，其中一 欲被施加至陽極電極的電壓被增加，使得高發光度之光可 以被得到。 ;線丨 為了達到上述目的，根據本發明，提供有一種真空螢 光顯示器，係包含：一用以發射電極之陰極電極；一用以 從陰極電極抽取電子之格柵電極；一用以加速從陰極電極 中抽取之電子的陽極電極；至少一殼層，其係在一真空空 間中容納陰極電極、格栅電極、及陽極電極並具有透光性 質之顯示部分；一磷層，其係被形成在殼層之顯示部分之 一内部表面上並適於在被陽極電極加速之電極撞擊時發出 光線；以及一頂蓋，其係由X射線遮蔽材料製成並支撐在 殼層外側*以便透過一間隙圍繞殼層之顯示部分，該頂蓋 係具有光出射表面，從磷層發出之光係從該光出射表面通 過殼層之顯示部分顯露出來。 本紙張尺度適用中國國家標準（CNS) A4規格（210X297公釐） 507242 A7 ____ B7 五、發:明説明（3 ) 圈式之簡短說明 第1圖為顯示根據本發明第一實施例之真空螢光顯示 器之示意配置狀態的截面圖； 第2A與2B圖分別為顯示其中第i圖所示之頂蓋被應用 至三色顯示器上之例示的前視圓與平面圓； 第3A圖為石墨柱體之截面透視囷； 第3B圖為構成第3A圖所示之石墨柱體之碳毫微管的 放大前視圖； 第3C圖為第3B圖所示之碳毫微管之尖端的放大前視 XSX · 園， 第4圖為根據本發明第二實施例之光源管的截面圖。 較佳實施例之說明 本發明將會參考附呈圖式而做詳細地說明。 第1圖顯示根據本發明第一實施例之真空螢光顯示 器，其係為場發射形燈泡。參考第1圖，殼層1的内部空間 被以真空維持。殼層1被由一圓錐玻璃球莖1-1、一被黏著 劑固定至玻璃球莖1-1之前表面侧開口上的圓形磷屏幕板 (顯示表面）1-2、以及被黏著劑固定在玻璃球莖1-1之後表 面側開口上之圓形玻璃柱1-3。玻璃球莖1-1具有2 mm的厚 度。磷屏幕板1-2被由具有光透射性質之4 mm厚的白色玻 璃製成。殼層1，亦即玻璃球莖卜1，具有約3 cm的直徑， 以及約10 cm的長度。 磷被塗覆至磷屏幕板1-2的内部表面上，以形成由磷 本紙張尺度適用中國國家標準（OiS) A4規格（210X297公釐） (請先閲諫背面之注意事项再填寫本頁)4 507242 A7 B7 V. Description of the invention (2) (Please read the notes on the back before filling this page) Separately adopted. In this situation, the cathode ray tube becomes large in size and weight, making it unsuitable for use in a small-sized vacuum fluorescent display. In order to avoid X-ray leakage, the display surface of the shell (phosphorus screen) can be made of lead glass. However, in this case, the blackening phenomenon may occur due to heat. Therefore, the display surface of the shell cannot be made of lead glass. SUMMARY OF THE INVENTION It is an object of the present invention to provide a vacuum display in which X-ray leakage and overheating of the phosphor layer are avoided with a simple structure. Another object of the present invention is to provide a vacuum display in which a voltage to be applied to an anode electrode is increased so that light having a high luminosity can be obtained. In order to achieve the above object, according to the present invention, there is provided a vacuum fluorescent display including: a cathode electrode for emitting an electrode; a grid electrode for extracting electrons from the cathode electrode; An anode electrode for the electrons extracted from the cathode electrode; at least one shell layer, which is a display part that contains the cathode electrode, the grid electrode, and the anode electrode in a vacuum space and has a light transmitting property; a phosphor layer, which is formed On an inner surface of one of the display portions of the shell and adapted to emit light when struck by an electrode accelerated by the anode electrode; and a cover which is made of an X-ray shielding material and is supported outside the shell * so as to pass through a The gap surrounds the display portion of the shell layer. The top cover has a light exit surface, and the light emitted from the phosphor layer is exposed from the light exit surface through the display portion of the shell layer. This paper size applies Chinese National Standard (CNS) A4 specification (210X297 mm) 507242 A7 ____ B7 V. Issue: Explanatory note (3) Short description of the circle type The first figure shows a vacuum fluorescent lamp according to the first embodiment of the present invention A cross-sectional view of a schematic configuration state of a light display; FIGS. 2A and 2B are respectively an exemplary front view circle and a plane circle in which the top cover shown in FIG. I is applied to a three-color display; Sectional perspective of the body 视图 Figure 3B is an enlarged front view of the carbon nanotubes constituting the graphite cylinder shown in Figure 3A; Figure 3C is an enlarged front view of the tip of the carbon nanotubes shown in Figure 3B XSX, Fig. 4 is a sectional view of a light source tube according to a second embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the accompanying drawings. Fig. 1 shows a vacuum fluorescent display according to a first embodiment of the present invention, which is a field emission type bulb. Referring to Fig. 1, the internal space of the shell layer 1 is maintained in a vacuum. The shell layer 1 is fixed by a conical glass bulb 1-1, a circular phosphor screen (display surface) 1-2 fixed to the front side opening of the glass bulb 1-1 by an adhesive, and fixed to the glass by an adhesive. A circular glass column 1-3 on the surface side opening of the bulb 1-1. The glass bulb 1-1 has a thickness of 2 mm. The phosphor screen plate 1-2 is made of 4 mm thick white glass having a light transmitting property. The shell layer 1, that is, the glass bulb 1, has a diameter of about 3 cm and a length of about 10 cm. Phosphorus is coated on the inner surface of the phosphor screen plate 1-2 to form the paper size of the phosphor paper. Applicable to the Chinese National Standard (OiS) A4 specification (210X297 mm) )
·、"I -6 - 507242 A7 B7 五、發明説明（4 ) 層所形成之磷屏幕2。在殼層1中，一陶瓷基材3被配置成 ^ 接近玻璃柱1-3，並且陰極電極4被安裝在陶瓷基材3之磷 屏幕2之側邊上。陰極電極4被由一電極4-1與大量被導電 黏著劑固定至電極4-1上之石墨柱體。各石墨柱體4-2被由 碳毫微管之聚體製成，並具有數//m至數mm長度的針狀 形狀。具有網眼5-1部分之格柵電極5在陰極電極4與磷屏 幕2之間被配置，以覆蓋石墨柱體4-2。一陽極電極6在磷 屏幕2與格栅電極5之間被配置成接近於磷屏幕2。 陰極電極4之結構被詳細地說明於由本申請人所申請 之美國專利第6,239,547號（參考資料1)與曰本專利公開第 2000-149765號（參考資料2)中。在參考資料1與2中所說明 之石墨柱體被由被朝向幾乎相同方向之碳毫微管4-2a之聚 體結構製成，如第3A圖所示。如第3B圖所示，各個碳毫 微管4-2a被完全地石墨化且呈圓錐形，並具有約4 nm至50 nm的直徑以及相當於l#m的長度。第3C圖放大地顯示碳 毫微管4-2a的尖端。 當DC電弧放電在相互被分開1 mm至2 mm的碳電極之 間的氦氣中被產生時，陽極的碳被揮發並聚集而於陰極側 陰極電極之尖端處形成沉積物，在此碳毫微管4-2a被形 成。換言之，當穩定的電弧放電在氦氣中被維持，而在碳 電極之間的間隙被以約1 mm維持時，一具有大約與陽極 碳電極相同直徑的柱狀沉積物於陰極尖端處被形成。 柱狀沉積物被由兩個區域形成，亦即，一外部硬殼體 及一内部脆性黑核心。内部核心被由具有在沉積柱轴向方 本紙張尺度適用中國國家標準（CNS) A4規格（210X297公釐） (請先閲讀背面之注意事項再填寫本頁) 丨 :線丨 507242 A7 _B7_ 五、發明説明（5 ) (請先閲秦背面t注意事项再填寫本頁) 向上延伸之纖維性織物的石墨柱組成。當沉積柱被切割 時，石墨柱4-2可以被得到。外部硬殼體被由石墨多晶體 製成。 在石墨柱4-2中，碳毫微聚多面體以及複數個碳毫微 管形成一聚體。碳毫微管被以其中單一石墨層被圓錐地封 閉之結構分類成一部分，如第3C圖示意地顯示，而被以 其中複數層被堆疊形成套疊結構之石墨層被圓錐地封閉之 共轴多層結構分類成一部分。各結構之中心部分為中空。 當一電壓通過鉛針7-1與7-2橫跨陰極電極4與格柵電 極5被施加時，高電場被集中至被固定在電極4-1上之石墨 柱4-2之碳毫微管4-2a的尖端上。因此，電子被從碳毫微 管4-2a的尖端被抽取並從網眼部分5-1發射。 一較格柵電極5之電位更高的電壓通過一鉛針7-3被施 加至陽極電極6上，並被配置成較磷屏幕2更接近格柵電極 5。來自陰極電極4並被從網眼部分5-1發射之電子被陽極 電極6加速，且對著磷屏幕2撞擊。因此，形成磷屏幕2之 磷被電子衝撞而激發，並且磷屏幕2會以對應於經激發之 磷的顏色而發光。由磷屏幕2所發出之光透過磷屏幕1-2板 被傳送。 由鉛玻璃所製成之裝底圓柱頂蓋9透過間隙8被連結至 殼層1的前側上，以便圍繞磷屏幕板1-2。更特定地，覆蓋 磷屏幕板1-2與接續磷屏幕板1-2之玻璃球莖1-1幾乎三分 之一的區域被頂蓋9覆蓋。頂蓋9為3 mm厚。一作為頂蓋9 之光出射部分9-1具有平坦的内部表面與外部表面（光出射 本紙張尺度適用中國國家標準（CNS) A4規格（210X297公釐） 507242 A7 B7 五、發明説明（6 ) 表面）°從磷屏幕2所發出並透過磷屏幕板1-2被傳送的光 線會從光出射部分9-1之光出射表面顯露出來。一用以增 加出射光的色彩純度之光學膜1〇被黏覆至光出射部分 之光出射表面上。 一間隙G1在光出射部分9-1與磷屏幕板1-2之間被形 成，且一間隙G2在頂蓋9之圓柱部分9-2的内部表面與玻 璃球莖1·1的外部表面之間被形成。間隙8被由間隙G1與G2 組成。諸如水之透明12被密封在間隙8中。冷卻液體12藉 由以矽膠11將一個在間隙9之圓柱部分9-2之尖端的内部表 面與玻璃球莖1-1的外部表面之間的部分封閉成似圓環的 形狀而被密封在間隙8中。間隙G1與G2各寬2 mm。 從磷屏幕2所發出的光透過磷屏幕板丨_2被傳送並透過 間隙8(冷卻液體12)—頂蓋9之光出射部分9-1—光學膜10 而呈現在外部。磷屏幕2的熱被在間隙8中之冷卻液體12吸 收。因此，磷屏幕2極劇的溫度增加被避免，並且高發光 度的光可以藉由增加欲被施加至陽極電極6上之電壓而得 到。當磷屏幕板1_2的厚度被減少時，磷屏幕2的冷卻效應 被進一步地提高。 本實施例之顯示器被與未具有頂蓋9之傳統場發射型 燈泡相比。根據本實施例，在由於磷屏幕2的溫度增加造 成高發光度時的發光度減少率是傳統場發射型燈泡的十分 之一。因為磷屏幕2被間隙8中的冷卻液體冷卻，使得由鉛 玻璃製成的頂蓋9之變黑現象被避免，該現象係因為頂蓋9 的溫度增加而造成。因為光學膜1〇的熱變質亦被避免，故 本紙張尺度適用中國國家標準（CNS) A4規格（210X297公釐〉 C請先閲讀背面之注意事項再填寫本頁) •裝· •、句| 線丨 9 507242 A7 B7 五、發明説明（7 ) 可藉由高色彩純度而得到高發光度及穩定的光發射。 (請先閲讀背面之注意事項再填寫本頁) ^--- 由磷屏幕2所產生的X射線透過間隙8(冷卻液體12)被 傳送並有透過頂蓋9之光出射部分9-1漏洩至外側的趨勢。 因為頂蓋被由鉛玻璃製成，故X射線被頂蓋9遮蔽。有從 玻璃球莖1-1漏洩的趨勢之X射線亦被頂蓋9之圓柱部分9-2 遮蔽。因此，漏洩至外侧的X射線總量非常小。 如上所述，根據本實施例，磷屏幕之X射線漏浪預防 與過熱預防能夠以簡單的配置狀態達到，其中由鉛玻璃所 製成之頂蓋9被應用至殼層1之前表面上，並且冷卻液體12 被密封在頂蓋9與殼層1之間的間隙8中。結果，欲被施加 至陽極電極6上的電壓被增加，使得高發光度的光線可以 被得到。 欲被密封在間隙8中之冷卻液體12的數量會考慮冷卻 液體12的熱膨脹來決定。間隙8的體積可藉由變更間隙G1 與G2的尺寸而被自由地調整。更特定地，冷卻液體12的 量與間隙8之體積可以被自由地設定。在間隙8中因為冷卻 液體12之熱膨脹而增加的壓力被封接間隙8之軟矽膠11吸 收。可以使用熒光橡膠來取代矽膠11。 雖然在上述實施例中冷卻液體12被密封在間隙8中， 但冷卻液體12不需要永遠被密封。當冷卻液體12未被密封 時，磷屏幕2的熱從頂蓋9中透過在殼層1之磷屏幕板1-2與 頂蓋9之間的間隙8被消散。在此情況下，磷屏幕2未被水 冷卻，而是藉由空氣達到過熱之預防。此時，間隙8不需 要被矽膠完全地密封，使得間隙8與外界可以相互連通。 本紙張尺度適用中國國家標準（CNS) A4規格（210X297公釐） 10 507242 A7 _— —_B7_ 五、發明説明（8 ) 在上述實施例中，間隙9被由鉛玻璃製成。然而，本 發明未被限制於此，並且間隙9可以被由任何一種X射線 遮蔽材料製成。冷卻液體12未被限制是水。例如，乙二醇 與二甘醇之液體混合物可以被採用。陰極電極4為使用碳 毫微管之電極。然而，陰極電極4未被限制是使用碳毫微 管之電極。 在上述實施例中，本發明被應用至發射一色光之顯示 器上。交替地，本發明亦可以被應用至發出三色光之顯示 器上。第2A與2B圖示意地顯示其中本發明被應用至三色 顯示器上之情況。在第2A圖中，一共用頂蓋9,在對應三 色之三個真空螢光顯示器之殼層la、lb&lc的前侧上被形 成。 更特定地，間隙9未被分別地提供至殼層la、lb及lc 上，但一頂蓋9,覆蓋殼層la、lb及lc之磷屏幕板la-2、lb-2與lc-2 ^ —光學膜1〇,被黏附至頂蓋9,之光出射表面上。 頂蓋91被以鉛玻璃形成為似盒體形狀並具有方形之光出射 表面。一冷卻液體藉由使用矽膠而被密封在頂蓋9,與殼層 la、lb及lc之間的間隙中。 本發明之第二實施例將會參考第4圖而做說明。 就局部遮蔽結構而言，當高電壓被施加時，有時會發 生閃光且穩定的驅動操作變成難以進行。因為鉛針未被遮 蔽’因此當高電壓被施加時，在針之間有時會發生放電。 此外’例如，因為顯示器未被與内部電場隔開，故難以進 行高電壓驅動。根據第二實施例之光源管具有一由碳毫微 本紙張尺度適用中國國家標準（CNS) A4規格（210X297公釐） (請先閲讀背面之注意事項再填寫本頁) 訂· :線丨 -11 507242 A7 B7 五、發明説明（9 ) 管或碳毫微纖維所形成之電子源，且被設置有X射線遮蔽 機構與冷卻結構。 X射線遮蔽機構被由一具有覆蓋除了電極部分外的殼 層1之圓柱X射線阻擋物19-1之頂蓋19，以及被由鉛玻璃 製成並被裝配至X射線阻檔物19-1之一開口中以對應光源: 管之光出射表面之前表面玻璃構件19-2組成。交替地，X 射線阻擋物19-1被由鉛玻璃或是無任何光透射性質之X射 線遮蔽材料製成。頂蓋19被以殼層1配置以形成間隙8。 冷卻機構被由形成在殼層1與間隙19之間的間隙8以及 被密封在間隙8中例如油的冷卻液體12構成。就本配置狀 態而言，整個光源管被以冷卻液體12覆蓋。 所以，光源管被與外部電場隔開。即使當高電壓被施 加時，光源管可以進行穩定的電子束驅動操作。一30 kV 至40 kV的高電壓亦可以被施加至陽極上，並且光源管之 前表面（磷屏幕）被冷卻，使得較高的發光度可以被得到。 冷卻液體被由諸如矽橡膠之絕緣材料所製成之密封構 件（棒桿）密封。密封構件13的外直徑稍大於殼層1之外直 徑。當冷卻液體12被以絕緣矽橡膠密封時，光源管與頂蓋 19可以被互相固定，而不會對覆蓋光源管之殼層的頂蓋 19(遮蔽玻璃管）之外部形狀有不利的影饗，並且冷卻液體 12可以被密封在光源管之殼層1與頂蓋19之間的間隙中。 各種型式的鉛針7-1至7-3被遮蓋並被固定在密封構件 13中。當各種型式的鉛針7-1至7-3被遮蓋且以此方式被一 絕緣密封構件固定時，在鉛針7-1至7-3之間的放電可以被 本紙張尺度適用中國國家標準（CNS) A4規格（210X 297公釐） (請先閲諫背面之注意事項再填寫本頁) 訂丨 .0 12 507242 A7 B7 Φ 五、發明説明（1G ) 避免，且即使是在高電壓的情況下，一鉛線可以被穩定的 延伸。 此外，一與間隙8連通之液體儲存槽14在密封構件13 中被形成。此可以吸收由於冷卻液體12之熱膨脹所造成在 體積上的改變。當此類液體儲存層槽14在密封構件13中被 形成時，密封構件13較佳具有彈性。 在本實施例中，構成X射線遮蔽結構之前表面玻璃構 件19-2未被限制是一平坦的玻璃構件，而可以形成一凸狀 或凹狀表面。在X射線遮蔽結構之前表面玻璃構件19_2與 光源管之前表面玻璃構件（磷屏幕板1-2)之間的距離可以 被任意地設定。 如上所述，根據本發明，一具有光透射性質並由X射 線遮蔽材料所製成之頂蓋被配置在殼層外側，以在以殼層 形成一間隙的同時圍繞顯示器表面。所以，X射線漏洩之 預防與磷屏幕過熱之預防能夠以一簡單的結構達到。同時 地，高發光度之光線可以藉由增加欲被施加至陽極電極之 電壓而得到。 因為冷卻液體被密封在間隙中，所以可以提高避免磷 屏幕過熱之效應。由於間隙被由鉛玻璃形成，故避免X射 線漏洩之效應可以被提昇。 (請先閲讀背面之注意事項再填寫本頁) 訂· .線丨 本紙張尺度適用中國國家標準（CNS) A4規格（210X297公釐） 13 507242 A7 B7 五、發明説明（11 ) 元件標號對照表 1 殼層 la 殼層 lb 殼層 lc 殼層 1-1 圓錐玻璃球莖 1-2 磷屏幕板 1-3 玻璃柱 la-2 磷屏幕板1 b-2 磷屏幕板 lc-2 磷屏幕板 2 磷屏幕 3 陶瓷基材 4 陰極電極 4-1 電極 4-2 石墨柱體 4-2a 碳毫微管 5 格柵電極 5-1 網眼 6 陽極電極 7-1 鉛針 7-2 鉛針 7-3 鉛針 8 間隙 9 頂蓋 9， 共用頂蓋 9-1 光出射部分 9-2 圓柱部分 10 光學膜 10， 光學膜 11 矽膠 12 冷卻液體. 13 密封構件 14 液體儲存槽 19 頂蓋 19-1 X射線阻擋物 19-2 前表面玻璃構件 G1 間隙 G2 間隙 (請先閲讒背面之注意事項再填寫本頁) 本紙張尺度適用中國國家標準（CNS) A4規格（210X297公釐） 14· &Quot; I -6-507242 A7 B7 V. Description of the invention (4) Phosphor screen 2 formed by layers. In the shell layer 1, a ceramic substrate 3 is arranged close to the glass columns 1-3, and the cathode electrode 4 is mounted on the side of the phosphor screen 2 of the ceramic substrate 3. The cathode electrode 4 is fixed by an electrode 4-1 and a large number of graphite pillars which are fixed to the electrode 4-1 by a conductive adhesive. Each graphite cylinder 4-2 is made of a polymer of carbon nanotubes, and has a needle-like shape with a length of several millimeters to several millimeters. A grid electrode 5 having a mesh 5-1 portion is arranged between the cathode electrode 4 and the phosphor screen 2 so as to cover the graphite pillar 4-2. An anode electrode 6 is arranged close to the phosphor screen 2 between the phosphor screen 2 and the grid electrode 5. The structure of the cathode electrode 4 is described in detail in U.S. Patent No. 6,239,547 (Reference 1) and Japanese Patent Publication No. 2000-149765 (Reference 2) filed by the applicant. The graphite cylinders described in References 1 and 2 are made of a polymer structure of carbon nanotubes 4-2a which are oriented in almost the same direction, as shown in Fig. 3A. As shown in FIG. 3B, each carbon nanotube 4-2a is completely graphitized and conical, and has a diameter of about 4 nm to 50 nm and a length equivalent to 1 # m. Figure 3C shows the tip of the carbon nanotube 4-2a on an enlarged scale. When a DC arc discharge is generated in helium gas between carbon electrodes 1 mm to 2 mm apart from each other, the carbon of the anode is volatilized and accumulated to form a deposit at the tip of the cathode electrode on the cathode side. Microtubules 4-2a are formed. In other words, when a stable arc discharge is maintained in helium and the gap between the carbon electrodes is maintained at about 1 mm, a columnar deposit having the same diameter as that of the anode carbon electrode is formed at the tip of the cathode . The columnar deposits are formed by two regions, i.e. an outer hard shell and an inner brittle black core. The inner core is made of paper with the size of the paper in the axial direction of the sedimentary column. It applies the Chinese National Standard (CNS) A4 specification (210X297 mm) (please read the precautions on the back before filling this page). 丨: Line 507242 A7 _B7_ Description of the Invention (5) (please read the precautions on the back of Qin before filling out this page) The composition of the graphite pillars of the fibrous fabric extending upward. When the deposition column is cut, a graphite column 4-2 can be obtained. The outer hard case is made of graphite polycrystal. In the graphite column 4-2, a carbon nanopolyhedron and a plurality of carbon nanotubes form a polymer. Carbon nanotubes are classified into a part by a structure in which a single graphite layer is conically closed, as shown schematically in FIG. 3C, and a coaxial layer in which a graphite layer in which a plurality of layers are stacked to form a nested structure are conically closed The multilayer structure is classified into a part. The central part of each structure is hollow. When a voltage is applied across the cathode electrode 4 and the grid electrode 5 through the lead pins 7-1 and 7-2, a high electric field is concentrated to the carbon nanometer of the graphite column 4-2 fixed on the electrode 4-1. On the tip of tube 4-2a. Therefore, electrons are extracted from the tip of the carbon nanotube 4-2a and emitted from the mesh portion 5-1. A voltage higher than the potential of the grid electrode 5 is applied to the anode electrode 6 through a lead pin 7-3, and is arranged closer to the grid electrode 5 than the phosphor screen 2. The electrons from the cathode electrode 4 and emitted from the mesh portion 5-1 are accelerated by the anode electrode 6 and hit against the phosphor screen 2. Therefore, the phosphorus forming the phosphor screen 2 is excited by the electron impact, and the phosphor screen 2 emits light in a color corresponding to the excited phosphor. The light emitted from the phosphor screen 2 is transmitted through the phosphor screen 1-2 plate. A bottom-mounted cylindrical top cover 9 made of lead glass is connected to the front side of the shell layer 1 through the gap 8 so as to surround the phosphor screen plate 1-2. More specifically, almost one third of the area covering the phosphor screen plate 1-2 and the glass bulb 1-1 following the phosphor screen plate 1-2 is covered by the top cover 9. The top cover 9 is 3 mm thick. First, the light emitting portion 9-1 as the top cover 9 has a flat inner surface and an outer surface (the light exiting the paper size applies the Chinese National Standard (CNS) A4 specification (210X297 mm) 507242 A7 B7. V. Description of the invention (6) Surface) ° The light emitted from the phosphor screen 2 and transmitted through the phosphor screen 1-2 will be exposed from the light exit surface of the light exit portion 9-1. An optical film 10 for increasing the color purity of the emitted light is adhered to the light emitting surface of the light emitting portion. A gap G1 is formed between the light emitting portion 9-1 and the phosphor screen plate 1-2, and a gap G2 is between the inner surface of the cylindrical portion 9-2 of the top cover 9 and the outer surface of the glass bulb 1.1 Be formed. The gap 8 is composed of gaps G1 and G2. A transparent 12 such as water is sealed in the gap 8. The cooling liquid 12 is sealed in the gap 8 by sealing a portion between the inner surface of the tip of the cylindrical portion 9-2 of the gap 9 and the outer surface of the glass bulb 1-1 with a silicone rubber 11 in a ring-like shape. in. The gaps G1 and G2 are each 2 mm wide. The light emitted from the phosphor screen 2 is transmitted through the phosphor screen plate 丨 _2 and passes through the gap 8 (cooling liquid 12) —the light exit portion 9-1 of the top cover 9—the optical film 10 and appears to the outside. The heat of the phosphor screen 2 is absorbed by the cooling liquid 12 in the gap 8. Therefore, a dramatic temperature increase of the phosphor screen 2 is avoided, and light of high luminosity can be obtained by increasing the voltage to be applied to the anode electrode 6. When the thickness of the phosphor screen plate 1_2 is reduced, the cooling effect of the phosphor screen 2 is further enhanced. The display of this embodiment is compared with a conventional field emission type bulb without the top cover 9. According to the present embodiment, the luminosity reduction rate when a high luminosity is caused due to an increase in the temperature of the phosphor screen 2 is one-tenth that of a conventional field emission type bulb. Since the phosphor screen 2 is cooled by the cooling liquid in the gap 8, the blackening phenomenon of the top cover 9 made of lead glass is avoided, which is caused by the temperature increase of the top cover 9. Since the thermal deterioration of the optical film 10 is also avoided, this paper size applies the Chinese National Standard (CNS) A4 specification (210X297 mm> C, please read the precautions on the back before filling out this page) • Install · •, sentence | Line 丨 9 507242 A7 B7 V. Description of the invention (7) High luminosity and stable light emission can be obtained by high color purity. (Please read the precautions on the back before filling this page) ^ --- The X-rays generated by the phosphor screen 2 are transmitted through the gap 8 (cooling liquid 12) and the light exit portion 9-1 through the top cover 9 leaks Trend to the outside. Since the top cover is made of lead glass, X-rays are shielded by the top cover 9. X-rays that have a tendency to leak from the glass bulb 1-1 are also blocked by the cylindrical portion 9-2 of the top cover 9. Therefore, the total amount of X-rays leaked to the outside is very small. As described above, according to the present embodiment, X-ray leakage prevention and overheating prevention of the phosphor screen can be achieved in a simple configuration state, in which the top cover 9 made of lead glass is applied to the front surface of the shell layer 1, and The cooling liquid 12 is sealed in a gap 8 between the top cover 9 and the shell layer 1. As a result, the voltage to be applied to the anode electrode 6 is increased, so that light having a high luminance can be obtained. The amount of the cooling liquid 12 to be sealed in the gap 8 is determined in consideration of the thermal expansion of the cooling liquid 12. The volume of the gap 8 can be freely adjusted by changing the sizes of the gaps G1 and G2. More specifically, the amount of the cooling liquid 12 and the volume of the gap 8 can be set freely. The increased pressure in the gap 8 due to the thermal expansion of the cooling liquid 12 is absorbed by the soft silicone rubber 11 sealing the gap 8. Instead of the silicone rubber 11, a fluorescent rubber may be used. Although the cooling liquid 12 is sealed in the gap 8 in the above embodiment, the cooling liquid 12 does not need to be sealed forever. When the cooling liquid 12 is not sealed, the heat of the phosphor screen 2 is dissipated from the top cover 9 through the gap 8 between the phosphor screen panel 1-2 of the shell layer 1 and the top cover 9. In this case, the phosphor screen 2 is not cooled by water, but is prevented from overheating by air. At this time, the gap 8 does not need to be completely sealed by the silicone, so that the gap 8 can communicate with the outside world. This paper size applies the Chinese National Standard (CNS) A4 specification (210X297 mm) 10 507242 A7 _ — — — B7_ V. Description of the invention (8) In the above embodiment, the gap 9 is made of lead glass. However, the present invention is not limited to this, and the gap 9 may be made of any kind of X-ray shielding material. The cooling liquid 12 is not limited to water. For example, a liquid mixture of ethylene glycol and diethylene glycol can be used. The cathode electrode 4 is an electrode using a carbon nanotube. However, the cathode electrode 4 is not limited to an electrode using a carbon nanotube. In the above embodiments, the present invention is applied to a display that emits one color of light. Alternatively, the present invention can be applied to a display which emits three colors of light. Figures 2A and 2B schematically show the case where the present invention is applied to a tri-color display. In Fig. 2A, a common top cover 9 is formed on the front sides of the shells la, lb & lc corresponding to three vacuum fluorescent displays of three colors. More specifically, the gap 9 is not provided to the shells la, lb, and lc, respectively, but a top cover 9 covers the phosphor screen panels la-2, lb-2, and lc-2 of the shells la, lb, and lc. ^ —The optical film 10 is adhered to the light exit surface of the top cover 9. The top cover 91 is formed in a box-like shape with lead glass and has a square light emitting surface. A cooling liquid is sealed in the gap between the top cover 9 and the shell layers 1a, 1b, and 1c by using silicone. A second embodiment of the present invention will be described with reference to FIG. 4. In the case of a partially shielded structure, when a high voltage is applied, flashing sometimes occurs and stable driving operation becomes difficult. Because the lead pin is not shielded ', when a high voltage is applied, a discharge may occur between the pins. In addition, for example, since the display is not separated from the internal electric field, it is difficult to perform high-voltage driving. The light source tube according to the second embodiment has a carbon nano-paper size applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) (please read the precautions on the back before filling this page) Order:: Line 丨- 11 507242 A7 B7 V. Description of the invention (9) An electron source formed by a tube or carbon nanofiber, and provided with an X-ray shielding mechanism and a cooling structure. The X-ray shielding mechanism is composed of a top cover 19 having a cylindrical X-ray barrier 19-1 covering the shell layer 1 except for the electrode portion, and is made of lead glass and assembled to the X-ray barrier 19-1. One of the openings is composed of a corresponding light source: the surface glass member 19-2 before the light exiting surface of the tube. Alternatively, the X-ray blocker 19-1 is made of lead glass or an X-ray shielding material without any light transmission property. The top cover 19 is configured with the shell layer 1 to form a gap 8. The cooling mechanism is composed of a gap 8 formed between the shell layer 1 and the gap 19, and a cooling liquid 12 sealed in the gap 8 such as oil. In this configuration, the entire light source tube is covered with the cooling liquid 12. Therefore, the light source tube is separated from the external electric field. Even when a high voltage is applied, the light source tube can perform a stable electron beam driving operation. A high voltage of 30 kV to 40 kV can also be applied to the anode, and the front surface (phosphorus screen) of the light source tube is cooled, so that higher luminosity can be obtained. The cooling liquid is sealed by a sealing member (rod) made of an insulating material such as silicone rubber. The outer diameter of the sealing member 13 is slightly larger than the outer diameter of the shell layer 1. When the cooling liquid 12 is sealed with insulating silicone rubber, the light source tube and the top cover 19 can be fixed to each other without adversely affecting the external shape of the top cover 19 (shielding glass tube) covering the shell layer of the light source tube. The cooling liquid 12 can be sealed in the gap between the shell layer 1 and the top cover 19 of the light source tube. The lead pins 7-1 to 7-3 of various types are covered and fixed in the sealing member 13. When various types of lead pins 7-1 to 7-3 are covered and fixed by an insulating sealing member in this way, the discharge between the lead pins 7-1 to 7-3 can be adapted to Chinese national standards on this paper scale (CNS) A4 specification (210X 297mm) (Please read the notes on the back of the page before filling out this page) Order 丨 .0 12 507242 A7 B7 Φ V. Description of the invention (1G) Avoidance, and even at high voltage In this case, a lead wire can be stably extended. Further, a liquid storage tank 14 communicating with the gap 8 is formed in the sealing member 13. This can absorb the change in volume caused by the thermal expansion of the cooling liquid 12. When such a liquid storage layer groove 14 is formed in the sealing member 13, the sealing member 13 preferably has elasticity. In this embodiment, the surface glass member 19-2 before forming the X-ray shielding structure is not limited to a flat glass member, but may form a convex or concave surface. The distance between the surface glass member 19_2 before the X-ray shielding structure and the surface glass member (phosphorus screen 1-2) before the light source tube can be arbitrarily set. As described above, according to the present invention, a cover having a light transmitting property and made of an X-ray shielding material is disposed on the outside of the casing to surround the display surface while forming a gap with the casing. Therefore, prevention of X-ray leakage and prevention of overheating of the phosphor screen can be achieved with a simple structure. At the same time, high-luminance light can be obtained by increasing the voltage to be applied to the anode electrode. Since the cooling liquid is sealed in the gap, the effect of avoiding overheating of the phosphor screen can be enhanced. Since the gap is made of lead glass, the effect of avoiding X-ray leakage can be enhanced. (Please read the precautions on the back before filling in this page) Order.. Line 丨 This paper size is applicable to China National Standard (CNS) A4 (210X297 mm) 13 507242 A7 B7 V. Description of the invention (11) Component reference 1 shell la shell lb shell lc shell 1-1 cone glass bulb 1-2 phosphor screen panel 1-3 glass column la-2 phosphor screen panel 1 b-2 phosphor screen panel lc-2 phosphor screen panel 2 phosphor Screen 3 Ceramic substrate 4 Cathode electrode 4-1 Electrode 4-2 Graphite cylinder 4-2a Carbon nanotube 5 Grid electrode 5-1 Mesh 6 Anode electrode 7-1 Lead pin 7-2 Lead pin 7-3 Lead pin 8 Clearance 9 Top cover 9, Common top cover 9-1 Light emitting part 9-2 Cylindrical part 10 Optical film 10, Optical film 11 Silicone 12 Cooling liquid. 13 Sealing member 14 Liquid storage tank 19 Top cover 19-1 X Ray blocker 19-2 Front surface glass member G1 gap G2 gap (please read the precautions on the back before filling this page) This paper size applies to China National Standard (CNS) A4 (210X297 mm) 14