200849307 九、發明說明 【發明所屬之技術領域】 本發明關於在工業用或醫療用等所使用之微小 微聚焦X射線管。 【先前技術】 以往，作爲這種領域之技術，具有如日本特開 1 3 28 26號公報。此公報所記載之X射線管是在玻 電子管固定有棒狀標靶，在電子管的開放端固定有 主體部。又，在社置於標靶支承體的前端之標靶， 電子槍所射出之電子，由標靶產生X射線，再由設 體部的X射線射出窗將X射線釋出至外部。又， 槍設有電氣供給用桿銷（s t e m p i η )，在桿銷固定 器、陰極、第1及第2閘極電極（grid electrode) 結構之電子槍被收容於金屬製電子槍殼體內。 [專利文獻1]日本特開2003 - 1 32826號公報 [專利文獻2 ]日本特開2 0 0 5 - 3 8 8 2 5號公報 [專利文獻3]美國專利6229876號說明書 【發明內容】 [發明所欲解決之課題] 前述以往的X射線之電子槍，若未在電子槍殻 正確地定位的話，則無法使由電子槍所射出的電子 射中標靶，無法獲得期望的X射線焦點。因此，需 焦點型 2003 - 璃製的 金屬製 射入由 置於主 在電子 有加熱 。這種 體內被 正確地 要將電 -4 - 200849307 子槍正確地定位於電子槍殻體內’但，伴隨χ射線管之小 型化，電子槍及電子槍殼體逐漸小型化，會產生例如在確 認定位之組裝時的作業困難之問題產生。 本發明之目的在於提供，組裝作業性良好之X射線管 [用以解決課題之手段] 本發明之X射線管，是用來使從具有桿銷之電子槍所 射出的電子射入至標靶，由標靶產生χ射線之χ射線管 ，其特徵爲：具備有：用來收容電子槍，並且具有形成於 筒狀的殼體本體部的第1開口部之電子槍殻體；及在內部 具有收容標靶的標靶收容空間之金屬製標靶收容主體，設 置於電子槍殻體之第1開口部被收容於標靶收容主體內。 在將電子槍高經度地定位於電子槍殼體內之際，因能 夠將第1開口部作爲以確認電子槍在電子槍殼體內的位置 爲目的的觀察窗來利用，所以，容易以目視來確認電子槍 與電子槍殻體的內表面是否有接觸等、或容易進行電子槍 在電子槍殼體內之位置的微調整。且在組裝X射線管之際 ，因能夠使電子槍殼體的第1開口部位置於標靶收容主體 內，所以，容易進行電子槍殼體對標靶收容主體之組裝作 業。因此，伴隨著電子槍殼體的組裝作業之容易化，可使 X射線管之組裝作業性變得良好。 又，在電子槍殼體的前端，具有一體地形成於殻體本 體部的筒狀突出部，在電子槍的前端，設有插入至突出部 -5- 200849307 內之筒狀集束電極部，第1開口部是與突出部接 者爲佳。針對在電子槍殼體的殼體本體部，接近 出部而形成有第1開口部，需要將設置於電子槍 筒狀集束電極部插入至設置於電子槍殼體的前端 出部內之本發明的X射線管，當在電子槍側的集 的前端與電子槍殼體的突出部的前端之距離具有 在集束電極部的電子透鏡效果上會產生參差不齊 得具有期望的X射線焦點之X射線管。因此， 槍側的集束電極部的前端與電子槍殼體的突出部 接的狀態下做成期望的狀態爲佳。在本發明之X 因由第1開口部插入鑷子等的治具，能夠以鑷子 取集束電極部的附近，所以，可使作業者的力量 達至集束電極部，可將筒狀的集束電極部確實地 狀的突出部內。因此，能夠使集束電極部的前端 殻體的突出部的前端確實地密接，而可獲得具有 射線焦點之X射線管。 又，在標靶收容主體，理想爲具備有：形成 容主體，將供電子槍殼體的前端側插入之殼體插 靶收容主體的標靶收容空間連通之第2開口部； 容空間與外部連通，並且在與第2開口部相對向 成於標靶收容主體的第3開口部；及用來關閉第 之蓋部。藉由這樣的結構，能夠使電子槍殻體的 第2開口部面臨於標靶收容空間內，可將棒狀的 3開口部插入至標靶收容空間內。因此，能夠將 近並形成 筒狀的突 的前端之 之筒狀突 束電極部 分佈時， ，無法獲 將使電子 的前端密 射線管， 等直接夾 確實地傳 壓入至筒 與電子槍 期望的X 於標靶收 入孔與標 將標靶收 的位置形 3開口部 突出部由 治具由第 棒狀的治 -6- 200849307 具之前端插入至突出部的前端開口內，故，能夠將電子槍 殼體的突出部安裝於正確位置。其結果，可使由集束電極 部所射出的電極正確地射中於標靶，獲得期望的X射線焦 點。 又’電子槍殻體的突出部對殼體本體部的管軸線呈偏 心爲佳。藉由這樣的結構，比起電子槍的集束電極部與電 子槍殼體的管軸線一致的X射線管，可縮短F Ο D，能夠提 高所攝像之放大透視圖像之放大率。又，前述第3開口部 之採用，對電子槍的集束電極部及電子槍殻體的突出部偏 心之情況特別有效。 [發明效果] 若根據本發明的話，可使電子槍的組裝作業性良好。 【實施方式】 以下，參照圖面，詳細說明本發明之X射線管的理想 實施形態。 如圖1及圖2所示，X射線管1是在工業用或醫療用 等所使用之微小焦點型微聚焦X射線管，具有保持真空之 密封構造。此X射線管1是具有玻璃製的電子管2，在此 電子管2的封閉之一端，固定有棒狀陽極3的基端，在電 子管2的另一端固定有圓筒狀金屬製環2a。再者，在陽極 3的前端，爲了藉由電子的衝突產生X射線，埋設有由鎢 所構成之圓板狀標靶3 a。 200849307 在設置於電子管2的金屬製環2a，藉由熔接，固定有 金屬製（例如不秀鋼製）的標靶收容主體4。在此標靶收 容主體4的上端側開口 4b，嵌入有蓋板6，蓋板6藉由熔 接來固定於標靶收容主體4。又’在此蓋板6的中央，設 有由B e材所構成的X射線輸出窗6 a。 且，在標靶收容主體4，設有收容X射線輸出窗6a 及對後述的電子槍殼體7的管軸線呈傾斜配置之標靶3 a 的標靶收容空間S。在標靶收容主體4，電子槍8被塡裝 於金屬製（例如不銹鋼）的電子槍殼體7之狀態的電子槍 組裝體A以電子槍殼體7的管軸線與陽極3的軸線大致呈 垂直地交叉的方式安裝著，電子槍組裝體A的前端面臨標 靶收容空間S內。因此，由鍋爐排廢氣排氣口 8所射出之 電子會與標靶3 a衝突，由標靶3 a所釋出的X射線通過X 射線輸出窗6 a射出至外部。 在此X射線管1，標靶3 a上的電子射入位置（X射線 焦點位置）與X射線輸出窗6a爲止的距離（FOD )越短 ，所攝像的放大透視圖像的放大率變大，藉由非破壞、非 接觸觀察所進行之檢查的精度變高。在X射線管1，爲了 縮短FOD，使設置於陽極3的標靶3a接近X射線輸出窗 6a，伴隨此，使由電子槍8所射出的電子之射出位置接近 X射線輸出窗6a。 接著，說明關於用來朝設置於這種位置的標靶3 a射 出電子之電子槍8及電子槍殼體7。 如圖1至圖3所示，收容電子槍8之電子槍殼體7是 -8- 200849307 由圓筒狀殼體本體部9、及一體地形成於殻體本體部9的 前端之圓筒狀突出部1 0所構成，在殼體本體部9的一端 ，設有連續於突出部1 0之縮徑部9a。突出部1 〇是對通過 殼體本體部9的中心之管軸線l朝X射線輸出窗6a側偏 心設置’並且並且，延伸於管軸線L方向。藉由這樣的偏 心構造，能使突出部1 0儘可能地接近X射線輸出窗6 a。 在電子槍8的桿板（stem plate) 11，固定有桿銷12 及金屬製圓同狀裙部13’在桿銷12a、12b，連接有加熱 器16。在桿銷12c，固定有用來調整由加熱器16所釋出 的電子量的第1閘極電極部1 4，該第1閘極電極部1 4於 平板狀部的週原具有覆蓋加熱器1 6之立設部。在桿銷i 2d ’用來將通過第1閘極電極部1 4的電子加以集束之圓筒 狀第2閘極電極部（集束電極部）1 5。又，第1閘極電極 部1 4與第2閘極電極部1 5之間，藉由未圖示的絕緣構件 保持著間隔。又，此第2閘極電極部1 5被插入至電子槍 殼體7的突出部10內。且，在7的殻體本體部9之外周 面的電子射出方向側端（縮徑部9a側端），於接近突出 部1 〇的位置設有矩形第丨開口部20 (參照圖6 )，此第1 開口部2 0被收容於標靶收容主體4內。 如圖4(a)所示，在將電子槍8裝塡至電子槍殼體7 內之際’夾持固定於桿板1 1的裙部1 3，使電子槍8由前 端逐漸進入到殼體本體部9的後端開口 9b內。然後，如 圖4 ( b)所示，將第2閘極電極部1 5插入至電子槍殼體 7的矢出部ι〇內。 -9 - 200849307 在將電子槍8高精度地定位於電子槍殼體7內 因前述之第1開口部2 0可作爲以確認8在+/內的 目的之觀察窗來加以利用，所以，對插入時及插入 子槍8與電子槍殻體7的內表面有無接觸等的確認 雖以往藉由X射線透視等進行，但本發明能以目視 。且，因第1開口部2 0亦可作爲鑷子P等的治具 口來利用，所以，亦可容易進行電子槍8在電子槍 內之位置的微調整。又，在電子槍殻體7內完成電 的位置調整後，將電子槍8的裙部1 3熔接於電子槍 ，完成電子槍組裝體A之組裝作業。 且，在將電子槍的圓筒狀第2閘極電極部1 5 電子槍殻體7的圓筒狀突出部1 0之際，當電子槍 第2閘極電極部1 5的前端1 5a與電子槍殼體7的 10的前端l〇a之距離產生不均時，則在第2閘極 1 5的電子透鏡效果上會產生參差不齊，無法獲得具 的X射線焦點之X射線管1。因此，如圖5 ( a )所 電子槍8側的第2閘極電極部1 5的前端1 5 a與電 體7的突出部1〇的前端l〇a密接的狀態作爲期望 (設計上的狀態）爲佳，因此’需要支承這些之密 另外，如圖5 ( b )所示，當第2閘極電極部15 15a與突出部1〇的前端l〇a分離時，則由於因應該 距離，在電子透鏡之形成上會產生變化，故變得極 獲得具有期望的X射線焦點之X射線管。 因此，在電子槍殼體7的殼體本體部9，接近 之際， 位置爲 後的電 作業， 來確認 之插入 殻體7 子槍8 殼體7 插入至 8側的 突出部 電極部 有期望 示，將 子槍殼 的狀態 接性。 的前端 分離的 爲不易 圓筒狀 -10- 200849307 的突出部10而形成第1開口部20，故，如圖4 ( b )所示 ，將鑷子P等的治具由第1開口部20插入，以鑷子P等 直接夾取第1閘極電極部1 4或第2閘極電極部1 5，藉此 ，可使作業者的力量直接傳達至第2閘極電極部1 5，可將 第2閘極電極部1 5確實地壓入至圓筒狀突出部1 〇內。因 此，藉由強力的按壓力，可使第2閘極電極部1 5的前端 1 5 a與電子槍殻體7的突出部1 〇的前端1 〇 a確實地密接。 且，在伴隨著X射線管1的小型化’也使電子槍8及 電子槍殻體7小型化之情況，必須降低電子槍8的X射線 管1或裙部1 3的機械性強度。在此，當不具有第1開口 部20時，則電子槍殼體7內之電子槍8必須僅以由殼體 本體部9的後端開口 9b壓入電子槍8來進行。但，由於 桿銷1 2或裙部1 3的機械性強度降低會造成不易進行經由 這些構件之充分的按壓，其結果，會產生7/內之電子槍8 的定位精度降低的可能性。因此，在電子槍殼體7設置第 1開口部20，對電子槍8的小型化產生極大的效果。 又，在封閉具有上述各種優點的第1開口部20之際 ，例如藉由熔接或軟焊接合平板狀的蓋與電子槍殼體7時 ，則不僅作業製程繁雜，且由於接合部位成爲電子槍8的 附近，故亦會直接受到熔接或軟焊時的熱所影響，對電子 槍8造成壞影響之虞。又，會有伴隨接合所產生之電子槍 殼體7內部空間側之第1開口部20的周緣之形狀變化會 對電子槍8的釋出特性產生變化之虞。 因此，如圖1至圖3及圖6所示，於在內部具有標靶 -11 - 200849307 收容空間s的標靶收容主體4 ’朝圓板狀突緣4a的徑方向 突出之電子槍裝設部2 1被一體地形成。再者，此電子槍 裝設部2 1，理想是設置成爲在突緣4a的徑方向，不會由 突緣4 a突出，在X射線射出方向，不會由X射線輸出窗 6a的外側表面（與標靶收容空間S側表面相對向的表面） 突出。 藉此，因容易製造標靶收容主體4，並且電子槍裝設 部2 1不會成爲阻礙，所以，能夠使X射線管1更接近被 照射物。又，在此電子槍裝設部2 1內’形成有延伸於徑 方向的剖面呈圓形之殻體插入孔22 (參照圖7 )，此殻體 插入孔22的直徑是與電子槍組裝體A的殼體本體部9之 直徑大致相同’形成殻體插入孔22之壁面22a與殼體本 體部9的外周面密接。藉由此壁面2 2 a，做成第1開口部 20之蓋（參照圖3 )。又，藉由在壁面22a的自由端與縮 徑部9 a的外周面進行熔接（或軟焊）D，進行標靶收容主 體4與電子槍組裝體A的固定，及密封保持，使外部環境 氣體不會由殻體插入孔22流入至X射線管1內。 再者，作爲第1開口部20的形成區域，爲殼體本體 部9的外周面中，對桿板1 1側，受到壁面22a所完全地 蓋住之範圍內’針對電子射出方向側，不會到達標靶收容 空間S之範圍內。即，殼體本體部9的外周面中，含於殼 體插入孔22 (壁面22a)之區域。這是由於針對桿板11 側，需要以熔接（或軟焊）來進行密封保持，針對電子射 出方向，在第1開口部20含於標靶收容空間S之情況， -12- 200849307 在露出於標靶收容空間s之第1開口部20的緣部，產生 電場的紊亂，會有產生由施加有高電壓的陽極3 (標靶3 a )朝緣部放電的可能性之故。 如此，因將形成殼體插入孔2 2的壁面2 2 a作爲第1 開口部2 0的蓋（封閉手段）來活用，所以，能以簡單的 插入作業，簡單地封住第1開口部2 0。並且，在對標靶收 容主體4將電子槍組裝體A進行固定及相互間的密封保持 之際，由於在將第1開口部20收容於殼體插入孔22內部 的狀態下能夠進行熔接（或軟焊）D，可對第1開口部20 不受熔接（或軟焊）D的影響地加以封住。因此，在組裝 X射線管1之際，因將電子槍殼體7的第1開口部20配 置於標靶收容主體4內，所以，容易進行電子槍殼體7對 標靶收容主體4之組裝作業。又，伴隨電子槍殼體7的組 裝作業容易化，使X射線管1的組裝作業性變得良好。 且，在殼體插入孔22的深部側，形成有用來使電子 槍殻體7的突出部1 0面臨於標靶收容主體4的標靶收容 空間S內之第2開口部3 0。此第2開口部3 0使殼體插入 孔22與標靶收容主體4的標靶收容空間S連通。又，在 標靶收容主體4，於與第2開口部3 0相對向的位置形成有 第3開口部40，此第3開口部40使標靶收容空間S與外 部連通。又，此第2開口部3 0受到圓板狀蓋部5 6所覆蓋 〇 此第3開口部4 0，利用來使電子正確地射中標® 3 a ，使電子槍殼體7的突出部1 〇正確地安裝於標靶收容空 -13 - 200849307 間S內。如圖6所示，作爲定位調整治具，可利用例如定 位棒5 4。 其次，說明關於將電子槍8與電子槍殼體7的組裝完 成之電子槍組裝體A組裝至標靶收容主體4的順序。 如圖7所示，在置於作業台上的平板狀台座塊R上， 配置標靶收容主體4，將定位棒54由第3開口部40插入 ，並且將電子槍組裝體A插入至標靶收容主體4的殼體插 入孔22內，使電子槍殼體7的突出部10之開口 l〇b插入 至定位棒5 4的前端。然後，使電子槍組裝體A抵接到殼 體插入孔22的深部，一邊維持此狀態，一邊藉由熔接（ 或軟焊）D將電子槍組裝體A的殻體本體部9固定於標靶 收容主體4的電子槍裝設部2 1。即，藉由殼體插入孔2 2 與定位棒5 4之相互作用，進行電子槍組裝體a對標靶收 容主體4之定位。再者，此熔接D是爲了確保氣密性，而 施工於殻體本體部9的全周範圍。 然後，由第3開口部4 0拔出定位棒5 4。又，將圓板 狀蓋部56(參照圖1及圖2)嵌入第3開口部40內，將 蓋部56熔接於標靶收容主體4，完成第3開口部40之封 閉。 如此’藉由在標靶收容主體4設置第3開口部40，可 由第3開口部40，將定位棒5 4插入至標靶收容空間s內 。因此’藉由將電子槍組裝體A插入至標靶收容主體4的 殼體插入孔22內，並且將定位棒54的前端插入至突出部 10的前端側之開口 l〇b內，可將電子槍組裝體A的突出 -14- 200849307 部1 0之開口 1 〇b安裝於正確的位置。 其結果，能夠在1 9 ·內將電子的射出位置予以正確地 定位，可使由第2閘極電極部1 5所射出的電子正確地射 中標靶3 a，獲得期望的X射線焦點。又，在電子槍8的 第2閘極電極部1 5及電子槍殼體7的突出部1 0對管軸線 L偏心之情況，當電子槍組裝體A的突出部1 0之開口 1 〇 b 之位置產生偏移時，則所獲得的X射線焦點會完全改變， 故設置此第3開口部4 0特別有效。 本發明不限於上述實施形態。例如適用於本發明之X 射線管的第1開口部20，亦可爲矩形，亦可爲橢圓形。電 子槍殻體7的突出部1 〇亦可與殼體本體部9的管軸線L 一致。 如圖8所示’做爲其他實施形態之χ射線管6〇，不 限於以壁面22a做成爲第丨開口部2〇的蓋，於在第1開 口部20與壁面22a間具有間隔的狀態下，亦可藉由熔接 (或軟焊）D ’將標靶收容主體4的電子槍裝設部2 1之自 由端與殻體本體部9的外周面接合。 [產業上的利用可能性] € ®據本發明的話，可使電子槍的組裝作業性變得良 好。 【圖式簡單說明】 B 1是顯示本發明之χ射線管的一實施形態的斷面圖 -15- 200849307 圖2是將圖1所示的X射線管予以分解之斷面圖。 圖3是圖1的局部放大斷面圖。 圖4是顯示電子槍組裝體之組裝順序的斷面圖。 圖5(a)是顯示電子槍的集束電極部被充分地嵌至電 子槍殼體的突出部內之狀態的斷面圖，（b )是顯示嵌合 不充分的狀態之斷面圖。 圖6是顯示標靶收容主體、電子槍組裝體及定位棒之 斜視圖。 圖7是顯示利用定位棒，將電子槍組裝體組裝至標靶 收容主體的狀態之斷面圖。 圖8是顯示本發明之X射線管的其他實施形態的斷面 圖。 【主要元件符號說明】 60 : X射線管 3 a :標靶 4 ··標靶收容主體 7 ··電子槍殻體 8 :電子槍 9 :殼體本體部 1 0 ··突出部 1 2 ··桿銷 1 5 ··第2閘極電極部（集束電極部） -16- 200849307 2 0 :第1開口部 · 22 :殼體插入孔 22a :殼體插入孔的壁面（關閉手段） 3 0 :第2開口部 40 :第3開口部 5 6 :蓋部 S :標靶收容空間 L :管軸線 P :鑷子（治具） •17-200849307 IX. Description of the Invention [Technical Field of the Invention] The present invention relates to a micro-microfocus X-ray tube used for industrial use or medical use. [Prior Art] Conventionally, as a technique in this field, there is a publication of Japanese Laid-Open Patent Publication No. 1 3 28 26 . The X-ray tube described in this publication has a rod-shaped target fixed to a glass tube, and a main body portion is fixed to the open end of the tube. Further, in the target placed at the tip end of the target support, the electrons emitted from the electron gun generate X-rays from the target, and the X-rays are emitted from the X-ray exit window of the set portion to the outside. Further, the gun is provided with an electric supply rod pin (s t e m p i η ), and the electron gun having the rod pin holder, the cathode, and the first and second grid electrode structures is housed in the metal gun housing. [Patent Document 1] Japanese Laid-Open Patent Publication No. JP-A No. 2003- No. Hei. No. Hei. No. Hei. No. Hei. Problem to be Solved The above-described conventional X-ray electron gun cannot accurately position the electron beam by the electron beam emitted from the electron gun, and the desired X-ray focus cannot be obtained. Therefore, it is required that the focus type 2003 - glass made of metal is placed by the main electron in the heating. This type of body is correctly positioned to properly position the electric-4 - 200849307 sub-gun in the electron gun housing. However, with the miniaturization of the x-ray tube, the electron gun and the electron gun housing are gradually miniaturized, resulting in assembly such as confirmation of positioning. The problem of difficult work at the time arises. An object of the present invention is to provide an X-ray tube having excellent assembly workability. [Means for Solving the Problem] The X-ray tube of the present invention is for injecting electrons emitted from an electron gun having a rod pin into a target. A x-ray tube that generates a x-ray from a target, comprising: an electron gun housing for accommodating an electron gun and having a first opening formed in a cylindrical casing main body; and a housing mark inside The metal target mounting body of the target receiving space of the target is housed in the target receiving body in the first opening of the electron gun housing. When the electron gun is positioned in the electron gun housing with high longitude, the first opening can be used as an observation window for confirming the position of the electron gun in the electron gun housing. Therefore, it is easy to visually confirm the electron gun and the electron gun housing. Whether the inner surface of the body has contact or the like, or the micro-adjustment of the position of the electron gun in the electron gun housing is easy. Further, when the X-ray tube is assembled, since the first opening portion of the electron gun case can be placed in the target housing main body, assembly work of the electron gun housing to the target housing main body can be easily performed. Therefore, the assembly workability of the X-ray tube can be improved as the assembly work of the electron gun case is facilitated. Further, the front end of the electron gun case has a cylindrical projecting portion integrally formed in the case main body portion, and a cylindrical collecting electrode portion inserted into the protruding portion -5 - 200849307 is provided at the tip end of the electron gun, and the first opening is provided. The department is better than the protruding part. In the case body portion of the electron gun case, the first opening portion is formed close to the outlet portion, and it is necessary to insert the electron gun cylindrical collecting electrode portion into the X-ray tube of the present invention provided in the front end portion of the electron gun housing. When the distance between the front end of the set on the electron gun side and the front end of the projection of the electron gun housing has an X-ray tube which is uneven in the effect of the electron lens of the bundle electrode portion to have a desired X-ray focus. Therefore, it is preferable that the tip end of the collecting electrode portion on the gun side is in a desired state in a state in which the protruding portion of the electron gun case is in contact with the protruding portion. In the jig of the present invention, since the jig of the tweezers or the like is inserted into the first opening, the vicinity of the collecting electrode portion can be taken by the tweezers, so that the strength of the operator can be made to reach the concentrated electrode portion, and the cylindrical collecting electrode portion can be sure Inside the ground-like protrusion. Therefore, the tip end of the protruding portion of the front end case of the bundle electrode portion can be surely adhered to each other, and an X-ray tube having a ray focus can be obtained. Further, the target housing main body preferably includes a second opening portion that forms a container body and that connects the distal end side of the electron gun housing into the target housing housing of the housing insertion housing main body; the housing space communicates with the outside And a third opening that faces the target housing body with respect to the second opening; and a lid that closes the first cover. With such a configuration, the second opening of the electron gun case can be faced in the target accommodating space, and the rod-shaped opening 3 can be inserted into the target accommodating space. Therefore, when the cylindrical protruding electrode portion of the tip end of the cylindrical protrusion can be formed, it is impossible to obtain a positive end of the electron dense tube, and the direct clamping is surely transmitted to the tube and the desired X of the electron gun. In the position of the target income hole and the target, the opening portion of the target is inserted into the front end opening of the protrusion from the front end of the rod-shaped treatment -6-200849307, so that the electron gun shell can be The protrusion of the body is mounted in the correct position. As a result, the electrode emitted from the cluster electrode portion can be accurately incident on the target to obtain a desired X-ray focal point. Further, the projection of the electron gun housing is preferably eccentric to the tube axis of the housing body portion. With such a configuration, F Ο D can be shortened compared to the X-ray tube in which the bundle electrode portion of the electron gun coincides with the tube axis of the electron gun housing, and the magnification of the magnified fluoroscopic image captured can be improved. Further, the use of the third opening portion is particularly effective in the case where the focusing electrode portion of the electron gun and the protruding portion of the electron gun housing are eccentric. [Effect of the Invention] According to the present invention, the assembly workability of the electron gun can be improved. [Embodiment] Hereinafter, a preferred embodiment of an X-ray tube according to the present invention will be described in detail with reference to the drawings. As shown in Fig. 1 and Fig. 2, the X-ray tube 1 is a micro focus type microfocus X-ray tube used for industrial use or medical use, and has a sealed structure for maintaining a vacuum. The X-ray tube 1 is an electron tube 2 made of glass. The base end of the rod-shaped anode 3 is fixed to one end of the closed tube of the tube 2, and a cylindrical metal ring 2a is fixed to the other end of the electron tube 2. Further, at the tip end of the anode 3, in order to generate X-rays by electron collision, a disk-shaped target 3a made of tungsten is buried. 200849307 The target housing main body 4 made of metal (for example, not made of steel) is fixed to the metal ring 2a provided in the electron tube 2 by welding. In the upper end side opening 4b of the target receiving body 4, a cover plate 6 is fitted, and the cover plate 6 is fixed to the target housing main body 4 by welding. Further, in the center of the cover 6, an X-ray output window 6a composed of a Be material is provided. Further, the target housing main body 4 is provided with a target housing space S in which the X-ray output window 6a and the target 3 a which is disposed obliquely to the tube axis of the electron gun housing 7 to be described later are housed. In the target housing main body 4, the electron gun assembly A in which the electron gun 8 is attached to the electron gun housing 7 made of metal (for example, stainless steel) intersects the axis of the anode 3 substantially perpendicularly with the tube axis of the electron gun housing 7. In the manner of mounting, the front end of the electron gun assembly A faces the target receiving space S. Therefore, the electrons emitted from the exhaust gas exhaust port 8 of the boiler collide with the target 3a, and the X-rays emitted from the target 3a are emitted to the outside through the X-ray output window 6a. In this X-ray tube 1, the shorter the distance (FOD) between the electron injection position (X-ray focus position) on the target 3a and the X-ray output window 6a, the enlargement magnification of the imaged enlarged fluoroscopic image becomes larger. The accuracy of the inspection by non-destructive, non-contact observation becomes high. In the X-ray tube 1, in order to shorten the FOD, the target 3a provided on the anode 3 is brought close to the X-ray output window 6a, and accordingly, the emission position of the electrons emitted from the electron gun 8 is made close to the X-ray output window 6a. Next, an electron gun 8 and an electron gun housing 7 for emitting electrons toward the target 3a provided at such a position will be described. As shown in FIGS. 1 to 3, the electron gun housing 7 accommodating the electron gun 8 is a cylindrical housing main portion 9 and a cylindrical projection integrally formed at the front end of the housing main portion 9 from -8 to 200849307. In the case of 10, a reduced diameter portion 9a continuous to the protruding portion 10 is provided at one end of the casing main body portion 9. The projection 1 is eccentrically disposed toward the X-ray output window 6a side by the tube axis 1 passing through the center of the housing body portion 9 and extends in the tube axis L direction. With such an eccentric structure, the projection 10 can be brought as close as possible to the X-ray output window 6a. A stem pin 12 and a metal-like skirt portion 13' are fixed to the stem plate 11 of the electron gun 8, and the heaters 16 are connected to the lever pins 12a and 12b. A first gate electrode portion 14 for adjusting the amount of electrons emitted from the heater 16 is fixed to the rod pin 12c, and the first gate electrode portion 14 has a cover heater 1 in the periphery of the flat portion. 6 standing department. In the rod pin i 2d ', a cylindrical second gate electrode portion (bundle electrode portion) 15 for collecting electrons passing through the first gate electrode portion 14 is used. Further, the gap between the first gate electrode portion 14 and the second gate electrode portion 15 is maintained by an insulating member (not shown). Further, the second gate electrode portion 15 is inserted into the protruding portion 10 of the electron gun case 7. Further, a rectangular second opening portion 20 (see FIG. 6) is provided at a position closer to the protruding portion 1 〇 at the electron emission direction side end (the reduced diameter portion 9a side end) of the outer peripheral surface of the casing main body portion 9 of the seventh embodiment. The first opening portion 20 is housed in the target housing main body 4. As shown in FIG. 4(a), when the electron gun 8 is mounted in the electron gun housing 7, the skirt portion 13 fixed to the lever plate 1 is clamped, and the electron gun 8 is gradually introduced from the front end to the housing body portion. 9 inside the rear opening 9b. Then, as shown in Fig. 4 (b), the second gate electrode portion 15 is inserted into the sagitating portion ι of the electron gun housing 7. -9 - 200849307 The high-precision positioning of the electron gun 8 in the electron gun housing 7 can be utilized as the observation window for confirming the purpose of 8 in +/ within the first opening 20, so The confirmation that the insertion probe 8 is in contact with the inner surface of the electron gun housing 7 has been conventionally performed by X-ray fluoroscopy or the like, but the present invention can be visually observed. Further, since the first opening portion 20 can also be used as a jig for the tweezers P or the like, the position of the electron gun 8 in the electron gun can be easily adjusted. Further, after the electric position adjustment is completed in the electron gun case 7, the skirt portion 13 of the electron gun 8 is welded to the electron gun to complete the assembly work of the electron gun assembly A. When the cylindrical second electrode portion 15 of the electron gun is in the cylindrical projecting portion 10 of the electron gun housing 7, the front end 15a of the second gate electrode portion 15 of the electron gun and the electron gun housing are used. When the distance between the front end 10a of 7 is uneven, the X-ray tube 1 having the X-ray focus cannot be obtained in the electron lens effect of the second gate 15. Therefore, as shown in Fig. 5 (a), the front end 1 5 a of the second gate electrode portion 15 on the side of the electron gun 8 is in close contact with the front end 10a of the protruding portion 1 of the electric body 7 as a desired state (design state) It is preferable that it is necessary to support the density. Further, as shown in FIG. 5(b), when the second gate electrode portion 15 15a is separated from the front end l〇a of the protruding portion 1〇, due to the distance, A change occurs in the formation of the electron lens, so that an X-ray tube having a desired X-ray focus is extremely obtained. Therefore, in the case where the case main body portion 9 of the electron gun case 7 is approaching, the position is a post-electric operation, and it is confirmed that the insertion portion of the housing 7 is inserted into the projection electrode portion of the housing 8 to the 8 side. , the state of the sub-gun shell. Since the first opening 20 is formed in the protruding portion 10 which is not easily cylindrical in the shape of the cylindrical form-10-200849307, the jig of the tweezers P or the like is inserted into the first opening 20 as shown in Fig. 4(b). The first gate electrode portion 14 or the second gate electrode portion 15 is directly sandwiched by the dice P or the like, whereby the operator's power can be directly transmitted to the second gate electrode portion 15 and can be The gate electrode portion 15 is surely pressed into the cylindrical projecting portion 1 . Therefore, the front end 15 5 a of the second gate electrode portion 15 can be surely adhered to the front end 1 〇 a of the protruding portion 1 电子 of the electron gun case 7 by a strong pressing force. Further, in the case where the size of the X-ray tube 1 is reduced, the electron gun 8 and the electron gun housing 7 are also miniaturized, and the mechanical strength of the X-ray tube 1 or the skirt portion 13 of the electron gun 8 must be lowered. Here, when the first opening portion 20 is not provided, the electron gun 8 in the electron gun housing 7 must be pressed only by the electron gun 8 by the rear end opening 9b of the casing main body portion 9. However, since the mechanical strength of the lever pin 12 or the skirt portion 1 is lowered, it is difficult to perform sufficient pressing through these members, and as a result, the positioning accuracy of the electron gun 8 within 7/ may be lowered. Therefore, the first opening portion 20 is provided in the electron gun housing 7, which greatly affects the miniaturization of the electron gun 8. Further, when the first opening 20 having the various advantages described above is closed, for example, when the flat cover and the electron gun housing 7 are welded or welded, the work process is complicated, and the joint portion becomes the electron gun 8. In the vicinity, it is also directly affected by the heat during welding or soldering, which has a bad influence on the electron gun 8. Further, the shape change of the peripheral edge of the first opening portion 20 on the inner space side of the electron gun case 7 due to the joining may change the release characteristics of the electron gun 8. Therefore, as shown in FIG. 1 to FIG. 3 and FIG. 6, the target gun housing main body 4' having the target -11 - 200849307 housing space s protrudes in the radial direction of the disc-shaped flange 4a. 2 1 is formed integrally. Further, the electron gun mounting portion 21 is preferably provided so as not to be protruded by the flange 4a in the radial direction of the flange 4a, and is not in the X-ray emitting direction by the outer surface of the X-ray output window 6a ( The surface opposite to the side surface of the target housing space S protrudes. Thereby, since the target housing main body 4 can be easily manufactured and the electron gun mounting portion 21 is not hindered, the X-ray tube 1 can be brought closer to the object to be irradiated. Further, in the electron gun mounting portion 21, a housing insertion hole 22 (see FIG. 7) having a circular cross section extending in the radial direction is formed. The diameter of the housing insertion hole 22 is the same as that of the electron gun assembly A. The casing body portion 9 has substantially the same diameter. The wall surface 22a forming the casing insertion hole 22 is in close contact with the outer circumferential surface of the casing body portion 9. The cover of the first opening portion 20 is formed by the wall surface 2 2 a (see Fig. 3). Further, by welding (or soldering) D to the outer peripheral surface of the reduced diameter portion 9a at the free end of the wall surface 22a, the target housing main body 4 and the electron gun assembly A are fixed, and sealed and held to allow external environmental gas. It does not flow into the X-ray tube 1 by the housing insertion hole 22. In addition, the formation region of the first opening portion 20 is in the range of the electron emission direction side in the outer peripheral surface of the case main body portion 9 in the range in which the wall surface 22a is completely covered by the side of the rod plate 1 1 Will reach the range of the target receiving space S. That is, the outer peripheral surface of the casing body portion 9 is included in the region of the casing insertion hole 22 (wall surface 22a). This is because the rod plate 11 side needs to be sealed and held by welding (or soldering), and the first opening portion 20 is included in the target receiving space S in the electron emission direction, and -12-200849307 is exposed. In the edge portion of the first opening portion 20 of the target accommodating space s, an electric field is disturbed, and there is a possibility that the anode 3 (target 3 a ) to which the high voltage is applied is discharged toward the edge portion. In this way, since the wall surface 2 2 a forming the case insertion hole 22 is used as the cover (closing means) of the first opening 20, the first opening 2 can be easily sealed by a simple insertion operation. 0. In addition, when the electron beam assembly A is fixed and sealed to each other in the target housing main body 4, the first opening 20 can be welded (or soft) while being housed inside the housing insertion hole 22. The welding D can seal the first opening 20 without being affected by welding (or soldering) D. Therefore, when the X-ray tube 1 is assembled, since the first opening portion 20 of the electron gun housing 7 is placed in the target housing main body 4, the assembly work of the electron gun housing 7 with the target housing main body 4 is facilitated. Moreover, the assembling work of the electron gun housing 7 is facilitated, and the assembling workability of the X-ray tube 1 is improved. Further, on the deep side of the casing insertion hole 22, a second opening portion 30 for facing the projecting portion 10 of the electron gun casing 7 in the target accommodating space S of the target accommodating body 4 is formed. The second opening portion 30 allows the case insertion hole 22 to communicate with the target accommodation space S of the target storage body 4. Further, in the target housing main body 4, a third opening portion 40 is formed at a position facing the second opening portion 30, and the third opening portion 40 allows the target housing space S to communicate with the outside portion. Further, the second opening portion 30 is covered by the disc-shaped cover portion 56 to the third opening portion 40, and the electrons are accurately shot by the standard ® 3 a so that the protruding portion 1 of the electron gun housing 7 is folded. Installed correctly in the target containment space -13 - 200849307. As shown in Fig. 6, as the positioning adjustment jig, for example, a positioning bar 54 can be utilized. Next, the procedure for assembling the electron gun assembly A in which the assembly of the electron gun 8 and the electron gun housing 7 is completed to the target housing main body 4 will be described. As shown in FIG. 7, the target housing main body 4 is placed on the flat pedestal block R placed on the workbench, the positioning rod 54 is inserted from the third opening 40, and the electron gun assembly A is inserted into the target housing. The housing of the main body 4 is inserted into the hole 22, and the opening 10b of the protruding portion 10 of the electron gun housing 7 is inserted into the front end of the positioning rod 54. Then, the electron gun assembly A is brought into contact with the deep portion of the casing insertion hole 22, and while maintaining this state, the casing main body portion 9 of the electron gun assembly A is fixed to the target receiving body by welding (or soldering) D. The electron gun mounting portion 2 of 4. That is, the positioning of the electron gun assembly a with respect to the target receiving body 4 is performed by the interaction of the housing insertion hole 2 2 with the positioning bar 54. Further, this welding D is applied to the entire circumference of the casing body portion 9 in order to ensure airtightness. Then, the positioning bar 5 4 is pulled out by the third opening portion 40. Further, the disk-shaped lid portion 56 (see Figs. 1 and 2) is fitted into the third opening portion 40, and the lid portion 56 is welded to the target container main body 4 to complete the sealing of the third opening portion 40. Thus, by providing the third opening 40 in the target housing main body 4, the positioning rod 5 4 can be inserted into the target housing space s by the third opening 40. Therefore, the electron gun assembly can be assembled by inserting the electron gun assembly A into the housing insertion hole 22 of the target housing main body 4 and inserting the front end of the positioning rod 54 into the opening l〇b of the front end side of the projection 10. The protrusion of body A-14- 200849307 The opening 1 of 110 is installed in the correct position. As a result, the electron emission position can be accurately positioned within 1 9 ·, and the electrons emitted from the second gate electrode portion 15 can be accurately incident on the target 3 a to obtain a desired X-ray focal point. Further, when the second gate electrode portion 15 of the electron gun 8 and the protruding portion 10 of the electron gun case 7 are eccentric to the tube axis L, the position of the opening 1 〇b of the protruding portion 10 of the electron gun assembly A is generated. When the offset is performed, the obtained X-ray focus is completely changed, so that the third opening portion 40 is particularly effective. The present invention is not limited to the above embodiment. For example, the first opening 20 to be applied to the X-ray tube of the present invention may be rectangular or elliptical. The projection 1 of the electron gun housing 7 may also coincide with the tube axis L of the housing body portion 9. As shown in FIG. 8 , the ray tube 6 其他 according to the other embodiment is not limited to the cover which is the second opening 2 以 by the wall surface 22 a, and is spaced apart from the wall surface 22 a between the first opening 20 and the wall surface 22 a. Alternatively, the free end of the electron gun mounting portion 21 of the target housing main body 4 may be joined to the outer peripheral surface of the casing main body portion 9 by welding (or soldering) D'. [Industrial Applicability] According to the present invention, the assembly workability of the electron gun can be improved. BRIEF DESCRIPTION OF THE DRAWINGS B 1 is a cross-sectional view showing an embodiment of a xenon tube of the present invention. -15- 200849307 FIG. 2 is a cross-sectional view showing the X-ray tube shown in FIG. Fig. 3 is a partially enlarged sectional view of Fig. 1; 4 is a cross-sectional view showing an assembly sequence of an electron gun assembly. Fig. 5 (a) is a cross-sectional view showing a state in which the collecting electrode portion of the electron gun is sufficiently fitted into the protruding portion of the electron gun housing, and Fig. 5 (b) is a cross-sectional view showing a state in which the fitting is insufficient. Fig. 6 is a perspective view showing the target housing main body, the electron gun assembly, and the positioning rod. Fig. 7 is a cross-sectional view showing a state in which an electron gun assembly is assembled to a target housing main body by using a positioning rod. Fig. 8 is a cross-sectional view showing another embodiment of the X-ray tube of the present invention. [Description of main component symbols] 60 : X-ray tube 3 a : Target 4 · Target mounting body 7 · Electron gun housing 8 : Electron gun 9 : Housing main body 1 0 · · Projection 1 2 ··Pole pin 1 5 ··2nd gate electrode part (bundle electrode part) -16- 200849307 2 0 : First opening part · 22 : Case insertion hole 22a : Wall surface of case insertion hole (closing means) 3 0 : 2nd Opening portion 40: third opening portion 5 6 : cover portion S: target accommodation space L: tube axis P: tweezers (fixture) • 17-