201110189 六、發明說明： 【發明所屬之技術領域】 本發明是關於一種短弧型放電燈（以 燈」），尤其是，關於一種短弧型放電燈 【先前技術】 習知的放電燈是具備：中央部鼓出的 管，及相對於此發光管的鼓出部的內部所 極。陽極是在相對於陰極的前端具有平坦 是相對於陽極的前端爲朝著前端外徑形成 錐狀。當通電至此放電燈，則從陰極所放 內的氣體碰撞而生成荷電粒子。此荷電粒 得封入於發光管內部的物質，例如水銀成 在兩極間形成有電弧。 又，電發中的電子是流在陽極側，而 端面。受到電子踫撞的陽極前端面成爲平 極中央部的電場強度是比周邊部還要強， 使得電流流進陽極中央部，眾知陽極中央 蒸發會消耗。 如此地，當陽極被消耗，則蒸發的陽 著於發光管的內壁，而產生黑化發光管的 。又，當發光管的內壁面進行黑化，則降 放射束，而有照射面所必需的放射照度不 須將放電燈更換新產品的燈》 下，稱爲「放電 的陽極構造。 石英玻璃製發光 配置的陽極與陰 的前端面。陰極 依次地變細的圓 出的電子是與燈 子是重複踫撞使 爲電漿狀態，而 踫撞於陽極的前 坦之故，因而陽 被其強電場吸引 部成爲高溫而且 極構成物質是附 內壁面的不方便 低來自放電燈的 足之故，因而必 -5- 201110189 於是，在點亮放電燈時，抑制陽極會溫度上昇，藉由 延遲陽極的消耗與發光管的內壁ή進行黑化，而爲了得到 高放射照度維持率的對策，以往就被檢討。 在專利文獻1，揭示著在除了陽極的前端部的側面燒 結碳化鎢（WC )及碳化鉬（TaC )與鎢（W)所成的混合 物以形成多孔質層的陽極。記載著此多孔質層是與母材的 密接性優異之故，因而成爲適當可抑制陽極的溫度上昇， 可減少陽極的消耗與發光管的內壁面的黑化，又可延長放 電燈的壽命。 又，如第7圖所示地，在專利文獻2、3及4，相對於陰 極90的陽極80的前端部設有凹部81。此凹部81是形成接近 在阻止從陰極90所放出的電子之處所發生的電場強度。依 照此些文獻，在陽極80表面的電流密度分布被分散，陽極 8 0的消耗變少，發光管的內壁面的黑化進行延遲，藉此， 可得到高放射照度維持率，而可延長放電燈的壽命。 被揭示於此些1至4的各專利文獻的技術，是都放在延 長放電燈的壽命，亦即以提高放射照度維持率作爲重點。 [專利文獻1]日本專利第3 598475號（日本特開平 09- 1 1 5479號公報） [專利文獻2]曰本專利第3U651 1號（日本特開平 10- 283988號公報） [專利文獻3]日本專利第4〇54198號（日本特開 2003-234083 號公報） [專利文獻4]日本專利第4132879號（日本特開 201110189 2003-257365 號公報） 然而，一般使用於曝光裝置的放電燈，是放射照度維 持率必須較高，惟其以外也被要求高放射亮度亦即也被求 出高放射束。 又，本案發明人等，除了至今的燈所具有的高放射照 度維持率，也進行提供高放射亮度亦即高放射束的放電燈 的檢討，在比此申請之前，作爲日本特願2009-154651號 進行專利申請。 此專利申請是槪略也如以下者。藉由陽極內壁面，平 坦的陽極內底面，及將環狀角部所成的凹部設於陽極前端 面，使得凹部的各點與陰極之電極間的距離變更，而在陽 極中心軸的位置與環狀角部的位置的2部位可保持電場強 度的峰値，此陽極中心軸的位置的電場強度的峰値是動作 成可維持放電燈的放射亮度，又環狀角部的位置的電場強 度的峰値是吸引電子而提昇此部分的電流密度來緩和陽極 前端面上的一部分領域的局部性電流的集中被緩和，而作 用於抑制陽極的消耗。 以下，依據第1圖及第2圖詳細地說明上述專利申請的 內容。 第1圖是表示放電燈的構成的槪略斷面圖。 放電燈10是具備：大約球狀地形成的發光部11及分別 連續於發光部11的兩端的直管狀密封部12A、12B所構成 的發光管。發光管是例如藉由石英玻璃一體地形成。在密 201110189 封部1 2A、1 2B，分別裝設具有圓筒形狀的饋電用的燈頭 1 3 A、1 3B » 在形成於發光管的內部的放電空間S，有陰極2與陽極 3互相相對配置在陽極中心軸L上，而且封入有發光物質。 發光物質是封入有氙氣體、氬氣體及氪氣體的至少1 種以上，及水銀。作爲發光物質，此些稀有氣體及水銀中 ，僅封入有一方也可以。 陰極2是藉由鎢等一體地形成被保持於密封部12A而 且面臨於放電空間S的圓柱狀胴部2A，及連續於胴部2A朝 著前端依次地形成外徑變細的圓錐狀的前端部2B。 陽極3是例如鎢一體地形成有圓柱狀胴部3 A，及分別 連續於胴部3 A的前端側與後端側所形成的圓錐台部3 B、 3C。在後端側的圓錐台3C，一體地連續有比胴部3A還要 小徑的桿狀引線部（未圖示），引線部被保持在密封部 12B。 陽極3是全長30〜100mm，胴部3A的直徑20〜40mm， 圓錐台部3B的前端徑5〜20mm，圓錐台部3B的後端徑20〜 4 0mm。陰極2及陽極3之間的電極間距離是3〜40mm。 第2(A)圖是擴大含有陽極中心軸L的斷面的斷面圖 。第2(B)圖是從表示於第2(A)圖的箭號B的方向觀看 陽極前端面的前視圖。 陽極3是具有朝著前端依次變細外徑的圓錐台部3B， 而在此圓錐台部3B的前端部形成有陽極前端面3D，在陽 極前端面3D的陽極中心軸L上形成有凹部30。 201110189 將凹部3 0的形狀加以說明，則此凹部3 0是具有：比陽 極前端面3D窪下朝圓周方向所形成的壁的陽極內壁面3 0Α ，及連續形成於上述陽極內壁面30Α，對於陽極中心軸L 朝直角於徑方向擴展，平坦地形成的壁的陽極內底面30Β ，及在陽極前端面3D及陽極內壁面30Α的境界中，從陽極 中心軸L朝徑方向隔開而圓周方向地形成的環狀角部30C ，此些三個構成所成的凹部30是從陽極前端面3D朝陽極3 的內方側窪下所形成。 凹部30是此些形狀之故，因而其全體形狀，是包含陽 極中心軸L的斷面爲矩形狀，亦即圓柱形狀。又，凹部3〇 是並不被限定於圓柱形狀，爲旋轉圓錐台形狀也可以。 使用此些形狀的陽極的放電燈，是當在陰極與陽極之 間施加高電壓，則在兩電極間形成有電弧。 在表不於第2圖的陽極3，具備比陽極前端面3_D還朝 陽極的內方側窪下的平坦的陽極內底面30B，在該陽極內 底面30B愈接近於陽極中心軸L愈使電場強度變高。又， 在從陽極中心軸L朝徑方向外方隔開的位置具備環狀角部 3 0C之故，因而在該裝置中，也使得電場強度成爲高狀態 〇 如此地，陽極3是藉由在陽極中心軸L與環狀角部30C 之雙方的位置使得電場強度成爲高狀態，從陰極2所發生 的電子分別分散於陽極中心軸L及環狀角部3 0C而被吸引 之故，因而被吸引於陽極中心軸L的電子的量被減低。 此陽極內底面30B的陽極中心軸L的位置的電場強度 -9 - 201110189 的峰値是動作成維持放電燈的亮度，而環狀角部的位置的 電場強度的峰値，是吸引電子而增加此部分的電流，會緩 和陽極前端面的局部性電流的集中被緩和，動作成抑制陽 極的消耗。 第8圖是表示針對於具備有從段落00 10至0015所說明 的陽極內壁面與平坦的陽極內底面與環狀角部所成的凹部 的表示於第2圖的陽極的放電燈（以下稱爲「燈1」）及具 備有接近在段落0006所說明的電場強度的凹部的表示於第 7圖的陽極的放電燈（以下，稱爲「燈2」）的各個，電弧 中的電場強度分布的模擬結果。第8圖的縱軸是表示電場 強度，而橫軸是表示來自陽極中心軸L的距離，實線是表 示燈1的陽極電場強度，而虛線是表示燈2的陽極電場強度 〇 在第8圖的實線所示地，在燈1的陽極中，電場強度的 敏銳峰値顯示在陽極中心軸L的位置與對應於凹部30的環 狀角部30C的位置，被推測電弧中的電子集中於陽極中心 軸L與環狀角部30C的樣子。另一方面，在燈2的陽極中， 因未看到此種峰値，因此被吸引至凹部8 1的邊緣部8 2的電 流的比率是較少。 如此地，燈1是藉由具有平坦的陽極內底面30B，陽極 中心軸L的電流密度是陽極未消耗的程度地適當地變高使 得放射亮度變高，而且藉由具有朝陽極中心軸L的徑方向 外方隔開地所形成的環狀角部3 0C，電流被分散於環狀角 部3 0C，對陽極中心軸L的局部性電流的集中，被緩和而 -10- 201110189 可抑制陽極的消耗，可作成高放射照度維持率。 因此’燈1是與燈2相比較，可成爲一面維持放射亮度 ，一面作成高放射照度維持率者。 以上，爲日本特願2009-154 65 1號的內容。 【發明內容】 以上所說明，揭示於日本特願2009- 1 5465 1號的燈1的 放電燈，也無法充分地滿足被使用於曝光裝置的光源所必 需的要求。 亦即，即使在高放射亮度的放電燈，在低放射照度維 持率的放電燈，使得發光管的內壁面在短時間也黑化，無 法在短時間內得到來自燈所必須的放射束，燈壽命變短而 必須頻繁地更換放電燈。此爲除了更換作業的煩雜性以外 ，還有隨著更換的曝光裝置的停止時間（停止時間），或 是點亮燈之後的曝光裝置恢復成穩定溫度爲止的時間等成 爲無法使用於曝光的時間，而有成爲生產性差的曝光裝置 的問題。 又，即使高放射照度維持率的放電燈，若紫外光的放 射亮度小，則也無法滿足曝光所必需的曝光量，結果曝光 時間變久而有成爲生產性差的曝光裝置的問題。 如此地，在曝光工程中，被要求縮短曝光時間，亦即 被要求增加通過量。貢獻於縮短曝光時間而爲了有助於提 昇曝光工程的生產性，在放電燈，也被要求有較多被放射 於其一定的點燈時間.之間的紫外光的總放射量的「積算放 -11 - 201110189 射量」。 在此，鑑於上述問題，本案發明之目的是在於提供一 種被使用於曝光裝置的短弧型放電燈，一面維持放射亮度 ，一面可作成高放射照度維持率，又，藉由作成「積算放 射量」較多的燈，提升曝光裝置的生產性的放電燈。 在此，考慮此積算放射量，與放射亮度或放射束之關 係。 將電弧的放射亮度分布作爲B，則「從電弧所放射的 放射束」L，是如以下的式（1 )所示地，藉由以面積（ds )及立體角（<1Ω)進行積分求出放射亮度分布B。201110189 VI. Description of the Invention: [Technical Field] The present invention relates to a short arc type discharge lamp (with a lamp), and more particularly to a short arc type discharge lamp. [Prior Art] A conventional discharge lamp is provided. : The tube bulged in the center portion and the inside of the bulging portion of the arc tube. The anode is flat at the front end with respect to the cathode, and is tapered toward the outer diameter of the front end with respect to the front end of the anode. When the discharge lamp is energized, the gas placed in the cathode collides to generate charged particles. The charged particles are enclosed in a material inside the arc tube, for example, mercury forms an arc between the electrodes. Moreover, the electrons in the electric hair flow on the anode side and the end faces. The electric field intensity at the center of the front end of the anode which is subjected to electron collision is stronger than that of the peripheral portion, so that current flows into the central portion of the anode, and it is known that the central portion of the anode is evaporated. Thus, when the anode is consumed, the evaporation is sensitized to the inner wall of the arc tube, and a blackened light-emitting tube is produced. Further, when the inner wall surface of the arc tube is blackened, the radiation beam is lowered, and the illuminance necessary for the irradiation surface is not required to replace the lamp with a new product, which is called "discharge anode structure." The anode and the cathode front end surface of the illuminating arrangement. The rounded electrons which are sequentially thinned by the cathode are repeated with the lamp to make the state of the plasma, and the smashing of the anode is caused by the front of the anode, and thus the yang is strongly electric field. The attracting portion becomes a high temperature and the extremely constituent material is inconvenient with the inner wall surface and is low in the foot from the discharge lamp. Therefore, it must be -5-201110189. Therefore, when the discharge lamp is turned on, the anode temperature is prevented from rising, and the anode is delayed. The consumption of the inner wall ή of the arc tube is blackened, and the countermeasure for obtaining a high irradiance maintenance rate has been conventionally reviewed. Patent Document 1 discloses that tungsten carbide (WC) is sintered on the side surface of the tip end portion of the anode. a mixture of molybdenum carbide (TaC) and tungsten (W) to form an anode of a porous layer. It is described that the porous layer is excellent in adhesion to a base material, and thus it is suitable to suppress yang. The temperature rises to reduce the consumption of the anode and the blackening of the inner wall surface of the arc tube, and to extend the life of the discharge lamp. Further, as shown in Fig. 7, in Patent Documents 2, 3 and 4, with respect to the cathode 90 The front end portion of the anode 80 is provided with a concave portion 81. This concave portion 81 forms an electric field intensity which is generated close to the electrons emitted from the cathode 90. According to these documents, the current density distribution on the surface of the anode 80 is dispersed, and the anode is dispersed. The consumption of 80% is reduced, and the blackening of the inner wall surface of the arc tube is delayed, whereby a high irradiance maintenance ratio can be obtained, and the life of the discharge lamp can be extended. The patent documents disclosed in these 1 to 4 are disclosed. The technique is to extend the life of the discharge lamp, that is, to increase the irradiance maintenance rate. [Patent Document 1] Japanese Patent No. 3 598475 (JP-A-H09- 1 1 5479) [Patent Document 2 [Patent Document 3] Japanese Patent No. 4, 54, 198 (Japanese Patent Laid-Open Publication No. 2003-234083) [Patent Document 4] Japanese Patent No. 4132879 (Japan special In the discharge lamp of the exposure apparatus, the illuminance maintenance rate is generally high, and the high radiation radiance is also required to be obtained, and the inventor of the present invention is also obtained. In addition to the high irradiance maintenance rate of the lamps that have been used in the past, a review of the discharge lamp that provides a high radiance, that is, a high-radiation beam is also carried out, and a patent application is made as Japanese Patent Application No. 2009-154651 before the application. This patent application is also as follows. The inner wall surface of the anode, the flat inner bottom surface of the anode, and the concave portion formed by the annular corner portion are provided on the front end surface of the anode so that the points between the concave portion and the electrode of the cathode are When the distance is changed, the peak of the electric field strength can be maintained at two locations of the position of the central axis of the anode and the position of the annular corner, and the peak of the electric field strength at the position of the central axis of the anode is operated to maintain the radiance of the discharge lamp. The peak of the electric field strength at the position of the annular corner is to attract electrons and raise the current density of this portion to alleviate a part of the field on the front end surface of the anode. The concentration of the partial current is moderated and is used to suppress the consumption of the anode. Hereinafter, the contents of the above patent application will be described in detail based on Figs. 1 and 2 . Fig. 1 is a schematic cross-sectional view showing the structure of a discharge lamp. The discharge lamp 10 includes a light-emitting portion 11 formed approximately in a spherical shape, and an arc tube composed of straight tubular seal portions 12A and 12B continuous at both ends of the light-emitting portion 11, respectively. The arc tube is integrally formed, for example, by quartz glass. In the case of the seals 1 2A and 1 2B, the caps 1 2 A and 1 2B having the cylindrical shape are respectively provided in the discharge space S formed inside the arc tube, and the cathode 2 and the anode 3 are mutually It is disposed opposite to the anode central axis L and is enclosed with a luminescent substance. The luminescent material is at least one type in which helium gas, argon gas, and helium gas are enclosed, and mercury. As the luminescent material, only one of these rare gases and mercury may be enclosed. The cathode 2 is formed by integrally forming a cylindrical crotch portion 2A that is held by the sealing portion 12A and faces the discharge space S by tungsten or the like, and a conical front end that is tapered toward the tip end in order from the crotch portion 2A. Part 2B. The anode 3 is formed of, for example, tungsten in which a cylindrical crotch portion 3 A is integrally formed, and truncated cone portions 3 B and 3C which are formed continuously on the front end side and the rear end side of the crotch portion 3 A, respectively. In the truncated cone 3C on the rear end side, a rod-shaped lead portion (not shown) having a smaller diameter than the crotch portion 3A is continuously continuous, and the lead portion is held by the sealing portion 12B. The anode 3 has a total length of 30 to 100 mm, the crotch portion 3A has a diameter of 20 to 40 mm, the tip end portion 3B has a front end diameter of 5 to 20 mm, and the truncated cone portion 3B has a rear end diameter of 20 to 40 mm. The distance between the electrodes between the cathode 2 and the anode 3 is 3 to 40 mm. Fig. 2(A) is a cross-sectional view showing an enlarged cross section including the anode central axis L. Fig. 2(B) is a front view of the front end surface of the anode as viewed from the direction indicated by the arrow B of the second (A) diagram. The anode 3 is a truncated cone portion 3B having a smaller outer diameter toward the front end, and an anode front end surface 3D is formed at a front end portion of the truncated cone portion 3B, and a concave portion 30 is formed on the anode central axis L of the anode front end surface 3D. . 201110189 The shape of the recessed portion 30 is described. The recessed portion 30 has an anode inner wall surface 30 Α which is formed in a circumferential direction from the anode front end surface 3D, and is continuously formed on the anode inner wall surface 30 Α. The anode central axis L is expanded at a right angle in the radial direction, and the anode inner bottom surface 30Β of the flatly formed wall and the boundary between the anode front end surface 3D and the anode inner wall surface 30Α are spaced apart from the anode central axis L in the radial direction and circumferentially The annular corner portion 30C formed in the ground is formed by the three end portions of the concave portion 30 formed on the inner side of the anode 3 from the anode front end surface 3D. Since the concave portion 30 has such a shape, the overall shape thereof is a rectangular shape including a cylindrical central axis L, that is, a cylindrical shape. Further, the recessed portion 3〇 is not limited to the cylindrical shape and may be in the shape of a rotating truncated cone. A discharge lamp using an anode of such a shape is such that when a high voltage is applied between the cathode and the anode, an arc is formed between the electrodes. In the anode 3 shown in Fig. 2, a flat anode inner bottom surface 30B which is lower than the anode front end surface 3_D toward the inner side of the anode is provided, and the closer the anode inner bottom surface 30B is to the anode central axis L, the more the electric field is. The intensity becomes higher. Further, since the annular corner portion 30C is provided at a position spaced apart from the anode central axis L in the radial direction, the electric field strength is also high in the device. Thus, the anode 3 is The positions of both the anode central axis L and the annular corner portion 30C cause the electric field strength to be high, and the electrons generated from the cathode 2 are dispersed in the anode central axis L and the annular corner portion 30C, respectively, and are attracted. The amount of electrons attracted to the anode central axis L is reduced. The peak of the electric field intensity -9 - 201110189 at the position of the anode central axis L of the anode inner bottom surface 30B is to maintain the brightness of the discharge lamp, and the peak of the electric field intensity at the position of the annular corner portion is increased by attracting electrons. The current in this portion moderates the concentration of the local current on the front end surface of the anode, and acts to suppress the consumption of the anode. Fig. 8 is a view showing a discharge lamp shown in Fig. 2 for a recess having a concave inner wall surface and a flat anode inner surface and an annular corner portion described in paragraphs 00 10 to 0015 (hereinafter referred to as a discharge lamp). The electric field intensity distribution in the arc is the "disc 1") and the discharge lamp (hereinafter referred to as "light 2") of the anode shown in Fig. 7 having a concave portion close to the electric field intensity described in paragraph 0006. Simulation results. The vertical axis of Fig. 8 represents the electric field intensity, and the horizontal axis represents the distance from the anode central axis L, the solid line represents the anode electric field strength of the lamp 1, and the broken line represents the anode electric field strength of the lamp 2, in Fig. 8 As shown by the solid line, in the anode of the lamp 1, the sharp peak 电场 of the electric field intensity is displayed at the position of the anode central axis L and the position corresponding to the annular corner 30C of the recess 30, and the electrons in the arc are estimated to be concentrated on The anode central axis L and the annular corner portion 30C look like this. On the other hand, in the anode of the lamp 2, since such a peak is not observed, the ratio of the current drawn to the edge portion 8 2 of the recess 8 1 is small. In this manner, the lamp 1 is appropriately raised by the flat anode bottom surface 30B, the current density of the anode center axis L is such that the anode is not consumed, so that the radiance becomes high, and by having the anode center axis L The annular corner portion 30C formed at the outer side in the radial direction is dispersed in the annular corner portion 30C, and the concentration of the local current on the anode central axis L is moderated. -10- 201110189 The anode can be suppressed. The consumption can be made as a high irradiance maintenance rate. Therefore, the lamp 1 can be made to have a high irradiance maintenance rate while maintaining the radiance while being compared with the lamp 2. The above is the content of Japan's special wish 2009-154 65 No. 1. DISCLOSURE OF THE INVENTION As described above, the discharge lamp of the lamp 1 disclosed in Japanese Patent Application No. 2009-15458-1 cannot sufficiently satisfy the requirements required for the light source used in the exposure apparatus. That is, even in a discharge lamp of high radiance, the discharge lamp of a low irradiance maintenance rate causes the inner wall surface of the arc tube to be blackened in a short time, and the radiation beam necessary for the lamp cannot be obtained in a short time. The life is shortened and the discharge lamp must be replaced frequently. This is in addition to the cumbersomeness of the replacement work, and the time during which the exposure time of the replacement exposure device (stop time) or the exposure device after the lamp is turned back to the stable temperature becomes unavailable. There is a problem that it becomes an exposure device with poor productivity. Further, even in the discharge lamp having a high irradiance maintenance rate, if the emission luminance of the ultraviolet light is small, the exposure amount necessary for the exposure cannot be satisfied, and as a result, the exposure time becomes long and there is a problem that the exposure apparatus is inferior in productivity. As such, in the exposure process, it is required to shorten the exposure time, that is, to increase the throughput. Contributing to shortening the exposure time and in order to help improve the productivity of the exposure project, the discharge lamp is also required to have a larger amount of total radiation of ultraviolet light that is emitted between its certain lighting time. -11 - 201110189 The amount of radiation." Here, in view of the above problems, an object of the present invention is to provide a short arc type discharge lamp used in an exposure apparatus, which can maintain a high irradiance maintenance rate while maintaining the radiance, and by creating an "integrated radiation amount" A number of lamps that increase the productivity of the exposure device. Here, consider the relationship between the amount of accumulated radiation and the radiance or radiation beam. When the radiance distribution of the arc is B, the "radiation beam emitted from the arc" L is integrated by the area (ds) and the solid angle (<1 Ω) as shown by the following formula (1). The radiance distribution B is obtained.
式（1) L=JXBdsdQ 「從點燈初期電弧所放射的放射束」Lo，是經由發光 管被取出之故，因而「從經過某一時間後的燈所放射的放 射束」L!，是若將發光管的穿透率作爲T時，則如以下的 式（2)所示地，以放射束L〇與穿透率T之積所表示。(1) L = JXBdsdQ "The radiation beam emitted from the arc at the beginning of the lighting" Lo is taken out through the arc tube. Therefore, "the radiation beam emitted from the lamp after a certain period of time" is L! When the transmittance of the arc tube is T, it is expressed by the product of the radiation beam L〇 and the transmittance T as shown by the following formula (2).
式（2) L 1 =L 〇 T 此穿透率T是大大地起因於來自陽極等的蒸發物隨著 時間附著於發光管所致的黑化或光的散射之故，因而置換 成以點燈時間的函數所表示的放射照度維持率7? (t) ( % ) 而可作成近似。因此，在時刻t的「從燈所放射的放射束 」L ! (t)是以 式（3) L,(t) = L0T(t) = L〇i!g -12- 201110189 所表示。 紫外線的總放射量的「積算放射量φ」，是以時刻t 的「從燈所放射的放射束」1^(0的時間積分所表示之故， 因而成爲表示於以下的式（4)。 式（4) Φ = JL,(t)dt = jL0T(t)dt = JL〇 在此，放射照度維持率77 (t)是密接地關連於對發光管 內面的上述蒸發物的堆積而以單純的指數函數可作成近似 之故，因而若將點燈tQ時間後的放射照度維持率作爲7? (to) ( % )，則以以下的式（5)可表示具衰減常數。 ln_ 式（5) α =-- 10 因此，當使用式（4 )，則點燈to時間後的積算放射 量Φ，是又如式（6)地所表示。 式（6) Φ = K^Λ = Uo^dt = ^(l-( 1 -UM) ί 100 { } .ΐαϋΜ\ 100) 100 由此式（6 )，可知積算放射量φ，是使用「從點燈 初期的電弧所放射的放射束」L〇，及t〇時間經過後的放射 照度維持率7? (tQ)可進行算出。 在以後的段落0042、0043中，欲求出積算放射量φ之 際’成爲使用此「從點燈初期的電弧所放射的放射束」L〇 、及tQ時間經過後的放射照度維持率^ (t〇)。 申請專利範圍第1項所述的一種短弧型放電燈，是互 相相對於發光管內的方式配置有陽極及陰極，在上述陽極 -13- 201110189 與上述陰極之間施加電壓而發生電弧的短弧型放電燈，其 特徵爲： 上述陽極是在陽極前端面的陽極中心軸上形成有凹部 上述凹部是由，比上述陽極前端面窪下而形成圓周方 向的陽極內壁面，及連續形成於上述陽極內壁面而對於陽 極中心軸朝徑方向擴散而平坦地形成的陽極內底面，及從 陽極中心軸朝徑方向隔開而在上述陽極前端面及上述陽極 內壁面的境界形成於圓周方向的環狀角部所構成，此些三 個構成所成的凹部是從上述陽極前端面朝電極的內方側窪 下所形成， 將表示上述電弧大小的指標作爲D0，將上述凹部的 直徑作爲D1 ( mm )時，則比例的値D1/D0是滿足0.25 S D1/D0S 1.2， 表示上述電弧的大小的指標D0，是以下述式所規定 D0=1.4 + 2.5(Ρ-1,6)0·5 但，P :燈電力（kW ) 申請專利範圍第2項所述的短弧型放電燈，是申請專 利範圍第1項所述的短弧型放電燈，上述凹部的深度是 0.1mm〜0.5mm，爲其特徵者。 本發明的短弧型放電燈是陽極爲在陽極前端面的陽極 中心軸上形成有凹部，該凹部是具備：陽極內壁面，及平 坦的陽極內底面，及從陽極中心軸朝徑方向外方隔開的環 -14 - 201110189 狀角部。藉此，可維持放射亮度，且可得到高放射照度維 持率的燈。 又，藉由表示形成於陽極與陰極之間的電弧的大小的 指標D0及設於陽極的凹部的直徑D 1 ( mm )的比例的値 D1/D0爲滿足0.25 S D1/D0S 1.2之關係，可得到積算放射 量多的燈。 又，藉由陽極的凹部深度爲0.1 mm〜0.5 mm，確實地 可提高放射亮度與放射照度維持率的雙方。 【實施方式】 以下，使用圖式來說明本案發明的放電燈。 放電燈的構成是與段落0010至0015的記載及第1圖與 第2圖的內容相同之故，因而省略了引用此部分的說明。 當在放電燈10的陰極2及陽極3之間施加有高電壓，則 在兩極間產生絕緣擊穿，而在陰極2及陽極3之間形成有電 弧AR。將其電弧AR的槪念圖表示於第3圖。電弧AR是依 存於燈電力P ( kW )而以陽極中心軸L作爲中心，進行擴 張或收縮。亦即，在燈電力變大則電弧AR會擴展變大， 而若燈電力變小，則電弧A R會收縮變小，若凹部3 0的大 小作成一定，則電弧AR是超過凹部30的環狀角部30C而也 有擴展至陽極前端面3D上，或是也有止於凹部30的環狀 角部3 0 C的內側。 若由此種凹部3〇與電弧AR的大小的關係，求出凹部 3 〇的大小D 1與電弧AR的大小D 0的比例的値D 1 /D 0 ,則此 -15- 201110189 比例的値是表示電弧AR覆蓋陽極前端面的凹部3〇的程度 ，若變更此比例的數値，亦即變更電弧AR覆蓋凹部30的 程度’則環狀角部3 0C藉由電場對於吸引電流的一部分的 效果上給予影響’而在發生於電極間的電子流動有所影響 ，使得放射量會變動。 因此’凹部3 0之大小與電弧A R之大小的比例的値 D1/D0是與在段落0022所說明的「積算放射量」有密接地 關連，而可考量可找出將積算放射量的最適當範圍作爲 D1/D0的函數。在此，凹部的大小D1是使用於表示電弧所 覆蓋的程度的指標的値，因必須對比此D 1與電弧的大小 ’作爲凹部的大小D1爲使用凹部的直徑，亦即使用環狀 角部的直徑。 以下，檢討如何地進行電弧的大小的特定。 電弧是指封入物被電漿化的領域者，很難測定，特定 其大小。 接著，例如，電弧是當然與電流密度分布密接地有關 連，電流密度分布可視爲電弧的分布的一形態之故，因而 測定電流密度分布而求出電弧的大小。然而，嚴密地直接 測定此電流密度分布是很難，又，此電流密度分布是連續 地變化之故，因而即使藉由此電流密度分布也很難明確地 決定電弧的分布而無法特定電弧的大小。如此地，藉由「 電流密度分布」的測定，極難或無法特定「電弧的大小」 〇 然而，電弧的電流密度分布是與放射亮度分布有密接 -16- 201110189 的關係’測定「放射亮度分布」，不但可看出電弧的「電 流密度分布」’還可看出「電弧的大小」。 接著，進行放射亮度分布的測定。 發光物質爲水銀時，當在陰極2與陽極3之間施加高電 壓，則從陰極2所放出的電子相撞於封入於放電空間s的水 銀的原子’水銀的原子成爲勵磁狀態，而從勵磁狀態轉變 至下位的能量狀態時會放射各種放射光。將此放射光經僅 通過例如波長3 65nm的特定波長的帶通濾波器，求出放射 的亮度分布。此波長3 6 5nm的紫外線的亮度分布，是電極 中心軸L上的任意點的徑方向的亮度分布，而將其表示於 第4圖。此分布的輪廓，是將放射亮度作爲1(〇，將來自徑 方向的電極中心軸的距離作爲r，則以下述式（7 )可近似 地表示。 式（7) J (r) = J〇exp〔一（r/r〇) 2〕 在此，Jo是電弧的中心的放射亮度，而r〇是來自中心 的放射亮度Jo衰減至Ι/e (与0.37 )處的中心的距離（mm )。上述放射亮度分布之式（7)，是表示流在電弧的電 流的大部分集中在從電極的中心距r〇的距離內。 將兩倍此rG所得到的2r〇假設爲「假想直徑」，則此 2r〇是可使用作爲「表示電弧大小的指標」DO。但是，實 際的電弧的大小是應注意超過此假想直徑的「表示電弧大 小的指標」DO的値而擴展的情形。 如上述地，「表示電弧大小的指標」是從放射亮度分 布，可求出，惟此方法是每當必須求出「表示電弧大小的 -17- 201110189 指標」，有進行放射亮度分布的測定的煩雜性。然而，發 明人等經專心硏究，找出放射亮度分布是與燈輸入電力有 強大關連的情形，藉此，事先求出燈電力與放射亮度分布 的關係，則在每當成爲需要，就可排除測定放射亮度分布 的煩雜性，成爲可從燈電力求出「表示電弧大小的指標」 〇 爲了求出此燈電力與「表示電弧大小的指標」D0之 關係的檢討，進行以下的實驗。 然而，電弧是受到電極前端的物理性形狀的影響而變 更其形狀。使用在陽極前端面設置凹部的電極的放電燈而 欲製作上述指標，則在每個凹部大小不相同的燈，電弧是 成爲從凹部受到不相同的影響。這樣子，每個燈，使得「 表示電弧大小的指標」D0會不相同而無法使用作爲基準 的指標。「表示電弧大小的指標」D0，是指標也作爲基 準的値之故，因而必須爲不變動又不會變更的値才可以。 如此’電弧不會受到陽極前端形狀之影響的方式，使用未 具有凹部的如平坦的普通的陽極的放電燈，來製作「表示 電弧大小的指標」D0，而將此作爲基準的指標。 接著，使用於製作「表示電弧大小的指標」D0的實 驗的實驗用放電燈A1〜A5，是使用在陽極前端面未具有 凹部的如平坦的普通的陽極。又，變更封入的水銀量與電 極間距離來製作5種類的實驗用放電燈A1〜A5 ^ 以表示於表1的燈電力P來點亮此實驗用放電燈A1〜 A5’進行測定陽極近旁的電弧的放射亮度分布，對於此 -18- 201110189 些的放射亮度分布依照式（7)進行饋電而求出rQ，並求 出「表示電弧大小的指標」D0的値。 將此些的實驗結果表示於表1。 [表1] 實驗用放電燈 水銀量 (mg/cm ) 電極間距離 (mm) 燈電力P (kW) 表示電弧大小的 指標D0 A1 5 5 2 3 A2 30 5 4.3 5.2 A3 36 16 16 11 A4 30 22 25 13.5 A5 25 32 35 16 以下，將表1的「表示電弧大小的指標J DO，及燈電 力P(kW)之關係以圓記號表示於第5圖》求出連結表示 於此第5圖的圓記號的近似曲線之式，得到次式（8 )。 式（8) DO = l· 4 + 2. 5 (P—1· 6) 〇* 5 從此式（8 ) ’針對於燈電力P ( kW )所知的燈，即 使未測定放射亮度分布，也可求出「表示電弧大小的指標 」D0。 如此地，若從燈電力P ( kW )決定「表示電弧大小的 指標」D0，則如記載於段落003 0地’以比例的値D1/D0作 成變數，就可找@積算放射量的最適當範圍。 接著，將凹部的直徑D 1與「表示電弧大小的指標」 D0的比例的値D1/D0 ’進行用以求出積算放射量的實驗。 201110189 (實施例1 ) 當進行實驗，製作準備實驗用放電燈B1〜B10°實驗 用放電燈B1〜B10，具有表示於以下的共通的燈基本構成 〈燈B1〜B10的基本構成〉 •陽極3的凹部深度 ：0.4mm •水銀量 ：25mg/cxn3 •氙氣體 ：在室溫2xl〇5Pa .電極間距離L :5.5mm •燈電力P :7.5kW (定電力） 各燈的陽極，是在其前端面具有與陽極內壁面平坦地 形成的陽極內底面與環狀角部所成的凹部，惟其凹部的大 小是如表2所示地，對於「表示電弧大小的指標」D0的凹 部30的直徑D1 ( mm )的比例的値D1/D0分別作成不相同 作爲比較例，也製作準備了比例的値D1/D0爲零，亦 即具備未具凹部的陽極的比較用放電燈X。比較用放電燈 X是除了在陽極前端面未具凹部以外，具有與實驗用放電 燈B相同的基本構成。 實驗用放電燈B 1〜B 1 0及比較用放電燈X的燈電力是 7.5kW之故，因而「表示電弧大小的指標」D0，是將 Ρ = 7·5代入段落0037的式（8)就可求出，而被求出D0 = 7.5 -20- 201110189 針對於實驗用放電燈B1〜B10及比較用放電燈X，在 點燈初期時及800小時定電力點燈後，測定波長3 65nm的 紫外光的放射照度。將此作爲實驗a。表2的「放射照度維 持率（％ )」，是將對於點燈初期的放射照度的800小時 點燈後的放射照度的比率，燈別地％表記者。 又，點燈實驗用放電燈B 1〜B 1 0及比較用放電燈X , 針對於各個放電燈，測定點燈初期的波長365nm的紫外光 的放射亮度，依照段落0022的式（1)，藉由放射亮度的 積分得到點燈初期的放射束L i。將此作爲實驗b。又，在 表2中，由實驗b的結果，求出對於比較用放電燈X的點燈 初期的放射束的實驗用放電燈B的點燈初期的放射束的比 率，將此相對値記載作爲「相對放射束」。 「積算放射量」是使用表2的「放射照度維持率（％ )」及「相對放射束」從段落0022的式（6)求出。又， 以積算放射量的最大値作爲1的相對値的「相對積算放射 量」來表示。 又，由式（6)可知，在計算積算放射量，需要「從 點燈初期的電弧所放射的放射束」。爲了慎重，針對於此 放射束與「從點燈初期的燈所放射的放射束」的關係加以 說明。 在段落0022的式（3 )中，點燈初期的狀態是時間t爲 〇之故’因而T⑴是在T(0)爲大約1，而成爲LKOhLo。此 爲，在實驗b可求出的各燈的點燈初期的放射束，是「從 -21 - 201110189 點燈初期的燈所放射的放射束」L! (0)，惟此放射束實際 是表示相等於「從點燈初期的電弧所放射的放射束」L〇。 因此，在式（6 )的「從點燈初期的電弧所放射的放射束 」L〇，可知代入在實驗b所求出的各燈的點燈初期的放射 束的値可加以計算。 [表2] 比較用及實 驗用放電燈 凹部的直徑 Dl(mm) 比例的値 D1/D0 放射照度維 持率(％) 相對放射束 相對積算放 射量 X 0 0 84 1 0.959 B1 1.1 0.15 84 0.999 0.958 B2 1.9 0.25 84.9 0.997 0.961 B3 2.9 0.39 89.6 0.993 0.983 B4 3.9 0.52 92.3 0.989 0.993 B5 4.9 0.65 94.5 0.984 1 B6 5.9 0.79 95 0.978 0.997 B7 8.3 1.1 93.7 0.968 0.979 B8 9 1.2 93 0.958 0.966 B9 9.8 1.3 91.5 0.943 0.943 B10 13.5 1.8 84.4 0.943 0.906 以下將表2的比例的値D 1 /D0，及相對積算放射量之 關係表示於第6圖。 縱軸是相對積算放射量，橫軸是比例的値D 1 /D0。 在比例的値D 1/D0較小的領域中，相對積算放射量是 幾乎沒有變化’由0.2附近增大，而在0.65附近成爲最大 ’之後減少。比例的値D1/D0爲1.2左右，而成爲與比例的 値D1/D0爲〇的情形相同之値，之後更減少。 -22- 201110189 在電極前端部未設置凹部的情形，亦即比例的値 D1/D0爲〇時，則相對積算放射量的値是0.959»超過此 0.959的値的範圍，則可作成相對積算放射量比具有無凹 部的陽極的燈還多的放電燈。因此，作爲相對積算放射量 有效果的範圍，是可知比例的値D1/D0爲0.25〜1.2。 又，若比例的値D1/D0爲0.3 9〜1.1，積算放射量表示 更高的値，可得到更顯著的效果較佳。 又，凹部30的深度Η是0.1mm〜0.5mm較佳。其理由是 如下述。 若凹部30的深度Η超過0.5mm，則電極間距離變長之 故，因而燈電壓會上昇。短弧型放電燈10，是作爲點燈用 電源使用定電力電源之故，因而如上述地，若燈電壓上昇 ，則控制成降低供應於陰極與陽極間的燈電流，而成爲使 放射高度降低的情形。降低此種放射亮度，是隨著凹部30 的深度Η愈深，愈顯著。 一方面，若凹部30的深度Η不足0.1mm，則實質上沒 有凹部30，而沒有依環狀角部的電場強度的集中效果，無 法得到高放射照度維持率。 因此，儘量地減小降低放電燈的放射亮度，且爲了得 到高放射照度維持率，將凹部3 0的深度Η作爲〇 . 1 mm〜 0.5 m m較佳。 【圖式簡單說明】 第1圖是表示放電燈的構成的一例子的斷面圖。 -23- 201110189 第2(A)圖及第2(B)圖是適用於放電燈的陽極的 說明圖。 第3圖是表示點燈放電燈時，形成於陰極與陽極之間 的電弧狀態的斷面圖。 第4圖是表示從圖示於第3圖的電弧所放射的波長 365nm的紫外光的放射亮度分布的輪廓。 第5圖是表示「表示電弧大小的指標」DO與燈電力P 之關係的圖表。 第6圖是表示相對積算放射量，及「表示電弧大小的 指標」D0與凹部的直徑D1的比例的値D1/D0之關係的圖表 〇 第7圖是表示習知的短弧型放電燈的電極構造的斷面 圖。 第8圖是表示電場強度分布的圖式。 【主要元件符號說明】 I 〇 :短弧型放電燈 II ’·發光部 12A、12B :密封部 1 3 A、1 3 B :燈頭 2 :陰極 2A :胴部 2B :前端部 3 :陽極 -24- 201110189 3 B、3 C :圓錐台部 3 A :胴部 3D :陽極前端面 3 0 :凹部 30A :陽極內壁面 30B:陽極內底面 30C :環狀角部 AR :電弧Formula (2) L 1 = L 〇 T This transmittance T is greatly caused by blackening or scattering of light caused by evaporation of an evaporate from an anode or the like over time, and thus is replaced by a point The irradiance maintenance rate represented by the function of the lamp time is 7? (t) (%) and can be approximated. Therefore, at the time t, "the radiation beam emitted from the lamp" L ! (t) is expressed by the equation (3) L, (t) = L0T(t) = L〇i!g -12 - 201110189. The "integrated radiation amount φ" of the total amount of ultraviolet rays is expressed by the time integral of "the radiation beam emitted from the lamp" at time t (0), and thus is expressed by the following formula (4). Equation (4) Φ = JL, (t)dt = jL0T(t)dt = JL〇 Here, the irradiance maintenance rate 77 (t) is a dense ground associated with the accumulation of the above-mentioned vaporized material on the inner surface of the arc tube. The simple exponential function can be approximated. Therefore, if the irradiance maintenance rate after the tQ time is 7? (to) (%), the attenuation constant can be expressed by the following equation (5). 5) α =-- 10 Therefore, when equation (4) is used, the integrated radiation amount Φ after the lighting time is expressed as in equation (6). Equation (6) Φ = K^Λ = Uo ^dt = ^(l-( 1 -UM) ί 100 { } .ΐαϋΜ\ 100) 100 From the equation (6), it is known that the total amount of radiation φ is used, and the "radiation beam emitted from the arc at the beginning of lighting" is used. 〇 及 及 放射 放射 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 004 The radiation beam emitted by the arc "L" and the irradiance maintenance rate after the tQ time ^ (t〇). A short-arc discharge lamp according to claim 1 is opposed to the inside of the arc tube. A short arc type discharge lamp in which an anode and a cathode are disposed, and a voltage is applied between the anode 13-201110189 and the cathode to generate an arc, wherein the anode is formed with a concave portion on an anode central axis of the anode front end surface. The concave portion is an anode inner wall surface which is formed in a circumferential direction below the anode front end surface, and an anode inner bottom surface which is continuously formed on the anode inner wall surface and which is diffused in the radial direction with respect to the anode central axis, and is formed from the anode. The central axis is formed in a radial direction at a boundary between the anode front end surface and the anode inner wall surface, and the three recesses are formed from the anode front end toward the electrode. The inner side is formed under the armpit, and the index indicating the arc size is D0, and when the diameter of the recess is D1 (mm), the ratio 値D1/D0 is full. 0.25 S D1/D0S 1.2, the index D0 indicating the size of the above arc, is defined by the following formula: D0=1.4 + 2.5(Ρ-1,6)0·5 However, P: lamp power (kW) Patent application scope The short arc type discharge lamp according to item 2 is the short arc type discharge lamp described in claim 1, wherein the depth of the concave portion is 0.1 mm to 0.5 mm, which is characterized by the short arc discharge of the present invention. The lamp is an anode having a recess formed on an anode central axis of the anode front end surface, the recess having an anode inner wall surface, a flat anode inner bottom surface, and a ring 14 spaced outward from the anode center axis in the radial direction. 201110189 Corner. Thereby, the radiance can be maintained, and a lamp having a high irradiance maintenance rate can be obtained. Further, 値D1/D0 indicating the ratio of the index D0 of the arc formed between the anode and the cathode and the diameter D 1 (mm) of the recess provided in the anode is such that the relationship of 0.25 S D1/D0S 1.2 is satisfied. A lamp with a large amount of accumulated radiation can be obtained. Further, since the depth of the concave portion of the anode is 0.1 mm to 0.5 mm, both the radiance and the irradiance maintenance rate can be surely improved. [Embodiment] Hereinafter, a discharge lamp of the present invention will be described using a drawing. The configuration of the discharge lamp is the same as the description of paragraphs 0010 to 0015 and the contents of Figs. 1 and 2, and therefore the description of this portion is omitted. When a high voltage is applied between the cathode 2 and the anode 3 of the discharge lamp 10, an insulation breakdown occurs between the two electrodes, and an arc AR is formed between the cathode 2 and the anode 3. A commemorative diagram of the arc AR is shown in Fig. 3. The arc AR is expanded or contracted depending on the lamp power P (kW) and centered on the anode center axis L. In other words, when the lamp power is increased, the arc AR is expanded and the arc AR is contracted to become smaller. If the size of the recess 30 is constant, the arc AR is a ring that exceeds the recess 30. The corner portion 30C may also extend to the anode front end surface 3D or may terminate inside the annular corner portion 30C of the recess portion 30. When 凹D 1 /D 0 of the ratio of the size D 1 of the concave portion 3 与 to the size D 0 of the arc AR is obtained from the relationship between the size of the concave portion 3 〇 and the arc AR, the ratio of the ratio of -15 to 201110189 is obtained. It is a degree indicating that the arc AR covers the concave portion 3〇 of the front end surface of the anode, and if the number of the ratio is changed, that is, the extent to which the arc AR covers the concave portion 30 is changed, the annular corner portion 30C is partially absorbed by the electric field. The effect is exerted' and the flow of electrons occurring between the electrodes is affected, so that the amount of radiation changes. Therefore, the ratio 値D1/D0 of the ratio of the size of the recessed portion 30 to the magnitude of the arc AR is closely related to the "integrated amount of radiation" described in paragraph 0022, and it can be considered to find the most appropriate amount of accumulated radiation. The range is a function of D1/D0. Here, the size D1 of the concave portion is an index for indicating the degree of coverage by the arc, and it is necessary to compare the size of the D 1 and the arc as the size D1 of the concave portion as the diameter of the concave portion, that is, the annular corner portion is used. diameter of. In the following, it is reviewed how to specify the size of the arc. Arcing refers to the field in which the enclosure is plasmaized, and it is difficult to measure and specify its size. Next, for example, the arc is of course connected to the current density distribution, and the current density distribution can be regarded as one form of the distribution of the arc. Therefore, the current density distribution is measured to determine the magnitude of the arc. However, it is difficult to directly measure the current density distribution strictly, and the current density distribution is continuously changed. Therefore, even by this current density distribution, it is difficult to clearly determine the distribution of the arc and the size of the arc cannot be specified. . In this way, it is extremely difficult or impossible to specify the "size of the arc" by the measurement of the "current density distribution". However, the current density distribution of the arc is closely related to the radiance distribution -16-201110189 'measurement' radiance distribution Not only can the "current density distribution" of the arc be seen, but the "size of the arc" can also be seen. Next, the measurement of the radiance distribution is performed. When the luminescent material is mercury, when a high voltage is applied between the cathode 2 and the anode 3, the electrons emitted from the cathode 2 collide with the atom of the mercury which is enclosed in the discharge space s, and the atom of mercury becomes excited. When the excitation state is shifted to the lower energy state, various kinds of radiation are emitted. This emitted light is subjected to a band pass filter of a specific wavelength of, for example, a wavelength of 3 to 65 nm to obtain a luminance distribution of the radiation. The luminance distribution of the ultraviolet light having a wavelength of 365 nm is a luminance distribution in the radial direction of an arbitrary point on the central axis L of the electrode, and is shown in Fig. 4. The outline of this distribution is such that the radiance is 1 (〇, and the distance from the central axis of the electrode in the radial direction is r, which is approximated by the following formula (7). Equation (7) J (r) = J〇 Exp[一(r/r〇) 2] Here, Jo is the radiance of the center of the arc, and r 〇 is the distance from the center of the radiance Jo to the center of the Ι/e (and 0.37) (mm) In the above formula (7), the majority of the current flowing through the arc is concentrated in the distance from the center distance r 电极 of the electrode. The 2r 得到 obtained by twice the rG is assumed to be "imaginary diameter". In this case, the 2r〇 can be used as the “indicator of the size of the arc”. However, the actual arc size is extended by the “indicator indicating the arc size” DO exceeding the virtual diameter. In addition, the "indicator of the size of the arc" is obtained from the radiance distribution. However, it is necessary to obtain the -17-201110189 index indicating the size of the arc every time, and it is necessary to measure the radiance distribution. However, the inventors have been concentrating on research, The radiance distribution is strongly related to the lamp input power. Therefore, by determining the relationship between the lamp power and the radiance distribution in advance, the nuisance of measuring the radiance distribution can be eliminated every time it is necessary. The "indicator indicating the size of the arc" was obtained from the lamp power. In order to obtain a review of the relationship between the lamp power and the "indicator indicating the arc size" D0, the following experiment was performed. However, the arc is subjected to the physical shape of the tip of the electrode. When the discharge lamp of the electrode having the concave portion is provided on the front end surface of the anode and the above-mentioned index is to be used, the arc is different from the concave portion in the lamp having a different size of each concave portion. In the case of the lamp, the "indicator indicating the size of the arc" D0 is different, and the index as the reference cannot be used. The "indicator indicating the size of the arc" D0 is the parameter that is also used as the reference, so it must be unchanged and not The change can only be made. So the way the arc is not affected by the shape of the front end of the anode, using a recess without a recess In the discharge lamp of the ordinary ordinary anode, the "indicator indicating the size of the arc" D0 is used as the reference index. Next, the experimental discharge lamp A1 for the experiment of "the index indicating the arc size" D0 is produced. In A5, a flat ordinary anode having no concave portion on the front end surface of the anode is used, and five types of experimental discharge lamps A1 to A5 are produced by changing the amount of mercury enclosed and the distance between the electrodes. The electric power P illuminates the experimental discharge lamps A1 to A5' to measure the radiance distribution of the arc near the anode, and the radiance distribution of the -18-201110189 is fed according to the equation (7) to obtain rQ, and The "indicia indicating the magnitude of the arc" D0 was obtained. The experimental results of these experiments are shown in Table 1. [Table 1] Experimental discharge lamp mercury amount (mg/cm) Distance between electrodes (mm) Lamp power P (kW) Indicates the index of the arc size D0 A1 5 5 2 3 A2 30 5 4.3 5.2 A3 36 16 16 11 A4 30 22 25 13.5 A5 25 32 35 16 In the following, the relationship between the index J DO indicating the arc size and the lamp power P (kW) in Table 1 is indicated by a circle in Fig. 5, and the connection is shown in Fig. 5. The approximate curve of the circular mark gives the following equation (8). Equation (8) DO = l· 4 + 2. 5 (P-1·6) 〇* 5 From this equation (8) 'For the lamp power P In the lamp known as (kW), even if the radiation intensity distribution is not measured, the "indicator indicating the arc size" D0 can be obtained. In this way, if the "indicator indicating the arc size" D0 is determined from the lamp power P (kW), the variable ΔD1/D0 is used as the variable described in paragraph 003 0. range. Then, 値D1/D0' of the ratio of the diameter D 1 of the concave portion to the "indicator indicating the arc size" D0 was used to obtain an experiment for calculating the accumulated amount of radiation. 201110189 (Example 1) When the experiment was carried out, the discharge lamps B1 to B10 for the preparation of the test lamps B1 to B10 for the test were prepared, and the basic configuration of the lamps (the basic configuration of the lamps B1 to B10) was shown below. Depth of recess: 0.4mm • Mercury amount: 25mg/cxn3 • Helium gas: 2xl〇5Pa at room temperature. Distance between electrodes L: 5.5mm • Lamp power P: 7.5kW (constant power) The anode of each lamp is in The front end surface has a concave portion formed by the anode inner bottom surface and the annular corner portion which are formed flatly on the anode inner wall surface. However, the size of the concave portion is as shown in Table 2, and the diameter of the concave portion 30 of the "indicator indicating the arc size" D0 is shown. The ratio 値D1/D0 of the ratio of D1 (mm) was made different as a comparative example, and the prepared discharge lamp X having the ratio 値D1/D0 was also zero, that is, the anode having the recessed portion. The comparative discharge lamp X has the same basic configuration as the experimental discharge lamp B except that the front end surface of the anode has no concave portion. The lamp lamps for the experimental discharge lamps B 1 to B 1 0 and the comparison discharge lamp X are 7.5 kW. Therefore, the "indicator indicating the arc size" D0 is the equation (8) in which Ρ = 7.5 is substituted into the paragraph 0037. It can be obtained, and D0 = 7.5 -20- 201110189 is obtained. For the experimental discharge lamps B1 to B10 and the comparative discharge lamp X, after the initial lighting and 800 hours, the measurement wavelength is 3 65 nm. The irradiance of ultraviolet light. Take this as experiment a. The "radiation illuminance retention rate (%)" in Table 2 is the ratio of the illuminance after lighting for 800 hours of the illuminance at the beginning of the lighting. Further, the discharge lamp B 1 to B 1 0 for lighting experiments and the discharge lamp X for comparison are used to measure the radiance of ultraviolet light having a wavelength of 365 nm at the initial stage of lighting for each discharge lamp, according to the formula (1) of paragraph 0022. The radiation beam L i at the beginning of the lighting is obtained by integration of the radiance. This was taken as experiment b. Further, in Table 2, the ratio of the radiation beam at the initial stage of the lighting of the experimental discharge lamp B for the radiation beam at the initial stage of the lighting of the comparison discharge lamp X is obtained from the result of the experiment b, and this relative 値 is described as "relative radiation beam". The "integrated radiation amount" is obtained from the equation (6) of the paragraph 0022 using the "radiation illuminance maintenance ratio (%)" and the "relative radiation beam" in Table 2. In addition, the maximum enthalpy of the integrated radiation amount is expressed as the "relative integrated radiation amount" of the relative enthalpy of one. Further, as is clear from the equation (6), in calculating the total amount of radiation, "the radiation beam emitted from the arc at the initial stage of lighting" is required. For the sake of caution, the relationship between the radiation beam and the "radiation beam emitted from the lamp at the beginning of lighting" will be described. In the equation (3) of the paragraph 0022, the state at the initial stage of lighting is that the time t is ’ ' and thus T(1) is about 1 at T(0), and becomes LKOhLo. In this case, the radiation beam at the beginning of the lighting of each lamp which can be obtained in the experiment b is "the radiation beam emitted from the lamp at the beginning of the light from -21 to 201110189" L! (0), but the radiation beam is actually It is equivalent to "the radiation beam emitted from the arc at the beginning of lighting" L〇. Therefore, in the "radiation beam emitted from the arc at the initial stage of lighting" of the equation (6), it can be understood that the enthalpy of the radiation beam at the initial stage of lighting of each lamp obtained in the experiment b can be calculated. [Table 2] 値D1/D0 illuminance maintenance ratio (%) of the ratio of the diameter D1 (mm) of the concave portion of the discharge lamp for comparison and experiment. Relatively calculated radiation amount relative to the radiation beam X 0 0 84 1 0.959 B1 1.1 0.15 84 0.999 0.958 B2 1.9 0.25 84.9 0.997 0.961 B3 2.9 0.39 89.6 0.993 0.983 B4 3.9 0.52 92.3 0.989 0.993 B5 4.9 0.65 94.5 0.984 1 B6 5.9 0.79 95 0.978 0.997 B7 8.3 1.1 93.7 0.968 0.979 B8 9 1.2 93 0.958 0.966 B9 9.8 1.3 91.5 0.943 0.943 B10 13.5 1.8 84.4 0.943 0.906 The relationship between 値D 1 /D0 of the ratio of Table 2 and the relative integrated radiation amount is shown in Fig. 6 below. The vertical axis is the relative integrated radiation amount, and the horizontal axis is the ratio 値D 1 /D0. In the field where the ratio 値D 1/D0 is small, the relative integrated radiation amount is hardly changed, 'increased from around 0.2, and becomes maximum after 0.6'. The ratio 値D1/D0 is about 1.2, which is the same as the case where the ratio 値D1/D0 is 〇, and then decreases. -22- 201110189 In the case where the concave portion is not provided at the tip end of the electrode, that is, when the ratio 値D1/D0 is 〇, the relative integrated radiation amount 0.9 is 0.959»The range of 値 above 0.959, the relative integrated radiation can be made. There are more discharge lamps than lamps with anodes without recesses. Therefore, as a range in which the relative amount of radiation is effective, it is known that the ratio 値D1/D0 is 0.25 to 1.2. Further, if the ratio 値D1/D0 is 0.3 9 to 1.1, and the integrated radiation amount indicates a higher enthalpy, a more remarkable effect can be obtained. Further, the depth Η of the concave portion 30 is preferably 0.1 mm to 0.5 mm. The reason is as follows. When the depth Η of the concave portion 30 exceeds 0.5 mm, the distance between the electrodes becomes long, and thus the lamp voltage rises. Since the short arc type discharge lamp 10 uses a constant power source as a power source for lighting, as described above, when the lamp voltage is increased, the lamp current supplied between the cathode and the anode is controlled to be lowered, and the radiation height is lowered. The situation. Reducing such radiance is more pronounced as the depth of the recess 30 is deeper and deeper. On the other hand, when the depth Η of the concave portion 30 is less than 0.1 mm, the concave portion 30 is substantially eliminated, and there is no effect of concentration of the electric field intensity at the annular corner portion, and a high irradiance maintenance ratio cannot be obtained. Therefore, it is preferable to reduce the radiance of the discharge lamp as much as possible, and in order to obtain a high irradiance maintenance ratio, the depth Η of the concave portion 30 is preferably 〇 1 mm to 0.5 m m. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing an example of a configuration of a discharge lamp. -23- 201110189 Figures 2(A) and 2(B) are explanatory diagrams of anodes suitable for discharge lamps. Fig. 3 is a cross-sectional view showing an arc state formed between a cathode and an anode when a discharge lamp is turned on. Fig. 4 is a view showing the outline of the radiance distribution of ultraviolet light having a wavelength of 365 nm emitted from the arc shown in Fig. 3. Fig. 5 is a graph showing the relationship between the "indicator indicating the arc size" DO and the lamp power P. Fig. 6 is a graph showing the relationship between the relative integrated radiation amount and the ratio 値D1/D0 of the ratio "the index indicating the arc size" D0 to the diameter D1 of the concave portion. Fig. 7 is a view showing a conventional short arc type discharge lamp. A cross-sectional view of the electrode structure. Fig. 8 is a view showing an electric field intensity distribution. [Description of main component symbols] I 〇: Short arc type discharge lamp II '·Light-emitting parts 12A, 12B: Sealing part 1 3 A, 1 3 B : Base 2: Cathode 2A: Crotch part 2B: Front end part 3: Anode-24 - 201110189 3 B, 3 C : Conical table portion 3 A : Crotch portion 3D : Anode front end face 3 0 : Recessed portion 30A : Anode inner wall surface 30B : Anode inner bottom surface 30C : Annular corner portion AR : Arc