JP3576132B2 - High pressure discharge lamp - Google Patents

Description

上表からわかるように、メタライズ封着先端部の外表面温度が９５０℃となるのは、非封着長Ｌｘが２．０ｍｍのときである。また、このときの、メタライズ封着先端部の、これに近い方の電極先端部からの、発光管管軸方向に測った距離は、（Ｌｏ−Ｌｅ）／２＋Ｌｘ＝４．７ｍｍとなる。したがって、メタライズ封着先端部の外表面温度が９５０℃を超えない範囲は、言いかえると、メタライズ封着先端部の、これに近い方の電極先端部からの、発光管管軸方向に測った距離が４．７ｍｍよりも短くならない範囲となる。
【００３２】
また、メタライズ封着先端部の外表面温度が７４０℃となるのは、非封着長Ｌｘが１４．０ｍｍのときであり、このときの、メタライズ封着先端部の、これに近い方の電極先端部からの、発光管管軸方向に測った距離は、（Ｌｏ−Ｌｅ）／２＋Ｌｘ＝１６．７ｍｍとなる。したがって、メタライズ封着先端部の外表面温度範囲が、７４０℃以上９５０℃以下となる範囲は、言いかえると、メタライズ封着先端部の、これに近い方の電極先端部からの、発光管管軸方向に測った距離が４．７ｍｍ以上１６．７ｍｍ以下の範囲となる。
【００３３】
なお、ここでは、発光管に亀裂破損が生じたり、発光光色が変化することなく、ランプ効率を向上させることを可能とする構成を、メタライズ封着先端部の電極先端部からの距離としても捉えたが、本件発明の本質は、やはり、定常点灯時における、メタライズ封着先端部の温度、ひいては、メタライズ封着先端部の外表面温度を規定したことにあるのである。すなわち、これら以外のパラメータ、例えば、細管部の全長Ｌａや非封着長Ｌｘなどでは基本的に規定し得ないのである。前記全長Ｌａや非封着長Ｌｘなどは、定格ランプ電力の大きさ、設定される管壁負荷、発光管の基本構造などに左右されて変動するものだからである。例えば、高圧放電ランプが使用される分野によっては、当該高圧放電ランプの長寿命化を図るため、発光管の管壁負荷は低めに設定されるのであるが、この場合、放電空間における点灯時温度を最適な高温状態に保持するためには、非封着長Ｌｘはより短縮されるからである。
【００３４】
以上、本発明を実施の形態に基づいて説明したが、本発明は、上記実施の形態に限られないことはもちろんであり、例えば、以下の形態とすることもできる。
（１）上記実施の形態では、本管部と細管部とを別個に作成して組み立てることにより発光管を形成することとしたが、これに限らず、本管部と細管部とを一体的に形成することとしてもよい。
【００３５】
（２）上記実施の形態では、発光管の両端とも、メタライズ封着によって封着することとしたが、一方は、フリット封着によって封着するようにしてもよい。この場合であっても、両端ともフリット封着による場合と比較して、発光管の全長が短くなり、ランプ効率が向上することとなる。フリット封着による場合には、モリブデン細管は用いられず、電極棒はセラミックセメント（フリット）を介して細管部に支持されると共に、当該細管部において封着がなされる。
【００３６】
【発明の効果】
以上説明したように、本発明に係る高圧放電ランプによれば、発光管に亀裂破損が生じたり、発光光色が変化することなく、ランプ効率を向上させることが可能となる。
【図面の簡単な説明】
【図１】実施の形態に係るメタルハライドランプの一部破断図である。
【図２】上記メタルハライドランプにおける発光部の縦断面図である。
【図３】上記発光部の発光管における、封着部の拡大断面図である。
【図４】メタライズ封着先端部の外表面温度と発光光色変化による不良発生率との関係を示す図である。
【図５】メタライズ封着先端部の外表面温度と細管部亀裂破損による不良発生率との関係を示す図である。
【図６】メタライズ封着先端部の外表面温度と、フリット封着によるメタルハライドランプに対するランプ効率の向上率との関係を示す図である。
【符号の説明】
１ 発光管
３ 本管部
４，５ 細管部
６，７ モリブデン細管
８，９ 接合体
１０，１１ タングステン電極
１２，１３ タングステン電極棒[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-pressure discharge lamp, and more particularly, to a technique for hermetically sealing a tube end of an arc tube made of a translucent ceramic material.
[0002]
[Prior art]
As a material used for the arc tube of a metal halide lamp, which is a kind of high-pressure discharge lamp, quartz glass has conventionally been the mainstream, but in recent years, a material using a translucent ceramic has been put into practical use. Since the translucent ceramic has higher heat resistance than quartz glass, the metal halide lamp can be operated at a higher temperature, and the lamp characteristics such as color rendering properties are improved.
[0003]
However, in the process of practical use, it was necessary to increase the total length of the arc tube. The frit sealing technology was used to seal the translucent ceramic, but the ceramic cement (frit) used for the sealing material reacts with the metal halide, which is a luminescent substance, at a high temperature. This is because the sealing part (tube end) by the frit had to be kept away from the high temperature part (discharge space).
[0004]
Naturally, the elongation of the arc tube becomes a hindrance to the downsizing of the entire metal halide lamp, and the heat capacity of the entire arc tube increases, so that the lamp efficiency decreases and it is against recent demands for energy saving. It will be.
Therefore, as a new sealing technique, a metallized sealing technique disclosed in JP-A-2000-100385 and JP-A-2001-58882 has attracted attention. The sealing portion formed by the metallized sealing technology has been known for a long time as having low reactivity with a metal halide and capable of obtaining a stronger sealing force than frit sealing. The technology described in (1) further improves the thermal shock resistance by forming an impregnated glass phase in the sealing portion.
[0005]
[Problems to be solved by the invention]
However, even if the thermal shock resistance is improved, if the arc tube is too short and the sealing portion is too close to the high temperature portion, cracks are generated in the arc tube in the sealing portion, or It has been found that the material forming the impregnated glass phase is eroded by the metal halide, which is a luminescent substance, causing a problem that the color of emitted light changes.
[0006]
In view of the above problems, an object of the present invention is to provide a high-pressure discharge lamp in which the overall length of the arc tube can be reduced as much as possible, and thus the lamp efficiency is improved.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a high-pressure discharge lamp according to the present invention includes a main tube portion forming a discharge space and thin tube portions provided on both sides of the main tube portion, and is formed of a translucent ceramic material. Having a shaft portion supported by the thin tube portion, and having a pair of electrodes provided so that tip portions thereof are opposed to each other at intervals in the discharge space. At least one of the electrodes is supported by the thin tube portion in a state where a shaft portion thereof is inserted through a cylindrical holding member made of a halide-resistant metal. The holding member and the thin tube portion are In a high-pressure discharge lamp sealed through a bonded body including a halide metal sintered body and a mixed glass impregnated in open pores of the sintered body, at the time of steady lighting, a bonding area of the bonded body is obtained. End temperature near the discharge space at Is evaluated at a surface temperature of the thin tube portion corresponding to a joining region of the joined body, which is closer to the discharge space, the surface temperature is 740 ° C. or more and does not exceed 950 ° C. And
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a high-pressure discharge lamp according to the present invention will be described based on a metal halide lamp, which is a type of high-pressure discharge lamp, with reference to the drawings.
FIG. 1 is a partially cutaway view of a metal halide lamp 21 according to the embodiment.
The metal halide lamp (hereinafter simply referred to as “lamp”) 21 has a rated lamp power of 150 [W] and is a type used for general indoor lighting.
[0010]
As shown in FIG. 1, the lamp 21 has a structure in which a light emitting section 2 having a light emitting tube 1 is housed in an outer bulb 22 provided with a base 23. A shield quartz tube 24 for preventing damage to the outer bulb 22 is arranged around the arc tube 1 in the outer bulb 22. The outer tube valve 22 is formed of quartz or hard glass, and a gas mainly composed of nitrogen is sealed in the outer tube valve 22.
[0011]
FIG. 2 is a longitudinal sectional view of the light emitting unit 2.
As shown in the figure, the light emitting section 2 has a light emitting tube 1 including a main tube portion 3 and thin tube portions 4 and 5 extending from both sides of the main tube portion 3. The main tube portion 3 and the thin tube portions 4 and 5 are both formed of a translucent polycrystalline alumina ceramic material having heat resistance of about 1200 ° C. The main tube portion 3 forms a discharge space, and the thin tube portions 4 and 5 support the shaft portions of the tungsten electrodes 10 and 11 (tungsten electrode rods 12 and 13). Also within the arc tube 1, a metal halide _{(DyI 3 + TmI 3 + HoI} 3 + TlI + NaI) luminescent material 20 consisting of, mercury becomes a buffer gas, and the starting argon as auxiliary rare gas have been respectively predetermined filling amount.
[0012]
Tungsten electrodes (hereinafter simply referred to as “electrodes”) 10 and 11 are wound around tungsten electrode rods (hereinafter simply referred to as “electrode rods”) 12 and 13 and one end side of the electrode rods 12 and 13. And tungsten coils 14 and 15 thus formed. Further, molybdenum coils 32 and 33 are wound around portions of the electrode rods 12 and 13 that overlap the thin tube portions 4 and 5 to fill the space in the thin tube portions 4 and 5 as much as possible.
[0013]
In the electrodes 10 and 11, electrode rods 12 and 13 as shafts thereof are inserted through molybdenum thin tubes 6 and 7 as electrode holding members, and are connected to the thin tube portions 4 and 5 via the molybdenum thin tubes 6 and 7. Supported. The thin molybdenum tubes 6, 7 are literally formed of molybdenum, and molybdenum is, of course, a halide-resistant metal. The electrode rods 12, 13 and the molybdenum thin tubes 6, 7 are hermetically joined (sealed) by laser welding near the outlets of the thin tube portions 4, 5 (18, 19). At this time, parts of the tungsten coils 14 and 15 are also melted together and are integrally joined. In addition, portions of the electrode rods 12, 13 projecting from both sides from the airtight joints 18, 19 are used as external lead wires.
[0014]
The molybdenum thin tubes 6, 7 and the thin tube portions 4, 5 are sealed by a metallized sealing technique performed via the joined bodies 8, 9.
FIG. 3 is an enlarged cross-sectional view of a part of the sealing portion formed by the bonded body 8, showing a bonding (sealing) state of the thin tube portion 4 (alumina ceramic) and the molybdenum fine tube 6 (molybdenum) by the bonded body 8. It is a figure shown in detail. Since the other joined body 9 is the same as the joined body 8, the joined body 8 will be described here as a representative.
[0015]
As shown in the figure, the junction body 8 has a main layer 81 in contact with the molybdenum thin tube 6, the interface of glass consisting of _Dy 2 _{O 3 -Al} 2 _O 3 based glass in the interface between the thin tube portion 4 and a main layer 81 And a layer 82. The main layer 81 is made of a sintered body of a metal powder such as molybdenum, and mainly includes a porous skeleton 83 having open pores and Dy ₂ O ₃ —Al ₂ O ₃ impregnated in the open pores. And an impregnated glass phase 84 comprising a Dy ₂ O ₃ —Al ₂ O ₃ mixed glass. The Dy ₂ O ₃ -Al ₂ O ₃ -based mixed glass may contain an auxiliary component such as La ₂ O ₃ or Y ₂ O ₃ . According to the joined body 8 having the above-described configuration, the mixed glass impregnated in the open pores functions as a kind of cushioning material, so that the thermal shock resistance is improved. That is, the joined body 8 includes a metal sintered body having open pores and a mixed glass impregnated in the open pores. In addition, since the said joined body 8 and its manufacturing method and the joining method using the said joined body are described in detail in Unexamined-Japanese-Patent No. 2001-58882, the further description is abbreviate | omitted.
[0016]
Returning to FIG. 2, the dimensions of the main components of the light emitting unit 2 having the above structure are as follows.
Main pipe part maximum inner diameter φ1: 10.7 [mm]
Overall length in main pipe Lo: 15.4 [mm]
Distance between electrodes Le: 10.0 [mm]
3.2 [mm]
Inner diameter of thin tube 1.30 [mm]
Molybdenum thin tube outer diameter 1.2 [mm]
Molybdenum tube thickness 0.10 [mm]
Electrode rod diameter 0.5 [mm]
In addition, the length (hereinafter, referred to as “metalized sealing length”) Lf of the arc tube 1 in the direction of the tube axis of the sealed portion formed by the metalized sealing is 3.5 mm. The metallized sealing length Lf is set to an indispensable length for ensuring airtightness. The tube wall load we of the arc tube 1 is set to about 27 [W / cm ² ].
[0017]
In the light emitting section 2 having the above-described configuration, the smaller the heat capacity of the thin tube sections 4 and 5, the higher the lamp efficiency. In order to adjust the heat capacity of the thin tube portions 4 and 5, a method of expanding and contracting the entire length and a method of expanding and contracting the outer diameter are considered. The inventor of the present application adopted a method of expanding and contracting the entire length, first produced (prototype) a metal halide lamp in which the total length of the thin tube portions 4 and 5 was extremely shortened to 4 mm, and performed a lighting test of the prototype lamp.
[0018]
As a result, the lamp efficiency was 97 [lm / W]. This value is about 8% higher than the lamp efficiency of 90 [lm / W] of a metal halide lamp (hereinafter, referred to as a “comparison lamp”) using the frit sealing technology having the same rated lamp power. Yes, as expected, it became a metal halide lamp with high lamp efficiency. Also, in the general color rendering index Ra, a value of 92 higher than 90 of the comparative lamp was obtained. Here, when the surface temperature of the root C at the end of the main pipe portion, which is the coldest temperature of the main pipe portion during steady lighting, was about 990 ° C. This means that the coldest point temperature of the comparative lamp is about 740 ° C., but has risen by 250 ° C. From this, it is considered that the improvement in the lamp efficiency and the improvement in the Ra value as compared with the comparative lamp are mainly due to the effect of the increase in the vapor pressure of the luminescent material composed of metal halide.
[0019]
However, when the prototype lamp was subjected to a life test in which lighting for 5.5 hours and turning off for 0.5 hour were repeated, about 500 hours after the start of the test, the sealing area by the metallized sealing ( There is a problem that crack damage occurs near the ends of the narrow tube portions 5 and 6 corresponding to the (joining region) near the discharge space. The crack breakage occurrence rate (defective occurrence rate) up to the rated life time of 6000 hours was 27%. This means that although the joints 8 and 9 contain a glass phase (mixed glass) as a buffer, the joints 8 and 9 are too close to the discharge space where the heat source is present, When the joints 8 and 9 are exposed to an excessively high temperature, the difference between the coefficient of linear expansion of the joints 8 and 9 and the coefficient of linear expansion of the translucent ceramic material forming the narrow tube portions 4 and 5 is also caused. It was thought that cracks occurred in the thin tube portions 4 and 5.
[0020]
Further, at least up to the above-mentioned rated life time, although a slow leak did not occur at the sealing portion, a change in luminescent color was observed. The rate of occurrence of the emission color change (defective rate) was about 4%. When examining the sealing portion of the prototype lamp in which the emission color change was recognized, the Dy ₂ O ₃ -Al ₂ O ₃ contained in the joined bodies 8 and 9 was found in the end region closer to the discharge space. system glass, in the light emitting material 20, in particular, NaI, DyI _3, and was found to be eroded by TmI _3. Change of emission color, the erosion, which is thought to be due to the _Dy 2 _{O 3 -Al} 2 _O 3 based glass which is discharged into the discharge space from the assembly 8,9. It was guessed that the above-mentioned erosion phenomenon was caused by exposing the joined bodies 8 and 9 to an excessively high temperature by bringing the joined bodies 8 and 9 too close to the discharge space where the heat source exists.
[0021]
Therefore, the inventor of the present invention produced a prototype lamp in which the total length La of the thin tube portion was changed (the non-sealing length Lx shown in FIG. 2 was gradually increased) while the metallized sealing length Lf was kept constant. A similar test was performed. To lengthen the non-sealing length Lx, the end portions 61 and 71 closer to the discharge space in the joining region of the joined bodies 8 and 9 (hereinafter, referred to as “metalized sealing tip”). This is because the temperature of the front end of the metallized sealing can be reduced by keeping the temperature away from the discharge space where the heat source exists.
[0022]
Since it is difficult to directly measure the temperature of the metallized sealing tip, the temperature at the surface P of the thin tube corresponding to the tip (hereinafter referred to as the “outer surface temperature of the metallized sealing tip”). )). The surface temperature was measured by a radiation thermometer having a measurement accuracy of ± 3.0% during steady lighting.
4 and 5 show the test results. FIG. 4 is a graph showing the relationship between the outer surface temperature of the metallized sealing front end portion and the defect occurrence rate due to the change in the color of the emitted light. FIG. 5 is a graph showing the outer surface temperature of the metallized sealing front end portion and the thin tube portion crack breakage. It is a graph which shows the relationship with a defect occurrence rate.
[0023]
From FIG. 4, it can be seen that when the outer surface temperature of the metallized sealing front end portion becomes 950 ° C. or less, the failure due to the color change of the emitted light does not occur. In other words, by setting the outer surface temperature of the metallized sealing tip not to exceed 950 ° C., it is possible to prevent the occurrence of defects due to a change in the color of emitted light. This means that when the outer surface temperature of the metallized sealing tip slightly exceeds 950 ° C., the temperature of the metallized sealing tip is changed to the Dy ₂ O ₃ —Al ₂ O ₃ by the luminescent material. This is considered to be because the lower limit temperature (erosion start temperature) at which the erosion action on the system glass works is reached. That is, by setting the outer surface temperature of the metallized sealing front end portion to a range not exceeding 950 ° C., the temperature of the metallized sealing front end portion is reduced by the luminescent substance to erosion of the Dy ₂ O ₃ —Al ₂ O ₃ system glass. The temperature does not exceed the lower limit temperature (erosion start temperature) at which the action is performed, so that the occurrence of defects due to the change in the color of the emitted light can be prevented.
[0024]
Further, FIG. 5 shows that when the outer surface temperature of the metallized sealing front end portion becomes about 983 ° C. or less, the failure due to the breakage of the thin tube portion does not occur.
From the above, by setting the outer surface temperature of the metallized sealing tip portion not to exceed 950 ° C., it is possible to prevent the above two defects from occurring at the same time.
[0025]
The inventor also measured the lamp efficiency in the test described above.
FIG. 6 shows the measurement results. This graph is a graph in which the horizontal axis indicates the outer surface temperature of the metallized sealing front end portion, and the vertical axis indicates the rate of improvement in lamp efficiency with respect to the comparative lamp.
From FIG. 6, it can be seen that the lamp according to the embodiment has a lamp efficiency about 6% higher than the comparative lamp even at the outer surface temperature of the metallized sealing tip of 950 ° C. where the above two defects do not occur. .
[0026]
Further, it can be seen that by setting the outer surface temperature of the metallized sealing front end portion to 740 ° C. or higher, a lamp efficiency equal to or higher than that of the comparative lamp can be obtained. Moreover, even when the lamp efficiency is equal to the comparative lamp (of course, even when the lamp efficiency is equal to or higher than the comparative lamp), the sealing portion having higher reliability than the comparative lamp is used in the lamp according to the present embodiment for the following reason. Can be obtained.
[0027]
That is, the frit of the comparative lamp usually contains a considerable amount of silica or the like in consideration of workability at the time of sealing and optimization of the coefficient of thermal expansion. However, the silica easily reacts with the metal halide, and the frit is destroyed during the lifetime. As a result, in the comparative lamp, during the life of the lamp, cracks occur in the sealed portion and the lamp does not light up, or the light-emitting substance gradually leaks to the outside of the light-emitting tube, causing a slow leak and causing a characteristic change. Would.
[0028]
On the other hand, in the lamp according to the present embodiment, since the joined body does not contain a substance which easily reacts with the metal halide such as silica, it is chemically stable to the metal halide, and thus the sealing portion In addition, the above-mentioned problems such as cracks and slow leak hardly occur. Therefore, the metallized seal can maintain the high airtightness of the sealed part longer than the frit sealed, and as a result, the metal halide lamp using the metallized seal is better than the one using the frit sealed. Also has a long life. In addition, even when silica is contained in the joined body, if the amount is small, the above-described crack and slow leak do not occur.
[0029]
As described above, the outer surface temperature range of the metallized sealing front end portion that can prevent occurrence of the above two defects and ensure lamp efficiency equal to or higher than that of the comparative lamp is 740 ° C. or more and 950 ° C. or less.
The lamp efficiency comparison test described above is performed at a rated lamp power of 150 [W]. Although detailed data is not shown, the present inventor conducted a similar test at a rated lamp power of 70 to 150 [W]. And confirmed that the same results as above were obtained.
[0030]
The correspondence between the outer surface temperature of the metallized sealing tip and the unsealed length Lx in the above test is as shown in Table 1.
[0031]
[Table 1]

As can be seen from the above table, the outer surface temperature of the metallized sealing tip portion becomes 950 ° C. when the non-sealing length Lx is 2.0 mm. At this time, the distance measured in the direction of the arc tube axis from the metallized sealing tip to the electrode tip closer to the metalized sealing tip is (Lo−Le) /2+Lx=4.7 mm. Therefore, the range in which the outer surface temperature of the metallized sealing tip does not exceed 950 ° C., in other words, was measured in the arc tube direction from the electrode tip of the metallized sealing tip closer to this. The range is such that the distance does not become shorter than 4.7 mm.
[0032]
The outer surface temperature of the metallized sealing tip is 740 ° C. when the non-sealing length Lx is 14.0 mm. At this time, the electrode closer to the metalized sealing tip is closer to the electrode. The distance measured from the tip end in the arc tube direction is (Lo−Le) /2+Lx=16.7 mm. Therefore, the range in which the outer surface temperature range of the metallized sealing tip is 740 ° C. or more and 950 ° C. or less, in other words, the arc tube from the electrode tip of the metallized sealing tip that is closer to this. The distance measured in the axial direction is in a range from 4.7 mm to 16.7 mm.
[0033]
In addition, here, the structure that enables the lamp efficiency to be improved without causing crack breakage in the arc tube or changing the color of emitted light is also referred to as the distance of the metallized sealing tip from the electrode tip. However, the essence of the present invention is that the temperature of the front end of the metallized sealing and the outer surface temperature of the front end of the metallized sealing at the time of steady lighting are defined. That is, parameters other than these, such as the total length La of the thin tube portion and the unsealed length Lx, cannot be basically defined. This is because the total length La and the unsealed length Lx vary depending on the magnitude of the rated lamp power, the set tube wall load, the basic structure of the arc tube, and the like. For example, depending on the field in which the high-pressure discharge lamp is used, the tube wall load of the arc tube is set to be low in order to extend the life of the high-pressure discharge lamp. This is because the non-sealing length Lx is further shortened in order to maintain the optimum high temperature state.
[0034]
As described above, the present invention has been described based on the embodiments. However, it is needless to say that the present invention is not limited to the above embodiments.
(1) In the above embodiment, the arc tube is formed by separately creating and assembling the main tube portion and the thin tube portion. However, the present invention is not limited to this, and the main tube portion and the thin tube portion are integrally formed. May be formed.
[0035]
(2) In the above embodiment, both ends of the arc tube are sealed by metallizing, but one of them may be sealed by frit sealing. Even in this case, the overall length of the arc tube becomes shorter and the lamp efficiency is improved as compared with the case where both ends are sealed by frit. In the case of frit sealing, the molybdenum thin tube is not used, and the electrode rod is supported by the thin tube portion via ceramic cement (frit), and sealing is performed in the thin tube portion.
[0036]
【The invention's effect】
As described above, according to the high-pressure discharge lamp according to the present invention, it is possible to improve the lamp efficiency without causing crack breakage in the arc tube or changing the color of emitted light.
[Brief description of the drawings]
FIG. 1 is a partially cutaway view of a metal halide lamp according to an embodiment.
FIG. 2 is a longitudinal sectional view of a light emitting section in the metal halide lamp.
FIG. 3 is an enlarged sectional view of a sealing portion in the arc tube of the light emitting section.
FIG. 4 is a diagram showing a relationship between an outer surface temperature of a metallized sealing front end portion and a defect occurrence rate due to a change in emitted light color.
FIG. 5 is a diagram showing a relationship between an outer surface temperature of a metallized sealing front end portion and a defect occurrence rate due to a thin tube portion crack breakage.
FIG. 6 is a diagram showing a relationship between an outer surface temperature of a metallized sealing front end portion and a rate of improvement in lamp efficiency with respect to a metal halide lamp by frit sealing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Arc tube 3 Main tube part 4, 5 Thin tube part 6, 7 Molybdenum thin tube 8, 9 Joined body 10, 11 Tungsten electrode 12, 13 Tungsten electrode rod

Claims (1)

An arc tube composed of a main tube portion forming a discharge space and thin tube portions provided on both sides of the main tube portion, and formed of a translucent ceramic material;
Having a shaft portion supported by the thin tube portion, and having a pair of electrodes provided so that tip portions thereof face each other at an interval in the discharge space,
Of the pair of electrodes, at least one of the electrodes is supported by the thin tube portion in a state where the shaft portion is inserted into a cylindrical holding member made of a halide-resistant metal,
A high-pressure discharge lamp in which the holding member and the thin tube portion are sealed via a joined body including a halide-resistant metal sintered body and a mixed glass impregnated in open pores of the sintered body. ,
At the time of steady lighting, when the end temperature closer to the discharge space in the joint region by the joined body is evaluated by the surface temperature closer to the discharge space of the thin tube portion corresponding to the joined region by the joined body. A high-pressure discharge lamp characterized in that the surface temperature is at least 740 ° C. and does not exceed 950 ° C.

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