JP2009032446A - High-voltage discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-voltage discharge lamp which restrains generation of cracks in a lifetime of a light-transmitting ceramic airtight container when vertically lighting the high-voltage discharge lamp of non-mercury having the light-transmitting ceramic airtight container, obtains desired light-emitting efficiency, and allows easy production of the integrally-molded light-transmitting ceramic airtight container. <P>SOLUTION: The high-voltage discharge lamp comprises the light-transmitting ceramic airtight container 1 in which a surrounding section 1a with a vertically-asymmetrical swollen shape and a pair of small-diameter cylindrical sections 1b having an upper swelling section 1a1, a lower swelling section 1a2 with a small diameter, and a connection section 1a3 for connecting between the upper swelling section 1a1 and the lower swelling section 1a2, are integrally formed; a pair of current leading conductors 2; a pair electrodes 3 wherein an upper electrode faces to an upper swelling section and a lower electrode faces to a lower swelling section and both tips are separately faced with each other; and a discharge medium including halide of a light-emitting metal and rare gas enclosed by the pressure of one atmospheric pressure or more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high pressure discharge lamp provided with a translucent ceramic hermetic container.

  Since environmental problems have become important, mercury-free high-pressure discharge lamps that essentially do not enclose mercury in high-pressure discharge lamps have been developed (see Patent Document 1). This lamp has already been put into practical use for automobile headlamps. It is expected that there will be further progress in the development of mercury-free products such as high-pressure discharge lamps for automotive headlamps.

  On the other hand, high-pressure discharge lamps using a translucent ceramic hermetic container having high corrosion resistance and high heat resistance have become widespread. According to this high pressure discharge lamp, it is easy to obtain a high color rendering property with high luminous efficiency.

  On the other hand, in a high-pressure discharge lamp equipped with an airtight container made of quartz glass, the inner diameter on the upper side is made larger than the inner diameter on the lower side so as to promote the distribution of the condensate of the discharge medium on the wall of the arc chamber surrounding the discharge space. It is known that it is made larger, or in addition to this, the protruding length of the upper electrode is made larger than that of the lower electrode (see Patent Document 2). Also, in a high-pressure discharge lamp using a translucent ceramic hermetic vessel, when the lamp is lit in a vertical position, an excessive amount of discharge medium is close to the top of the discharge quality, so that the coldest spot is formed so as to form the coldest spot. It is known that the protruding length of the electrode is reduced, the thickness of the upper cap of the discharge quality is increased, or the electrode conductor of the upper electrode is made larger than that of the lower conductor (see Patent Document 3).

JP 11-238488 A Japanese Patent Laid-Open No. 62-110251 JP-A-2005-51068

  Mercury-free high-pressure discharge lamps are known to achieve the desired luminous efficiency if the noble gas filling pressure is 1 atm or higher. However, in the case of vertical lighting, the upper part of the translucent airtight container is excessive. It was found that cracking was likely to occur during the lifetime of the ceramics, especially when the translucent airtight container was made of ceramics. Therefore, if the tube wall load is lowered as a countermeasure, the generation of cracks can be reduced, but there is a problem that the desired luminous efficiency cannot be obtained because the luminous efficiency is too low.

  The present invention suppresses the generation of cracks during the life of the translucent ceramic hermetic container when the mercury-free high-pressure discharge lamp equipped with the translucent ceramic hermetic container is vertically lit, and a desired luminous efficiency is obtained. An object of the present invention is to provide a high-pressure discharge lamp in which an integrally molded translucent ceramic hermetic container can be easily manufactured.

    The high-pressure discharge lamp according to the first aspect of the present invention connects the upper bulging portion, the lower bulging portion having a small inner diameter, and the upper bulging portion and the lower bulging portion with a continuous curved surface in the vertical lighting posture. An encircling part having a vertically curved asymmetrical bulging shape and having a discharge space formed therein, and a pair of small-diameter cylindrical parts communicating with the inside of the encircling part are integrally formed, and a small-diameter cylinder A translucent ceramics hermetic container provided with a sealing part formed in a portion of the shape part; a pair of current introduction conductors introduced airtightly through the sealing part of the translucent airtight container; The upper electrode faces the upper bulging portion, the lower electrode faces the lower bulging portion, and the tips are spaced apart from each other. A pair of electrodes; a luminescent metal halide and a rare gas sealed at a pressure of 1 atmosphere or more It is characterized in that it comprises a; hints, and a discharge medium enclosed inside the surrounding portion of essentially light-transmissive airtight envelope not include mercury.

  The first invention includes the following aspects.

  [Translucent Ceramic Hermetic Container] The translucent ceramic hermetic container is a single crystal metal oxide such as sapphire, a polycrystalline metal oxide such as translucent hermetic aluminum oxide, yttrium-aluminum garnet (YAG). , Yttrium oxide (YOX), polycrystalline non-oxide, such as aluminum nitride (AlN), which is made of ceramic material with light transmission and heat resistance, and the discharge space is formed airtight inside Container. However, among the above materials, translucent polycrystalline alumina ceramics are suitable as a constituent material for translucent ceramic discharge vessels because they can be mass-produced industrially and are relatively easily available.

  The translucent ceramic hermetic container includes an encircling part to enclose the discharge space. The inside of the enclosure, that is, the discharge space is allowed to have an appropriate shape, for example, a spherical shape, an elliptical spherical shape, a substantially cylindrical shape, or the like. However, when the high pressure discharge lamp is vertically lit, the shape of the surrounding portion is different between the upper side bulging portion and the lower side bulging portion. The upper bulging portion has an inner diameter larger than that of the lower bulging portion. Moreover, the connection part which connects between the upper side bulging part and the lower side bulging part by a linear or curved continuous surface is provided. Note that various values can be selected as the volume of the discharge space according to the rated lamp power of the high-pressure discharge lamp, the distance between the electrodes, and the like. For example, in the case of a liquid crystal projector lamp, it can be 0.5 cc or less. Moreover, in the case of the lamp for general illumination, it can be set to either 1 cc or more and the following according to rated lamp electric power.

  Further, the translucent ceramic hermetic container includes a pair of small-diameter cylindrical portions communicating with the surrounding portion. The small diameter cylindrical portion functions to seal the translucent ceramic hermetic container by inserting at least a current introducing conductor, which will be described later, into the small diameter cylindrical portion and sealing the current introducing conductor to the small diameter cylindrical portion. Moreover, it can be made to function also in order to enclose the discharge medium mentioned later in the inside of a translucent ceramic airtight container, ie, an enclosure part.

  Furthermore, the translucent ceramic hermetic container is formed by integrally molding an enclosing portion and a pair of small diameter cylindrical portions. It is possible to continuously form the surrounding part and the boundary part of the surrounding part and the small-diameter cylindrical part by a smooth curve by integral molding, in which case a thermal discontinuity part is formed at the boundary part between them It becomes difficult to be done.

  Furthermore, the small diameter cylindrical portion is formed with a sealing portion for sealing the inside of the translucent ceramic hermetic container with respect to the outside. The sealing portion is formed by directly or indirectly sealing the small diameter cylindrical portion and the current introduction conductor. In the present invention, the sealing portion may be formed using a known frit glass or may be another sealing structure. For example, the sealing portion may be formed by fusing a small-diameter cylindrical portion or the same quality ceramic. In the case of using frit glass, it is preferable to form a so-called capillary structure inside the small diameter cylindrical portion.

  [About Current Introducing Conductor] The current introducing conductor is a conductor that functions to apply a voltage to an electrode to be described later, supply current to the electrode, and seal the translucent ceramic hermetic container. For this purpose, the tip side portion inserted into the inside of the small-diameter cylindrical portion of the translucent ceramic hermetic container is connected to the electrode, and the proximal end side is exposed to the outside of the translucent ceramic hermetic container. It should be noted that being exposed to the outside of the light-transmitting airtight container may or may not protrude outward from the light-transmitting ceramic airtight container. It only has to be there.

  In addition, the current introduction conductor is a sealing metal, that is, niobium (Nb), tantalum (which is a conductive metal whose thermal expansion coefficient is similar to that of the translucent ceramic constituting the translucent ceramic hermetic container. Metals such as Ta), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), platinum (Pt), molybdenum (Mo), and tungsten (W), cermet, and the like can be used. When aluminum oxide such as alumina ceramics is used as the material of the light-transmitting ceramic hermetic container, niobium and tantalum have an average thermal expansion coefficient almost the same as that of aluminum oxide, and molybdenum has an average thermal expansion coefficient. Since it is close to that of the oxide, it is suitable for sealing. In the case of yttrium oxide and YAG, the difference is small. When aluminum nitride is used for the translucent ceramic hermetic container, zirconium may be used for the current introduction conductor. Further, the current introduction conductor can be formed by joining a plurality of material portions. For example, a part is a metal part selected from the above group, and a cermet is joined to the metal part in the tube axis direction.

  The cermet may be made of one or more metals selected from the above group, such as molybdenum or tungsten, in which the ceramic material is alumina ceramic. Further, the cermet part sealed in the translucent ceramic hermetic container of the current introduction conductor includes at least a metal component such as niobium (Nb), molybdenum (Mo) and tungsten, and a ceramic component such as alumina, YAG and yttria. Including, the content ratio of the metal component is allowed to be 5 to 60% by mass.

  Thus, when the cermet is configured as described above, when the portion to be sealed by the heating means is heated, it generally depends on the heating method, but in a translucent ceramic hermetic container, heat absorption is generally performed. Hard to occur. On the other hand, heat absorption increases on the cermet surface. As a result, the surface of the cermet is heated and the temperature rises, and further, the heat is transferred to the small-diameter cylindrical portion of the translucent ceramic hermetic container, so that the planned sealing portion melts. In addition, airtightness in the translucent ceramic airtight container is ensured.

  Further, since the content of the metal component is 60% by mass or less, there is no large difference in the coefficient of thermal expansion of the translucent ceramic hermetic container, and the high pressure discharge lamp is compared with the case where the translucent ceramic hermetic container is in direct molybdenum contact. Damage and leakage due to heat shock when is turned on are less likely to occur.

  Furthermore, the function of the current introduction conductor is mainly divided into a portion that is sealed to the small diameter cylindrical portion of the translucent ceramic hermetic container and a portion that mainly supports the electrode. Therefore, in order to optimize each part for each function, each part is made of a different material or formed in a different size and structure, and connected to each other to form a current introduction conductor. Can be configured. For example, it is known that a portion sealed mainly to a small-diameter cylindrical portion of a translucent ceramic hermetic container is made of niobium and a portion mainly supporting an electrode is made of a halogen-resistant metal. Also in the present invention, it is allowed to configure the current introduction conductor by changing the specifications such as the material, size and shape according to the main function and connecting them in the tube axis direction. However, a conductive member of the same material can be used throughout the entire length of the current introduction conductor as desired. In this case, other materials can be added around the conductive member as necessary in order to perform the respective functions.

  [Regarding Electrode] The electrode is a means for causing discharge of a discharge medium, which will be described later, inside the translucent ceramic hermetic container. In general, a pair of electrodes are disposed so as to be opposed to each other so that arc discharge is generated between the electrodes inside the translucent ceramic hermetic container. In the present invention, at least one electrode is connected to the introduction conductor and sealed in the translucent ceramic hermetic container.

  The electrode is connected to the current introduction conductor and supported at a predetermined position in the translucent ceramic hermetic container. For example, the proximal end of the electrode is connected to the distal end portion located on the inner side of the translucent ceramic hermetic container of the current introduction conductor.

  Furthermore, an electrode can be comprised by an electrode main part or / and an electrode axial part. The electrode main part is a part that serves as a starting point of discharge, and therefore functions mainly as a cathode and / or an anode, and can be directly connected to the current introduction conductor without going through the electrode shaft part as desired. Further, in order to increase the surface area of the electrode main part to improve heat dissipation, a tungsten coil can be wound as necessary, or the diameter can be made larger than that of the electrode shaft part. When the electrode includes an electrode shaft portion, the electrode shaft portion is integrally or welded with the electrode main portion, protrudes rearward from the back surface of the electrode main portion, supports the electrode main portion, and the current introduction conductor. Connect to. If desired, the electrode shaft portion and the tip portion of the current introduction conductor can be integrated with a single tungsten.

  Furthermore, tungsten, doped tungsten, triated tungsten, rhenium, tungsten-rhenium alloy, or the like can be used as an electrode material.

  Furthermore, when a pair of electrodes is used, they have a symmetrical structure in the case of an AC lighting type, but can be made an asymmetric structure in the case of a DC lighting type.

  [Discharge Medium] The discharge medium is a means for obtaining desired light emission by the discharge, but the configuration is not particularly limited in the present invention. For example, the following modes are allowed. However, it is preferably composed of a luminescent metal halide, a lamp voltage forming medium and a rare gas. In the present invention, “high-pressure discharge” refers to a discharge in which the pressure during lighting of the ionized medium is equal to or higher than atmospheric pressure, and is a concept including so-called ultrahigh-pressure discharge.

  The luminescent metal halide is a luminescent metal halide that mainly emits visible light, and various known metal halides can be employed. That is, the metal halide of the luminescent metal obtains visible light radiation having desired luminescent characteristics with respect to luminescent color, average color rendering index Ra, luminescent efficiency, etc., and further, the size and input of the translucent ceramic discharge vessel Depending on the power, any desired metal halide can be selected as desired. For example, sodium (Na), scandium (Sc), rare earth metals (such as dysprosium (Dy), thulium (Tm), holmium (Ho), praseodymium (Pr), lanthanum (La) and cerium (Ce)), thallium (Tl) ), Indium (In) and lithium (Li), one or a plurality of halides selected from the group consisting of.

  The lamp voltage forming medium is an effective medium for forming a lamp voltage. For example, mercury or a metal halide described below can be used. That is, a halide as a lamp voltage forming medium is a metal such as aluminum, which has a relatively high vapor pressure during lighting and a small amount of light in the visible region compared to the amount of light emitted in the visible region. Halides such as (Al), iron (Fe), zinc (Zn), antimony (Sb), and manganese (Mn) are suitable.

  The rare gas has an enclosure pressure in the light-transmitting ceramic hermetic container of 1 atmosphere or more at room temperature. If the enclosed pressure is 1 atm or higher, a desired high luminous efficiency can be obtained even if the discharge medium is anhydrous silver. Note that the rare gas sealing pressure is preferably 16 atm or less, mainly from the viewpoint of rupture of the translucent ceramic hermetic container and ease of sealing. Further, the rare gas acts as a starting gas and a buffer gas, and xenon (Xe), argon (Ar), krypton (Kr), neon (Ne), or the like can be used alone or in combination.

  Next, in the halide of the luminescent metal, any one or plural kinds of iodine, bromine, chlorine or fluorine can be used as the halogen.

  Thus, in the first invention, since the discharge medium is anhydrous silver, the discharge arc becomes thinner than when mercury is enclosed. Further, since the rare gas is sealed at a pressure of 1 atm or higher, the convection of the discharge medium during lighting becomes strong. However, the surrounding portion of the translucent ceramic hermetic container has an upper bulging portion, a lower bulging portion having a small inner diameter, and a connecting portion that connects the upper bulging portion and the lower bulging portion with a continuous curved surface. By having the asymmetric bulging shape, the temperature of the upper part of the surrounding part of the translucent ceramic hermetic container is unlikely to rise during vertical lighting, and the occurrence of cracks during the lifetime is remarkably suppressed.

  In addition, since the shape of the surrounding portion is as described above, the surrounding portion of the translucent ceramic hermetic container and the pair of small diameter cylindrical portions can be obtained by integral molding. There is no loss of sex.

  The high-pressure discharge lamp according to the second aspect of the present invention is a pair of a surrounding portion in which the wall thickness is continuously increased from the lower part to the upper part in the vertical lighting posture and a discharge space is formed inside, and a pair of communicating with the inside of the surrounding part. A light-transmitting ceramic hermetic container in which a small-diameter cylindrical portion is integrally formed and having a sealing portion formed in the small-diameter cylindrical portion; and airtightly penetrating the sealing portion of the translucent air-tight container A pair of current introduction conductors introduced into the inside; an upper electrode facing the upper part and a lower electrode inside the lower part of the enclosure of the translucent airtight container disposed at the tip of the current introduction conductor A pair of electrodes facing each other and spaced apart from each other; a light-transmitting hermetic container containing a halide of a luminescent metal and a rare gas sealed at a pressure of 1 atm or higher and essentially free of mercury A discharge medium enclosed in the enclosure of It is characterized by a door.

  In the second invention, the translucent ceramic hermetic container continuously increases in thickness from the lower part to the upper part when the thickness of the surrounding portion is in the vertical lighting posture. In addition, the shape of the discharge space formed inside the surrounding portion can be made symmetric in the vertical direction. However, if desired, the configuration of the first invention may be added to make the outer shape asymmetrical in the vertical direction.

  Thus, in the second invention, since the heat capacity of the upper part of the surrounding part of the translucent ceramic hermetic container is larger than that of the lower part, the temperature of the upper part of the surrounding part is unlikely to rise during vertical lighting. Further, since the wall thickness of the surrounding portion is continuously changed from the lower part to the upper part, the surrounding part of the translucent ceramic hermetic container and the pair of small diameter cylindrical parts can be obtained by integral molding. The manufacturability of the ceramic hermetic container is not impaired.

  A high pressure discharge lamp according to a third aspect of the present invention is formed by integrally forming a surrounding portion in which a discharge space is formed and a pair of small diameter cylindrical portions communicating with the inside of the surrounding portion, and is formed in a portion of the small diameter cylindrical portion. A translucent ceramic hermetic container provided with a sealed portion; a pair of current introduction conductors that are airtightly penetrated through the sealing portion of the translucent airtight container; A pair of electrodes disposed at the front end portion of the current introduction conductor and facing each other at a distance from each other in the surrounding portion of the light-transmitting hermetic container, the upper side being a cathode and the lower side being an anode; And a discharge medium that contains a rare gas sealed at a pressure of 1 atm or higher and that is essentially free of mercury and sealed inside the enclosure of the light-transmitting hermetic container. It is said.

  In DC lighting where the upper electrode is the cathode, the lower electrode is the anode. When the high-pressure discharge lamp is dc-lit, a large amount of electron flow in the discharge current flows into the anode, so the anode becomes relatively hot. On the other hand, since a small proportion of the ionic current in the discharge current flows into the cathode, the cathode becomes relatively cold.

In the third aspect of the invention, the upper electrode has a cathode and the lower electrode has an anode, so that the vertical temperature distribution of the high-pressure discharge lamp is improved in the leveling direction.

In the first aspect, the second aspect in which the thickness of the upper part of the translucent ceramic hermetic container is larger than the thickness of the lower part, and the third aspect having both the first and second aspects. is there.

  In the first aspect, the distance between the upper part of the discharge arc, which is a heat source, and the upper inner wall surface of the surrounding part of the translucent ceramic hermetic container is increased, so that heat conduction to the upper inner wall surface is reduced. In the second aspect, since the heat capacity of the upper part of the translucent ceramic hermetic container is increased, the temperature rise of the upper part is reduced. Therefore, in the third aspect, the effects of the first and second aspects can be obtained. As a result of the above action, according to the first to third aspects, the temperature rise in the vertical direction of the translucent ceramic hermetic container is improved by suppressing the temperature rise in the upper part of the translucent ceramic hermetic container. The occurrence of cracks in the translucent ceramic hermetic container is reduced.

  In the first to third inventions, the following modes can be adopted.

  The first mode is a mode in which the amount of protrusion of the electrode located in the upper part into the surrounding part is larger than that of the electrode located in the lower part in the vertical lighting posture. In this embodiment, since the protruding amount of the upper electrode is large, the extent to which the discharge arc as a heat source and the bright spot generated at the tip of the electrode are separated from the upper part of the translucent ceramic hermetic vessel is increased, Less heat conduction.

  The second mode is a mode in which the outer diameter of the upper electrode is larger than the outer diameter of the lower electrode in the vertical lighting posture. In the second aspect, since the heat capacity of the upper electrode is increased, the temperature rise of the upper portion of the translucent ceramic hermetic container is suppressed. Further, in the second aspect, since the temperature rise of the upper electrode is reduced, the occurrence of blackening is reduced as a result of suppressing the evaporation of the electrode material. Furthermore, the outer diameter of the lower electrode does not need to be the same as the outer diameter of the upper electrode, and the optimum outer diameter can be selected as the lower electrode, so the temperature of the lower electrode is too low and reignition failure occurs. Can be avoided. When the outer diameter of the upper electrode is R1, the outer diameter of the lower electrode is R2, and the ratio R1 / R2 is S, generally 1.15 <S <1.7, preferably 1.2 <S. <1.3 is recommended. The ratio S of the electrode diameter has a correlation with the rare gas filling pressure. When the rare gas filling pressure is P (atmospheric pressure), the ratio S / P is expressed by the formula: 0.1 <S / P <. When 1 is satisfied, the occurrence of cracks in the translucent ceramic hermetic container can be effectively suppressed.

  A 3rd aspect is an aspect which prescribes | regulates the outer surface temperature of a translucent ceramic airtight container. That is, the distance between the electrodes, which is the distance between the tips of the pair of electrodes, is G, and the translucent ceramics facing the distance equal to G / 2 up and down from the center in the tube axis direction of the enclosure portion of the translucent ceramic hermetic container When the outer surface temperature of the hermetic container is T1 (° C.) and T2 (° C.) and the temperature difference between them is ΔT (° C.), ΔT satisfies the formula: ΔT ≦ 100, preferably 20 ≦ ΔT ≦ 80 It is configured as follows. In addition, when the said temperature difference exceeds 100 degreeC, the stress by a temperature difference will become large and it will become easy to generate | occur | produce a crack in a translucent ceramic airtight container during a lifetime. In the second aspect, in order for the temperature difference ΔT to satisfy the above mathematical expression, it is realized by implementing any one or more of the first to third inventions and the first and second aspects described above. Can do.

  A 4th aspect is an aspect whose rated lamp electric power is 100 W or less. In addition, Preferably it is 50 W or less.

  A 5th aspect is an aspect which comprises an outer tube | pipe. The high-pressure discharge lamp of the first to third inventions can be configured to light up in a state where the translucent ceramic hermetic container is exposed to the atmosphere. However, it is allowed to have an outer tube if desired. The outer tube is added as desired for the purpose of accommodating the arc tube inside thereof, keeping the arc tube warm, protecting it mechanically, or blocking ultraviolet rays emitted from the arc tube. Moreover, various known configurations along the main purpose can be employed.

  When the high-pressure discharge lamp of the present invention is used as a light source of an illuminating device, it comprises: an illuminating device main body; a high-pressure discharge lamp of the present invention disposed in the illuminating device main body; and a lighting circuit for lighting the high-pressure discharge lamp. Therefore, the lighting device can be configured. The lighting device is a concept including all devices using a high-pressure discharge lamp as a light source. Examples include various outdoor and indoor lighting fixtures, automobile headlamps, image or video projection devices, marker lamps, signal lights, indicator lights, chemical reaction devices, inspection devices, and the like. The illuminating device main body refers to the remaining part of the illuminating device excluding the high-pressure discharge lamp and the lighting circuit. The lighting circuit may be disposed at a position separated from the lighting device main body.

  According to the first to third aspects of the present invention, even if the convection of the discharge medium during lighting is increased by encapsulating noble gas at a pressure of 1 atm or more with anhydrous silver, the translucent ceramics in the vertical lighting posture Since the temperature of the upper part of the enclosure portion of the hermetic container is unlikely to rise, it is possible to provide a high-pressure discharge lamp that suppresses the generation of cracks during the lifetime and obtains a desired luminous efficiency.

  FIG. 1 is a sectional view showing an embodiment for carrying out the high-pressure discharge lamp of the first invention. The discharge lamp MHL of this embodiment includes a translucent ceramic hermetic container 1, a pair of current introduction conductors 2, 2, a pair of electrodes 3, 3, and a discharge medium.

  The translucent ceramic hermetic container 1 includes an enclosing portion 1a and a pair of small diameter cylindrical portions 1b and 1b. The surrounding portion 1a includes an upper bulging portion 1a1, a lower bulging portion 1a2, and a connecting portion 1a3, and a discharge space 1c is formed therein. The upper bulged portion 1a1 is a bulged portion having a large inner diameter, and has a shape obtained by cutting a spherical shape, an elliptical sphere shape, a spindle shape, or the like into about a half. The lower bulge portion 1a2 is a bulge portion whose inner diameter is smaller than that of the upper bulge portion 1a1, and has a shape in which a spherical shape, an elliptical sphere shape, a spindle shape, or the like is cut to about half. In addition, each said internal diameter is taken as the numerical value in a surface perpendicular | vertical with respect to the tube axis which cross | intersects the front-end | tip of a pair of electrode. The connecting portion 1a3 connects the upper bulging portion 1a1 and the lower bulging portion 1a2 with a continuous surface. Therefore, the surrounding portion 1a forms an internal space 1c that exhibits an asymmetrical bulging shape when the high-pressure discharge lamp is in a vertical lighting posture.

  The pair of small diameter cylindrical portions 1b are divided and connected to both ends of the surrounding portion 1a in the tube axis direction, and the inside communicates with the surrounding portion 1a. Further, a sealing portion SP is formed in the small diameter cylindrical portion 1b. The configuration of the sealing portion SP is not particularly limited. In the illustrated form, the molten frit glass is allowed to enter and solidify into a gap formed between an end portion of the small-diameter cylindrical portion 1b and a later-described current introduction conductor 2 inserted into the small-diameter cylindrical portion 1b. The configuration is adopted.

  The current introduction conductor 2 has a base end side 2a exposed to the outside made of niobium, and a tip end side 2a inserted into the translucent ceramic hermetic vessel 1 made of molybdenum, which are joined together by welding. It has a rod shape. Therefore, the distal end portion of the current introduction conductor 2 is located in the small diameter cylindrical portion 1 b and the proximal end portion is exposed to the outside of the translucent ceramic hermetic container 1.

  The electrode 3 is made of a tungsten wire, and the diameter of the shaft portion is the same over the distal end portion, the intermediate portion, and the proximal end portion in the axial direction, and a part of the distal end portion and the intermediate portion is exposed in the discharge space 1c. Further, the electrode 3 is supported along the tube axis direction of the translucent ceramic discharge vessel 1 by connecting the base end of the electrode 3 to the tip of the tip side 2 a of the current introduction conductor 2 by welding. A slight gap, that is, a capillary is formed in the tube axis direction between the intermediate portion of the electrode 3 or the distal end side of the current introduction conductor 2 and the inner surface of the small diameter cylindrical portion 1b.

  The discharge medium includes a light emitting metal halide, a lamp voltage forming medium, and a rare gas. The medium for forming the lamp voltage is made of mercury or a halide for forming a lamp voltmeter. The lamp voltage forming halide is a metal halide having a high vapor pressure and a small amount of luminescence in the visible region in the coexistence with the luminescent metal halide compared to the luminescent metal. Mercury is not used. The rare gas has an enclosure pressure of 1 atm or higher.

  Example 1 is a high-pressure discharge lamp shown in FIG.

Translucent ceramic hermetic container: made of integrally molded translucent polycrystalline alumina ceramics,
Enclosure: Upper bulge inner diameter 12mm, Lower bulge inner diameter 8mm
Pipe axis length 17mm, wall thickness 0.8mm
Small-diameter cylindrical part; inner diameter 1.0mm, wall thickness 0.8mm, length 15mm
Current introduction conductor: Diameter 0.95mm
Electrode: W rod, diameter 0.4mm, distance between electrodes 8mm
Discharge medium: CsI-NaI-TlI-TmI 3 -ZnI 2 = 8.0mg, Xe13 atm outer tube: Outside 40 mm, when the internal vacuum vertical lighting [Delta] T: 10 ° C.
Luminous efficiency (lamp power 100W): 80lm / W
The occurrence of rupture due to cracks in the translucent airtight container was less than 5% after 1000 hours of life test.

[Comparative Example 1]
Translucent airtight container: Made of integrally molded translucent polycrystalline alumina ceramics,
Enclosure: 16mm length in the tube axis direction, maximum inner diameter 9.5mm, oval spherical inner surface shape,
Wall thickness 0.8mm
Small-diameter cylindrical part; inner diameter 1.0mm, wall thickness 0.8mm, length 15mm
The other specifications are the same as those in the first embodiment.

ΔT during vertical lighting; 120 ° C
Luminous efficiency (lamp power 100W): 80lm / W
30% of rupture due to cracks occurred in the translucent ceramic hermetic container up to 1000 hours of life test.

FIG. 2 is a cross-sectional view showing a translucent ceramic hermetic container in one embodiment for carrying out the second invention. In the figure, the same parts as those in FIG. In this embodiment, the surrounding portion 1a of the translucent ceramic hermetic container 1 is formed such that the wall thickness t1 of the upper bulge portion is larger than the wall thickness t2 of the lower bulge portion in the vertical lighting posture of the high-pressure discharge lamp. The wall thickness increases continuously from the bottom to the top.

  FIG. 3 is a sectional view showing an embodiment for carrying out the third invention. In the figure, the same parts as those in FIG. In this embodiment, the pair of electrodes 2K, 2A faces the inside of the upper bulging portion 1a1 in the vertical lighting posture of the high-pressure discharge lamp, with the electrode 2K being a cathode. The electrode 2K is thinner than the distal end side 2a of the current introduction conductor 2. On the other hand, the electrode 2A is an anode and faces the inside of the lower bulging portion 1a2. The electrode 2A is thicker than 2a.

  Example 2 is a high-pressure discharge lamp shown in FIG.

Translucent ceramic hermetic container: made of integrally molded translucent polycrystalline alumina ceramics,
Enclosed part: 8mm length in the tube axis direction, maximum inner diameter 6mm, oval spherical inner shape,
Wall thickness 0.5mm
Small-diameter cylindrical part: 0.7mm inner diameter, 0.5mm wall thickness, 13mm length
A pair of electrodes: Cathode diameter 0.25mm, anode diameter 0.4mm, tip spherical part diameter 0.6mm
Discharge medium: CsI-NaI-TlI-ZnI ₂ = 4.0 mg, Xe13 atmospheric pressure Other specifications are the same as those in Example 1.

ΔT during DC lighting in a vertical position: 50 ° C
Luminous efficiency (lamp power 35W): 80lm / W
The occurrence of rupture due to cracks in the light-transmitting airtight container was 5% after 1000 hours of life test.

Sectional drawing which shows one form for implementing the high pressure discharge lamp of 1st invention Sectional drawing of the translucent ceramics airtight container in one form for implementing the high pressure discharge lamp of 2nd invention Sectional drawing which shows one form for implementing the high pressure discharge lamp of 3rd invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Translucent ceramic airtight container, 1a ... Enveloping part, 1b ... Small diameter cylinder part, 1b1 ... Locking step part, 2 ... Current introduction conductor, 2a ... Base end side, 2b ... Tip side, 3 ... Electrode, SP ... Sealing part

Claims (4)

It has an up-and-down asymmetrical bulging shape with an upper bulging part, a lower bulging part with a small inner diameter, and a connecting part that connects the upper bulging part and the lower bulging part with a continuous surface in the vertical lighting position. And an enclosing portion in which a discharge space is formed and a pair of small-diameter cylindrical portions communicating with the inside of the enclosing portion are integrally formed, and includes a sealing portion formed in a portion of the small-diameter cylindrical portion. A translucent ceramic hermetic container;
A pair of current-introducing conductors introduced air-tightly through the sealing portion of the translucent air-tight container;
The upper electrode faces the upper bulging portion, the lower electrode faces the lower bulging portion, and the tips are spaced apart from each other. A pair of electrodes;
A discharge medium containing a halide of a luminescent metal and a rare gas sealed at a pressure of 1 atm or more, and being essentially free of mercury and sealed inside the enclosure of the translucent airtight container;
A high-pressure discharge lamp comprising: An enclosure in which the wall thickness is continuously increased from the lower part to the upper part in the vertical lighting posture and a discharge space is formed inside, and a pair of small-diameter cylindrical parts communicating with the inside of the enclosure part are integrally formed. And a translucent ceramic hermetic container provided with a sealing portion formed in the small diameter cylindrical portion;
A pair of current-introducing conductors introduced air-tightly through the sealing portion of the translucent air-tight container;
A pair of electrodes disposed at the tip of the current introduction conductor, the upper electrode faces the upper part, the lower electrode faces the lower part, and the tips are spaced apart from each other inside the enclosure of the translucent airtight container When;
A discharge medium containing a halide of a luminescent metal and a rare gas sealed at a pressure of 1 atm or more, and being essentially free of mercury and sealed inside the enclosure of the translucent airtight container;
A high-pressure discharge lamp comprising: An enclosing portion in which a discharge space is formed and a pair of small-diameter cylindrical portions communicating with the inside of the enclosing portion are integrally formed and includes a sealing portion formed in the small-diameter cylindrical portion. An optical ceramic airtight container;
A pair of current-introducing conductors introduced air-tightly through the sealing portion of the translucent air-tight container;
A pair of electrodes which are disposed at the tip of the current introduction conductor in the vertical lighting position and are opposed to each other at the inside of the surrounding portion of the translucent airtight container, the upper side being a cathode and the lower side being an anode. ;
A discharge medium containing a halide of a luminescent metal and a rare gas sealed at a pressure of 1 atm or more, and being essentially free of mercury and sealed inside the enclosure of the translucent airtight container;
A high-pressure discharge lamp comprising:   The translucent ceramic hermetic container has a length along the tube axis direction of the surrounding portion when the outer surface temperature of the upper and lower portions of the surrounding portion in the stable lighting state is G (mm) between the pair of electrodes. 4. The high-pressure discharge lamp according to claim 1, wherein a temperature difference ΔT (° C.) at each position of G / 2 from the center to the top and bottom satisfies the formula: ΔT ≦ 100.

Images