JP2008288043A - Discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp which is improved so that, even if ceramic constituting a fusion part is exposed at the back of the inside of a small diameter cylinder, the deterioration of light flux or a change of a light color is effectively suppressed by a reaction of the fusion part and isolated halogen. <P>SOLUTION: The discharge lamp MHL includes a translucent airtight vessel 1 having an enclosure part 1a and a small diameter cylinder 1b, and having a seal part SP formed at the end of the small diameter cylinder, a current introducing conductor 2 introduced inside by penetrating the seal part airtightly, electrodes 3, and a discharge medium. The seal part SP is formed by using the ceramic of the substantially same property as that of the ceramic of the end of the small diameter cylinder as a main composition, arranging a ceramic sleeve 4 in which the current introducing conductor penetrates the end of the small diameter cylinder, and fusing the ceramic sleeve, the end of the small diameter cylinder and the current introducing conductor, and at least a part exposed to the inside of the small diameter cylinder of the translucent airtight vessel contains a rare earth metal oxide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge lamp having a light-transmitting hermetic container sealing structure suitable for a light-transmitting ceramic hermetic container.

  In a high-pressure discharge lamp equipped with a conventional translucent ceramic hermetic container, various modes have been proposed or attempted to seal the hermetic container via a current introduction conductor. Among them, the most widespread is an embodiment using a glass frit (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 06-196131

However, when a translucent ceramic discharge vessel is sealed using a glass frit as described in Patent Document 1, it cannot be said that the heat resistance of the glass frit is sufficiently high. In order to obtain it, the temperature of the sealing portion must be suppressed as required, and therefore the following configuration must be adopted.
(1) A so-called capillary structure is formed in which the small-diameter cylindrical portion extends in the tube axis direction from both ends of the surrounding portion that defines the discharge space.
(2) Reduce the tube wall load.

  The use of the above configuration causes the following problems.

As a result of the above (1), the total length of the lamp is increased. This leads to the following problem.
・ The capillary part is easily broken.
-The amount of discharge medium such as halide to be sealed needs to be several times or more, in some cases 10 times or more, compared to the case where no capillary is formed. As a result, problems such as an increase in cost, stability of the discharge medium, a decrease in startability due to an increase in impure gas discharged from the discharge medium, white turbidity, blackening, and electrode wear are likely to occur.

  Since the temperature is lowered by performing the above (2), the halide is not sufficiently evaporated and the vapor pressure cannot be increased. As a result, the luminous efficiency cannot be increased to the expected level. Further, it is not possible to use a halide having good light emission characteristics but high reactivity.

  As a result of research on sealing a light-transmitting ceramic discharge vessel without using frit glass, the present inventors have found a frit glass-less configuration. This frit glass-less configuration includes several embodiments using various materials and structures.

  When the translucent ceramic hermetic container is made of translucent polycrystalline alumina ceramics in the frit glass-less configuration described above, if niobium or cermet is used in the portion embedded in the sealing portion of the current introduction conductor, thermal expansion with the ceramics will occur. This is convenient because the difference in coefficients is small.

  However, niobium reacts with the metal halide and the free halogen generated by the disappearance of the metal of the metal halide during the lamp operation, so it must be prevented from being exposed to the inside of the translucent ceramic hermetic container. Further, since the cermet also reacts with free halogen relatively easily and is deteriorated, it is desirable that the cermet is not exposed to the inside of the translucent ceramic hermetic container. Therefore, when fusing ceramics of the same material as the translucent ceramic hermetic container, if the inner surface of the current introduction conductor niobium or cermet is covered with the fused ceramic, the niobium or cermet becomes a metal halide or free halogen. Since it is not touched, reaction of niobium or cermet with halogen can be prevented.

  However, when ceramics that are fused to form a sealing portion, for example, alumina ceramics, are exposed in the small-diameter cylindrical portion, the exposed portion located in the inner portion of the small-diameter cylindrical portion where the temperature is relatively low is exposed to the metal halide. In addition, free halogen aggregates. As a result, it has been found that there is a problem that this ceramic easily reacts with free halogen to cause a decrease in luminous flux and a change in light color.

  The present invention is improved so that, even if the ceramic forming the fusion part is exposed in the inner part of the small-diameter cylindrical part, the reduction of luminous flux and light color change are effectively suppressed by the reaction of the part with free halogen. It is an object to provide a discharge lamp.

    The discharge lamp of the present invention includes an enclosure portion in which a discharge space is formed and a small-diameter cylindrical portion mainly formed of ceramics that communicates with the inside of the enclosure portion, and a sealing portion at the end of the small-diameter cylindrical portion A translucent airtight container formed with; a current introduction conductor introduced airtightly through the sealing portion of the translucent airtight container; and a translucent airtightness disposed at the tip of the current introduction conductor An electrode facing the discharge space of the container; and a discharge medium enclosed in the enclosure of the light-transmitting hermetic container, wherein the sealing part of the light-transmitting hermetic container is an end of the small-diameter cylindrical part A ceramic sleeve formed mainly of ceramics of substantially the same quality as the ceramics and having a current introduction conductor penetrated therein is disposed at the end of the small-diameter cylindrical portion, and the ceramic sleeve and the small-diameter cylindrical portion of the translucent airtight container The end of the wire and the current introduction conductor are formed by fusing Together it is, is characterized in that the portion exposed to the inside of the small diameter cylinder portion of the at least light-transmissive airtight envelope is contained rare earth metal oxides.

  The present invention includes the following aspects.

  [Translucent Airtight Container] The translucent airtight container includes an enclosing portion and a small diameter cylindrical portion. In the present invention, at least the small diameter cylindrical portion communicates with the surrounding portion and is formed mainly of ceramics. Note that “mainly ceramics” means that at least a portion to be fused at the time of sealing, that is, a portion to be sealed, is formed of ceramics. However, in the translucent airtight container, both the surrounding portion and the small-diameter cylindrical portion are preferably made of translucent ceramics. Ceramics include single crystal metal oxides such as sapphire, polycrystalline metal oxides such as translucent airtight aluminum oxide, ie translucent polycrystalline alumina ceramics, yttrium-aluminum garnet (YAG), yttrium oxide. (YOX) and a polycrystalline non-oxide such as aluminum nitride (AlN), which is made of a ceramic material having optical transparency and heat resistance, in which a discharge space is formed in an airtight manner with respect to the outside. is there. However, among the above materials, translucent polycrystalline alumina ceramics are suitable as a constituent material of a translucent airtight container because they can be mass-produced industrially and are relatively easily available.

  Although this was unexpected, the present inventor has found that translucent ceramics can be melted relatively easily. The present invention has been made based on this discovery.

  Further, the light-transmitting polycrystalline alumina ceramics generally used has an average crystal grain size of about 70 μm, but in the present invention, it is at least close to the sealing portion of the small-diameter cylindrical portion described later. In other words, if the average crystal grain size before melting for sealing is 30 μm or less, cracks are unlikely to occur and preferable fusion can be performed. That is, when the average crystal grain size of the above portion is 30 μm or less, when sealing is performed by melting the ceramic of the small-diameter cylindrical portion, the familiarity with the introduction conductor is good, and the small-diameter cylindrical portion and the current are introduced by melting. During cooling after bonding with the conductor, cracks are unlikely to occur at the bonded portion or in the vicinity thereof. In addition, when the average crystal grain size is 1 μm or less, cracking due to bonding is extremely reduced, which is more preferable. Furthermore, when the average crystal grain size is 0.5 μm or less, no cracks are generated due to bonding. Therefore, it is generally desirable that the thickness is 0.1 to 30 μm. Moreover, it is much more preferable if it is 0.5-20 micrometers. Furthermore, 1 to 10 μm is optimal.

  The portion where the crystal average particle size of at least the small-diameter cylindrical portion of the translucent airtight container described above is 30 μm or less is preferable as long as it is at least a portion to be sealed of the small-diameter cylindrical portion. Also good.

  The translucency in the translucent airtight container means that the light generated by the discharge can be transmitted to the outside and transmitted to the outside, not only transparent but also light diffusive. Good. Further, at least the main part of the part surrounding the discharge space only needs to have translucency, and if necessary, when it has an incidental structure other than the main part, the part may be light-shielding. .

  The translucent airtight container is provided with an enclosing portion for enclosing 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. 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. In the case of a vehicle headlamp, it can be 0.05 cc or less. In the case of a general illumination lamp, it can be set to 1 cc or more and any of the following depending on the rated lamp power.

  Further, the translucent airtight container includes a small-diameter cylindrical portion that communicates with the surrounding portion. The small-diameter cylindrical portion supports at least a current introduction conductor, which will be described later, and forms a sealing portion in cooperation with the current introduction conductor when the portion to be sealed is heated and melted together with the ceramic sleeve. Functions to seal the translucent airtight container.

  The number of the small-diameter cylindrical portions is two for the configuration of sealing a general pair of electrodes, but it should be one to three or more depending on the number of current introduction conductors to be arranged. Allow. When two small-diameter cylindrical portions are provided to seal a pair of electrodes, each small-diameter cylindrical portion is arranged at a position separated from each other, but is preferably separated at both ends of the enclosure portion along the tube axis. Opposite. In addition, the ceramic which comprises a small diameter cylinder part may be light-shielding.

  In the present invention, the small diameter cylindrical portion may or may not form a capillary structure inside. Therefore, the length of the small diameter cylindrical portion is not particularly limited in the present invention. In short, it is sufficient that the length is such that at least the sealing portion between the ceramic sleeve and the current introduction conductor formed by melting the ceramic in the small-diameter cylindrical portion can be easily formed. The length of the small-diameter cylindrical portion described above can be clearly shorter than the length of the small-diameter cylindrical portion in the case of sealing using conventional frit glass.

  In addition, a locking step portion can be formed at the opening end of the small-diameter cylindrical portion as desired in order to support a ceramic sleeve described later at a predetermined position. The locking step portion may be formed over the entire inner peripheral surface of the small diameter cylindrical portion, or may be partially formed by forming a protrusion on a part of the inner peripheral surface. Thus, when the ceramic sleeve is inserted into the opening end of the small diameter cylindrical portion, the support position of the ceramic sleeve is regulated by the locking step portion, and as a result, the ceramic sleeve is locked at a predetermined position with respect to the small diameter cylindrical portion. The According to the aspect in which the locking step portion is formed, the outer diameter of the ceramic sleeve can be set regardless of the capillary (slight gap) formed inside the small diameter cylindrical portion. If desired, the outer diameter of the small-diameter cylindrical portion corresponding to the formation step portion may be larger than that of the other portions.

  Further, when the locking step portion is not provided at the opening end of the small-diameter cylindrical portion, the ceramic sleeve described later is supported and sealed at the opening end of the small-diameter cylindrical portion with the tube axis in the vertical direction. It is also acceptable. In this embodiment, the small-diameter cylindrical portion and the ceramic sleeve are mainly fused, and the ceramic sleeve and the current introduction conductor are fused to form the sealing portion. In addition, you may form a small diameter cylinder part and a ceramic sleeve integrally.

  [Regarding Ceramic Sleeve] The ceramic sleeve is interposed between the small-diameter cylindrical portion and the current introduction conductor and contributes to form a sealing portion by fusion bonding of ceramics. And the main component is the same quality as the ceramic of a small diameter cylinder part, and an electric current introduction conductor penetrates inside. Further, in a state where the sealing portion is formed, a rare earth metal oxide is added to a part of the ceramic sleeve so that the portion exposed to the inside of the small diameter cylindrical portion contains the rare earth metal oxide. Or a rare earth metal oxide is added to the entire ceramic sleeve.

  In the configuration in which a part of the ceramic sleeve is added with the rare earth metal oxide, the ceramic sleeve is divided into at least two regions in the axial direction, and one region is doped with the rare earth metal oxide, In this region, rare earth metal oxide is not added. The two regions may be integrated or may be separated.

  As the rare earth metal oxide, one or more selected from the group of lanthanum (La), neodymium (Nd), gadolinium (Ga), dysprosium (Dy) and fornium (Ho) can be preferably used. When the rare earth metal oxide is added to the ceramic sleeve, the rare earth metal oxide is exposed to the portion of the ceramic exposed in the inner part of the small-diameter cylindrical portion of the translucent airtight container of the sealing portion formed by fusing the ceramic. Can be contained. The rare earth metal oxide content in the ceramic sleeve is not particularly limited in the present invention, but is preferably in the range of 1 to 50% by volume, and preferably 20 to 30% by volume.

  Further, when the ceramic sleeve has an average crystal grain size of 30 μm or less, preferably 20 μm or less, and optimally 10 μm or less, the sealing portion formed by melting the ceramic sleeve and the small-diameter cylindrical portion is cracked. It becomes difficult to do. In this case, if the average particle size of the ceramic particles of the portion to be sealed in the small-diameter cylindrical portion of the light-transmitting hermetic container is 30 μm or less, preferably 20 μm or less, and optimally 10 μm or less, the generation of cracks is significantly reduced. However, even if only the average particle diameter of the ceramic particles of the ceramic sleeve is selected as described above, a considerable effect can be achieved in practice.

  Further, as described above, the ceramic sleeve may be supported by inserting at least a part of the opening end of the small diameter cylindrical portion, or may be supported by being placed or joined to the end of the small diameter cylindrical portion. . In the latter case, the translucent airtight container can be supported in a vertical state, and the ceramic sleeve can be simply placed on and supported by the end of the small diameter cylindrical portion. Alternatively, the ceramic sleeve may be supported by using an adhesive on the end surface of the small-diameter cylindrical portion, or by bonding each of them after temporary sintering. Further, the ceramic sleeve and the small diameter cylindrical portion may be integrally formed in advance.

  [Current Induction Conductor] The current introduction conductor applies voltage to an electrode, which will be described later, supplies current to the electrode, and forms a ceramic fused portion in cooperation with the small diameter cylindrical portion and the ceramic sleeve. It is a conductor that functions to seal the light tight container. Therefore, the distal end side portion inserted into the small-diameter cylindrical portion of the translucent airtight container is connected to the electrode, and the proximal end side is exposed to the outside of the translucent airtight container. In addition, in the above, being exposed to the outside of the translucent airtight container may or may not protrude from the translucent airtight container to the extent that power can be supplied from the outside. It means that you only have to face the outside.

  In addition, the current introduction conductor can be configured by using a sealing metal or a cermet in a portion to be sealed that forms the ceramic fused portion.

  Examples of the sealing metal include niobium (Nb) and tantalum (Ta), which are conductive metals whose thermal expansion coefficients are similar to those of ceramics and ceramic sleeves constituting the small-diameter cylindrical portion of the translucent airtight container. Metals such as titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), platinum (Pt), molybdenum (Mo), and tungsten (W), cermet, and the like can be used. Further, when aluminum oxide such as translucent polycrystalline alumina ceramics is used as a constituent material of at least the small-diameter cylindrical portion of the translucent airtight container, niobium and tantalum have an average thermal expansion coefficient substantially the same as that of aluminum oxide. Since molybdenum has an average coefficient of thermal expansion close to that of the above oxide, it can be used for a portion to be sealed if desired. In the case of yttrium oxide and YAG, the difference is small. When aluminum nitride is used for the translucent airtight container, zirconium is preferably used for the current introduction conductor. Further, the current introduction conductor can be formed by joining a plurality of material portions.

  As a configuration aspect of the current introduction conductor, for example, the base end portion in the longitudinal direction may be a sealing metal portion or cermet selected from the above group, and the tip portion may be a halogen-resistant metal such as molybdenum. Further, the base end portion can be made of the sealing metal portion, the intermediate portion can be made of a cermet portion, and the tip portion can be made of a halogen-resistant metal. Note that, in the former mode, a part of the base end portion is surrounded by the ceramic of the sealing portion. Moreover, in the latter aspect, a part of the intermediate portion constitutes a portion to be sealed. Furthermore, if the planned sealing portion of the current introduction conductor is a cermet, the temperature rise of the ceramic is facilitated by the reason described later when the small diameter cylindrical portion and the ceramic sleeve are sealed by melting the ceramic. Easy to form.

  The cermet is a mixed sintered body of ceramics and metal. For example, the material component ceramics is alumina ceramics, and the metal is one or more kinds of metals selected from the above group, such as molybdenum or tungsten. be able to. The cermet of the portion to be sealed in the translucent ceramic discharge vessel 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. The content ratio of the metal component is allowed to be 5 to 60% by volume.

  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 heat absorption occurs in the translucent airtight container. Hateful. On the other hand, heat absorption increases on the surface of the cermet, and as a result, the surface of the cermet is heated and the temperature rises. .

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

  If the said cermet is taken from the following viewpoints different from the above, it is preferable that the content rate of a metal component is 50-80 volume%.

  That is, from the viewpoint of placing importance on the conductivity of the cermet, sufficient conductivity can be obtained if the content ratio of the metal component is within the above range. And if a cermet is the above structures, even if it is a cermet which has required electroconductivity, since the diameter can be made small, the sealing by this invention becomes still easier.

  However, if the content of the metal component exceeds 80% by volume, the coefficient of thermal expansion with the translucent airtight container becomes too large, making it difficult to obtain a desired seal. Further, when the content of the metal component is 50% by volume, it becomes difficult to obtain desired conductivity.

  Further, if desired, at least the cermet in the portion to be sealed is located, the first cermet having mainly good sealing properties is located on the outer peripheral side, and the second cermet having mainly good conductivity is located on the center side. A concentric inclined structure can also be used. In this case, the first and second cermets can be stepped or steplessly tilted.

  Furthermore, the current introduction conductor mainly has a function of a portion that is sealed to the small-diameter cylindrical portion of the translucent airtight container via a ceramic sleeve and a portion that mainly supports the electrode. Therefore, in order to optimize each part for each function, each part is formed using a different material or a different size and structure, and they are connected in the axial direction. To construct a current introduction conductor. For example, it is known in a structure in which a portion sealed mainly to a small-diameter cylindrical portion of a light-transmitting airtight container is a cermet and a portion mainly supporting an electrode is formed of a halogen-resistant metal such as molybdenum and sealed with frit glass. is there. Also in the present invention, specifications such as material, size and shape corresponding to the main function are varied, and the current introduction conductor is configured by connecting them in the axial direction. However, in the present invention, if desired, the current introduction conductor can be configured using a conductive member made of the same material throughout its entire length.

[Regarding the sealing step] The heating step performed to seal the light-transmitting hermetic container by fusing the small-diameter cylindrical portion, the ceramic sleeve, and the portion to be sealed of the current introduction conductor by melting ceramics is, for example, the following mode Can be done.
In order to seal the light-transmitting hermetic container, means for melting the ceramic and the ceramic sleeve of the small-diameter cylindrical portion are not particularly limited in the present invention. For example, if the ceramics of the small diameter cylindrical part and the ceramic sleeve are heated and the temperature is raised above the melting temperature, the ceramics melt and penetrate into the ceramic sleeve arranged in the small diameter cylindrical part. Can be fused to the current introduction conductor. Then, if heating is stopped and the familiar part is cooled, the ceramic solidifies and the current introduction conductor is sealed to the fused part, and as a result, the small diameter cylindrical part is sealed and the translucent airtight container is sealed. Stopped. As a means for heating the ceramic in the small diameter cylindrical portion, for example, a heat ray projection type local heating means such as a laser or a halogen bulb with a reflecting mirror, an induction heating means, an electric heater, or the like can be used. As the laser, can be used, for example a YAG laser, CO ₂ laser and the like.

  When heating the entire circumference of the sealing target portion of the small-diameter cylindrical portion using the local heating means of the heat ray projection type, the local heating means is fixed to a predetermined separation position with respect to the planned portion, for example, the side of the planned portion. If either one or both of the small-diameter cylindrical portion and the local heating means of the translucent airtight container are rotated while operating the local heating means, the entire circumference of the small-diameter cylindrical portion and the ceramic sleeve can be heated uniformly. it can. However, if desired, the laser is irradiated from the extending direction of the small-diameter cylindrical portion, for example, the tube axis direction, a plurality of local heating means are arranged around the small-diameter cylindrical portion fixedly arranged, or the local heating means is The translucent ceramic discharge vessel can be heated in a stationary state by rotating around the small-diameter cylindrical portion or by providing a heating means surrounding the entire circumference of the small-diameter cylindrical portion.

  Then, the sealing portion is formed by heating the portion to be sealed and mainly melting the ceramic of the small diameter cylindrical portion and fusing it to the current introduction conductor. In many cases, the sealing portion is a solid solution in which the components of the current introduction conductor are dissolved. A preferable sealing portion has an average crystal grain size of alumina on the outer surface thereof larger than an average crystal grain size of alumina on the outer surface of the non-sealing portion. In the case where the sealing part has the above-described form, crystal growth is performed in the whole or part of the melted part, and as a result, the crystal direction becomes random, so that heat resistance and mechanical strength are increased. For this reason, it becomes difficult to generate | occur | produce the breakage and leak by the heat shock by lamp lighting.

  Next, in order to manufacture a translucent ceramic discharge vessel, the surrounding portion may be formed by integrally molding, or may be formed by joining or fitting a plurality of constituent members. Good. For example, when an incidental structure such as a small-diameter cylindrical portion is provided in addition to the surrounding portion, the incidental structure can be integrally formed from the beginning at both ends or one end of the surrounding portion. However, it is also possible to form an integral translucent ceramic discharge vessel by, for example, pre-sintering the surrounding portion and the incidental structure separately from each other and then joining them as required to sinter the whole. Alternatively, the cylindrical portion and the end plate portion can be pre-sintered separately and then joined together to sinter the whole, thereby forming an integrated surrounding portion.

  [Regarding Electrode] The electrode is a means for causing discharge of a discharge medium, which will be described later, inside the translucent ceramic discharge vessel. 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 airtight container. In the present invention, at least one electrode is connected to the introduction conductor and sealed in the translucent airtight container.

  The electrode is connected to the current introduction conductor and supported at a predetermined position in the translucent airtight container. For example, the proximal end of the electrode is connected to the distal end portion located on the inner side of the translucent airtight 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 has 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 serves as a current introduction conductor. Connecting. 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. The present invention is particularly suitable when applied to a high-pressure discharge lamp, but can also be applied to a low-pressure discharge lamp. The “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 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.

  1. Luminescent metal halide + mercury + noble gas: a so-called mercury-containing metal halide lamp.

  2. Luminescent metal halide + halide as lamp voltage forming medium + rare gas: This is a so-called mercury-free metal halide lamp configuration that does not use mercury with a large environmental load.

  3. Mercury + noble gas: This is a so-called high-pressure mercury lamp configuration.

  4). Noble gas: When Xe is used as a noble gas, it is a so-called xenon lamp configuration.

  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.

  [Other Configurations of the Present Invention] Although not an essential component of the present invention, the function of a high-pressure discharge lamp can be added or the performance can be improved by including some or all of the following configurations as desired. To do.

  (1) (Outer tube) The high-pressure discharge lamp of the present invention can be configured to light up in a state where the translucent ceramic discharge vessel is exposed to the atmosphere. However, if necessary, the translucent ceramic discharge vessel can be accommodated in the outer tube. Note that the inside of the outer tube may be vacuum, gas-filled, or an atmosphere communicating with the atmosphere.

  (2) (Reflecting mirror) The high-pressure discharge lamp of the present invention can be integrated with a reflecting mirror.

    Next, in the present invention, when the discharge lamp is lit, the lighting circuit may have any configuration. Moreover, any lighting system of AC lighting and DC lighting may be used. In the case of AC lighting, for example, an electronic lighting circuit mainly composed of an inverter can be configured. If desired, a DC-DC converter circuit such as a step-up chopper or a step-down chopper can be added to a DC power source connected between the input terminals of the inverter. In the case of DC lighting, for example, an electronic lighting circuit mainly composed of the above-described DC-DC conversion circuit can be configured.

    In the present invention, when the discharge lamp is applied to a lighting device, the lighting device includes a lighting device body, the high-pressure discharge lamp of the present invention disposed in the lighting device body, and a lighting circuit for lighting the high-pressure discharge lamp. can do.

  The lighting device is a concept including all devices using a high-pressure discharge lamp as a light source. For example, various outdoor and indoor lighting fixtures, automobile headlamps, image or video projection devices, marker lamps, signal lights, indicator lights, chemical reaction devices, and inspection devices.

  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 present invention, the sealing portion of the light-transmitting hermetic container is formed of a ceramic having the same quality as the ceramic at the end of the small-diameter cylindrical portion, and the ceramic sleeve through which the current introduction conductor passes is formed in the small-diameter cylindrical portion. The small-diameter cylindrical portion, the ceramic sleeve, and the current introduction conductor are formed by fusing by melting ceramics, and at least exposed to the inside of the small-diameter cylindrical portion of the translucent airtight container. Since the rare earth metal oxide is contained in the ceramic portion of the sealing portion, free halogen generated from the metal halide sealed in the translucent airtight container and the sealing portion exposed inside the small diameter cylindrical portion Since the reaction with the ceramic portion is suppressed, it is possible to provide a discharge lamp in which the change in light color and the lifetime are improved until the end of the lifetime.

  Further, since the sealing portion is covered with the melted ceramic, the cermet or sealing metal portion on the proximal end side of the current introduction conductor is not exposed inside the translucent airtight container. The reaction of the adherent metal portion with the metal halide and free halogen is prevented, and as a result, the shortening of the life of the discharge lamp due to the deterioration of the current introduction conductor is suppressed.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  1 and 2 show a metal halide high-pressure discharge lamp as a first embodiment for carrying out the discharge lamp of the present invention, FIG. 1 is a sectional view of the whole lamp, and FIG. 2 is an explanatory view of a sealing process. It is.

  As shown in FIG. 1, the discharge lamp MHL of this embodiment includes a translucent airtight container 1, a current introduction conductor 2, an electrode 3, a ceramic sleeve 4 and a discharge medium, and has a sealing portion SP. The arc tube can be sealed at a predetermined position of the outer tube.

  As shown in FIG. 1 in this embodiment, the light-transmitting airtight container 1 is formed by integral molding with a light-transmitting polycrystalline alumina ceramic having an average crystal grain size of 30 μm or less on the outer surface as a main material. 1a and a pair of small diameter cylindrical portions 1b and 1b. The average crystal grain size of the ceramic can be easily recognized by enlarging the outer surface of the small-diameter cylindrical portion 1b with a discharger microscope, and the reference straight line is placed at an appropriate site on the outer surface of the translucent airtight container 1. The average value of the diameters of a large number of crystal grains intersecting with the reference line is set.

  The surrounding portion 1a is formed in a substantially spherical shape, and a discharge space 1c having the same shape is formed therein.

  The pair of small-diameter cylindrical portions 1b and 1b are each formed by a cylindrical portion that is shorter than the surrounding portion 1a and integrally formed from both ends of the surrounding portion 1a in the tube axis direction. A locking step 1b1 having a large diameter is formed on the inner peripheral surface of the opening end of the small diameter cylindrical portion 1b. A portion on the end side of the small-diameter cylindrical portion 1b is a portion to be sealed, and the ceramic is melted in cooperation with the ceramic sleeve 4 described later to form the sealing portion SP. The sealing process for forming the sealing part SP will be described later.

  The ceramic sleeve 4 is made of ceramics having an average crystal grain size of 30 μm or less, and a current introduction conductor 2 described later passes through the ceramic sleeve 4. The ceramic sleeve 4 is heated and melted while being inserted and locked into the formation step portion 1b1 of the small-diameter cylindrical portion 1b, and due to melting of the ceramic, the sealing portion of the small-diameter cylindrical portion 1b, the ceramic sleeve 4 and A sealing portion SP in which a current introducing conductor 2 described later is fused is formed at the end of the small diameter cylindrical portion 1b.

  Further, as shown in FIG. 2, the ceramic sleeve 4 is divided into two regions 4a and 4b along the axial direction thereof, but is joined and integrated. One region 4a is doped with rare earth metal oxide. The other region 4b is not added with a rare earth metal oxide.

  As shown in FIG. 2, the current introduction conductor 2 has a base end 2a exposed to the outside made of niobium and a tip end 2a inserted into the translucent ceramic hermetic vessel made of molybdenum 2b. Are joined to form a single bar. A pair of current introduction conductors 2, 2 are inserted into the respective small-diameter cylindrical portions 1 b of the translucent airtight container 1 via the ceramic sleeve 4.

  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 airtight container 1. The small-diameter cylindrical portion 1b is heated together with the ceramic sleeve 4 when the current introduction conductor 2 is sealed, and the first and second regions 2a and 2b of the current introduction conductor 2 are sufficiently melted. The sealing portion SP is formed by enclosing the joint surface and welding ceramics.

  The sealing portion SP is formed mainly by the ceramic sleeve 4. When the ceramic is melted, the sealing portion SP bulges outward from the surface of the small-diameter cylindrical portion 1 b while condensing in the axial direction due to surface tension, and is elliptically spherical. Although it tends to be deformed into teardrops, it has various shapes depending on processing factors such as heating time and temperature. And since the junction part of the 1st area | region 1b1 and 2nd area | region 1b2 of niobium is surrounded by the 2nd area | region 4b of the ceramic sleeve 4, it does not expose inside the translucent airtight container 1. FIG. Moreover, since the site | part exposed inside the translucent airtight container 1 of the sealing part SP is formed of the 1st area | region 4a of the ceramic sleeve 4, it contains rare earth metal oxide.

  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. 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 current introduction conductor 2 by welding. A slight gap g that is short in the tube axis direction, that is, a capillary, is formed 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. However, this capillary can be clearly shortened compared to that in a conventional high-pressure discharge lamp in which a translucent ceramic discharge vessel is sealed using frit glass.

  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.

  Next, the sealing process of the discharge lamp MDL will be described with reference to FIGS.

  First, in FIG. 2 (1), a current introduction conductor / electrode assembly in which the electrode 3 is connected to the tip of the current introduction conductor 2 is prepared, and then the ceramic sleeve 4 is placed in the direction of the arrow indicated by the dotted line. The electrode assembly MA is fitted. Then, the ceramic sleeve 4 is inserted until the joint surface between the proximal end side (cermet) and the distal end side (molybdenum) of the current introduction conductor 2 is located in the other region 4b of the ceramic sleeve 4, and FIG. The electrode mount DM shown in FIG.

  Next, in FIG. 2 (3), the translucent airtight container 1 prepared in advance is supported in the vertical position, and then the ceramic sleeve of the electrode mount EM is placed in the locking step portion 1b1 of the small-diameter cylindrical portion 1b located at the top. 4 is inserted and supported in the direction of the dotted arrow, and the sealing position is determined as shown in FIG.

  Finally, in FIG. 2 (5), for example, laser irradiation is performed from the direction of the thick solid arrow to heat the ceramic sleeve 4, the portion to be sealed (near the opening end) of the small diameter cylindrical portion 1b, and the current introduction conductor 2. As a result, the ceramics in the ceramic sleeve 4 and the portion to be sealed of the small-diameter cylindrical portion 1b are eventually melted, and the ceramic sleeve 4 and the portion to be sealed in the small-diameter cylindrical portion 1b (near the opening end) and the current introduction conductor 2 are hermetically sealed. The sealing portion SP is formed by fusing to the light-transmitting air-tight container 1, and the translucent airtight container 1 is sealed. If the lower small-diameter cylindrical portion (not shown) is sealed in advance, the discharge medium is transmitted through the opening end of the upper small-diameter cylindrical portion 1b before the upper sealing portion SP is formed. The sealed portion SP in which the ceramic sleeve 4 is mainly used can be formed as indicated by a dotted lead line while cooling the discharge medium with a refrigerant such as liquid nitrogen and being enclosed in the inside of the gastight container 1.

Example 1 is a high-pressure discharge lamp shown in FIG.
Translucent airtight container: Made of integrally molded translucent polycrystalline alumina ceramics,
Enclosed part: 6mm length in the tube axis direction, maximum inner diameter 5mm, spherical inner surface shape (no straight part),
Wall thickness 0.8mm
Small diameter cylindrical part: 0.7mm inside diameter, 0.5mm wall thickness, 6mm length,
Locking step inner diameter of open end 1.25mm
Depth 3mm
Ceramic sleeve: Alumina ceramics with alumina particle diameter 10μm, outer diameter 1.2mm,
0.7mm ID, 4mm length
One region: 25% La oxide added
The other area; rare earth metal oxide not added Current introduction conductor: Ni rod, diameter 0.65mm
Electrode: W bar, diameter 0.65mm, distance between electrodes 3mm
Discharge medium: DyI ₃ -NdI ₃ -CsI = 3mg, Xe1Mpa

The sealing part of the translucent airtight container was good without generation of cracks.

[Comparative Example 1]
Translucent airtight container: Made of integrally molded translucent polycrystalline alumina ceramics,
Enclosed part: 6mm length in the tube axis direction, maximum inner diameter 5mm, spherical inner surface shape (no straight part),
Wall thickness 0.8mm
Small-diameter cylindrical part: 0.7mm ID, 0.5mm wall thickness, 12mm length
Discharge medium: DyI ₃ -NdI ₃ -CsI = 3mg, Xe0.3Mpa
Sealant: Al ₂ O ₃ —SiO ₂ frit glass

  The other specifications are the same as those in the first embodiment.

Cracks occurred in the sealed portion of the translucent airtight container.

    FIG. 3 is an explanatory view of an airtight container sealing step showing a second embodiment for carrying out the discharge lamp of the present invention.

  In this embodiment, the entire ceramic sleeve 4 contains a rare earth metal oxide, and is supported by being joined to the opening end of the small diameter cylindrical portion 1b prior to the formation of the sealing portion SP. In order to support the ceramic sleeve 4 on the small diameter cylindrical portion 1b, for example, the translucent airtight container 1 can be formed separately from the ceramic sleeve 4 and then joined to the open end of the small diameter cylindrical portion 1b.

  Further, the rare earth metal oxide is added in advance to the ceramic of the portion forming the open end of the small diameter cylindrical portion 1b and sintered to form the light-transmitting hermetic container 1, whereby the ceramic sleeve 4 has a small diameter. The structure which joined in the state which the cylinder part 1b and the ceramic sleeve 4 integrated is sufficient.

Next, the sealing process in a 2nd form is demonstrated with reference to FIG. 3 (1)-(4).
First, in FIG. 3A, the current introduction conductor 2 and the electrode 3 are joined to form the electrode mount EM.

  In FIG. 3B, a translucent airtight container 1 is prepared in which a ceramic sleeve 4 containing a rare earth metal oxide as a whole is joined to the open end of the small-diameter cylindrical portion 1b.

  Next, in FIG. 3 (3), the electrode mount EM is inserted into the ceramic sleeve 4 and the small diameter cylindrical portion 1 b joined to the tip of the small diameter cylindrical portion 1 b of the translucent airtight container 1. The joint portion between the end side 2a and the front end side 2b is placed at a position located inside the ceramic sleeve 4.

  Finally, when the ceramic sleeve 4 and the opening end of the small diameter cylindrical portion 1b and the current introduction conductor 2 are heated to melt the ceramic in the ceramic sleeve 4 and the small diameter cylindrical portion 1b, the opening end of the ceramic sleeve 4 and the small diameter cylindrical portion 1b and Since the current introduction conductor 2 is hermetically fused with the melted ceramics to form the sealing portion SP mainly composed of the ceramic sleeve 4 as indicated by a dotted lead line, the translucent airtight container 1 is sealed. Stopped.

Translucent airtight container: Made of integrally molded translucent polycrystalline alumina ceramics,
Enclosed part: 6mm length in the tube axis direction, maximum inner diameter 5mm, spherical inner surface shape (no straight part),
Wall thickness 0.8mm
Small diameter cylindrical part: 0.7mm inside diameter, 0.5mm wall thickness, 6mm length
Ceramic sleeve: Alumina ceramic with alumina particle size of 10μm, La oxide 25% by volume,
Inner diameter 0.7mm, wall thickness 0.5mm, length 2.5mm, integrated with open end of small diameter cylinder

    The other specifications are the same as those in the first embodiment.

The sealing part of the translucent airtight container was good without generation of cracks.

Sectional drawing of the whole lamp | ramp which shows the metal halide type high pressure discharge lamp as 1st form for implementing the discharge lamp of this invention Similarly explanatory drawing of sealing process Explanatory drawing of the sealing process of the airtight container which shows the 2nd form for implementing the discharge lamp of this invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Translucent airtight container, 1a ... Enclosing part, 1b ... Small diameter cylindrical part, 1b1 ... Locking step part, 2 ... Current introduction conductor, 2a ... Base end side, 2b ... Tip side, 3 ... Electrode, 4 ... Ceramic Sleeve, 4a ... 1st area | region, 4b ... 2nd area | region, SP ... Sealing part

Claims (4)

A light-transmitting air-tightness comprising an enclosure portion in which a discharge space is formed and a small-diameter cylindrical portion formed mainly of ceramics that communicates with the inside of the enclosure portion, and a sealing portion is formed at the end of the small-diameter cylindrical portion A container;
A current introduction conductor introduced air-tightly through the sealing portion of the translucent air-tight container;
An electrode disposed at the tip of the current introduction conductor and facing the discharge space of the translucent airtight container;
A discharge medium enclosed within the enclosure of the translucent airtight container;
Comprising
The sealing portion of the light-transmitting hermetic container is formed of a ceramic sleeve that is substantially the same quality as the ceramic at the end of the small-diameter cylindrical portion, and a ceramic sleeve through which a current introduction conductor penetrates is formed at the end of the small-diameter cylindrical portion And is formed by fusing the ceramic sleeve, the end of the small-diameter cylindrical portion of the translucent airtight container, and the current introduction conductor, and at least inside the small-diameter cylindrical portion of the translucent airtight container The exposed sites contain rare earth metal oxides;
A discharge lamp characterized by that.   The discharge lamp according to claim 1, wherein the ceramic sleeve is formed using a ceramic containing a rare earth metal oxide.   The ceramic sleeve has a portion located on the electrode side made of a ceramic containing a rare earth metal oxide, a portion located on the side opposite to the electrode made of a ceramic containing no rare earth metal oxide, and a translucent airtight container The discharge lamp according to claim 1, wherein the discharge lamp is fused to an end of the small-diameter cylindrical portion. The translucent airtight container has an opening in which an end portion of the small-diameter cylindrical portion has a locking step formed on the inner surface;
The ceramic sleeve forms a sealing portion in a state of being locked to the locking step at the end of the small-diameter cylindrical portion;
The discharge lamp according to any one of claims 1 to 3, characterized in that:

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