JP2008108714A - High-pressure discharge lamp, high-pressure discharge lamp lighting device, and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-pressure discharge lamp sealed by fusion of ceramic with high reliability and stability by regulating thermal physical characteristics of ceramic and a current introducing conductor in an intended seal part within a prescribed range, a high-pressure discharge lamp lighting device, and a lighting system. <P>SOLUTION: This high-pressure discharge lamp MHL is equipped with a translucent ceramic discharge vessel 1 having an enclosing part 1a and a small diameter tube part 1b, the current introducing conductor 3 inserted into the inside of the small diameter tube part of the translucent ceramic discharge vessel and sealed to the small diameter tube part mainly by fusion of the ceramic in the small diameter tube part of the translucent ceramic discharge vessel, an electrode 2 sealed and mounted in the translucent discharge vessel by connecting it to the current introducing conductor, and a discharge medium. The difference of thermal conductivity of both members of the ceramic of the small diameter tube part of the translucent ceramic discharge vessel and the current introducing conductor which forms the sealed pat is within 75 W/m*K. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high-pressure discharge lamp including a translucent ceramics discharge vessel, a high-pressure discharge lamp lighting device using the same, and an illumination device.

  In a high-pressure discharge lamp equipped with a conventional translucent ceramic discharge vessel, various modes have been proposed or attempted in order to seal the discharge vessel 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.

  However, the structure that can be sealed with relatively high reliability and stability is a sealing structure in which a portion to be sealed of the translucent ceramic discharge vessel is heated and melted and welded to the current introduction conductor. I understood.

  Therefore, as a result of further research on a sealing structure in which a portion to be sealed of a translucent ceramic discharge vessel is heated and melted and welded to a current introduction conductor, the present inventor has further ensured high reliability and stability. In order to seal, it was found that the thermal physical properties such as the thermal conductivity and the linear expansion coefficient of the translucent ceramic discharge vessel and the current introduction conductor must be within a certain range.

That is, since a member having high thermal conductivity is usually a current introduction conductor, when the portion to be sealed is heated by YAG laser irradiation, the current introduction conductor absorbs heat. If the thermal conductivity of the current introduction conductor is too high, the heat of the absorbing portion is transmitted to the ceramic side of the translucent ceramic discharge vessel having a low thermal conductivity, and in the direction of the non-sealed portion in the axial direction of the current introduction conductor. Increases the flow rate. Therefore, the heat is dispersed, and it becomes difficult to heat and melt the pinpoint of only the ceramic of the portion to be sealed. In addition, when heated by CO ₂ laser irradiation, the heat around the portion to be sealed heated by the irradiation diffuses through the current introduction conductor. For this reason, since the temperature of the current introduction conductor in the part to be sealed is unlikely to rise until the ceramics becomes familiar, a desired seal may not be obtained.

  On the other hand, a member with a high coefficient of linear expansion is usually a current introduction conductor, so if the part to be sealed is heated by YAG laser irradiation, it melts between the ceramic side of the translucent ceramic discharge vessel with a low coefficient of linear expansion. Excessive stress is generated due to, and cracks are generated at the time of sealing, which tends to cause poor sealing. Moreover, even if it does not crack at this time, the stress by the difference in thermal expansion coefficient of each member remains, and there is a possibility that cracking may occur due to the subsequent heat treatment or lighting of the high-pressure discharge lamp.

  The present invention relates to a sealing structure in which a portion to be sealed of a translucent ceramic discharge vessel is heated and melted and welded to a current introduction conductor, and the thermal physical characteristics of the ceramic and the current introduction conductor in the portion to be sealed are predetermined. An object of the present invention is to provide a high-pressure discharge lamp, a high-pressure discharge lamp lighting device, and a lighting device that are specified within the range and sealed with high reliability and stability.

    A high-pressure discharge lamp according to a first aspect of the present invention is a translucent ceramics discharge vessel provided with an enclosing part and a small-diameter cylindrical part connected to the enclosing part; and inserted into the small-diameter cylindrical part of the translucent ceramics discharge container A current introduction conductor sealed in the small diameter cylindrical portion mainly by fusion of ceramics in the small diameter cylindrical portion of the translucent ceramic discharge vessel; and connected to the current introduction conductor and sealed in the translucent ceramic discharge vessel And a discharge medium sealed in the translucent ceramic discharge vessel, both members forming a sealing portion of the ceramic and the current introduction conductor of the small-diameter cylindrical portion of the translucent ceramic discharge vessel The difference in thermal conductivity is within 75 W / m · K.

  The present invention includes the following aspects.

  [Translucent Ceramic Discharge Vessel] The translucent ceramic discharge vessel is composed of a single crystal metal oxide such as sapphire and a polycrystalline metal oxide such as translucent airtight aluminum oxide, ie translucent polycrystalline alumina ceramics. , Yttrium-aluminum-garnet (YAG), yttrium oxide (YOX) and polycrystalline non-oxide, such as aluminum nitride (AlN), a light-transmitting and heat-resistant ceramic material, and discharge inside This is a container in which the space is formed airtight with respect to the outside. 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.

  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.

  In addition, the commonly used translucent polycrystalline alumina ceramics has an average crystal grain size of several tens of μm, but in the present invention, at least the small-diameter cylindrical part or its sealing part, A crystal having an average crystal grain size of 4 μm or less in the non-sealing part approaching the sealing part is suitable. That is, when the average crystal grain size of the above portion is 4 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. In the present invention, it is particularly excellent. Furthermore, when the average crystal grain size is 0.5 μm or less, cracks are not generated at all by joining, which is optimal.

  In the embodiment in which the crystal average particle size of at least the small diameter cylindrical portion of the translucent ceramic discharge vessel is 4 μm or less, the portion where the crystal average particle size is 4 μm or less may be only the small diameter cylindrical portion. The entire translucent ceramics discharge vessel may be used. Further, if desired, the average crystal grain size may be 4 μm or less in some parts other than the small diameter cylindrical part.

  The translucency in the translucent ceramic discharge vessel 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. Also 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 ceramics discharge vessel is provided with an enclosing portion in order 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. 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.

  Moreover, the translucent ceramics discharge container is provided with the small diameter cylinder part connected to the surrounding part. The small diameter cylindrical portion functions to seal the translucent ceramic discharge vessel by inserting at least a current introducing conductor, which will be described later, 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 ceramics discharge container, ie, an enclosure part.

  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 openings are provided to seal a pair of electrodes, each small-diameter cylindrical portion is provided at a position spaced apart from each other, but preferably is spaced apart from each other along the tube axis. 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 only necessary to have a length at which it is easy to form a sealing portion with at least the current introduction conductor by melting the ceramic of the small diameter cylindrical portion. 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 order to seal the translucent ceramic discharge vessel, the means for melting the ceramic of the small diameter cylindrical portion is not particularly limited in the present invention. For example, if the ceramic in the small-diameter cylindrical portion is heated and the temperature is raised above its melting temperature, the ceramic can be melted and adapted to the surface of the current introduction conductor inserted in the small-diameter cylindrical portion. Then, if heating is stopped and the familiar part is cooled, the ceramic is solidified, the current introduction conductor is sealed in the opening, and the small diameter cylindrical part is sealed. 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. Then, if one or both of the small-diameter cylindrical portion and the local heating means of the translucent ceramic discharge vessel are rotated while operating the local heating means, the entire circumference of the small-diameter cylindrical portion can be uniformly heated. 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.

  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.

  [About the current introduction conductor] The current introduction conductor is a conductor that supports an electrode described later, applies a voltage to the electrode, supplies current to the electrode, and functions to seal the translucent ceramic discharge vessel. is there. For this purpose, the distal end portion inserted into the small diameter cylindrical portion of the translucent ceramic discharge vessel supports the electrode, and the proximal end side seals in cooperation with the small diameter cylindrical portion of the translucent ceramic discharge vessel. And a part thereof is exposed to the outside from the sealing. The term “exposed to the outside of the translucent ceramic discharge vessel” means that it may or may not protrude from the translucent ceramic discharge vessel. You just have to face. The portion that supports the electrode can be formed using a halogen-resistant metal such as molybdenum or tungsten.

  Further, the current introduction conductor has a sealed portion made of a sealing metal or cermet, and a thermal conductivity difference with the ceramic of the translucent ceramic discharge vessel of the portion is 75 W / m · K or less, preferably It is necessary to select so as to be 58 W / m · K or less. When the difference in thermal conductivity is 75 W / m · K or less, the minimum heating diameter can be made sufficiently small, and the temperature difference between the ceramic and the current introduction conductor is small, so that sealing can be performed even if the melted part size is small. The part can be made small. When the sealing portion is small, the generation of cracks is reduced and good sealing can be obtained.

  On the other hand, in the range where the thermal conductivity difference exceeds 75 W / m · K, since the thermal conductivity of the current introduction conductor is generally relatively large, heat during heating is transmitted through the current introduction conductor. The rate of running away increases. For this reason, the heating range is expanded around the portion to be sealed, and therefore, the temperature rise of the portion to be sealed is delayed, and the temperature rise of the portion to be sealed of the current introduction conductor is also deteriorated. As a result, the temperature difference between the ceramic of the portion to be sealed and the portion of the current introduction conductor facing the ceramic becomes large, so that it becomes difficult for the ceramic to become familiar with the current introduction conductor. Therefore, a desired seal cannot be obtained.

  In addition, if the thermal conductivity difference is 58 W / m · K or less, it becomes easier to locally heat the part to be sealed more pinpointly, the temperature difference between the ceramic and the current introduction conductor is further reduced, and the ceramic It is suitable for directly sealing the current introduction conductor.

  Furthermore, if the thermal conductivity difference is 5 or more, desired high conductivity can be obtained.

  For the above reasons, the thermal conductivity difference is preferably 5 to 75, and more preferably 5 to 58.

  When the translucent ceramic discharge vessel is translucent alumina ceramic, the thermal conductivity is 34 W / mK. Therefore, the current introduction conductor has a thermal conductivity larger than the thermal conductivity of the ceramic and has a sealing property. When a metal that is a conductive metal and has a small difference in linear expansion coefficient and is less oxidizable, a single metal that satisfies this condition is not readily available. On the other hand, cermet is a mixed sintered body of ceramics and metal, and a desired linear expansion coefficient can be obtained within a wide range depending on the blending ratio thereof. For example, in the case of a 50:50 volume ratio cermet of alumina ceramics and molybdenum, it is about 78 to 98 W / m · K.

  Therefore, a cermet is suitable as a member in at least the part to be sealed of the current introduction conductor. Further, even when a known sealing metal such as molybdenum (Mo) or tungsten (W) is used as the current introduction conductor, a composite structure using cermet for at least a part of the planned sealing portion Is preferred. The cermet in this case can adopt a stepped structure in the axial direction of the current introduction conductor, a stepped structure around the axis, or a stepless inclined structure around the axis or around the axis. As a step-up structure around the shaft, for example, a two-step connection structure in which a highly conductive cermet is located in the center and a non-conductive cermet is located in the outer peripheral portion, or an intermediate conductive property in the middle. A multi-stage joint structure with cermets interposed can be employed. Also, in the stepless inclined structure around the axis, the conductivity changes in the same manner as in the above-described stepped structure, but the change can be made stepless.

  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 portion 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. Including, the content ratio of the metal component is allowed to be 5 to 60 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 the translucent ceramic discharge vessel generally does not absorb heat. Hard to occur. On the other hand, heat absorption increases on the cermet surface, and as a result, the surface of the cermet is heated and the temperature rises. To do.

  Further, if the content of the metal component is 60% by mass or less, there is no great difference in the coefficient of thermal expansion of the translucent ceramic discharge vessel, compared with the case where the translucent ceramic discharge vessel is in direct contact with molybdenum, Damage and leakage due to heat shock when the high-pressure discharge 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 mass%.

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 a structure as mentioned above, even if it is a cermet which has required electroconductivity, since the diameter can be made small, sealing becomes still easier.

  However, if the content of the metal component exceeds 80% by mass, the difference in coefficient of thermal expansion with the translucent ceramic discharge vessel becomes too large, so that a crack is generated in the sealing portion and a desired sealing is obtained. Becomes difficult. Moreover, when content of a metal component will be less than 50 mass%, it will become a little difficult to obtain desired electroconductivity.

  Furthermore, the current introduction conductor mainly has a function of a portion that is sealed to the small-diameter cylindrical portion of the translucent ceramic discharge vessel 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, formed in a different size or structure, and connected to form a current introduction conductor. I can do it. For example, it is known that a portion sealed mainly to a small-diameter cylindrical portion of a translucent ceramic discharge vessel is a cermet, and a portion mainly supporting an electrode is formed of a halogen-resistant metal. Also in the present invention, it is permitted to configure the current introduction conductor by connecting the materials in the tube axis direction with different specifications such as the material, the size and the shape such as the diameter according to the main function.

  Other aspects different from the above are as follows. That is, the portion sealed mainly to the small-diameter cylindrical portion of the translucent ceramic discharge vessel can be constituted by a serially joined body of niobium and cermet. In this case, the sealing portion formed by the ceramic welding is formed across the niobium and cermet regions. According to this aspect, niobium is not inadvertently exposed inside the small diameter cylindrical portion. In addition, when forming a cermet part on a part of the current introduction conductor, a part mainly supporting an electrode made of a halogen-resistant metal such as molybdenum is extended to the base end side of the current introduction conductor, and the extension part is a core material. The cermet portion can be formed around the core material. However, in the present invention, a conductive member made of the same material can be used over almost the entire length of the current introduction conductor if desired.

  [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 an arc discharge is generated between the electrodes inside the translucent ceramic discharge vessel. In the present invention, at least one electrode is connected to the introduction conductor and sealed in the translucent ceramic discharge vessel.

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

A high pressure discharge lamp according to a second aspect of the present invention is a translucent ceramics discharge vessel provided with an enclosing part and a small diameter cylindrical part connected to the enclosing part; and inserted into the small diameter cylindrical part of the translucent ceramics discharge container A current introduction conductor sealed in the small diameter cylindrical portion mainly by fusion of ceramics in the small diameter cylindrical portion of the translucent ceramic discharge vessel; and connected to the current introduction conductor and sealed in the translucent ceramic discharge vessel And a discharge medium sealed in the translucent ceramic discharge vessel, both members forming a sealing portion of the ceramic and the current introduction conductor of the small-diameter cylindrical portion of the translucent ceramic discharge vessel The difference in the linear expansion coefficient is 4 × 10 ⁻⁶ / K or less.

In the present invention, the difference in linear expansion coefficient between the ceramic and the current introduction conductor in the sealing portion is within 4 × 10 ⁻⁶ / K. If the linear expansion coefficient difference is within 4 × 10 ⁻⁶ / K, the stress at the time of sealing is reduced and the occurrence of cracks is significantly reduced. A difference in linear expansion coefficient within 1.87 × 10 ⁻⁶ / K is preferable because cracks are further reduced. Moreover, if the linear expansion coefficient difference is 0.6 × 10 ⁻⁶ / K or more, the conductivity of the current introduction conductor is high. Therefore, the difference in linear expansion coefficient between ^{0.6 × 10 -6 / K~4 × 10} -6 / K is the preferred range.

On the other hand, if the linear expansion coefficient difference exceeds 4 × 10 ⁻⁶ / K, excessive stress is generated due to sealing, and as a result, cracks may occur during sealing or subsequent heat treatment and lamp lighting. There is.

  In the present invention, as to other configurations, the configurations described in regard to the first invention can be appropriately adopted as desired.

A high-pressure discharge lamp according to a third aspect of the present invention is a translucent ceramics discharge vessel provided with an enclosing part and a small-diameter cylindrical part connected to the enclosing part; and inserted into the small-diameter cylindrical part of the translucent ceramics discharge container A current introduction conductor sealed in the small diameter cylindrical portion mainly by fusion of ceramics in the small diameter cylindrical portion of the translucent ceramic discharge vessel; and connected to the current introduction conductor and sealed in the translucent ceramic discharge vessel And a discharge medium sealed in the translucent ceramic discharge vessel, both members forming a sealing portion of the ceramic and the current introduction conductor of the small-diameter cylindrical portion of the translucent ceramic discharge vessel The difference in thermal conductivity between the two members is 75 W / m · K or less, and the difference in linear expansion coefficient between both members is 4 × 10 ⁻⁶ / K or less.

  The present invention has both the characteristic configurations of the first and second inventions. Therefore, it is allowed to appropriately adopt the configuration described with respect to the first and second inventions described above as desired.

    Next, a high pressure discharge lamp lighting device according to the present invention includes the high pressure discharge lamp according to the present invention; and a lighting circuit for lighting the high pressure discharge lamp.

  In the present invention, 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.

    The illuminating device of the present invention is characterized by comprising: 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.

  In the present invention, the illumination 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 and second inventions, in the sealing structure in which the sealing portion of the translucent ceramic discharge vessel is heated and melted and welded to the current introduction conductor, the ceramic and the current introduction conductor in the sealing portion are sealed. By defining the thermal physical characteristics within a predetermined range, it is possible to provide a high-pressure discharge lamp, a high-pressure discharge lamp lighting device, and a lighting device that are sealed with high reliability and stability.

  In addition, according to the first invention, the difference in thermal conductivity between the ceramics in the small-diameter cylindrical portion and the current introduction conductor in the sealing portion is regulated to within 75 W / m · K, so that the ceramic in the planned sealing portion is heated and melted. Thus, it is possible to obtain a reliable seal that is welded to the current introduction conductor.

Furthermore, according to the second invention, the stress at the time of sealing is reduced by defining the difference in linear expansion coefficient between the ceramic of the small-diameter cylindrical portion and the current introduction conductor in the sealing portion within 4 × 10 ⁻⁶ / K. Thus, crack generation is effectively suppressed.
Furthermore, according to the third invention, both the effects of the first and second inventions are obtained.

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

    1 and 2 show a metal halide lamp for an automobile headlamp as a first embodiment for implementing a high-pressure discharge lamp according to the present invention, FIG. 1 is a front view of the entire lamp, and FIG. 2 is an enlarged view of an arc tube. It is sectional drawing. The metal halide lamp MHL for automobile headlamps is mainly composed of a luminous tube IT, lead wires L1 and L2, an insulating tube T, an outer tube OT, and a base B.

  The arc tube IT includes a translucent ceramic discharge vessel 1, a current introduction conductor 2, an electrode 3, and a discharge medium.

  As shown in FIG. 2, the translucent ceramic discharge vessel 1 is formed by integral molding using translucent ceramic as a main material, and includes an enclosing portion 1a and a pair of small-diameter cylindrical portions 1b and 1b. The surrounding portion 1a is formed into a hollow spindle shape having a substantially constant thickness, and a discharge space 1c having the same shape is formed therein. The internal volume of the discharge space 1c is about 0.05 cc or less. The pair of small-diameter cylindrical portions 1b and 1b are formed by relatively short and thin cylindrical portions that are integrally extended from both ends of the surrounding portion 1a in the tube axis direction.

  In the current introduction conductor 2, a portion 2a to be sealed is made of a sealing member such as a cermet or a niobium rod, and a portion 2b supporting an electrode 3 to be described later is made of a halogen resistant metal such as molybdenum. Then, the sealing portion SP is inserted by being inserted into each small-diameter cylindrical portion 1b of the translucent ceramic discharge vessel 1 and at least the ceramic of the small-diameter cylindrical portion 1b is fused to the portion 2a to which the current introduction conductor 2 is sealed. Sealed.

  Accordingly, 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 discharge vessel 1. In addition, although the ceramic in the planned sealing portion of the small diameter cylindrical portion 1b is heated and sufficiently melted when the current introduction conductor 2 is sealed, the ceramic is condensed in the axial direction due to surface tension. While bulging in the radial direction and deforming into an oval or teardrop shape, it is fused to the sealed portion 2a of the current introduction conductor 2 and solidified to form the sealed portion SP. The translucent ceramic discharge vessel 1 is hermetically sealed by the sealing portion SP.

  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 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.

  The lead wires L1 and L2 are connected to the base ends of the current introduction conductors 2 and 2 by welding to support the arc tube IT. The lead wire L1 extends along the tube axis, is led out into a base B which will be described later, and is connected to the other base terminal having a pin shape disposed in the center (not shown). The lead wire L2 is folded back along an outer tube OT described later, introduced into the base B, and connected to one base terminal t1 having a ring shape disposed on the outer peripheral surface of the base B. .

  The insulating tube T is made of a ceramic tube and covers the lead wire L2.

  The outer tube OT has an ultraviolet ray cutting performance, accommodates the arc tube IT therein, and the diameter-reduced portions 4 at both ends (only one end on the right side is shown in the figure) are connected to the lead wire L2. Glass welded. However, the inside of the outer tube OT is not airtight but communicates with the outside air.

  The base B is standardized for automotive headlamps. It supports the arc tube IT and the outer tube OT planted along the central axis, and is attached to and detached from the back of the vehicle headlamp. Installed as possible. In addition, one cap terminal t1 having a ring shape disposed on the outer peripheral surface of the cylindrical portion so that it can be connected to the lamp socket on the power source side when mounted, and a concave portion with one end open formed inside the cylindrical portion In the inside, it is configured to include the other base terminal having a pin shape disposed so as to protrude in the axial direction at the center.

It is the structure shown in FIG. The current-introducing conductor 2 has a cermet at a portion 2a to be sealed, and the cermet has a volume ratio of alumina and molybdenum of 50:50 and a thermal conductivity of about 78 to 98 W / m · K. The translucent ceramic discharge vessel 1 is made of translucent polycrystalline alumina ceramics and has a thermal expansion coefficient of 34 W / m · K. Therefore, in Example 1, the thermal conductivity difference was 44 to 64 W / m · K.

It is the structure shown in FIG. In the current introduction conductor 2, the portion 2a to be sealed is a cermet, and the cermet has a volume ratio of alumina and molybdenum of 40:60, and a linear expansion coefficient of about 6.8 × 10 ^{−6 /} K to 7.4. × 10 ⁻⁶ / K. The translucent ceramic discharge vessel 1 is made of translucent polycrystalline alumina ceramics and has a linear expansion coefficient of 8 × 10 ⁻⁶ / K. Accordingly, in the second embodiment, the linear expansion coefficient difference was ^{0.6 × 10 -6 /K~1.2×10 -6 / K} .

It is the structure shown in FIG. In the current introduction conductor 2, the portion 2a to be sealed is a niobium rod, and the linear expansion coefficient is 7.2 × 10 ⁻⁶ / K. The translucent ceramics discharge vessel 1 is the same as that of Example 2. Therefore, in Example 3, the linear expansion coefficient difference was 0.8 × 10 ⁻⁶ / K.

    FIG. 3A is an enlarged cross-sectional view of a portion near the enveloping portion side of the sealing portion in the second embodiment for implementing the high-pressure discharge lamp of the present invention, and FIG. 3B is a current introduction conductor in the same cross section. It is an expanded sectional view. In the figure, the same parts as those in FIG. In this embodiment, a cermet 2a1 in which a portion 2a to be sealed to the small-diameter cylindrical portion 1b of the current introduction conductor 2 facing the closest portion of the sealing portion SP on the side of the enveloping portion 1a has a step-gradient structure around the axis and serially joined thereto The niobium rod (not shown) and the molybdenum rod (not shown) for supporting the electrode 3 are formed. The current introducing conductor 2 is connected in series from the base end in the order of a niobium rod, a cermet 2a1, and a molybdenum rod.

  That is, the portion 2a to be sealed has a three-layer structure in which the cermet 2a1 is formed of three layers l1, l2, and l3 stacked around the axis, and a core material 2a3 made of a molybdenum rod is inserted in the center thereof. is doing. The cermet 2a1 is a first cermet in which the layer l1 in contact with the outer surface of the core material 2a2 has a thickness of 0.1 mm, the Mo content is 80% by mass, and the layer l2 that overlaps the layer l1 has a thickness of 0.1 mm. 2, the Mo content is 40 mass%, the layer l3 overlapping the layer l2 is a third cermet having a thickness of 0.1 mm, and the Mo content is 15 mass%. The core material 2a2 comprises a molybdenum rod, which is a halogen-resistant metal that supports the electrode 3, constitutes the base end of the current introduction conductor 2, and extends to a niobium rod that forms part of the sealed portion 2a, and The niobium rod is joined in series to the tip by welding.

  Therefore, in this embodiment, the portion 2a to which the current introduction conductor 2 is sealed becomes the niobium rod and the cermet 2a1. Then, the ceramic of the small-diameter cylindrical portion 1b is heated and melted and welded over both the niobium rod and the cermet 2a1 to form the sealing portion SP.

It is the structure shown in FIG. In the current introduction conductor 2, the linear expansion coefficient of the niobium rod 2a1 of the portion 2a to be sealed is 7.2 × 10 ⁻⁶ / K, and the linear expansion coefficient of the layer 13 of the cermet 2a2 is 7.4 × 10 ⁻⁶ / K. It is -7.8 * 10 < ^-6 > / K. The translucent ceramics discharge vessel 1 is the same as that of Example 1. Therefore, in Example 4, the difference in linear expansion coefficient between the niobium rod 2a1 is 0.8 × 10 ⁻⁶ / K, and the difference with the layer 13 of the cermet 2a2 is 0.2 × 10 ⁻⁶ / K˜0. It was 6 × 10 ⁻⁶ / K.

    FIG. 4 shows the difference in thermal conductivity between the two members in the small-diameter cylindrical portion and the sealed portion of the current introduction conductor, the minimum heatable diameter, the temperature difference of the current introduction conductor portion facing the ceramic melting portion, and the resistance value of the current introduction conductor. It is a graph which shows the relationship. In the figure, the horizontal axis represents the thermal conductivity difference (W / m · K), the vertical axis represents the minimum diameter that can be heated on the left side, and the relative value of the minimum diameter that can be heated (curve with the measurement point is ◆) and The temperature difference of the sealed part conductor with respect to the molten part alumina, which means the temperature difference between the current-introducing conductor part facing the ceramic melting part (curve with the measurement point ■), and the right-side means the resistance value of the current-introducing conductor Resistivity relative values of the conductors (curves whose measurement points are Δ) are shown respectively.

  As can be seen from the figure, if the difference in thermal conductivity is within 75 W / m · K, the minimum diameter of the heating part that can be heated to such an extent that it can be sealed is small, so that the sealing part can be minimized. By reducing the temperature difference between the ceramics to be sealed and the current-introducing conductor, both become easy to become familiar with. In addition, a reasonably good range of the conductivity of the current introduction conductor can be obtained.

FIG. 5 is a graph showing the relationship between the difference in linear expansion coefficient between the two members in the small-diameter cylindrical portion and the sealed portion of the current introduction conductor, the crack generation rate associated with the sealing, and the resistance value of the current introduction conductor. In the figure, the horizontal axis indicates the difference in linear expansion coefficient (× 10 ⁻⁶ / K), and the vertical axis indicates the crack generation rate associated with sealing, with the crack generation rate within 100 h (%) (measurement point) Indicates the relative resistance value of the conductor (curve whose measurement point is ■), and the right side indicates the resistance value of the current introduction conductor.

As can be seen from the figure, if the difference in linear expansion coefficient is within 4 × 10 ⁻⁶ / K, the crack generation rate within 100 hours of lighting from the time of sealing is significantly reduced.

    FIG. 6 is a block circuit diagram showing an embodiment of the high pressure discharge lamp lighting device of the present invention. The high pressure discharge lamp lighting device of the present invention includes the first or second high pressure discharge lamp and a lighting circuit for lighting the high pressure discharge lamp. In this embodiment, the lighting circuit employs a low-frequency AC lighting circuit system.

  In this embodiment, the lighting circuit is digitized and includes a DC power source DC, a boost chopper BUT, a full bridge inverter FBI, and an igniter IG, and lights a metal halide lamp MHL for an automobile headlamp.

  The DC power source DC is composed of, for example, a car battery.

  The input terminal of the boost chopper BUT is connected to the DC power source DC.

  The full bridge type inverter FBI has its input terminal connected to the output terminal of the boost chopper BUT.

  The igniter IG receives a low-frequency AC output from the full-bridge inverter FBI, generates a high-voltage start pulse, and applies it between a pair of electrodes of a metal halide lamp MHL for an automobile headlamp described later at the start.

  The metal halide lamp MHL for automobile headlamps has the configuration shown in FIG. 1, FIG. 2 or FIG. 3, and is connected between the output terminals of the full bridge type inverter FBI and is lit at a low frequency AC.

    FIG. 7 is a conceptual side view showing an automobile headlamp as an embodiment of the illumination device of the present invention. In the figure, 11 is a headlamp body, 12 is a high pressure discharge lamp lighting device, and 13 is a metal halide lamp for automobile headlamps.

  The headlamp body 11 has a container shape, and includes a reflecting mirror 11a inside, a lens 11b on the front surface, and a lamp socket not shown.

  The high-pressure discharge lamp lighting device 12 has a circuit configuration shown in FIG. 6 and includes a main lighting circuit 12A and a starter 12B. The main lighting circuit 12A includes the boost chopper BUT and the full bridge inverter FBI of FIG. 6 as main components. Similarly, the starter 12B includes an igniter IG as a main component.

  The metal halide lamp 13 for automobile headlamps is mounted on the lamp socket and lights up.

The front view which shows the metal halide lamp for motor vehicle headlamps as 1st Embodiment in the high pressure discharge lamp of this invention Similarly enlarged sectional view of arc tube (A) in the second embodiment for implementing the high-pressure discharge lamp of the present invention is an enlarged cross-sectional view of the immediate vicinity portion of the sealing portion in the second embodiment for implementing the high-pressure discharge lamp of the present invention. , (B) is an enlarged cross-sectional view of a current introduction conductor in the same cross section The relationship between the difference in thermal conductivity between the two members in the small-diameter cylindrical part and the sealed part of the current introduction conductor, the minimum heatable diameter, the temperature difference of the current introduction conductor part facing the ceramic melting part, and the resistance value of the current introduction conductor are shown. Graph A graph showing the relationship between the difference in linear expansion coefficient of both members in the small-diameter cylindrical portion and the sealed portion of the current introduction conductor, the crack generation rate associated with the sealing, and the resistance value of the current introduction conductor The block circuit diagram which shows one Embodiment in the high pressure discharge lamp lighting device of this invention The conceptual side view which shows the motor vehicle headlamp as one Embodiment in the illuminating device of this invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Translucent ceramics discharge container, 1a ... Enveloping part, 1b ... Small diameter cylindrical part, 2 ... Current introduction conductor, 3 ... Electrode, 4 ... Reduced diameter part, B ... Base, g ... Gap, IT ... Arc tube, L1 , L2 ... Lead wire, MHL ... Metal halide lamp for automotive headlamp, OT ... Outer tube, t1 ... Base terminal, T ... Insulating tube

Claims (5)

A translucent ceramics discharge vessel comprising a surrounding portion and a small diameter tubular portion formed connected to the surrounding portion;
A current-introducing conductor inserted into the small-diameter cylindrical portion of the translucent ceramic discharge vessel and sealed to the small-diameter cylindrical portion mainly by fusion of ceramics in the small-diameter cylindrical portion of the translucent ceramic discharge vessel;
An electrode connected to a current introducing conductor and sealed in a translucent ceramic discharge vessel;
A discharge medium enclosed in a translucent ceramic discharge vessel;
And the difference in thermal conductivity between the two members forming the sealing portion of the small diameter cylindrical portion of the translucent ceramic discharge vessel and the current introduction conductor is 75 W / m · K or less. High-pressure discharge lamp. A translucent ceramics discharge vessel comprising a surrounding portion and a small diameter tubular portion formed connected to the surrounding portion;
A current-introducing conductor inserted into the small-diameter cylindrical portion of the translucent ceramic discharge vessel and sealed to the small-diameter cylindrical portion mainly by fusion of ceramics in the small-diameter cylindrical portion of the translucent ceramic discharge vessel;
An electrode connected to a current introducing conductor and sealed in a translucent ceramic discharge vessel;
A discharge medium enclosed in a translucent ceramic discharge vessel;
And the difference between the linear expansion coefficients of the two members forming the sealing portion of the small diameter cylindrical portion of the translucent ceramic discharge vessel and the current introduction conductor is within 4 × 10 ⁻⁶ / K. High-pressure discharge lamp characterized. A translucent ceramics discharge vessel comprising a surrounding portion and a small diameter tubular portion formed connected to the surrounding portion;
A current-introducing conductor inserted into the small-diameter cylindrical portion of the translucent ceramic discharge vessel and sealed to the small-diameter cylindrical portion mainly by fusion of ceramics in the small-diameter cylindrical portion of the translucent ceramic discharge vessel;
An electrode connected to a current introducing conductor and sealed in a translucent ceramic discharge vessel;
A discharge medium enclosed in a translucent ceramic discharge vessel;
And the difference in thermal conductivity between the two members forming the sealing portion of the ceramic and the current introduction conductor of the small-diameter cylindrical portion of the translucent ceramic discharge vessel is within 75 W / m · K, and both members The high-pressure discharge lamp is characterized in that the difference in linear expansion coefficient is 4 × 10 ⁻⁶ / K or less. A high-pressure discharge lamp according to any one of claims 1 to 3;
A lighting circuit for lighting the high-pressure discharge lamp;
A high-pressure discharge lamp lighting device comprising: A lighting device body;
A high-pressure discharge lamp according to any one of claims 1 to 3 disposed in a lighting device body;
A lighting circuit for lighting the high-pressure discharge lamp;
An illumination device comprising:

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