JP2008177151A - 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 composed by suppressing the occurrence of a crack generated in ceramics of a sealing part by setting an average crystal grain size of a small-diameter pipe part in an intended sealing part within a predetermined range. <P>SOLUTION: This high-pressure discharge lamp MHL includes: a translucent ceramics discharge vessel 1 having a surrounding part 1a formed of translucent ceramics, and a small-diameter pipe part 1b formed by being connected to the surrounding part, and formed of polycrystalline alumina ceramics having an average crystal grain size on the outer surface of ≤50 μm in a position close to an intended sealing part; a current introducing conductor 3 inserted into the small-diameter pipe part of the translucent ceramics discharge vessel, and sealed to the small-diameter part mainly at a sealing part SP formed by fusion of the polycrystalline alumina ceramics in the intended sealing part of the small-diameter pipe part of the translucent ceramics discharge vessel; an electrode connected to the current introducing conductor; and a discharge medium. <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).

  In addition, in order to prevent the occurrence of cracks and breakage in the frit seal part of the alumina ceramic thin tube part in the 200 to 400 W high watt type by improving the mode of sealing using the glass frit, it is applied to the seal part. It is known that the average crystal grain size of the narrow tube part in contact is reduced to 20 μm or less, and the average crystal grain size of the narrow tube part not in contact with the sealing part is increased to 25 μm or more (patent document). 2). The high-pressure discharge lamp described in Patent Document 2 increases the mechanical strength by reducing the average crystal grain size of the narrow tube portion in contact with the sealing portion in other portions, thereby increasing the cracks in the frit sealing portion. -It is trying to prevent the occurrence of damage without impairing the lamp characteristics.

Japanese Patent Laid-Open No. 06-196131 JP 2003-059451 A

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.

  Moreover, the high-pressure discharge lamp described in Patent Document 2 is an invention that is not related to the meltability of the polycrystalline alumina ceramics that constitute the sealing portion of the narrow tube portion on the premise of frit sealing.

  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 the ceramic in the portion to be sealed of the translucent ceramic discharge vessel is heated and melted and welded to the current introduction conductor. I understood that.

  Therefore, the present inventors have further studied the sealing structure in which the ceramics to be sealed in the translucent ceramic discharge vessel are heated and melted and welded to the current introduction conductor, and as a result, the following has been found. That is, cracks may occur due to thermal shock before the ceramic melts and solidifies, and it is difficult to form a good sealing portion with a high yield.

  The present invention provides 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 average crystal grain size of the small-diameter cylindrical portion in the portion to be sealed is within a predetermined range. Accordingly, an object of the present invention is to provide a high-pressure discharge lamp, a high-pressure discharge lamp lighting device, and an illuminating device that suppress the generation of cracks in the ceramic of the sealing portion.

    The high-pressure discharge lamp of the present invention is formed by connecting to an enclosure part and an enclosure part made of translucent ceramics, and has an average crystal grain size on the outer surface at a position close to the sealing part of the polycrystalline alumina of 50 μm or less A translucent ceramic discharge vessel having a small-diameter cylindrical portion made of ceramic; and inserted into the small-diameter cylindrical portion of the translucent ceramic discharge vessel, mainly in a planned sealing portion of the small-diameter cylindrical portion of the translucent ceramic discharge vessel A current-introducing conductor sealed in a small-diameter cylindrical part in a sealing part formed by fusion bonding of polycrystalline alumina ceramics; an electrode connected to the current-introducing conductor and sealed in a translucent ceramic discharge vessel; And a discharge medium sealed in a photoceramic discharge vessel.

  The present invention includes the following aspects.

  [Translucent Ceramic Discharge Vessel] The translucent ceramic discharge vessel includes an enclosing portion and a small-diameter cylindrical portion as will be described later, and the enclosing portion is made of a single crystal metal oxide such as sapphire and polycrystalline. Metal oxides such as translucent airtight aluminum oxides, ie translucent polycrystalline alumina ceramics, yttrium-aluminum-garnet (YAG), yttrium oxide (YOX) and polycrystalline non-oxides such as aluminum nitride (AlN) The container is made of a ceramic material having such light transmittance and heat resistance as described above, and in which a discharge 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.

  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, the average crystal grain size before melting for sealing is generally 50 μm or less. That is, when the average crystal grain size of the above part is 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less, the familiarity with the introduced conductor is good when sealing is performed by melting the ceramic in the small-diameter cylindrical portion. And, at the time of cooling after the small-diameter cylindrical portion and the current introduction conductor are joined by melting, cracks are unlikely to occur in the joint portion and the vicinity thereof. For the above reason, the average crystal grain size of the portion to be sealed of the small diameter cylindrical portion is preferably 0.1 to 30 μm, and more preferably 0.5 to 20 μm.

  In an embodiment in which the average crystal grain size at a position close to at least the sealed portion of the small-diameter cylindrical portion of the translucent ceramic discharge vessel is generally 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less. The portion that defines the crystal grain size as described above may be only the small-diameter cylindrical portion or the entire light-transmitting ceramic discharge vessel.

  However, when the average crystal grain size of the portion to be sealed of the small-diameter cylindrical portion is 4 μm or less, preferably 3 μm or less, more preferably 1 μm or less, the formation of the sealing portion by fusion bonding of alumina ceramics is further facilitated. I found out that This is because when the average crystal grain size is 4 μm or less, preferably 3 μm or less, preferably 1 μm or less, the generation of cracks due to bonding is extremely reduced, and when the average crystal grain size is 3 μm or less, the average crystal grain size is This is because the melting point is lower than that of alumina ceramics having a large average grain size, and therefore, deformation and creep are likely to occur at a lower temperature. Further, when the average crystal grain size is 0.5 μm or less, no cracks are generated due to bonding. In this embodiment, the surrounding portion also uses polycrystalline alumina ceramics. Therefore, in the case of the embodiment in which the entire translucent ceramic discharge vessel is formed of polycrystalline alumina ceramics, the average grain size on the outer surface of the surrounding portion described later is 15 to It can select suitably from the range of 80 micrometers. When the average crystal grain size is 15 to 80 μm, the melting point does not decrease as described above, and translucency can be ensured. Thus, according to this aspect, it is possible to achieve both the suppression of crack generation and the securing of lamp characteristics, particularly luminous efficiency and color rendering. The lower limit value of the average crystal grain size of the polycrystalline alumina ceramic is theoretically not limited. However, practically, the lower limit is about 0.1 μm, preferably about 0.5 μm, from the viewpoint of manufacturing.

  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. It is allowed that the discharge space formed inside the surrounding portion has 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 inserts 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 planned sealing portion is heated and melted. Functions to seal the container. And it is prescribed | regulated to the value from which the cross-sectional area nearest to the sealing part in a small diameter cylinder part becomes the predetermined relationship mentioned later. 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.

Although the sealing part is formed in the small-diameter cylindrical part, it is allowed to be the following mode in the manufacturing stage before forming the sealing part. That is,
(1) A mode in which at least the end portion of the small-diameter cylindrical portion has a predetermined average crystal grain size and the end portion is fused.
(2) A mode in which a ceramic sleeve having a predetermined average crystal grain size is interposed inside the end portion of the small diameter cylindrical portion and around the current introducing conductor, and the sleeve is fused to the small diameter cylindrical portion and the current introducing conductor. .
(3) A ceramic ring body having a predetermined average crystal grain size is brought into contact with the end portion of the small-diameter cylindrical portion, and the ring body is melted to enter and solidify into a gap between the small-diameter cylindrical portion and the current introduction conductor. In this mode, the small diameter cylindrical portion and the current introducing conductor are fused.

  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 sufficient that the sealing portion is formed at least in the small-diameter cylindrical portion so as to easily form a sealing portion by direct or indirect ceramic welding of the small-diameter cylindrical portion and the current introduction conductor. 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, means for melting the ceramic is not particularly limited in the present invention when the sealing portion is formed by fusing the ceramic to the small diameter cylindrical portion. 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 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 the predetermined portion with respect to the predetermined portion, for example, at the side of the predetermined 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.

  Then, the sealing portion is heated to mainly melt the ceramic in the small-diameter cylindrical portion, and is fused to the small-diameter cylindrical portion and the current introduction conductor, thereby forming a sealing portion by the ceramic fusion. In many cases, the sealing portion is a solid solution in which the components of the current introduction conductor are dissolved. And the preferable sealing part has the average crystal grain diameter of the alumina in the outer surface larger than the average crystal grain diameter of the alumina in the outer surface of a non-sealing part. Note that this includes the case of amorphous (non-crystallized). When 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 or amorphous, so that the heat resistance and Increases mechanical strength. For this reason, it is considered that breakage and leakage due to heat shock due to lamp lighting are less likely to occur.

  Next, in order to manufacture a translucent ceramic discharge vessel, the surrounding portion and the small-diameter cylindrical portion can be integrally formed. However, it may be formed by joining or fitting a plurality of constituent members as desired. 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 functions to apply voltage to the electrode described later, supply current to the electrode, and seal the translucent ceramic discharge vessel in cooperation with the small diameter cylindrical portion. Conductor. Therefore, the tip side portion inserted into the small diameter cylindrical portion of the translucent ceramic discharge vessel is connected to the electrode, and the base end side is exposed to the outside of the translucent ceramic discharge vessel. In addition, in the above, being exposed to the outside of the translucent ceramic discharge vessel may or may not protrude from the translucent ceramic discharge vessel, but power can be supplied from the outside. It only needs to face the outside.

  Further, the current introduction conductor can be configured using a sealing metal or cermet. Sealing metals include niobium (Nb) and tantalum (Ta), which are conductive metals whose thermal expansion coefficient approximates that of translucent ceramics constituting the small-diameter cylindrical portion of translucent ceramic discharge vessel. ), Titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), platinum (Pt), molybdenum (Mo), tungsten (W), and other metals, and their cermets. Also, when aluminum oxide such as translucent polycrystalline alumina ceramics is used as the material of translucent ceramic discharge vessel, niobium and tantalum have the same average thermal expansion coefficient as aluminum oxide, and molybdenum Since the average coefficient of thermal expansion is close to that of the oxide, it is suitable for sealing. In the case of yttrium oxide and YAG, the difference in average thermal expansion coefficient is small. When aluminum nitride is used for the translucent ceramic discharge vessel, zirconium may be used for the current introduction conductor. Further, the current introduction conductor can be formed by joining a plurality of material portions. For example, a part of the metal selected from the above group may be used, and a cermet may be joined to the metal part in the tube axis direction or may be joined in the circumferential direction orthogonal to the tube axis. When a cermet is used for at least a part of the current introduction conductor, the small diameter cylindrical portion of the translucent ceramic discharge vessel and the current introduction conductor at the part of the cermet or the part straddling both the cermet and the sealing metal. When sealing is performed in the meantime, the temperature of the ceramic is easily increased during sealing by melting the ceramic in the small-diameter cylindrical portion for the reason described later, so that a good sealed portion can be easily formed.

  The cermet is a mixed sintered body of ceramics and metal. For example, the ceramic of the material component is alumina ceramics, and the metal is one or more kinds of metals selected from the above group, for example, molybdenum (Mo), tungsten (W ) Or a conductive metal such as niobium (Nb) can be used. The cermet of the portion to be sealed in the translucent ceramic discharge vessel of the current introduction conductor includes at least conductive metal components such as niobium (Nb), molybdenum (Mo) and tungsten, and ceramics such as alumina, YAG and yttria. The content ratio of the metal component is allowed to be 5 to 60% by mass.

  Thus, when the cermet is configured as described above, when the portion to be sealed by the heating means is heated, it generally depends on the heating method, but 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 large 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 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 mass, the coefficient of thermal expansion with the translucent ceramics discharge vessel becomes too large, making it difficult to obtain a desired seal. Moreover, when content of a metal component will be less than 50 mass%, it will become difficult to obtain desired electroconductivity.

  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 supports the electrode, which mainly contributes to forming the sealing portion by directly or indirectly sealing the small diameter cylindrical portion of the translucent ceramic discharge vessel, In addition, it has a function of supplying current. 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, a frit glass is mainly formed by using a cermet as a part that forms a sealing part in cooperation with a small-diameter cylindrical part of a translucent ceramic discharge vessel, and forming a part that mainly supports an electrode from a halogen-resistant metal such as molybdenum. It is known in the structure to be sealed. 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 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 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. In addition, when using a pair of electrodes, in the case of an alternating current lighting type, they have a symmetric structure, but in the case of a direct current lighting type, an asymmetric structure can be used.

  [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. Note that any one or a plurality of iodine, bromine, chlorine, and fluorine can be used as the halogen of the halide of the light emitting metal.

  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 has a relatively high vapor pressure during lighting, and a metal such as aluminum (e.g. Al halides such as Al), iron (Fe), zinc (Zn), antimony (Sb), and manganese (Mn) are suitable.

  The noble gas acts as a starting gas and a buffer gas. For example, xenon (Xe), argon (Ar), krypton (Kr), neon (Ne), or the like can be used alone or in combination.

A configuration example of a discharge medium for obtaining desired light emission is as follows.
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, other modes allowed in the present invention will be described. In addition, although the following aspects can implement this independently, it cannot be overemphasized that it can combine with this invention if desired, or can combine and implement arbitrary some aspects of each aspect.

The first aspect is characterized in that the effective length L of the small-diameter cylindrical portion of the translucent ceramic discharge vessel is in the range of 0.5 to 3.0 as a ratio L / D _O to the outer diameter D _O of the small-diameter cylindrical portion. It is said.

In this embodiment, the effective length L of the small-diameter cylindrical portion is defined within the predetermined range by the ratio L / D _O to the outer diameter D _O of the small-diameter cylindrical portion, so that the discharge medium sealed inside the translucent ceramic discharge vessel The amount of this is to be as small as possible. The effective length L of the small-diameter cylindrical portion is the length of the portion excluding the sealing portion in the length of the small-diameter cylindrical portion in the tube axis direction. Further, the outer diameter D _O of the small-diameter cylindrical portion is the outer diameter at a position close to the sealing portion of the small-diameter cylindrical portion.

The reason why the length L of the small diameter cylindrical portion is defined by the ratio L / D _O to the outer diameter D _O of the small diameter cylindrical portion is as follows. That is, in the case of the present invention, the length L of the small-diameter cylindrical portion necessary for forming the required sealing of the translucent ceramic discharge vessel is affected according to the outer diameter D _O of the small-diameter cylindrical portion, and the small diameter This is because the length of the tube portion depends on the amount of the discharge medium staying in the tube portion, and hence the amount of the discharge medium enclosed. Since frit glass is not used, even if the length L of the small-diameter cylindrical portion is shortened and the sealing portion becomes high temperature, the sealing portion is hardly deteriorated and can be endured throughout the life of the lamp.

If the ratio L / D _O is within the above range, the amount of discharge medium encapsulated necessary for obtaining the desired lamp characteristics may be relatively small, but if the ratio L / D _O exceeds 3.0, the lamp is lit. Since the amount of a discharge medium such as a metal halide that agglomerates in the coldest part formed in the small-diameter cylindrical portion suddenly increases, it is necessary to increase the amount of discharge medium enclosed for light emission. This phenomenon occurs remarkably when D 2 _O is in the range of 1.0 to 5.0 mm and L is in the range of 0.5 to 15 mm. Further, when the ratio L / D _O is less than 0.5, the amount of discharge medium enclosed becomes small, but the small-diameter cylindrical portion becomes too short or the outer diameter becomes too large so that the translucent ceramic discharge vessel is good. It becomes difficult to perform sealing.

The second aspect is characterized in that the internal diameter D _I of the small diameter cylinder portion of the light-transmissive ceramic discharge vessel is within the range of 1.4 to 17 at a ratio D _{I /} t for the thickness t of the small-diameter cylindrical portion .

This aspect, the inner diameter D _I of the small diameter cylinder portion, the ratio D _{I /} t for the thickness t of the small-diameter cylindrical portion by defining the predetermined range, the discharge medium sealed in the translucent ceramics discharge vessel The amount is as small as possible. Incidentally, the inner diameter D _I and a wall thickness t of the small-diameter cylindrical portion of the small diameter cylinder portion, the inner diameter and wall thickness of the portion close to the sealing portion of the small diameter cylinder portion.

An inner diameter D _I of the small-diameter cylindrical portion to define the ratio D _{I /} t for the thickness t of the small-diameter cylindrical portion for the following reason. That is, in the case of the present invention, the inner diameter D _I of the small diameter cylinder portion to the required sealing of the translucent ceramics discharge vessel, together with associated that depends on the thickness t of the small diameter cylinder portion, remaining in the small diameter cylinder portion discharge This is because the amount of medium, and hence the amount of enclosed discharge medium, depends on the inner diameter of the small-diameter cylindrical portion.

If the ratio D _I / t is within the above range, the amount of discharge medium encapsulated necessary for obtaining the desired lamp characteristics may be relatively small, but if the ratio D _I / t exceeds 17, the lamp is in operation. Since the amount of the discharge medium such as a metal halide aggregated in the coldest part formed in the small-diameter cylindrical portion increases rapidly, it is necessary to increase the amount of the discharge medium necessary for light emission. This phenomenon _{D I} is 0.5 to 1.5 mm, t is remarkably occurs when in the range of 0.3 to 2.0 mm. Further, when the ratio D _I / t is less than 1.4, the amount of discharge medium enclosed is drastically reduced, but the inner diameter of the small-diameter cylindrical portion becomes too small or the wall thickness becomes too thin, and the translucent ceramic discharge It becomes difficult to perform good sealing of the container. The optimum range of the ratio _D I / t is 1.6 to 2.5.

  The third aspect is a mercury-free type high-pressure discharge lamp in which the entire translucent ceramic discharge vessel has an average crystal grain size of 50 μm or less and the xenon sealing pressure of the discharge medium is 0.3 to 2 MPa at 25 ° C. It is characterized by that.

  In the present invention, the average crystal grain size of the entire translucent ceramic discharge vessel is 50 μm or less, optimally 0.5 to 20 μm, and the xenon sealing pressure is 0.5 to 1.2 MPa in the present invention. A preferable effect is obtained.

  In the case of a translucent ceramic discharge vessel provided with a small-diameter cylindrical portion, stress concentrates on the small-diameter cylindrical portion. Therefore, when the translucent ceramic discharge vessel is insufficient in pressure resistance, the small-diameter cylindrical portion tends to be damaged. There is.

  If the enclosed pressure of xenon is within the above range, there is no problem with the pressure resistance of the translucent ceramic discharge vessel, and therefore the translucent ceramic discharge vessel, particularly its small-diameter cylindrical portion, may be undesirably damaged during lighting. At the same time, a desired luminous flux rise characteristic is obtained.

  [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, 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 present invention, 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, at least the small-diameter cylindrical portion of the translucent ceramic discharge vessel is to be sealed. High pressure discharge lamp and high pressure discharge lamp lighting device in which cracks generated in ceramics in sealing portion are suppressed by being formed of polycrystalline alumina ceramic having an average crystal grain size of 50 μm or less on the outer surface at a position close to the portion And a lighting device can be provided.

  Further, the heat resistance and mechanical strength of the sealed portion should be increased by making the average crystal grain size of alumina on the outer surface of the sealed portion larger than the average crystal size of alumina on the outer surface of the non-sealed portion. Can do.

  Further, the surrounding portion of the translucent ceramic discharge vessel is made of polycrystalline alumina ceramics having an average crystal grain size of 15 to 80 μm, and the polycrystalline crystal having an average crystal grain size of 3 μm or less on the surface close to the sealing portion of the small diameter cylindrical part By using alumina ceramics, the melting point when forming a sealing part by fusion bonding of ceramics becomes low, the formation of the sealing part becomes easy, crack generation is effectively suppressed, and the heat resistance of the surrounding part is reduced. Since the temperature can be maintained high, it is possible to obtain a high-pressure discharge lamp with high operating temperature and good luminous efficiency and color rendering.

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

    1 to 4 show a metal halide lamp for an automobile headlamp as a first embodiment for carrying out the high-pressure discharge lamp of the present invention, FIG. 1 is a front view of the entire lamp, and FIG. 2 is an enlarged view of an arc tube. Sectional view, FIG. 3 is an enlarged photograph of an electron microscope for explaining the crystal grain size of polycrystalline alumina ceramics on the outer surface of the small-diameter cylindrical portion, and FIG. 4 is a reference straight line for explaining a method for measuring the average crystal grain size It is an electron microscope enlarged photograph of polycrystalline alumina ceramics.

  The metal halide lamp MHL for automobile headlamps according to the present embodiment is composed mainly of an arc tube IT, lead wires L1 and L2, an insulating tube T, an outer tube OT, and a base B.

  As shown in FIG. 2, the arc tube IT is composed of a translucent ceramic discharge vessel 1, a current introduction conductor 2, an electrode 3, and a discharge medium, and has a sealing portion SP.

  As shown in FIG. 2, the translucent ceramic discharge vessel 1 is formed by integral molding using translucent polycrystalline alumina ceramics having an average crystal grain size on the outer surface of 50 μm or less, preferably 30 μm or less as a main material, as shown in FIG. And includes a surrounding portion 1a and a pair of small diameter cylindrical portions 1b and 1b. The crystal grain size CS can be easily recognized by enlarging the outer surface of the small-diameter cylindrical portion 1b with a discharger microscope as shown in FIG. Further, in order to measure the average crystal grain size, for example, a reference straight line having a length of about 100 times the average crystal grain size in the electron microscope enlarged photograph image of the outer surface of the light-transmitting polycrystalline alumina ceramics shown in FIG. Is set at an appropriate site in the alumina ceramic. And average crystal grain size data can be obtained by calculating | requiring the average value of the diameter about many crystal grains which cross | intersect the said reference line.

  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 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. And the sealing part SP is formed in the sealing plan part of the edge part side.

  As shown in FIG. 2, the sealing portion SP is formed by melting and solidifying ceramics of the small-diameter cylindrical portion 1b in the portion to be sealed.

  The current introduction conductor 2 is made of cermet, is inserted into each small-diameter cylindrical portion 1b of the translucent ceramic discharge vessel 1, and is sealed by fusion of at least the ceramics of the small-diameter cylindrical portion 1b. The container 1 is sealed.

  Therefore, the distal end portion of the current introduction conductor 2 is located in the small diameter cylindrical portion 1 b and the proximal end portion is exposed to the outside of the translucent ceramic discharge vessel 1. In addition, when the current introduction conductor 2 is sealed, the small-diameter cylindrical portion 1b is heated and sufficiently melted, and is swelled in the radial direction while condensing in the axial direction due to surface tension, and deformed into an elliptical spherical shape or a teardrop shape. However, the shape varies depending on processing factors such as heating time and temperature.

  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.

Example 1 is a high-pressure discharge lamp shown in FIGS. 1 and 2.
Translucent ceramic discharge vessel: Made of integrally molded translucent polycrystalline alumina ceramic,
Enclosure: Maximum inner diameter 6mm, Maximum inner diameter 5mm, Wall thickness 0.5mm,
Small diameter cylindrical part: 1.7mm outer diameter, 0.7mm inner diameter, 5mm length, average grain size 30μm
Current-introducing conductor: Mo-Al ₂ O ₃ = 50: 50% by volume cermet rod, diameter 0.65mm
Electrode: 3mm distance between electrodes
Discharge medium: DyI ₃ -NdI ₃ -CsI = 3mg, Xe
0.5MPa
Rated lamp power: 35W

[Comparative Example 1]
Translucent ceramic discharge vessel: Made of integrally molded translucent polycrystalline alumina ceramic,
Enclosure: Maximum inner diameter 6mm, Maximum inner diameter 5mm, Wall thickness 0.8mm,
Small diameter cylindrical part: Outer diameter 1.7mm, Inner diameter 0.7mm, Length 12mm,
Average grain size 70μm
Current introduction conductor: Nb bar, diameter 0.65mm

Other specifications are the same as those in the first embodiment.

  Hereinafter, other embodiments will be described. 5 to 14, the same parts as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

    FIG. 5 is a cross-sectional view of a translucent ceramic discharge vessel showing a second embodiment for implementing the high-pressure discharge lamp of the present invention. In this embodiment, the surrounding part 1a and the small-diameter cylindrical part 1b of the translucent ceramic discharge vessel 1 are made the main function of the surrounding part 1a and the main function of the small-diameter cylindrical part 1b by using translucent ceramics having different linear transmittances. We are trying to optimize it.

  That is, in the examples (a) to (d) in the figure, the main part of the surrounding portion 1a is a ceramic having a high linear transmittance, such as single crystal alumina, a high linear transmittance translucent polycrystalline alumina ceramic, or the like. . The small-diameter cylindrical portion 1b is a polycrystalline alumina ceramic having an average crystal grain size of 30 μm or less, which is a characteristic configuration of the present invention. In order to manufacture the translucent ceramic discharge vessel 1 having such a two-member configuration, a known ceramic member manufacturing method such as a shrink-fit structure can be used.

Next, examples (a) to (d) will be described.
(A) is prepared by presintering, for example, a small-diameter cylindrical portion 1b in which the main portion of the spindle-shaped surrounding portion 1a with both ends cut away and the portion with the expanded tip are integrated, The above-mentioned members are combined and housed in a mold, and are sintered to obtain a translucent ceramic discharge vessel 1 that is integrally molded.
(B) shows that the surrounding portion 1a is formed integrally with a pair of end plates having openings corresponding to the outer diameter of the small-diameter cylindrical portion at both ends of the cylindrical body, and matches the opening of the end plate of the surrounding portion 1a. A small-diameter cylindrical portion having a flange portion whose diameter is smaller than the outer diameter of the surrounding portion is prepared by sintering separately, and the flange portion is joined to the end plate with the openings aligned and shrink-fitted.
(C) is a shrink fit structure similar to (b) above, but the surrounding portion 1b has a spindle shape.
(D) is substantially the same as (b) above, but has a structure in which the outer diameter of the collar is equal to that of the surrounding portion 1a.

The high pressure discharge lamp has a structure shown in FIG.
Translucent ceramic discharge vessel: Two-piece translucent alumina ceramic,
Enclosure: Linear transmittance 40% polycrystalline alumina ceramics,
Maximum inner diameter 6mm, maximum inner diameter 5mm, wall thickness 0.8mm,
Small diameter cylindrical part: Alumina ceramics, outer diameter 1.7mm, inner diameter 0.7mm,
Length 5mm, average grain size 1μm
Current-introducing conductor: Cermet (Mo-Al ₂ O ₃ = 1: 1 volume ratio) rod, diameter 0.65mm

Other specifications are the same as those in the first embodiment.

The high pressure discharge lamp has a structure shown in FIG.
Translucent ceramic discharge vessel: Two-piece translucent alumina ceramic,
Enclosure: Linear transmittance 40% polycrystalline alumina ceramics,
Maximum inner diameter 6mm, maximum inner diameter 5mm, wall thickness 0.8mm,
Small diameter cylindrical part: Alumina ceramics, outer diameter 1.7mm, inner diameter 0.7mm,
Length 5mm, average grain size 1μm
Current-introducing conductor: Cermet (Mo-Al ₂ O ₃ = 1: 1 volume ratio) rod, diameter 0.65mm

Other specifications are the same as those in the first embodiment.

[Comparative Example 2]
Translucent ceramic discharge vessel: Made of integrally molded translucent polycrystalline alumina ceramic,
Enclosure: Maximum inner diameter 6mm, Maximum inner diameter 5mm, Wall thickness 0.8mm,
Linear transmittance 19%
Small diameter cylindrical part: 1.7mm outer diameter, 0.7mm inner diameter, 12mm length, average grain size 70μm
Current introduction conductor: Nb bar, diameter 0.65mm

Other specifications are the same as those in the first embodiment.

    6 and 7 show a third embodiment for carrying out the high-pressure discharge lamp of the present invention, FIG. 6 is a cross-sectional view of a translucent ceramic discharge vessel, and FIG. 7 heats a portion to be sealed by laser irradiation. It is a graph which shows the relationship between the elapsed time in the case of carrying out, and the relative output of a laser. In this embodiment, laser irradiation is performed in the direction of the arrow from the top to the bottom in the figure while rotating the translucent ceramic discharge vessel 1 and the current introduction conductor 3 with respect to the YAG laser beam LB as indicated by the arrow on the right side in the figure. As for the method of forming the sealing part SP by performing the above, the output of laser irradiation is controlled to a predetermined value as shown in FIG. In this embodiment, the current introduction conductor 2 is made of a cermet rod.

  That is, assuming that the laser output is 100% in relative value, the laser output is gradually increased until the portion to be sealed of the small-diameter cylindrical portion 1b is melted, and when the output reaches 100%, for example, 100 for a few seconds. % Is maintained in a sufficiently molten state. After that, the sealing output is gradually reduced from 100% to 0% in anticipation of when the current introduction conductor 3 gets wet and becomes familiar with the ceramic. Note that the laser beam is irradiated with the focal position shifted somewhat toward the back of the heated portion.

  Thus, by irradiating the planned sealing portion while controlling the laser output, a good sealed portion SP can be obtained without causing cracks or bubbles during sealing.

    FIG. 8 is a cross-sectional view of a translucent ceramics discharge vessel showing a fourth mode for carrying out the high-pressure discharge lamp of the present invention. This form is a joined body structure in which the current introduction conductor 2 joins the cermet rod 2a and the Mo rod 2b in the axial direction, and a third structure shown in FIG. 6 is obtained except that sealing is performed at the portion of the cermet rod 2a. The form is the same.

    FIG. 9 is a cross-sectional view of a translucent ceramics discharge vessel showing a fifth mode for carrying out the high-pressure discharge lamp of the present invention. In this embodiment, as shown in the drawing, the sealing portion SP bulges in a direction perpendicular to the tube axis and has an irregular shape. This is mainly because when the ceramic of the small-diameter cylindrical portion 1b in the portion to be sealed is melted, it contracts in the tube axis direction due to surface tension. Further, the sealing portion SP often forms a solid solution by dissolving the components of the current introduction conductor 2 described later in the ceramic, and in this case, the color is changed to a color different from the intrinsic color of the ceramic. .

10 and 11 show a sixth mode for carrying out the high-pressure discharge lamp of the present invention, FIG 10 is a graph illustrating the amount of enclosed relationship between the specific L / D _O and the discharge medium, 11 Toru A cross-sectional view along the tube axis of the high-pressure discharge lamp explaining the dimensional relationship of each part of the photoceramic discharge vessel (top) and along a plane perpendicular to the tube axis at a position close to the sealing portion of the small-diameter cylindrical portion It is an expanded sectional view (below). In FIG. 10, the horizontal axis represents the ratio L / D _O of the effective length L of the small-diameter cylindrical portion to the outer diameter D _O of the small-diameter cylindrical portion, and the vertical axis represents the enclosed amount (relative value) of the discharge medium.

In this embodiment, the high-pressure discharge lamp has an effective length L of the small-diameter cylindrical portion 1b of the translucent ceramic discharge vessel 1 of 0.5 to 3.0 in a ratio L / D _O to the outer diameter D _O of the small-diameter cylindrical portion 1b. It is configured to be in range. The effective length L of the small-diameter cylindrical portion 1b is the length of the portion excluding the sealing portion SP from the length of the small-diameter cylindrical portion 1b, and indicates the length of the portion where the discharge medium can stay inside. . The outer diameter D _O of the small-diameter cylindrical portion 1b is an outer diameter at a position close to the sealing portion SP of the small-diameter cylindrical portion 1b.

As can be understood from FIG. 10, when the ratio L / D 2 _O is in the range of 0.5 to 3.0, the amount of discharge medium enclosed can be relatively reduced.

FIG. 12 is a graph for explaining the relationship between the ratio D _I / t and the amount of enclosed discharge medium in the seventh embodiment for implementing the high-pressure discharge lamp of the present invention. Incidentally, in the figure, the horizontal axis represents the ratio D _{I /} t for the thickness t of the small-diameter cylindrical portion of the inner diameter D _I of the small diameter cylinder portion, enclosed amount of the vertical axis discharge medium (relative value), respectively.

In this embodiment, the high-pressure discharge lamp, the inner diameter _{D I} of the small-diameter cylindrical portion 1b of the translucent ceramics discharge vessel 1 is in the range of 1.4 to 17 at a ratio _D I / t for the thickness t of the small-diameter cylindrical portion 1b It is configured as follows. Incidentally, as shown in FIG. 12, the inner diameter D _I of the small-diameter cylindrical portion 1b, the inner diameter at the position close to the sealing portion SP, t is the same thickness.

As can be understood from FIG. 12, when the ratio D _I / t is in the range of 1.4 to 17, the amount of discharge medium enclosed can be relatively reduced.

Example 4 is a high-pressure discharge lamp shown in FIGS. 1 and 2.
Translucent ceramic discharge vessel: Made of integrally molded translucent polycrystalline alumina ceramic,
Average crystal grain size of the entire container 10μm
Enclosure: Maximum inner diameter 6mm, Maximum inner diameter 5mm, Wall thickness 0.4mm
Small diameter cylindrical part: Outer diameter (D _O ) 1.5mm, Inner diameter (D _I ) 0.7mm, Wall thickness (t) 0.4mm
Effective length (L) 0.75mm, L / D _O = 0.5, D _I /t=1.8
Current-introducing conductor: Mo-Al ₂ O ₃ = 50: 50% by volume cermet rod, diameter 0.65mm
Electrode: 3mm distance between electrodes
Discharge medium: DyI ₃ -NdI ₃ -CsI = 3mg, Xe1MPa
Rated lamp power: 35W

Translucent ceramic discharge vessel: Made of integrally molded translucent polycrystalline alumina ceramic,
The average crystal grain size of the whole container is 10μm,
Enclosure: Maximum inner diameter 6mm, Maximum inner diameter 5mm, Wall thickness 0.4mm
Small diameter cylindrical part: Outer diameter (D _O ) 1.5mm, Inner diameter (D _I ) 0.7mm,
Effective length (L) 1.5mm, L / D _O = 1.0, D _I /t=1.8

Others are the same as the fourth embodiment.

Translucent ceramic discharge vessel: Made of integrally molded translucent polycrystalline alumina ceramic,
The average crystal grain size of the whole container is 10μm,
Enclosure: Maximum inner diameter 6mm, Maximum inner diameter 5mm, Wall thickness 0.4mm
Small diameter cylindrical part: Outer diameter (D _O ) 1.5mm, Inner diameter (D _I ) 0.7mm,
Effective length (L) 4.5mm, L / D _O = 3.0, D _I /t=1.8

Others are the same as the fourth embodiment.

Translucent ceramic discharge vessel: Made of integrally molded translucent polycrystalline alumina ceramic,
The average crystal grain size of the whole container is 10μm,
Enclosure: Maximum inner diameter 6mm, Maximum inner diameter 5mm, Wall thickness 0.5mm
Small diameter cylindrical part: Outer diameter (D _O ) 2.05mm, Inner diameter (D _I ) 1.0mm,
Effective length (L) 6.0mm, L / D _O = 3.0, D _I /t=2.0

Others are the same as those in the fourth embodiment.

[Comparative Example 3]
Translucent ceramics discharge vessel: Made of monolithic translucent polycrystalline alumina ceramics,
Average crystal grain size of the entire container 70μm
Enclosure: Maximum inner diameter 6mm, Maximum inner diameter 5mm, Wall thickness 0.8mm
Small diameter cylindrical part: Outer diameter (D _O ) 1.5mm, Inner diameter (D _I ) 0.7mm,
Effective length (L) 12mm, L / D _O = 8.0, D _I /t=1.8

Others are the same as the fourth embodiment.

    FIG. 13 is a graph showing the relationship between the average crystal grain size and the pressure resistance for explaining the eighth embodiment for carrying out the high-pressure discharge lamp of the present invention. In the figure, the horizontal axis represents the average crystal grain size (μm), and the vertical axis represents the pressure resistance (Pa) in the lamp lighting state. In this embodiment, if the average crystal grain size is 50 μm or less, a maximum pressure resistance value of 0.8 MPa or more is obtained. Similarly, if it is 30 μm or less, 1.1 MPa or more, and if it is 20 μm or less, 1.8 MPa or more and 10 μm or less. If so, a maximum pressure resistance value of 2.5 MPa or more can be obtained.

  Therefore, the range of this embodiment is that the average crystal grain size is 50 μm or less and the sealed pressure is 0.3 to 2.0 MPa. Further, the range of the average crystal grain size of 0.5 to 20 μm and the sealing pressure of 0.5 to 1.2 MPa is the optimum range.

    FIG. 14 is a process diagram for explaining the sealing process of the translucent ceramics discharge vessel in the ninth embodiment for carrying out the high-pressure discharge lamp of the present invention. In the figure, the same parts as those in FIG. 2 and FIG. In this embodiment, the translucent ceramic discharge vessel 1 has an average crystal grain size on the end side of the small-diameter cylindrical portion 1b that is different from the average crystal grain size of the other portions and the surrounding portion 1a.

  That is, the average crystal grain size of the outer surface on the end 1b1 side of the small-diameter cylindrical portion 1b is 3 μm or less, and the average crystal grain size on the outer surface at a position close to the sealing portion even after the sealing portion SP is formed. Is essentially unchanged from before the sealing portion SP is formed. On the other hand, the average crystal grain diameter in the other part of the small diameter cylindrical part 1b and the outer surface of the surrounding part is in the range of 15 to 80 μm. However, the entire translucent ceramic discharge vessel 1 is formed by integral molding.

  In this embodiment, the process of forming the sealing portion SP is performed in the order of (a), (b), and (c) in FIG. That is, first, as shown in FIG. 14A, the illustrated electrode mount and the illustration are omitted, but the translucent ceramic discharge vessel 1 shown in FIG. 14B is prepared separately. The electrode mount is an assembly of the current introduction conductor 2 and the electrode 3. In addition, the current introduction conductor 2 has a series connection structure of a niobium portion 2a1, a cermet portion 2a2, and a molybdenum portion 2b from the base end in the length direction toward the tip end. The cermet part 2a2 is made of a sintered body of alumina ceramic powder and molybdenum powder.

  Next, as shown in FIG. 14B, the electrode mount is inserted to a predetermined position inside the small-diameter cylindrical portion 1 b of the translucent ceramic discharge vessel 1. Then, the niobium part 2a1 and the cermet part 2a2 of the current introduction conductor 2 facing the end 1b1 are intensively heated around the end 1b1 of the small-diameter cylindrical part 1b, and the temperature rises due to heat absorption. The heat of the niobium part 2a1 and the cermet part 2a2 is conducted to the end part 1b1, and the temperature of the part increases. When the temperature of the end portion 1b1 eventually reaches the melting point, the ceramic of the end portion 1b1 melts and gets wet with the niobium portion 2a1 and the cermet portion 2a2 facing the current introduction conductor 2.

  Next, as shown in FIG. 14C, when the heating is stopped, the melted portion of the ceramic mainly constituting the end portion 1b1 is solidified, and the small-diameter cylindrical portion 1 and the current introduction conductor 2 are sealed by ceramic fusion. A sealed portion SP is formed which is stopped. In addition, since the surface of the sealing portion SP contracts due to surface tension when the end portion 1b1 is melted, the sealing portion SP is shortened in the tube axis direction and slightly bulged in the radial direction.

  Thus, in this embodiment, since the average crystal grain size of the end portion 1b1 of the small diameter cylindrical portion 1b is 3 μm or less, the melting point of the ceramic is lower than the melting points of the other portions of the small diameter cylindrical portion 1b and the surrounding portion 1a. Therefore, sealing becomes easy and the operating temperature of the surrounding portion 1a can be set relatively high, so that the lamp characteristics can be improved. Further, since the sealing portion SP is ceramic-fused to the niobium portion 2a1 and the cermet portion 2a2 of the current introduction conductor 2, the cermet portion 2a2 reliably prevents the liquid-phase discharge medium from reaching the niobium 2a1. Therefore, sealing with excellent reliability and durability can be performed.

    FIG. 15 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.

  As the metal halide lamp MHL for automobile headlamps, one shown in each embodiment for implementing the high-pressure discharge lamp of the present invention described above can be selected and used as desired, and the output terminal of the full bridge inverter FBI can be used. Connect in between and turn on low-frequency alternating current.

    FIG. 16 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 the circuit configuration shown in FIG. 9, 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. 3 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 whole 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 Similarly, an electron microscope enlarged photograph explaining the crystal grain size of polycrystalline alumina ceramics on the outer surface of the small diameter cylindrical part Electron microscope enlarged photograph of polycrystalline alumina ceramics with reference lines for explaining the method of measuring average grain size Sectional drawing of the translucent ceramics discharge container which shows the 2nd form for implementing the high pressure discharge lamp of this invention Sectional drawing of the translucent ceramics discharge container in the 3rd form for implementing the high pressure discharge lamp of this invention Graph showing the relationship between the elapsed time and the relative output of the laser when heating the part to be sealed by laser irradiation Sectional drawing of the translucent ceramics discharge container which shows the 4th form for implementing the high pressure discharge lamp of this invention Sectional drawing of the translucent ceramics discharge container which shows the 5th form for implementing the high pressure discharge lamp of this invention The graph explaining the relationship between ratio L / _DO and the enclosure amount of a discharge medium in the 6th form for implementing the high pressure discharge lamp of this invention Similarly, a cross-sectional view along the tube axis of the high-pressure discharge lamp explaining the dimensional relationship of each part of the translucent ceramic discharge vessel and a surface orthogonal to the tube axis at a position close to the sealing portion of the small-diameter cylindrical portion Expanded cross-sectional view (bottom) Graph illustrating the relationship between the sealing amount of the seventh ratio D _{I /} t and the discharge medium showing a mode for carrying out the high-pressure discharge lamp of the present invention The graph which shows the relationship between the average crystal grain diameter and withstand pressure pressure for demonstrating the 8th form for implementing the high pressure discharge lamp of this invention Process drawing explaining the sealing process of the translucent ceramics discharge container in the 9th form for implementing the high pressure discharge lamp of this invention 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 cylinder part, 2 ... Current introduction conductor, IT ... Arc tube, SP ... Sealing part

Claims (8)

An enveloping part made of translucent ceramics and a small-diameter cylindrical part made of polycrystalline alumina ceramics formed on and connected to the enveloping part and having an average crystal grain size of 50 μm or less on the outer surface at a position close to the sealing part A translucent ceramic discharge vessel;
Inserted inside the small-diameter cylindrical portion of the translucent ceramic discharge vessel and sealed to the small-diameter cylindrical portion at the sealing portion formed mainly by the fusion of polycrystalline alumina ceramics in the small-diameter cylindrical portion of the translucent ceramic discharge vessel. A current introduction conductor;
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;
A high-pressure discharge lamp comprising:   2. The translucent ceramics discharge vessel is made of polycrystalline alumina ceramics having an average crystal grain size of 0.5 to 4 [mu] m on the outer surface at a position close to the sealing part of the small-diameter cylindrical part. High pressure discharge lamp.   3. The high pressure according to claim 1, wherein the sealing portion has an average crystal grain size of alumina on an outer surface thereof larger than an average crystal grain size on the outer surface at a position close to the sealing portion. Discharge lamp. The translucent ceramics discharge vessel has an effective length L of a small-diameter cylindrical portion in a range of 0.5 to 3.0 as a ratio L / D _O to an outer diameter D _O of the small-diameter cylindrical portion. The high-pressure discharge lamp according to any one of 1 to 3. Translucent ceramics discharge vessel, 1 claims, characterized in that the internal diameter D _I of the small-diameter cylindrical portion is within the range of 1.4 to 17 at a ratio D _{I /} t for the thickness t of the small-diameter cylindrical portion 5. The high pressure discharge lamp according to any one of 4 above.   The translucent ceramic discharge vessel is made of polycrystalline alumina ceramic having an average crystal grain size of 15 to 80 μm on the outer surface of the surrounding portion, and has an average crystal grain size on the outer surface at a position close to the sealing portion of the small-diameter cylindrical portion. The high-pressure discharge lamp according to any one of claims 1 to 5, wherein is made of polycrystalline alumina ceramics of 3 µm or less. A high-pressure discharge lamp according to any one of claims 1 to 6;
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 6, disposed in a lighting device body;
A lighting circuit for lighting the high-pressure discharge lamp;
An illumination device comprising:

Images