JP2007179975A - High-pressure discharge lamp, and illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high pressure discharge lamp which has a translucent airtight container using a translucent polycrystalline ceramic having a linear transmissivity of 20% or more and in which deterioration of the linear transmissivity due to occurrence of cloudiness is suppressed, and an illumination device using the same. <P>SOLUTION: The high pressure discharge lamp is equipped with a translucent airtight container 1 which is made of a translucent polycrystalline ceramic and has an envelope part 1a to envelope a discharge space 1c and a pair of small-diameter tube parts 1b extending from both ends in tube axis direction of the envelope part continuously integrated, and in which a linear transmissivity of the main part of the envelope part is over 20%, and a projection part 1d with its height 10-80% of the maximum inner diameter of the envelope part is formed on the inner face at lower half part in horizontal lighting of the envelope part, a pair of electrodes 2, 2, and an ionized medium filled into the translucent airtight container. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high-pressure discharge lamp including a light-transmitting hermetic container made of a light-transmitting polycrystalline ceramic, and an illumination device using the same.

  In recent years, the need for reducing environmental pollutants has increased. In high-pressure discharge lamps that have been put to practical use, mercury, which is an environmental pollutant, is enclosed, but instead of mercury, the vapor pressure of zinc (Zn) is relatively high and it is difficult to emit light in the visible range. A mercury-free metal halide lamp (hereinafter referred to as “mercury-free lamp” for the sake of convenience) in which a metal halide is enclosed has been invented (see Patent Document 1).

  Mercury-free lamps are particularly expected and developed as metal halide lamps for automotive headlamps that are trying to eliminate the use of environmentally hazardous substances.

  On the other hand, when looking at the material of the light-transmitting hermetic container of the conventional high-pressure discharge lamp, quartz glass has generally been used, but recently, it has a light-transmitting property with excellent heat resistance and corrosion resistance. The adoption of ceramic airtight containers is increasing. Polycrystalline translucent alumina ceramics are mainly used as translucent ceramics, but conventional ones are not suitable for high-pressure discharge lamps for condensing purposes because they do not have high linear transmittance.

  On the other hand, a technique for obtaining polycrystalline alumina ceramics with high linear transmittance is also disclosed (Non-Patent Document 1).

JP 11-238488 A K. Morinaga, T. Torikai, K. Nakagawa, and S. Fujino, “lochFabrication of fine α loch-alumina powders by thermaldecomposition of ammonium aluminum carbonate hydro-oxide (AACH)” lochActamaterialia, 48, p4375-4741 (2000)

  Non-Patent Document 1 discloses a technique for obtaining polycrystalline alumina ceramics having a high linear transmittance, but does not mention the configuration of a light-transmitting hermetic container of a high-pressure discharge lamp.

  The present inventor has found that in the process of developing a high-pressure discharge lamp using polycrystalline ceramics having a high linear transmittance, there is a problem that white turbidity tends to occur at the upper surface of the translucent airtight container. This white turbidity is often caused by a reaction product between the discharge medium and translucent polycrystalline ceramics, or because the ceramic constituents are sublimated or crystallized for some reason. When white turbidity occurs, the transparency is lost, and the linear transmittance is greatly reduced although the total transmittance is not deteriorated. For this reason, when white turbidity arises, there exists a problem of affecting a condensing performance.

  When this inventor investigated about the above-mentioned cloudiness generation | occurrence | production, the tendency for the cloudiness to concentrate on the high temperature part which the discharge arc approached especially was seen. Therefore, if a part having a higher temperature than the high temperature part of the surrounding part of the translucent airtight container is made separately, white turbidity is intensively generated in the part, and the white turbidity in the wall surface part where white turbidity occurs when the part is not formed Was found to decrease significantly. The present invention has been made based on this discovery.

  Further, in the high-pressure discharge lamp for mercury-free automotive headlamps, the occurrence of white turbidity is relatively significant. This is because the xenon is sealed at a higher pressure than the mercury-containing high-pressure discharge lamp and the mercury is not sealed, so that the discharge arc becomes thin and the convection of the discharge medium becomes intense and the curvature of the discharge arc becomes large. For this reason, the upper surface portion of the surrounding portion of the translucent airtight container is likely to be overheated, resulting in white turbidity.

  The present invention relates to a high-pressure discharge lamp having a translucent airtight container using translucent polycrystalline ceramics having a linear transmissivity of 20% or more, and suppressing a decrease in linear transmissivity due to the occurrence of white turbidity, and the same. It is a general object to provide a lighting device.

  In addition, the present invention is a mercury-free high-pressure discharge suitable for automobile headlamps, which includes a light-transmitting hermetic container using light-transmitting polycrystalline ceramics and suppresses a decrease in linear transmittance due to the occurrence of white turbidity. A specific object is to provide a lamp.

    A high-pressure discharge lamp according to a first aspect of the present invention is formed by continuously integrating a surrounding portion made of translucent polycrystalline ceramics and surrounding a discharge space and a pair of small-diameter cylindrical portions extending from both ends of the surrounding portion in the tube axis direction. Provided, the linear transmittance of the main part in the surrounding part exceeds 20%, and the projection part whose height is 10 to 80% with respect to the maximum inner diameter of the surrounding part is on the inner surface of the lower half part in the horizontal lighting of the surrounding part A translucent airtight container formed; a pair of electrodes sealed in the translucent airtight container; and an ionization medium sealed in the translucent airtight container. .

  The height of the protrusion refers to the distance from the intersection of the virtual straight line connecting the tip of the protrusion and the tube axis position in the cross section perpendicular to the tube axis including the tip to the tip of the surrounding portion to the tip. . If the tip position of the protrusion is within the range of 10 to 80%, preferably 20 to 70%, with respect to the maximum inner diameter of the surrounding part, the tip is slightly higher than the high temperature part of the surrounding part, and as a result Cloudiness can be generated intensively at the tip.

  When the height of the protrusion is less than 10%, the tip of the protrusion is too far from the discharge arc, the thermal resistance of the protrusion is reduced, and the temperature of the protrusion is difficult to increase. On the other hand, when the height of the protrusion exceeds 80%, the protrusion is too close to the discharge arc, so that the discharge arc is thick, but for example, the discharge arc is the thinnest as in the case of mercury-free. And even if it is the aspect which is unevenly distributed in the upper part of an envelopment part, the deterioration by the cloudiness and sublimation of the front-end | tip of a projection part becomes remarkable. In some cases, deterioration such as cracking due to thermal shock occurs. It has been found that if the height is 70% or less, it is even easier to avoid deterioration.

  The length, thickness, and number of protrusions in the tube axis direction are not particularly limited. The thickness of the protruding portion refers to a width at a position that is 1/2 of the height of the protruding portion in a cross section perpendicular to the tube axis including the protruding portion. The protrusion may be single or plural.

    The high-pressure discharge lamp of the second invention is formed by continuously integrating a surrounding portion made of translucent polycrystalline ceramics and surrounding a discharge space and a pair of small-diameter cylindrical portions extending from both ends of the surrounding portion in the tube axis direction. A translucent part in which the linear transmittance of the main part in the surrounding part exceeds 20%, and a protrusion that is higher than the temperature of the surrounding part at the time of lighting is formed on the inner surface of the lower half part in the horizontal lighting of the surrounding part And a pair of electrodes sealed in the light-transmitting airtight container; and an ionization medium sealed in the light-transmitting airtight container.

  In the second invention, if the protrusion is heated to a higher temperature than the high temperature part of the surrounding part at the time of lighting, white turbidity generated on the wall surface resulting in a high temperature of the surrounding part is suppressed, so that the shape and size are particularly limited. Not. It should be noted that the temperature of the protruding portion only needs to be slightly higher than the temperature of the high temperature portion on the inner surface of the surrounding portion.

  In the first and second inventions, if the linear transmittance in the main portion of the enclosing portion of the translucent airtight container is less than 20%, it becomes difficult to control light distribution, so that it is not suitable for the purpose of condensing light. That is, when the linear transmittance is less than 20%, even if there is a white turbidity suppressing effect by the protrusions, 80% or more of light diffuses, and thus it cannot contribute to light distribution control. In addition, in the range where the linear transmittance exceeds 20%, as the linear transmittance increases, the degree of contribution to the light distribution control of the white turbidity suppressing effect by the protrusions sequentially increases, and if the linear transmittance exceeds 50%, Will contribute significantly. Therefore, the preferable range of the linear transmittance is 50% or more.

  Further, the protruding portion is disposed in the lower half portion of the surrounding portion in the horizontal lighting. This is because the lower half has little influence on the light distribution when the high-pressure discharge lamp is lit horizontally.

  Furthermore, at least a part of the tip of the protrusion is formed in the region between the pair of electrodes. And the projection part is integrally formed with the translucent airtight container. The linear transmittance of the translucent polycrystalline ceramic forming the protrusions may not exceed 20%, but preferably the linear transmittance exceeds 20%.

  Furthermore, the thickness of the protruding portion may be 20 to 400% of the thickness of the surrounding portion. Note that the thickness of the surrounding portion is an average value of the maximum value and the minimum value of the thickness in the region facing the pair of electrodes. If the thickness of the protrusion is less than 20% of the wall thickness of the surrounding part, the thermal resistance of the protrusion will increase even if the wall thickness of the surrounding part is large, for example 1.5 to 2.5 mm. Therefore, there is a problem that the tip of the protrusion is deteriorated. Further, in the case of a light-transmitting hermetic container in which the thickness of the surrounding portion is small with respect to a certain thickness of the protruding portion, the thickness of the protruding portion is a relatively large value when expressed by the thickness ratio of the surrounding portion. However, if the thickness of the protruding portion is 50% or more regardless of the thickness of any surrounding portion, it works well as the protruding portion. Therefore, a preferable lower limit value of the thickness of the protrusion is 50%.

  On the other hand, the upper limit value of the thickness of the protrusion is 400% or less. However, in the case of the smallest thickness portion such as 0.2 to 0.3 mm, the upper limit value of the thickness of the appropriate protrusion is appropriate. Becomes a value close to 400%. As the wall thickness of the surrounding portion increases, the upper limit value of the appropriate protrusion thickness decreases. However, if the thickness of the protrusion exceeds 400% regardless of the thickness of any surrounding portion, not only the formation of the protrusion becomes difficult, but the thermal resistance becomes too low, and the tip temperature of the protrusion Decreases, and the desired effect of suppressing white turbidity cannot be obtained. Such a problem does not occur if the thickness of the protrusion is 200% or less. Therefore, a suitable upper limit value of the thickness of the protrusion is 200%.

  According to the present invention, since the occurrence of white turbidity in the surrounding portion is suppressed by providing the predetermined protrusion, the linear transmittance of the surrounding portion due to the occurrence of white turbidity is unlikely to be reduced. It is possible to provide a high-pressure discharge lamp suitable for condensing use and a lighting device using the same. This effect is particularly remarkable in mercury-free high-pressure discharge lamps.

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

    1 to 3 show a first embodiment for implementing a high-pressure discharge lamp according to the present invention. FIG. 1 is a cross-sectional view along the tube axis direction, and FIG. 2 is an end view in a cross section perpendicular to the tube axis. 3 is an explanatory view of the structure of the protrusion. In this embodiment, the high-pressure discharge lamp includes a light-transmitting hermetic container 1, a pair of electrodes 2, 2, and an ionization medium.

  First, the translucent airtight container 1 will be described.

  The translucent airtight container 1 is made of translucent polycrystalline ceramics, preferably translucent polycrystalline alumina ceramics, and is integrally formed. And it has the surrounding part 1a, a pair of small diameter cylinder parts 1b and 1b, and the projection part 1d. In addition, integrally molding means not only integral molding, but also, for example, by joining and sintering component parts manufactured in a plurality of parts, resulting in a single, integrally molded translucent It is meant to include what forms an airtight container.

  The surrounding portion 1a is a hollow portion that surrounds the discharge space 1c. In the case of a high-pressure discharge lamp for automobile headlamps, the discharge space 1c preferably has a substantially cylindrical shape. It is preferable that the thickness of the region facing at least a pair of electrodes 2 and 2 described later is substantially uniform. Accordingly, the surrounding portion 1a in this case is substantially cylindrical. However, the outer shape of the surrounding portion 1a and the shape of the discharge space 1c are allowed to have other shapes such as a spherical shape and an elliptical spherical shape as desired. Various values can be selected as the volume of the discharge space 1c formed in the surrounding portion 1a according to the rated lamp power of the high-pressure discharge lamp, the distance between the electrodes, and the like.

  In the present invention, the surrounding portion 1a has a linear transmittance of more than 20%, preferably more than 30%, and more preferably more than 50% in the main part. The main part is an important part having a great influence on light distribution with respect to the derivation of the light generated by the discharge, and is mainly a part facing between a pair of electrodes 2 and 2 described later.

  Then, if the linear transmittance of the main part of the surrounding part 1a is within the above range, light distribution control becomes easy for the purpose of condensing light combined with an optical system such as a reflecting mirror. A high-pressure discharge lamp suitable for such applications can be obtained. However, if the linear transmittance is 20% or less, the discharge arc appears to be too thick, making it difficult to control the light distribution, and a desired light distribution pattern cannot be obtained. Therefore, when it is required to strictly control the light distribution so as to be incorporated in an automobile headlamp or the like and satisfy a predetermined standard, it becomes difficult. In addition, if the linear transmittance is more than 30%, the apparent discharge arc becomes thinner and the light distribution control becomes easier. Furthermore, if it exceeds 50%, the light distribution control becomes even easier. In the present invention, since the higher linear transmittance is preferable, there is no upper limit.

Means for forming the surrounding portion 1a having a high linear transmittance is known. Therefore, if a known means is used, the surrounding portion 1a having a high linear transmittance can be realized as described above. Therefore, in the present invention, the means for forming the surrounding portion 1a having a high linear transmittance is not particularly limited. However, an example of means for forming the surrounding portion 1a having a high linear transmittance is listed as follows.
(1) Translucent polycrystalline ceramics, for example, ceramic fine particles made of alumina ceramics have an average particle size of submicron order, for example, high linear transmittance ceramic fine particles having an average particle size of 0.1 to 6 μm. The airtight container 1 is formed.
(2) The surface of a desired portion of the translucent airtight container 1 such as the inner surface, the outer surface or the inner surface and the outer surface is polished after the translucent polycrystalline ceramic is formed.
(3) The high linear transmittance ceramic fine particles are used for the surrounding portion 1a, and the small diameter cylindrical portion 1b is integrally formed using ceramic fine particles whose general average particle size is one digit or more larger than that of the high linear transmittance ceramic fine particles. Mold.
(4) The above means (1) to (3) are appropriately combined.

  Translucent polycrystalline ceramics formed using high linear transmittance ceramic fine particles have higher mechanical strength than conventional translucent polycrystalline ceramics, so they are formed using the former ceramics. It has been found that the surrounding portion 1a can retain the required mechanical strength even if the wall thickness is reduced compared to the wall thickness of the small-diameter cylindrical portion formed using the latter ceramic.

  For the above reasons, the wall thickness is preferably within a range of 0.2 to 1.5 mm and substantially constant in the region facing the pair of electrodes 2 and 2 of the surrounding portion 1a in the translucent airtight container 1. Can be formed. If the thickness at the above-mentioned part is within the above range, there is no problem with the pressure resistance of the surrounding portion 1a at the time of lighting, and the linear transmittance of the surrounding portion 1a is within the predetermined range of the present invention according to the small thickness. Easy to fit in. However, when the thickness is less than 0.2 mm, the pressure resistance is too low, and when it exceeds 1.5 mm, it is difficult to keep the linear transmittance within the above range. The wall thickness of the surrounding portion 1a is preferably 0.3 to 0.8 mm. Within this range, both the linear transmittance and the withstand voltage are even more preferable. Note that the size of the surrounding portion in the tube axis direction is up to a portion where a small-diameter cylindrical portion to be described later is joined, and this portion is a portion where the curvature greatly changes.

  Further, if the thickness of the predetermined portion of the surrounding portion 1a is substantially constant, the light distribution pattern of the high-pressure discharge lamp does not cause undesired deterioration and difficulty in light distribution design due to the uneven thickness. It should be noted that the thickness of the surrounding portion 1a may be constant only in the region facing the pair of electrodes 2 and 2, and the remaining regions may have different thicknesses or the thicknesses may be uneven. It may be. This is because the remaining area has little influence on the light distribution. For example, the remaining region of the surrounding portion 1a may be configured such that the thickness increases sequentially from the region facing the pair of electrodes 2 and 2 to the portion from the small diameter cylindrical portion 1b. If desired, the average thickness in the remaining area of the translucent airtight container 1 excluding the area facing the L between the pair of electrodes 2 and 2 in the surrounding part 1a, that is, in the area from the tip of the electrode 2 to the small-diameter cylindrical part 1b. It can be configured such that the thickness is larger than that in the portion facing between the pair of electrodes 2 and 2, and the thickest portion is in the range of 0.8 to 2.5 mm. Thus, the remaining area does not have much influence on the light distribution of the high-pressure discharge lamp, and therefore it may be thick. Further, with such a configuration, the mechanical strength of the translucent airtight container 1 is ensured, the degree of freedom in designing the translucent airtight container 1 is increased, and manufacturing is facilitated.

  In the present invention, the inner diameter of the surrounding portion 1a is not particularly limited. In the case of a high-pressure discharge lamp for automobile headlamps, etc., the discharge space 1c has a substantially columnar shape, the main part of the surrounding portion 1a has a cylindrical shape, and the inner diameter is preferably 2.1 to It is optimal when it is within the range of 3.7 mm or 4.5 mm, preferably 2.4 to 3.4 mm.

  That is, unlike the case where the light-transmitting hermetic container 1 is made of quartz glass, the refractive index and thickness of the material are different, so that even if a discharge arc having the same shape occurs, the apparent arc bending amount is reduced. This is because polycrystalline ceramics and quartz glass look different. However, when the inner diameter is less than 2.1 mm, the inner surface of the surrounding portion is likely to become clouded or crack due to ceramic sublimation due to the high heat of the discharge arc. On the other hand, if it exceeds 3.7 mm or 4.5 mm, the curvature due to the buoyancy of the discharge arc becomes large, and a desired light distribution pattern cannot be obtained particularly for automobile headlamps.

  Next, the pair of small diameter cylindrical portions 1b and 1b are connected to both ends of the surrounding portion 1a in the tube axis direction. The inner diameter of the small-diameter cylindrical portion 1b is clearly smaller than the inner diameter of the surrounding portion 1a, for example, 1/3 or less. And in the state which the translucent airtight container 1 is not sealed, it has the elongate through-hole extended in a pipe-axis direction inside the small diameter cylinder part 1a, The one end is in the discharge space 1c of the enclosure part 1a. The other end is open to the outside.

  Further, the linear transmittance of the pair of small diameter cylindrical portions 1b and 1b is lower than the linear transmittance of the surrounding portion 1a. Since the linear transmittance of the small-diameter cylindrical portion 1b hardly affects the light distribution directly, it may be lower than the linear transmittance of the surrounding portion 1a.

  If the linear transmittance is relatively low, the surface of the small-diameter cylindrical portion 1b, for example, the outer surface is polished even when the surface of the surrounding portion 1a, for example, the outer surface is polished to increase the linear transmittance. The small-diameter cylindrical portion 1b can be formed using translucent ceramic particles having a large average particle diameter that is usually used as described above. Therefore, the high-pressure discharge lamp can be easily manufactured and is inexpensive.

  The surrounding portion 1a and the pair of small diameter cylindrical portions 1b, 1b of the translucent airtight container 1 are continuously integrated. For this reason, the translucent airtight container 1 is not formed with thermal and optical discontinuous portions. According to the most typical structure in this configuration, the surrounding portion 1a and the pair of small diameter cylindrical portions 1b, 1b of the translucent airtight container 1 are formed by integral molding. Further, according to the different structure, in the stage before forming the translucent airtight container 1, the whole of the surrounding portion 1 a and the pair of small diameter cylindrical portions 1 b, 1 b or those portions are used as separate members, respectively. It is prepared by compression molding or pre-sintering, and then each member is assembled in the form of a light-transmitting airtight container in the sintering mold and then sintered, so that it is adjacent to another member. The ceramic particles in between are directly bonded to obtain a light-transmitting hermetic container 1 having no thermal and optical discontinuities. In the translucent airtight container having a so-called shrink-fit structure, a thermal and optical discontinuous portion is formed. However, as long as there is an effect of the present invention, it can be applied unless there are special circumstances. is there.

  Next, the protrusion 1d will be described.

  The projecting portion 1d is formed so as to extend vertically from the center of the bottom surface in the horizontal lighting of the inner surface of the surrounding portion 1a and in the tube axis direction, and project in a hook shape. As shown in FIG. 3, the height of the projection 1d is perpendicular to the tube axis x and connects the tip 1d1 and the tube axis x in a cross section including the tip 1d1 of the projection 1d. This value is obtained from the distance L from the intersection P between the virtual straight line sl and the inner surface of the surrounding portion 1a toward the tube axis x, and this height L is set to 10 to 80% with respect to the maximum inner diameter of the surrounding portion 1a. Yes.

  Further, the thickness t, which is a width at half the height of the protruding portion 1d, is set to 20 to 400% of the wall thickness of the surrounding portion. Further, the protruding portion 1d is positioned between a pair of electrodes 2 and 2, which will be described later, in the tube axis direction, and extends in the tube axis direction.

  Next, the pair of electrodes 2 and 2 will be described.

  The pair of electrodes 2 and 2 are disposed so as to be sealed in the translucent airtight container 1 and face the discharge space 1c inside. The distance between the electrodes formed between the pair of electrodes 2 and 2 is generally preferably 1.0 to 50 mm, and in the case of a high-pressure discharge lamp for an automobile headlamp, 5 mm or less is preferable. The center value is 4.2 mm.

  Further, the constituent material of the electrode 2 is heat-resistant and has a conductive metal such as pure tungsten (W), a dopant (such as scandium (Sc), aluminum (Al), potassium (K) and silicon (Si). 1) or a doped tungsten containing thorium oxide, rhenium (Re) or tungsten-rhenium (W-Re) alloy, or the like. Can do.

  Furthermore, in the case of a small high-pressure discharge lamp, a straight rod-shaped wire or a wire with a large diameter formed at the tip can be used as the electrode. In the case of a medium or large electrode, an electrode coil made of an electrode constituent material can be wound around the tip of the electrode shaft. The pair of electrodes 2 and 2 have the same structure when operating with an alternating current. However, when operating with direct current, since the temperature of the anode is generally large, the heat radiation area is larger than that of the cathode, and thus the main part can be thick.

  In addition, the pair of electrodes 2 and 2 have intermediate portions and proximal ends inserted into the small diameter cylindrical portions 1b and 1b of the translucent airtight container 1, if desired, and are referred to as capillaries between the inner surfaces of the small diameter cylindrical portions 1b. It is permissible to form a slight gap. The base ends of the pair of electrodes 2 and 2 are connected to and supported by the distal end of an introduction conductor 3 described later.

  Next, the ionization medium will be described.

  The ionization medium includes at least a starting gas and an ionization medium that contributes to light emission. Note that the start gas may serve as a medium that contributes to light emission if desired. In the case of a mercury-free high-pressure discharge lamp, it is preferably allowed to contain an ionization medium for forming a lamp voltage.

  The starting gas also acts as a buffer gas, and can enclose one kind of group such as xenon (Xe), argon (Ar), and neon (Ne) alone, or a mixture of plural kinds. The enclosure pressure of the rare gas can be appropriately set according to the use of the high pressure discharge lamp.

  Among rare gases, xenon has a relatively low thermal conductivity because its atomic weight is larger than other rare gases, so that it is sealed at 0.6 atm or more, preferably at least 5 atm. This contributes to the formation of the lamp voltage and emits white visible light when the vapor pressure of the halide is low, thereby contributing to the rise of the luminous flux, which is effective in the case of a high-pressure discharge lamp for a headlamp. In this case, the preferable sealing pressure of xenon is 6 atmospheres or more, more preferably in the range of 8 to 16 atmospheres. For this reason, it contributes to luminous flux rise and light color rise immediately after lighting, and can satisfy the standard of white light emission as an HID light source for automobile headlamps immediately after lighting.

  The medium that contributes to light emission is mainly composed of a halide of a light emitting metal, and it is allowed to enclose the light emitting metal as it is if desired. In the present invention, the luminescent metal is not particularly limited, but as a preferred example, a thulium (Tm) halide can be mainly encapsulated.

  Thulium halide is a luminescent metal halide suitable as a mercury-free high-pressure discharge lamp, and mainly emits visible light by discharge. Further, thulium halide can be sealed at a maximum sealing ratio in the ionization medium sealed in the light-transmitting hermetic container 1, preferably 40 to 90% by mass in addition to this condition. Thulium halide itself has a high vapor pressure, which is an ionization medium for forming a lamp voltage, which will be described later, and is itself a potential between electrodes 2 and 2 in the presence of a metal halide that emits less visible light. It has the effect of increasing the gradient and hence the lamp voltage.

  In addition, thulium halide has a low vapor pressure, but the thulium emission peak coincides with the peak of the visibility curve. Therefore, thulium halide is a luminescent metal that is extremely effective for improving the luminous efficiency. The emission intensity of thulium greatly depends on the operating temperature during lighting of the high-pressure discharge lamp, and the efficiency becomes maximum under the condition that the coldest part temperature is about 800 ° C. When the translucent airtight container 1 is made of translucent ceramics, there is no problem in operation under conditions where the coldest part temperature is about 800 ° C., and the chemical resistance is strong. The inclusion of the halide does not adversely affect the lamp life and the luminous flux maintenance factor. That is, thulium halide is a luminescent metal halide suitable for a high-pressure discharge lamp using an airtight container made of translucent ceramics.

  In addition to the above, other luminescent metal halides allowed to be sealed include the following.

  1. (Alkali Metal) As the alkali metal, sodium (Na), but optionally and / or at least one of cesium (Cs) and lithium (Li) can be selectively encapsulated.

  Sodium (Na) mainly contributes to the improvement of luminous efficiency. Cesium (Cs) contributes to the improvement of life characteristics by optimizing the discharge arc temperature. Lithium (Li) contributes to the improvement of red color rendering.

  2. (Other Rare Earth Metal Halides) In addition to thulium halides, the following metal halides can be encapsulated mainly as luminescent metal halides. One or a plurality of halides of rare earth metals in the group consisting of praseodymium (Pr), cerium (Ce), holmium (Ho), neodymium (Nd) and samarium (Sm).

  The rare earth metal is useful as a luminescent metal next to thulium halide, and is allowed to be encapsulated at an encapsulation ratio of a predetermined amount or less. That is, any of the rare earth metals has an infinite number of bright line spectra in the vicinity of the peak wavelength of the visibility characteristic curve, and thus can contribute to an improvement in luminous efficiency.

  In addition, when the rare earth metal halide is added, it is preferable that the encapsulation ratio with respect to the total ionization medium including the thulium (Tm) halide is 50 mass% or more.

  3. (Thallium or / and indium halide) The thallium (Tl) and / or indium (In) halide is selectively encapsulated as a secondary component for the purpose of obtaining a desired color rendering property and / or color temperature. It is acceptable. Indium is also effective as an ionization medium for forming a lamp voltage.

  The thallium (Tl) halide can add a green component of thallium having an emission line at a wavelength of 535 nm during light emission. In addition, it is desirable that the enclosure ratio range of thallium halide that can be generally adopted is less than 30% by mass with respect to all the metal halides to be enclosed. When the enclosure ratio range of thallium halide is 30% by mass or more, the decrease in luminous efficiency becomes significant. In addition, it is preferable to enclose within a range of less than 15% by mass.

  Further, by adding indium (In) halide, the blue component can be increased during light emission of the halide, and also contributes to the formation of a lamp voltage.

  As the halogen of each luminescent metal halide described above, iodine is suitable because it has moderate reactivity. However, if desired, either bromine or chlorine may be used, and iodine, bromine and chlorine may be used. Two or more desired ones may be used.

  Next, as a lamp voltage forming ionization medium, when a mercury-free high-pressure discharge lamp is obtained, it is preferable to enclose a metal halide having a high vapor pressure and low visible light emission as described above. In this case, it is preferable not to contain mercury (Hg) at all for the purpose of reducing environmentally hazardous substances, but it is acceptable even if it is contained to the extent of impurities. Further, when obtaining a high-pressure discharge lamp containing mercury, mercury is enclosed.

  In the case of mercury-free, for example, the following metals are effective to be sealed as an ionization medium for forming a lamp voltage. That is, zinc (Zn), aluminum (Al), magnesium (Mg), iron (Fe), cobalt (Co), chromium (Cr), nickel (Ni), manganese (Mn), aluminum (Al), antimony (Sb) ), Beryllium (Be), rhenium (Re), gallium (Ga), titanium (Ti), zirconium (Zr), and hafnium (Hf). Since each metal halide has a high vapor pressure, a large cross-sectional area of collision with electrons, and a large ionization potential, in combination with the light-transmitting hermetic vessel 1 described above, a lamp voltage can be formed instead of mercury. It is a material suitable as an ionization medium for use.

  Next, other configurations will be described.

  In this embodiment, in addition to the main components described above, the following components can be provided.

  1. About the introduction conductor 3.

  The introduction conductor 3 is a member having a function for supplying power to the electrode 2, a function for sealing the translucent airtight container 1 in cooperation with the small-diameter cylindrical portion 1 b and a sealing material 4 described later, and a function for supporting the electrode 2. It is. The base end portion is exposed to the outside from the end portion of the small-diameter cylindrical portion 1 b and connected to a lighting circuit (not shown), and the tip end portion is connected to the base end of the electrode 2. The distal end portion of the introduction conductor 3 is inserted into the small diameter cylindrical portion 1b of the translucent airtight container 1, and is further connected to the proximal end of the electrode 2 inside the small diameter cylindrical portion 1b.

  Further, the diameter of the portion inserted into the small diameter cylindrical portion 1b of the introduction conductor 3 can be made larger than at least the base end portion of the electrode 2, preferably the diameter of the electrode shaft. Thereby, the diameter of the electrode 2 or the electrode shaft 2a can be set to an optimum size without being influenced by the diameter of the introduction conductor 3, and erosion due to the retention of the ionized medium is reduced.

  Further, the entire introduction conductor 3 may be formed of a sealing conductive member, or may be formed of a series connection structure of a sealing conductive member and a halogen-resistant conductive member. When the entire introduced conductor 3 is formed of a sealing conductive member, it is a matter of course that the sealing conductive member takes into account the above three functions. On the other hand, when the introduction conductor 3 is formed of a serially connected structure of a sealing conductive member and a halogen-resistant conductive member, the sealing conductive member cooperates with the small-diameter cylindrical portion and a sealing material 4 described later. Thus, the function of sealing the translucent airtight container 1 is in charge, the halogen-resistant conductive member is in charge of the function of supporting the electrode, and both members are in charge of the function of supplying power to the electrode.

  As the sealing conductive member, a conductive member having a thermal expansion coefficient close to that of the electrode is preferably used. For example, niobium (Nb), tantalum (Ta), platinum (Pt), or the like can be used depending on the type of translucent ceramic. In addition, niobium is suitable when the translucent airtight container 1 is made of translucent polycrystalline alumina ceramics.

  As the halogen-resistant conductive member, a member having fire resistance that can withstand heat transfer from the electrode and a thermal expansion coefficient close to that of the electrode constituent material is preferably used. For example, it can be selected from tungsten (W), molybdenum (Mo), cermet and the like. The cermet is formed by firing a mixture of ceramic particles and refractory conductive metal (for example, Mo or W) powder.

  In order to connect the electrode 2 to the lead-in conductor 3 in advance to support the electrode 2 and facilitate assembly with respect to the translucent airtight container 1, for example, they can be integrated by butt welding to form an electrode mount. Further, when the lead-in conductor 3 is formed of a sealing conductive member and a halogen-resistant conductive member, they can be integrated by butt welding.

  2. About the sealing material 4.

  The sealing material 4 is made of high melting point frit glass or the like, and enters between the inner surface of the small-diameter cylindrical portion 1b of the translucent airtight container 1 and the introduction conductor 3 to seal the translucent airtight container 1 in an airtight manner. In order to perform this sealing, pellets of the sealing material 4 are applied around the introduction conductor 3 at the end of the small-diameter cylindrical portion 1b and melted by heating, as is adopted as a general method. Can do. If it does so, since the sealing material 4 fuse | melted at high temperature will approach into the slight clearance gap formed between the inner surface of the small diameter cylinder part 1b, and the introductory conductor 3, it will solidify. Since the sealing material 4 covers a portion that functions to seal the introduction conductor 3, even if the introduction conductor 3 is partly or entirely formed of a material that is inferior in halogen resistance such as niobium. no problem.

  3. About the outer tube.

  An assembly comprising the translucent airtight container 1, the pair of electrodes 2, 2, the ionization medium, the current introduction conductor 3, and the seal material 4 is used as an arc tube, and this arc tube is further accommodated in an outer tube (not shown). be able to.

  Example 1 relates to the high-pressure discharge lamp shown in FIGS. 1 and 2.

Translucent airtight container: integrally molded, surrounding portion length 8 mm, maximum inner diameter 2.9 mm,
Uniform thickness of 0.5mm, the surrounding part linear transmittance 30%,
Small diameter cylindrical part inner diameter 0.7mm, wall thickness 0.5mm, length 12mm,
Small-diameter cylindrical part linear transmittance 20%
Projection height 1.45mm, thickness 0.5mm, length 3mm
Ionization medium: TmI ₃ -TlI-NaI-ZnI ₂ = 3 mg
(50: 20: 20: 10), Xe 10 atm,
The number in parentheses is the enclosing ratio (mass%)
Rated lamp power: 35W
The degree of white turbidity: 1000 hours after lighting, and about 1/4 of the comparative example having the same specifications as in this example except that no protrusions were provided.

4 and 5 show a second embodiment for carrying out the high-pressure discharge lamp of the present invention. FIG. 4 is a sectional view along the tube axis direction, and FIG. 5 is an end view in a section perpendicular to the tube axis. . In addition, in each figure, about the same part as FIG. 1 and FIG. 2, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In this embodiment, the structure of the protrusion 1d is different. In other words, in the present embodiment, the protrusions 1d and 1d that form a pair of rods project from the lower side of the left and right wall surfaces of the surrounding portion 1a toward the tube axis x toward the tube axis x and project obliquely upward. Yes. Further, the projecting portions 1d and 1d are formed in a substantially central portion between the pair of electrodes 2 and 2 in the tube axis direction.

  Example 2 relates to the high-pressure discharge lamp shown in FIGS. 4 and 5.

Protrusion part: Diameter 0.8mm, height 1.2mm
Others are the same as Example 1.

The degree of white turbidity: 1000 hours after lighting, and about 1/3 of the comparative example having the same specifications as in this example except that no protrusions were provided.

Next, with reference to FIGS. 6 to 8, the influence when the linear transmittance of the protrusion and the surrounding portion is changed will be described.

    FIG. 6 is a graph showing the results of testing the relationship between the white turbidity suppressing effect and the deterioration of the protrusion when the height of the protrusion is changed. In the figure, the horizontal axis indicates the height (%) of the protrusion, and the vertical axis indicates the white turbidity generation inhibition rate (%) and the deterioration failure occurrence rate (%). The height of the protrusion is a ratio with respect to the maximum inner diameter of the surrounding portion. In the figure, the curve A shows the white turbidity occurrence suppression rate, and the curve B shows the deterioration failure occurrence rate.

  As can be seen from the figure, when the height is 20 to 80%, the higher the color, the more the occurrence of white turbidity is suppressed. However, when the height of the protrusion exceeds 80%, the rate of occurrence of deterioration defects increases. Too much.

    FIG. 7 is a graph showing the relationship between the white turbidity suppressing effect and the deterioration of the protrusions when the thickness of the protrusions is changed. In the figure, the horizontal axis indicates the thickness (%) of the protrusion, and the vertical axis indicates the white turbidity generation inhibition rate (%) and the deterioration failure occurrence rate (%). In addition, the thickness of the protrusion is shown as a ratio to the thickness of the surrounding portion. In the figure, the curve C indicates the white turbidity occurrence suppression rate, and the curve D indicates the deterioration failure occurrence rate.

  As can be seen from the figure, when the thickness is 20 to 400%, the cloudiness is more suppressed when the thickness is thicker. However, when the thickness of the protrusion exceeds 400%, the increase in the occurrence rate of deterioration is remarkable. become.

    FIG. 8 is a graph showing the relationship between the linear transmittance of the surrounding portion and the light distribution controllable rate. In the figure, the horizontal axis represents the linear transmittance (%), and the vertical axis represents the light distribution controllable rate (%).

  As can be understood from the figure, when the linear transmittance is 20% or more, the light distribution controllable rate increases proportionally.

    FIG. 9 is a circuit diagram showing a high pressure discharge lamp lighting device for lighting the high pressure discharge lamp of the present invention. In the figure, the high pressure discharge lamp lighting device comprises a DC power source 21, a boost chopper 22, an inverter 23 and a control circuit 24, and lights any one of the high pressure discharge lamps 13 shown in FIGS. The DC power source 21 includes a battery power source, a rectified DC power source, and the like, and has a smoothing capacitor C1 connected between DC output terminals. The step-up chopper 22 boosts the DC voltage supplied from the DC power supply 21 to a required voltage, smoothes it, and supplies the input voltage to the inverter 23 described later. Reference numeral 22a denotes a drive circuit that drives the switching element of the step-up chopper 22. The inverter 23 is a full bridge type inverter. Then, four switching elements Q1 to Q4 are bridge-connected, and a pair of switching elements Q1 and Q3 constituting the opposite two sides and a pair of switching elements Q2 and Q4 constituting the other two opposite sides are alternately switched. Then, a rectangular wave AC voltage is output between the output terminals. Reference numeral 23a denotes a drive circuit that drives the switching elements Q1 to Q4 of the inverter 23. The control circuit 24 requires the step-up chopper 22 and the inverter 23, for example, when the high-pressure discharge lamp 13 is in a cooled state, about twice or more, for example, 2.5 times the rated lamp power for a few seconds immediately after the high-pressure discharge lamp 13 is started. It is controlled so that it is lit at a certain level and then gradually reduced to shift to the rated lamp power during stable lighting.

  The starter 12B outputs a high voltage pulse when the high pressure discharge lamp 13 is started and applies it to the high pressure discharge lamp 13 to start it instantaneously.

    FIG. 10 is a conceptual diagram showing an automobile headlamp as an embodiment for carrying out the lighting 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 high pressure discharge lamp.

  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. 4 and includes a main lighting circuit 12A and a starter 12B.

  The high-pressure discharge lamp 13 is mounted on the lamp socket and lights up.

Sectional drawing which follows the pipe-axis direction which shows the 1st form for implementing the high-pressure discharge lamp of this invention An end view of the cross section perpendicular to the tube axis Similarly, the structure of the protrusion Sectional drawing which follows the pipe-axis direction which shows the 2nd form for implementing the high-pressure discharge lamp of this invention An end view of the cross section perpendicular to the tube axis A graph showing the relationship between the clouding suppression effect and the deterioration of the protrusion when the height of the protrusion is changed A graph showing the relationship between the clouding suppression effect and the deterioration of the protrusion when the thickness of the protrusion is changed A graph showing the relationship between the linear transmittance of the surrounding part and the light distribution controllable rate The circuit diagram which shows the high pressure discharge lamp lighting device for lighting the high pressure discharge lamp of this invention The conceptual diagram which shows the motor vehicle headlamp as one form for implementing the illuminating device of this invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Translucent airtight container, 1a ... Enclosing part, 1a1 ... Straight part, 1b ... Sealing part, 1c ... Discharge space, 1d ... Projection part, 2 ... Electrode, 3 ... Introduction conductor, 4 ... Sealing material

Claims (4)

Consists of a light-transmitting polycrystalline ceramic that surrounds the discharge space and a pair of small-diameter cylindrical portions that extend from both ends in the tube axis direction of the envelope in a continuous and integrated manner. A translucent airtight container having a rate of more than 20% and a height of 10 to 80% of the maximum inner diameter of the surrounding portion formed on the inner surface of the lower half of the surrounding portion in horizontal lighting; ;
A pair of electrodes sealed in a translucent airtight container;
An ionization medium enclosed in a translucent airtight container;
A high-pressure discharge lamp comprising: Consists of a light-transmitting polycrystalline ceramic that surrounds the discharge space and a pair of small-diameter cylindrical portions that extend from both ends in the tube axis direction of the envelope in a continuous and integrated manner. A translucent airtight container in which the rate exceeds 20% and a protrusion that is higher than the temperature of the surrounding portion when lit is formed on the inner surface of the lower half of the surrounding portion in the horizontal lighting;
A pair of electrodes sealed in a translucent airtight container;
An ionization medium enclosed in a translucent airtight container;
A high-pressure discharge lamp comprising:   The high pressure discharge lamp according to claim 1 or 2, wherein the translucent airtight container has a thickness of a projection of 20 to 400% of a thickness of the surrounding portion. A lighting device body;
A high-pressure discharge lamp according to any one of claims 1 to 3 disposed in a lighting device body;
An illumination device comprising:

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