JP4289430B2 - Metal halide lamp and lighting device using it - Google Patents

Description

  The present invention relates to a ceramic halide tube metal halide lamp used for outdoor illumination, high ceiling illumination, and the like.

  In recent years, ceramic metal halide lamps using ceramics have been actively developed as arc tube materials for metal halide lamps. A ceramic arc tube has a feature that it has less reaction with the luminescent material than a quartz arc tube.

  Taking advantage of this feature, ceramic metal halide lamps using halides, which have a relatively large reaction with quartz and have been difficult to use with quartz arc tubes, have been studied (hereinafter simply referred to as ceramic metal halide lamps). This is called “metal halide lamp”).

  Among metal halide lamps using a ceramic arc tube, there is a metal halide lamp containing Ce (cerium) in the arc tube (for example, Patent Document 1). This metal halide lamp includes Ce and Na (sodium) iodide in a ceramic discharge tube, where EA / Di> 5, where EA is the distance between the tips of the electrodes and Di is the inner diameter of the discharge tube. Disclosure. According to Patent Document 1, it is described that a lamp with a color rendering index Ra of 45 to 64 can be obtained with a luminous efficiency of 110 to 177 LPW by the above configuration. Here, “LPW” is an abbreviation of “lumen per Watt” and means “lm / W”. Although this metal halide lamp has a relatively high luminous efficiency, the light color tends to be biased to green, and the color rendering index Ra for evaluating the appearance of the color also shows a low value.

As a means for improving color rendering, there is a metal halide lamp containing a rare earth metal and Ca (calcium) in the arc tube (for example, Patent Document 2). In Patent Document 2, a ceramic discharge vessel has a halide of at least one element of Na (sodium), Tl (thallium), Dy (dysprosium) and Ho (holmium) in addition to mercury. Having a molar amount of CaI ₂ (calcium iodide) that is between 30 and 50% of the total molar amount of the halide. It is described that this configuration reduces the crest factor, which is the ratio between the reignition voltage and the arc voltage.
JP 2000-501563 A (page 8-9) JP 2000-511689 (page 6-8)

  However, when the technology of Patent Document 1 and the technology of Patent Document 2 are combined, a metal halide lamp in which a halide of cerium, sodium and calcium is sealed in a ceramic arc tube having various aspect ratios is prototyped. It has been newly found that a problem arises that a crack occurs in a part of a ceramic arc tube and leaks.

In a metal halide lamp using a ceramic arc tube containing sodium (Na), thallium (Tl), dysprosium (Dy), holmium (Ho), etc. that are currently commercialized, cracks occur in such an arc tube. The phenomenon has not been seen. This phenomenon occurs remarkably when Ce halide and Na halide contain Ca halide (for example, CaI ₂ ).

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to contain Ce halide and Ca halide in an arc tube made of ceramic that does not crack during lighting. An object of the present invention is to provide a metal halide lamp and a lighting device using the metal halide lamp.

  In order to solve the above-mentioned problems, a metal halide lamp according to the present invention includes an arc tube formed of a translucent ceramic, a pair of opposed electrodes, and an outer tube made of hard glass provided outside the arc tube. A halide of Ce (cerium), a halide of Na (sodium), and a halide of Ca (calcium) enclosed in the arc tube, wherein the light emission When the inner diameter of the tube is D (mm) and the distance between the tips of the electrodes is L (mm), L / D is

の関係を満たし、前記Ｃａのハロゲン化物の封入量をＨ_ca（ｍｏｌ）、前記Ｃｅのハロゲン化物の封入量をＨ_ce（ｍｏｌ）とした場合に、Ｈ_ca／Ｈ_ceは、

H _ca / H _ce is obtained when the amount of Ca halide enclosed is H _ca (mol) and the amount of Ce halide enclosed is H _ce (mol).

の関係を満たし、前記封入物のうち、前記Ｃａのハロゲン化物以外のハロゲン化物の総封入量をＨ_t（ｍｏｌ）とした場合に、Ｈ_ca／Ｈ_tは、

H _ca / H _t , where H _t (mol) is the total encapsulated amount of halide other than the Ca halide among the encapsulated materials,

の関係を満たし、３００Ｋにおいて、前記外管の内側と前記発光管の外側の空間の気圧が、５×１０⁴（Ｐａ）以下の関係を満たす。

At 300K, the atmospheric pressure in the space inside the outer tube and outside the arc tube satisfies the relationship of 5 × 10 ⁴ (Pa) or less.

The present invention relates to an arc tube formed of a translucent ceramic, a pair of opposing electrodes, an outer tube made of hard glass provided outside the arc tube, and a halide sealed in the arc tube. When the inner diameter of the arc tube is D (mm) and the distance between the tips of the electrodes is L (mm), L / D is 1 or less, and the amount of Ca halide enclosed is H _ca (Mol) When the amount of Ce halide enclosed is H _ce (mol), cracks are suppressed and lamp efficiency is improved by setting H _ca / H _ce to be 0.4 or more and 15 or less. be able to. Further, dimming was performed by making H _ca / H _t larger than 0.03 and smaller than 0.3 when the total amount of halides other than the Ca halide was H _t (mol). Sometimes the color change can be reduced. Furthermore, at 300K, lamp performance such as luminous efficiency can be enhanced by satisfying a relationship of 5 × 10 ⁴ (Pa) or less in the space inside the outer tube and outside the arc tube.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited only to the following embodiment.

(Embodiment 1)
FIG. 1 shows a partial cross-sectional view of a metal halide lamp 10 of the present embodiment. The metal halide lamp 10 is largely divided into an arc tube 20, an outer tube 11 provided outside the arc tube, and a base 12 fitted in the outer tube 11.

The outer tube 11 has a substantially spherical shape and is made of borosilicate glass that is hard glass. The atmospheric pressure in the space between the inner side of the outer tube 11 and the outer side of the arc tube 20 is a reduced pressure state and is 1 × 10 ⁻¹ (Pa) at 300K.

  The base 12 is electrically connected to lead-in electrode wires 14 and 15 made of nickel or mild steel. The wire 14 and the wire 15 are connected through the flare 16 made of borosilicate glass. The flare 16 is disposed at the position of the base 12 and extends into the outer tube 11 along the central axis (dashed line 104 in FIG. 1) in the major axis direction of the arc tube 20.

  The portion of the wire 15 parallel to the central axis 104 passes through the aluminum oxide ceramic tube 18 so that no photoelectrons are generated from the surface of the wire 15 during lamp operation. A getter 19 that captures gas impurities is supported on a portion of the wire 15 parallel to the central axis 104.

  Further, each of the wire 14 and the wire 15 is welded to a pair of lead wires 26 taken out from the arc tube 20, and the arc tube 20 is fixed by the wire 14 and the wire 15.

  Further, the tip of the wire 15 (the end in the direction opposite to the base 12 in FIG. 1) has a ring shape, and meshes with a recess provided in the outer tube 11 and is fixed.

  Next, the arc tube 20 will be described in detail with reference to FIG.

  An enlarged cross-sectional view of the arc tube 20 is shown in FIG. The arc tube 20 includes an arc tube central portion 25 that serves as a light emission space (or also called “discharge space”) by enclosing an enclosure, and a pair of cylindrical tubes 21. The tube 21 is shrink-fitted to the corresponding end portions of the two open end portions of the arc tube central portion 25.

  The arc tube 20 is made of translucent ceramic. In this embodiment, it is made of polycrystalline alumina. The arc tube 20 may be made of a material selected from yttrium-aluminum-garnet (so-called YAG), aluminum nitride, yttria, zirconia, and the like.

  The arc tube central portion 25 includes a cylindrical first cylindrical shell portion 101, cylindrical second cylindrical shell portions 102 having extremely small diameters provided at both ends, an end portion of the first shell portion 101, and a second portion. It has a conical shell portion 103 that joins the end of the shell portion 102 to form a light emitting space.

  A part of a pair of electrodes in which a main electrode 31 made of tungsten and an electrode coil 32 made of tungsten are integrated by welding are disposed in the light emitting space of the arc tube central portion 25, and the electrode coil 32 is a light emitting space. It arrange | positions so that it may oppose in.

  A pair of lead wires 29 made of molybdenum is connected to one end of each main electrode 31, and each lead wire 29 is disposed in the tube 21.

  A pair of lead wires 26 made of niobium is connected to the other end of each lead-in wire 29 opposite to the end to which the main electrode 31 is connected. The lead wire 26 is connected to the arc tube 20. Has been taken out of the outside. Further, the lead wire 26 is sealed with a glass frit 27 having a thermal expansion characteristic relatively close to that of the tube 21. One lead wire 26 is welded to the wire 14, and the other lead wire 26 is welded to the wire 15. The arc tube 20 is arranged and supported on the wire 14 and the wire 15 by these weldings.

  With the above configuration, the electric power input from the base 12 is provided to the arc tube 20 through the wire 14 and the wire 15.

  The diameter of the lead wire 26 is typically 0.9 mm. The diameter of the main electrode shaft 31 is typically 0.5 mm.

In this embodiment, the distance L between the tips of the pair of opposed electrodes is 32 mm, and the inner diameter D of the arc tube central portion 25 of the arc tube central portion 25 located at the center between the tips of the electrodes is 4 mm. That is, L / D = 8. In addition, the substantial inner volume of the arc tube 25 when the electrode is inserted is about 0.45 cc. Further, the tube wall load of the arc tube 20 is about 20 to 35 W / cm ² .

  Here, as the enclosure to be enclosed in the arc tube 20, cerium iodide, which is a halide of cerium (Ce), sodium iodide, which is a halide of sodium (Na), and iodide, which is a halide of calcium (Ca). Trials (samples 1 to 15) were made using calcium and varying the amount of each encapsulated. Further, the arc tube 20 is filled with xenon (Xe) gas at room temperature and a pressure of about 20 kPa. In Samples 1 to 15, 3 to 12 mg of sodium iodide was sealed, and the molar ratio of calcium iodide to cerium iodide was changed from 0 to 18.0. At this time, the amount of encapsulation was changed between 0 to 4 mg for cerium iodide and 0.5 to 15 mg for calcium iodide.

  The metal halide lamp of this embodiment was lit with an electronic ballast, lit with a rectangular wave alternating current with a rated power of 150 W and a frequency of 150 Hz, and a lighting test was performed while repeating at a constant ON / OFF cycle.

  As a result of the lighting test evaluation, it has been found that there is a metal halide lamp that becomes inconspicuous as a result of cracks occurring near the end of the arc tube central portion 25 during lighting and leakage.

The result is shown in FIG. The table of FIG. 3 shows H _ca / H _ce when the number of moles of cerium iodide sealed in the arc tube 20 of the prototype is H _ce , and the number of moles of calcium iodide is H _ca, and the enclosed halogen. The total amount (mg) of the compound, the presence or absence of cracks, and the color rendering index Ra are shown.

As can be seen from the results of FIG. 3, it was found that the lamp encapsulated so that H _ca / H _ce was 16 or more was cracked. On the other hand, the lamp with H _ca / H _ce of 15 or less did not crack until the end of the lighting test.

In addition, FIG. 4 shows the result of examining the luminous flux and the color rendering index Ra for H _ca / H _ce when the rated lighting is performed. The horizontal axis is H _ca / H _ce , the right vertical axis is the lamp efficiency [LPW] (black rhombus mark), and the left vertical axis is the color rendering index Ra (white square mark). The data obtained as a result of examining the color rendering index Ra is described in FIG. It can be seen from the results of FIG. 4 that the color rendering index Ra increases as H _ca / H _ce increases. Therefore, it has been newly found that the color rendering index Ra has a correlation with H _ca / H _ce .

The lamp with H _ca / H _ce = 0 means a lamp not containing calcium iodide. Here, when H _ca / H _ce is 0.4 or more, the color rendering index Ra is about 70 or more, and a lamp not containing calcium iodide has a color rendering index Ra 64, so the difference is about 10% or more. Therefore, H _ca / H _ce is more preferably 0.4 or more. At this level, the color rendering can be clearly improved. Further, as H _ca / H _ce is increased, the color rendering index Ra is improved and can exceed 90. This is considered to be because the light emission in the red region, which was relatively weak in the light emission of cerium and sodium, was complemented by the red region of calcium, thereby improving the color rendering.

In addition, as H _ca / H _ce is increased from FIG. 4, the lamp efficiency gradually decreases until H _ca / H _ce reaches 10, but the lamp starts when H _ca / H _ce exceeds 10. It turns out that efficiency falls rapidly. This is because the amount of calcium encapsulated increases more than the amount of cerium encapsulated, so that the light emission in the red region, where the relative luminous sensitivity of calcium is low, increases, and conversely, the emission of cerium decreases. Think. From FIG. 4, the inflection point of the luminous efficiency has an H _ca / H _ce ratio of about 15. Therefore, in order to suppress a rapid decrease in the luminous efficiency, the H _ca / H _ce ratio is preferably 15 or less.

From the above results, in order to obtain a lamp that can prevent cracks during lighting and that has high efficiency and high color rendering, H _ca / H _ce is

の関係を満たすことが好ましい。

It is preferable to satisfy the relationship.

  The above effect was obtained even when the inclusion was not only iodide but also bromide, that is, halide. However, from the viewpoint of preventing electrode erosion, iodination is preferred.

(Embodiment 2)
The second embodiment will be described below.

  A lamp having the same metal halide lamp as the lamp shown in the first embodiment, which is different only in the shape of the inclusion in the arc tube 20 and the arc tube 20 was manufactured and evaluated. The changes are as follows.

The arc tube 20 is filled with 0.5 mg of mercury and 1.0: 10.5: 2.0 of cerium iodide, sodium iodide, and calcium iodide in a molar ratio as encapsulated halides, respectively. the mol amount of halide H _ca, when the mol amount of Ce halides and H _ce, H _ca / H _ce is 2. The total amount of halide is approximately 14 mg.

Various prototype lamps with various ratios of L / D from 1 to 20 and a ratio of the distance L between the electrode tips and the inner diameter D of the arc tube while keeping the inner volume of the arc tube 20 substantially constant (about 0.45 cc) are prepared. Then, the light output characteristics of each lamp were measured. For reference, the L / D = 8 lamp has L = 32 mm and D = 4 mm. At this time, the tube wall load of the arc tube is approximately 20 to 35 W / cm ² .

As a result of performing a lighting test on these prototype lamps under the same conditions as in the first embodiment, the lamp of this embodiment satisfies the condition of H _ca / H _ce ≦ 15 shown in the first embodiment. Nevertheless, some cracks occurred during lighting.

Therefore, when the common characteristics of lamps that generate cracks other than H _ca / H _ce were investigated, it was newly found that those having L / D smaller than 1 cause cracks. Thereafter, other parameters were also investigated for correlation with cracks, but none of them correlated with cracks. From the above results, in order to prevent cracks in the arc tube 20, in addition to (Equation 1)

を満たす必要があることがわかった。

I found it necessary to satisfy.

  Hereinafter, the result of having considered about the generation mechanism of a crack is shown.

  First, L / D can be considered as follows.

  In the lamp of the present embodiment including a halide of cerium, sodium, and calcium, it has been confirmed that the upward curve of the arc becomes remarkable when the lamp has an L / D smaller than 1. For this reason, the distance between the surface of the arc tube central portion 25 of the arc tube 20 and the arc greatly varies from part to part. For this reason, it is considered that cracks are generated as a result of the temperature difference between the portions of the arc tube surface becoming large and distortion. However, when L / D is 1 or more, a tube-stable arc is formed, and arc bending is suppressed. Therefore, it is considered that the temperature difference generated on the arc tube surface is reduced.

Next, the H _ca / H _ce ratio can be considered as follows.

  Since calcium (Ca) has a lower vapor pressure than cerium (Ce) and sodium (Na), the calcium halide evaporated in the arc tube tends to exist as an iodide liquid even at a relatively high temperature. It is believed that there is. Therefore, compared to cerium and sodium, it is considered that they are concentrated in a high temperature portion on the inner surface of the arc tube 20. As a result of this localization of calcium, the distribution of the amount of halide in the arc tube increases, and the thermal conductivity changes depending on the amount of halide, resulting in a large temperature difference between arc tube portions and distortion. It is thought that cracks occur.

  Considering from the mechanism as described above, it is presumed that there is no influence other than the above two parameters on the crack.

  Summarizing the results of the first and second embodiments, a new problem arises that a ceramic metal halide lamp encapsulating cerium halide, sodium halide, and calcium halide causes a crack in the arc tube under certain conditions. I understood. This problem is a new problem that is not disclosed in Patent Documents 1 and 2. The present inventor has found that this problem can be solved under a specific condition. The condition is to satisfy (Equation 1) and (Equation 2).

  In addition, the lamp of the second embodiment also has the following characteristics.

  Further, the lamp shown in the second embodiment can obtain a lamp having a new feature by defining L / D. FIG. 5 shows the luminous efficiency and the color rendering index of the lamp when the lamp is lit with a rectangular wave current having a rating of 150 W and a lighting frequency of 150 Hz.

From FIG. 5, the luminous efficiency of the lamp depends on L / D, and exceeds 105 LPW when L / D is 1 or more. This is because a metal halide lamp of a high efficiency and high color rendering type currently on the market (a typical metal halide lamp on the market is a ceramic arc tube having an L / D of 2, and CeI ₃ , NaI is contained in the arc tube. , KI, ScI ₃ , and InI are encapsulated (hereinafter referred to as a “conventional lamp”). 150 W is 90 to 95 LPW, and when L / D is 1 or more, the luminous flux is about 10 % Up. When lit at the same W, a 10% increase in luminous flux is considered to be a level at which a human can feel a slight increase in brightness. Therefore, the effect of a higher efficiency lamp can be realized by this luminous flux increase. In addition, the color rendering evaluation number Ra shows a relatively high value of 80, which achieves both high efficiency and high color rendering. Considering that the Ra of the metal halide lamp containing Ce and Na and not containing Ca was about 64, it means that the radical Ra can be improved.

  In addition, preferably, when L / D is 4 or more, it exceeds 115 LPW. This is about 20% higher than 95LPW, which is a typical value for a conventional high efficiency lamp. This value of 20% up is an amount by which humans can clearly feel the improvement in brightness. An efficiency increase of 20% compared to the conventional lamp means an epoch-making efficiency. In addition, Ra of this lamp shows a very high value of 90.

  In addition, L / D is preferably 10 or less. This is because a lamp with very little blackening of the arc tube during its life can be obtained by defining it in this range. On the other hand, in the lamp containing Ce halide and Na halide shown in Patent Document 1 and not containing Ca halide, there was no relationship between the occurrence of blackening and L / D. .

  To suppress blackening with high efficiency, L / D is

の範囲に規定することが好ましい。

It is preferable to define in the range.

  Further, from FIG. 5, when L / D is between 7 and 9, the luminous efficiency has a peak, which is higher than about 130 LPW. This is as high as 35% of the 95 LPW of the conventional lamp, and a very high luminous efficiency can be obtained. In addition, the lamp has a Ra of about 90, and has a very high luminous efficiency and color rendering.

  Therefore, in order to realize a lamp with high efficiency and high color rendering properties, L / D is preferably 7 or more and 9 or less.

  Although not shown in FIG. 5, when L / D is 20, the luminous efficiency is 95 LPW, and when it exceeds 20, it becomes 95 LPW or less, so that it is equivalent to the level of the conventional high efficiency lamp in terms of lamp efficiency. become. On the other hand, if it exceeds 20, the starting voltage of the lamp becomes high, which is not preferable. Accordingly, L / D is preferably in the range of up to substantially 20.

  As described above, although the lamp efficiency varies depending on the value of L / D, the color rendering index Ra is 80 or more, which is greatly improved from 64 of the lamp not including Ca. Therefore, if L / D is in the above range, a lamp having both high luminous efficiency and high color rendering can be obtained.

(Embodiment 3)
Hereinafter, Embodiment 3 will be described.

  The metal halide lamp prototyped in Embodiment 1 and Embodiment 2 is dimmed and lit using a lighting circuit that can dim the lamp with power from 25% to 100% of the rated power of the metal halide lamp. The light output characteristics of the lamp were measured.

As a result of numerous studies, it has been found that a lamp satisfying the following relational expression is suitable for dimming. Details are described below. When the amount of calcium iodide, which is a Ca halide enclosed in the arc tube 20, is H _ca (mol) and the amount of halide other than calcium is H _t (mol), H _ca / H _t But

の関係を満たすことによって、調光したときに色変化が少なくなるという新たな効果を有する。本実施の形態のランプは、実施の形態１および２において、定格１５０Ｗで点灯したときの特性について説明したが、本実施の形態のランプは、クラックを生じない、高効率、高演色などの特徴の他に、調光したとき、色温度の変化が非常に少ないという特別な効果を持っている。

By satisfying this relationship, there is a new effect that the color change is reduced when dimming. The lamp according to the present embodiment has been described with respect to the characteristics when the lamp is lit at a rated power of 150 W in the first and second embodiments. However, the lamp according to the present embodiment has features such as high efficiency and high color rendering that do not cause cracks. In addition, there is a special effect that the color temperature changes very little when dimming.

The lamp of this embodiment starts dimming from a rated power of 150 W, and even if the input is continuously reduced to approximately 38 W, which is 25% of the rated power, the change in color temperature is ± 300 K or less. It can be said that it is a level which is hardly worried about the change of 300K or less. On the other hand, a lamp whose H _ca / H _t is out of the above range has a rapid change in color temperature, shows a color change of about 500K or more, and becomes a lamp that feels the color change.

As an example, FIG. 6 shows the measurement result of the color temperature change during dimming of the lamp of the present invention with H _ca / H _t = 0.1 and L / D = 8 and the conventional lamp. The horizontal axis of FIG. 6 is the lamp power (W) that is the power supplied to the lamp, and the vertical axis is the color temperature (K). It can be seen that the color temperature of the conventional lamp is greatly increased when the lamp power is 120 W or less, whereas the lamp of the present invention does not change greatly when the lamp power is 120 W or less.

  In addition, when the lighting is less than about 38W at a rating of 25%, there may be a case where the flickering of the arc is large and flickering occurs, or the lighting cannot be maintained and the lamp will disappear. It is preferable to light up.

  In addition, the lamp of the third embodiment is preferably lit at a lighting frequency of 100 Hz to 500 Hz. This is because it has been found that the color rendering index Ra hardly decreases (about 5), and good color rendering can be obtained even if the light is adjusted. When lighting is performed at a frequency lower than 100 Hz or a frequency higher than 500 Hz, the reduction range of Ra change during dimming increases rapidly and becomes 10 or more.

  Moreover, when dimming, it is preferable to light with a substantially rectangular wave current using an electronic ballast. This is because if the conventional general magnetic ballast is used to reduce the input and dimming, it becomes difficult to maintain lighting. This is because, in order to maintain lighting, the secondary side open-circuit voltage of the ballast must be higher than the re-ignition voltage during AC lighting, but in the case of a magnetic ballast, the input voltage is lowered for dimming. Then, the re-ignition voltage may be lower than the secondary open circuit voltage.

(Embodiment 4)
Hereinafter, the fourth embodiment will be described.

  In the lighting test, the metal halide lamp prototyped in the first embodiment and the second embodiment is lit with alternating current of a rectangular wave with a rating of 150 W and a frequency of 150 Hz, and the lighting is repeated for 5.5 hours and for 0.5 hours. The test was conducted under the conditions, and the life characteristics were measured.

As a result of numerous studies, it has been found that a lamp satisfying the following relational expression has good life characteristics. The relationship between H _ca and H _t shown in Embodiment 3 is

の関係を満たすランプは、点灯中の電極の形状変化が少ないランプとなることがわかった。さらに、（式５）の範囲では、加えて、点灯中にチラツキが発生することなく良好な特性を示した。

It was found that the lamp satisfying the above relationship is a lamp with little change in the shape of the electrode during lighting. Furthermore, in the range of (Expression 5), in addition, good characteristics were exhibited without flickering during lighting.

  In addition, it turned out that the starting voltage becomes higher by 10% or more when the amount of calcium sealed per arc tube inner volume is 20 mg / cc or more compared to a lamp of 20 mg / cc or less.

  This can be estimated as follows. Calcium halides have strong moisture adsorption and are more likely to introduce impurities such as moisture into the arc tube than other halides. Therefore, it is considered that the amount of calcium halide enclosed has an extreme influence on the starting voltage. Therefore, the amount of calcium halide enclosed is preferably 20 mg / cc or less.

In all the above embodiments, the space between the outside of the arc tube 20 and the inside of the outer tube 11 is in a reduced pressure state (specifically, an air pressure of 1 × 10 ⁻¹ (Pa)) at 300K. In this example, nitrogen gas was sealed in this space to change the gas pressure. As a result, the same performance was obtained when the gas pressure was 300 K and the range was approximately 1 × 10 ³ Pa (= about 0.01 atmosphere). However, when the pressure was 1 × 10 ³ Pa or more, the light emission efficiency tended to decrease. This is thought to be because heat loss increases because the heat of the arc tube conducts gas in the space and is transmitted to the outer tube. In particular, when the pressure is 5 × 10 ⁴ Pa (= about 0.5 atm) or more, the light emission efficiency starts to rapidly decrease, and at 5 × 10 ⁴ Pa (= about 0.5 atm), the light emission efficiency is reduced by about 5 LPW. confirmed.

As can be seen from this result, the lamp performance of the lamp of this embodiment can be further improved by controlling the thermal design. Therefore, the space between the outer side of the arc tube 20 and the inner side of the outer tube 11 is preferably about 5 × 10 ⁴ Pa or less at 300K, and more preferably 1 × 10 ³ Pa or less.

  In all the embodiments described above, lighting can be performed regardless of horizontal lighting (lighting method for lighting with the arc tube substantially horizontal) or vertical lighting (lighting method for lighting with the arc tube substantially vertical). However, the horizontal lighting is preferable because the luminous flux maintenance factor is slightly higher than the vertical lighting. When the lamp is lit horizontally, the lamp life is increased by about 200 to 400 hours when the lamp life is reached (time when the luminous flux is reduced to 70%), compared with the vertical lamp. The above-mentioned effect of extending the lifetime is sometimes remarkable in the combination of the lamp enclosures and the enclosure ratio shown in the present embodiment. On the other hand, such a difference does not occur in the conventional metal halide lamp shown in the first embodiment. However, there is no problem even in vertical lighting, since it can be lit without problems and a practically sufficient life can be obtained.

  Because these phenomena are lit horizontally, the metal halide that can be supplied into the arc during lighting can be kept high because there are few metal halides that enter the narrow tube part located at both ends of the arc tube during lighting. In addition, it is conceivable that the chemical reaction between the metal halide that has entered the narrow tube portion and the thin tube can be suppressed.

  In addition, in all of the above embodiments, it has been surprisingly found that the lamp of the present invention to which the rare earth halide cerium iodide is added exhibits good life characteristics without shortening the lamp life.

Furthermore, in all the embodiments described above, it is preferable that the tube wall load at the time of rated lighting of the arc tube 20 be limited to a maximum of about 35 W / cm ² . This is because, as the tube wall load increases, the chemical reaction between the active material salt and the tube wall and frit material of the arc tube 20 usually becomes a serious problem, and obtaining a sufficiently useful operating life from such a lamp This is because it is substantially difficult. Further, the lower limit is preferably 20 W / cm ² or more. By designing in this range, a lamp having both good efficiency and color rendering can be obtained.

Among them, a particularly preferable range is 28 to 33 W / cm ² , and by defining within this range, a lamp with the best balance of lamp life, luminous efficiency, and Ra can be obtained.

In addition, the enclosed amount of the halide in this specification refers to the molar amount of the metal halide only. For example, 1 mol of cerium iodide (CeI ₃ ) indicates that the Ce atom is 1 mol. For reference, the I atom is 3 mol.

  In addition, about Embodiment 1 and 2, although the case of the lamp of rating 150W was demonstrated, it is not limited to this W.

  However, in general, a lamp having a high W increases the luminous efficiency of the lamp because the ratio of loss power such as electrode loss to the total power consumption decreases. On the other hand, the lamp with low W tends to decrease the light emission efficiency because the ratio of loss power increases. Therefore, the luminous efficiency of the present embodiment is a lamp value of about 150 W, and the value varies depending on the lamp W, but the luminous efficiency is relatively improved as compared with the conventional lamp regardless of the effect. Can get a lamp.

  In all the embodiments described above, the arc tube 20 may have a shape different from the configuration of FIGS. 1 and 2. Since each lamp shape has its characteristics, it is possible to design the lamp shape according to the application.

  Hereinafter, schematic diagrams of examples of possible arc tube shapes are shown in FIGS. The drawing schematically shows the shape of the inner wall of the arc tube, and a thin tube portion into which electrodes formed at both ends of the arc tube are inserted may be provided, but is omitted in this drawing. In each of the examples shown in FIGS. 1 and 2 and FIGS. 7 to 13, the inner surface of the tube wall and the outer surface of the tube wall are surfaces of a rotating body whose rotation axis is the major axis of the arc tube. Not shown in the figure. The effective diameter D of the inner surface of the tube wall that is not a rotating body can be obtained by obtaining the inner area of the cross-sectional view between the electrodes (that is, over the distance L between the electrodes) and dividing this area by L. Other types of inner surfaces may require more complicated averaging procedures to determine their effective diameter. In the case of a rotating body, D is the inner diameter of the arc tube located at the center between the electrode tips.

  FIG. 7 shows an arc tube whose section corresponding to the arc tube central portion 25 of FIG. 1 (hereinafter simply referred to as “arc tube central portion”) is elliptical.

  FIG. 8 shows an arc tube having a right circular cylinder cross-section cut so that both ends of the arc tube center are flat. This arc tube shape is characterized by a small change in color temperature during lighting. Therefore, it is particularly effective when the change in the emission color is anxious.

  FIG. 9 shows an arc tube having a cross section in which both ends of the central portion of the arc tube are hemispheres and the side surface of the central portion of the arc tube is concave.

  FIG. 10 shows an arc tube having a cross section of a right circular cylinder cut so that both ends of the central portion of the arc tube become hemispheres.

  FIG. 11 shows an arc tube having a cross section in which both ends of the arc tube central portion are hemispheres and the side surface of the arc tube central portion is elliptical.

  FIG. 12 shows the shape used in the first and second embodiments.

  FIG. 13 shows an arc tube having a cross section of a right circular cylinder cut so that the diameter at both ends of the central portion of the arc tube is large and flat.

  The characteristics of each arc tube shape are shown below.

  The arc tube shown in FIGS. 7 and 11 has a feature that there is particularly little individual variation in color temperature when mass-produced. Therefore, when a large amount is used for ceiling lighting or the like and color temperature variation is conspicuous, a particularly preferable arc tube shape is obtained.

  The arc tube of FIG. 9 and FIG. 13 has a feature that the light rise at the start is quick. Although it depends on the design, the time to reach the rated light output can be shortened by about 10 to 20%. In addition, it is possible to obtain a lamp that has particularly small arc curvature during horizontal lighting and that has particularly small flickering during lighting.

  10 and 12 can obtain a lamp with the least change in color temperature during lighting.

  The arc tube shown in FIG. 8 has a feature that its production cost is low because of its simple structure.

  The metal halide lamp using the ceramic arc tube of the present invention is useful for outdoor lighting, high ceiling lighting, and the like.

The front view of the metal halide lamp which is embodiment of this invention Sectional front view of the arc tube portion of the metal halide lamp shown in FIG. The figure which shows the presence or absence of a crack in the lamp | ramp of this Embodiment 1, and Hca / Hce dependence of Ra. The figure which shows the luminous efficiency in the lamp | ramp of this Embodiment 1, and Hca / Hce dependence of Ra. The figure which shows the L / D dependence of the luminous efficiency in the lamp | ramp of this Embodiment 2. The figure which shows the electric power dependence of the color temperature in the lamp | ramp of this Embodiment 3. The figure which shows an example of a deformation | transformation of the arc tube center part The figure which shows an example of a deformation | transformation of the arc tube center part The figure which shows an example of a deformation | transformation of the arc tube center part The figure which shows an example of a deformation | transformation of the arc tube center part The figure which shows an example of a deformation | transformation of the arc tube center part The figure which shows an example of a deformation | transformation of the arc tube center part The figure which shows an example of a deformation | transformation of the arc tube center part

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Metal halide lamp 101 1st cylindrical shell part 102 2nd cylindrical shell part 103 Conical shell part 11 Outer tube 20 Arc tube 21 Tube 25 Arc tube center part

Claims (5)

An arc tube formed of translucent ceramic;
A pair of opposing electrodes;
An outer tube made of hard glass provided outside the arc tube;
A metal halide lamp comprising a Ce (cerium) halide, a Na (sodium) halide, and a Ca (calcium) halide enclosed in the arc tube,
When the inner diameter of the arc tube is D (mm) and the distance between the tips of the electrodes is L (mm), L / D is

Satisfy the relationship
When the amount of Ca halide enclosed is H _ca (mol) and the amount of Ce halide enclosed is H _ce (mol), H _ca / H _ce is

Satisfy the relationship
Of the inclusions, when the total inclusion amount of halides other than the Ca halide is H _t (mol), H _ca / H _t is

Satisfy the relationship
A metal halide lamp at 300K, wherein the pressure in the space inside the outer tube and outside the arc tube is 5 × 10 ⁴ (Pa) or less. An arc tube formed of translucent ceramic;
A pair of opposing electrodes;
A metal halide lamp comprising a Ce (cerium) halide, a Na (sodium) halide, and a Ca (calcium) halide enclosed in the arc tube,
When the inner diameter of the arc tube is D (mm) and the distance between the tips of the electrodes is L (mm), L / D is

Satisfy the relationship
When the amount of Ca halide enclosed is H _ca (mol) and the amount of Ce halide enclosed is H _ce (mol), H _ca / H _ce is

Satisfy the relationship
Of the inclusions, H _ca / H _t , where H _t (mol) is the total encapsulation amount other than the Ca halide,

Satisfy the relationship
A metal halide lamp in which a tube wall load of the arc tube (rated power consumption per unit arc tube surface area) is 28 to 33 (W / cm ² ). The metal halide lamp according to claim 1 or 2,
A lighting device for a metal halide lamp, comprising: a lighting circuit that adjusts power to be supplied to the metal halide lamp. A metal halide lamp according to any one of claims 1 to 3,
A lighting device for a metal halide lamp, comprising: a lighting circuit for dimming and lighting the metal halide lamp with a power of 25% to 100% of a rated power of the metal halide lamp.   The lighting device for a metal halide lamp according to claim 3 or 4, wherein the lighting circuit is an electronic ballast that lights the metal halide lamp with a substantially rectangular current of 100 Hz to 500 Hz.

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