JP2000315476A - Metal halide lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal halide lamp more excellent in efficiency than the metal halide lamp currently used in the same electric power level. SOLUTION: This metal halide lamp is constructed of an arc tube 1 of a light-transmissive sealed container disposed a pair of tungsten electrodes 2 on each end thereof and a filling substance is sealed within the arc tube 1. The filling substance is composed of a mercury, a rare gas and a mixture of a cerium halide (CeX3) and a sodium halide (NaX). The halide (X) is an iodine or bromine. The weight of the mercury is limited to 2.67 mg or under per volume unit cm3 of the arc tube 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide (MH) lamp suitable for both indoor lighting and outdoor lighting and used for general purpose lighting and special optical applications.

[0002]

2. Description of the Related Art In recent years, metal halide lamps have been used in stores,
It has been widely used for lighting of roads, malls, hotels and the like.
Arc tubes are often located within an outer jacket. That is, the lamp is fused quartz (Si
O ₂ ) which includes an arc tube that provides the illuminating portion of the lamp. The tungsten electrode is sealed with molybdenum foil and attached to an external conductor.

[0003]

In the metal halide lamp of the present invention, during startup, the metal halide in the arc tube melts (along with mercury and noble gases) and exists in a liquid state during lamp preheating. . Some of the metal halide evaporates to a gaseous state, and the metal halide vapor dissociates into metal and halogen atoms in the high temperature region of the arc column due to the electrons in the current. Metal atoms are excited by the arc and emit their unique spectral lines. Therefore, compared to a high-pressure mercury lamp (HPM), the MH lamp is superior in luminous efficiency and color rendering. N
_{aI-TlI-InI, ScI 3} -NaI and DyI
₃ -TlI-HoI ₃ -TmI ₃ -NaI like metal iodide metal halide lamp which contains are widely used in practical applications.

Generally, in the above-mentioned metal halide lamp, ScI ₃ is used for high luminous efficiency.
Generally, the efficiency of a lamp increases as the power increases. For a 400 W MH lamp, about 100 lp
w (lumens / watt) is commonly obtained. U.S. Pat. No. 3,979,624 to Lee et al. Discloses that the molar ratio of alkali metal halide to scandium halide greatly increases the system efficiency of visible light generation.
It is disclosed from about 1.7: 1 to about 5: 1.
Its efficiency can be as high as 32%.

US Pat. No. 3,78, Zolbeig et al.
No. 6,297 shows another form for a metal halide discharge device, in which cerium halide, cesium halide and large amounts of mercury are used. Large amounts of mercury have been used to obtain high efficiency lamps with relatively low cold spot temperatures. In the preferred embodiment disclosed in this patent, alkali metal iodides and rare earth metal iodides are used in grams approximately equal to the mole fraction.

The document discloses many other forms of metal halide lamps. These devices generally tend to exhibit higher efficiencies when compared to standard high pressure mercury discharge lamps. They also improve the color characteristics in terms of the appearance of the light source and with regard to the color rendering of the object illuminated by the lamp.

However, none of the prior arts resulted in 7
Practical lamps having a color rendering index greater than 0, having an efficiency substantially exceeding 100 lpw, or having a white color with a very small deviation from the blackbody locus (Duv) at the 400 W level have not been realized. . At this power level, such lamps can be used for large outdoor applications, such as parks, residential areas, and complex business locations. In addition, it can be used for many buildings with high ceilings, such as warehouses, malls, sports facilities, and museums.

[0008] Recently, with increasing interest in the environment, such as energy savings, which has been largely driven by the desire to reduce harmful gases and greenhouse effects, light sources with higher energy efficiency have been sought.

Within this framework, it is an object of the present invention to provide a metal halide light source that is more efficient at the same power level than the currently utilized metal halide light sources.

It is a further object of the present invention to provide an existing N
SUMMARY OF THE INVENTION An object of the present invention is to provide a metal halide light source having a CRI of at least 65-75 so that it can be substituted for a / Sc metal halide light source.

Another object of the present invention is to provide an MH light source having white light (small Duv) having little deviation from the locus of a black body so that the hue of light is nothing but white. is there.

It is another object of the present invention to provide a light source family having an input power of 20-3000 W in various designs.

[0013] Furthermore, the object of the present invention is to provide a temperature of 3000 ° K-6.
It provides a white halide light source having a color temperature in the range of 000 ° K.

It is also an object of the present invention to provide a metal halide light source which can be manufactured with conventional manufacturing equipment and processing techniques, thereby resulting in the same manufacturing cost as conventional products.

[0015]

According to a first aspect of the present invention, there is provided a metal halide lamp, comprising: a light-transmitting hermetic container in which a filling material is sealed; A pair of electrodes disposed at each end of the tube, wherein the fill material includes mercury, a noble gas, and a mixture of cerium halide (CeX ₃ ) and sodium halide (NaX); The halide (X) is iodine or bromine, and the weight of the mercury is
2.67 m per cm ³ of volume of the arc tube
g or less.

According to a second aspect of the present invention, in the metal halide lamp according to the first aspect, the arc tube has an elliptical shape.

According to a third aspect of the present invention, in the metal halide lamp according to the first aspect, the arc tube has an elliptical shape, and is obtained by dividing a longitudinal length inside the arc tube by an inner diameter thereof. The aspect ratio obtained is a value between 2 and 3.

The invention according to claim 4 is the invention according to claim 1 or 3.
2. The metal halide lamp according to claim 1, wherein said cerium halide (CeX ₃ ) and sodium halide (N
The molar ratio of aX) substantially satisfies the relationship of 3 <NaX / CeX ₃ <4.

[0019] According to a fifth aspect of the invention, the metal halide lamp of claim 1, wherein the cerium halide (CeX ₃₎ and sodium halide (NaX) and each yaw cerium (CeI ₃₎ and sodium iodide (NaI ) And these cerium iodides (Ce)
The total weight of I ₃ ) and sodium iodide (NaI)
It is characterized in that the value is between 0.3 mg / cm ³ and 0.7 mg / cm ³ .

According to a sixth aspect of the present invention, in the metal halide lamp according to the first aspect, the arc tube is made of fused quartz (SiO ₂ ).

According to a seventh aspect of the present invention, in the metal halide lamp according to the first aspect, the arc tube has a heat retaining element around at least one end.

According to an eighth aspect of the present invention, in the metal halide lamp according to the first aspect, the arc tube is disposed inside a vacuum outer jacket.

According to a ninth aspect of the present invention, in the metal halide lamp according to the first aspect, the arc tube is made of a polycrystalline alumina (PCA) material.

According to a tenth aspect of the present invention, in the metal halide lamp according to the first aspect, the arc tube has an ellipsoidal shape, and the aspect ratio of the ellipsoid is 2 or less or 3 or more, The cerium halide (Ce)
X ₃ ) and sodium halide (NaX) have a molar ratio (NaX / CeX ₃ ) of 3 or more.

According to an eleventh aspect of the present invention, in the metal halide lamp according to the first aspect, the arc tube is formed in a cylindrical shape so as to increase the vapor pressure of the halide so that the coldest point temperature increases. A heating means is provided in the end recess.

According to a twelfth aspect of the present invention, in the metal halide lamp according to the first aspect, the arc tube is formed substantially spherical, and the arc length between the pair of electrodes is shorter than the diameter of the vessel of the arc tube. It is characterized by having.

According to a thirteenth aspect of the present invention, in the metal halide lamp according to the eleventh aspect, the arc tube is formed using a polycrystalline alumina (PCA) material.

According to a fourteenth aspect of the present invention, in the metal halide lamp according to the twelfth aspect, the arc tube is formed using a polycrystalline alumina (PCA) material.

Here, as described above, the present invention relates to a metal halide lamp having a new enclosure and optimum parameters as a practical device. This new fill is based on a combination of cerium and sodium halides. With this filling, the amount of mercury introduced into the arc tube was optimized. As an example, arc tube configurations and shapes have been carefully selected and optimized.
Focus was placed on 0W metal halide arc tubes. In this particular fill, experiments were performed on various different compositions and different weights of cerium halide and sodium halide to optimize the arc tube configuration as described above. In addition, questions such as starting gas and starting gas pressure were investigated. A study was made of the amount of all halides and their effect on lamp properties. Furthermore, problems such as arc tube material and electrode insertion length, reflection coating in the end recess of the arc tube, and optimization of the outer jacket were also investigated. As a result of all these studies, the final shape lamp after 100 hours of operation at a level of 400 W at 1
It was concluded that one could have a new optimized encapsulant based on cerium halide and sodium halide to yield efficiencies in excess of 30 lpw.

As a result, a very good CR exceeding 72 was obtained.
Color temperatures between I and, furthermore, between 3500 K-4500 K were obtained. However, as is well known in the art of high intensity discharge arc tube design, the color temperature could be changed by slightly changing the composition.

In addition to these experiments, a configuration was realized in which the light output of the lamp was very close to blackbody radiation. Duv was 10 or less, which is a criterion for evaluating the deviation of the light source from the blackbody locus multiplied by 1000 in the uv coordinates. This is considered a white criterion and is very good, especially for outdoor applications. For 130 lpw, the competitor closest to this lamp at this point is about 100 lpw of Na /
It is considered to be a sealed material of Sc, and has an effect about 30% better than that of the prior art. The present invention can be a direct replacement for outdoor metal halide lighting sources based on sodium / scandium inclusions.

Various experiments on the Na / Ce chemistry (salts, molar ratios, thermal balance, etc.) optimize this fill for at least a 400 W arc tube which is a preferred means for the present invention. Valuable information was obtained. The best molar ratio found in terms of efficiency and overall desirable performance was NaI / CsI ₃ (= 3.5: 1). Performance sensitivity to the amount of halide was less than the molar ratio. Nevertheless, about 10-15mg
It was found that a more stable arc was obtained with all the halides.

When the performance with respect to the coating amount of the heat insulating film at the end was checked, it was found that there was no high sensitivity with respect to the coating amount of the heat insulating film at the end. However, there was a large difference in efficiency between the case where the heat insulating film was not applied and the case where the heat insulating film was applied to the end portion (the efficiency was greatly reduced without the heat insulating film). On the other hand, the insertion length of the electrode did not significantly affect the performance of the arc tube.

[0034]

FIG. 1 shows NaI / CeI._Three Filled
This figure shows the cross section of the arc tube of a metal halide lamp.
An embodiment of the present invention will be described with reference to FIG. In FIG.
The light emitting portion of the arc tube 1 has a substantially elliptical shape.
Its maximum inner diameter is 20mm, its maximum internal length is about 48mm,
And the internal volume is about 24cm^ThreeIt is. The arc tube 1
Fused quartz (SiO_Two ). tungsten
Electrode 2 (pure tungsten coil 2a and starting voltage
ThO to reduce_Two Made of tungsten containing 2%
Is composed of a molybdenum foil 10 and an external
It is connected to the conductor 4. Distance between two electrode tips
(Arc length) is about 35 mm. ZrO _Two The main component
The heat insulating film at the end of the arc tube 1 is at one end on the outer surface of the arc tube 1.
And preferably on both ends. Hold the end
The hot film acts as a heat storage element. The arc tube 1
6mg CeI_Three , 6 mg NaI, 54 mg mercury,
And 32 torr of Ar as starting gas
I have. The arc tube 1 has a hard tube attached to a lamp base.
Inside the outer jacket of tempered glass (indicated by the dotted line)
It is installed. Preferably, a vacuum inside the outer jacket
It is. Alternatively, cover the performance according to performance requirements.
In some cases, the gas may be filled in the unit. Some of them are orchids
The lamp may be lit without an external jacket. run
The lamp is typically operated at 400 W and the lamp voltage is 13
5V and the lamp current is 3.2A.

FIG. 2 shows a spectral distribution diagram of the lamp of this embodiment. The strong peak (line spectrum) around 590 nm
Sodium emission and the nearly continuous profile between 400 and 700 nm is Ce emission. These emissions have a luminous efficiency of 137 lm / W (with zero hour lighting)
Has contributed to the improvement. The nearly continuous profile of the radiation contributes to obtaining good color rendering. In this embodiment, the CRI is generally measured at about 72. 670n
m Li line is an impurity in NaI, and the efficiency and CRI
Does not have any significant effect.

The proper color balance between Ce and Na radiation contributes to obtaining white. Therefore, the deviation from the locus of the black body on the chromaticity table is within the allowable range. The color temperature is about 3700 ° K. This value is useful for many outdoor and indoor applications.

In this embodiment, the weight of mercury is 54 mg. In other words, the weight of mercury is 2 mg / cm ^{3 of} arc tube volume.
67 mg or less. The reason for this is as follows: During operation of the lamp, all added mercury
Evaporates and acts as a buffer gas to obtain the proper lamp voltage. In experiments with varying amounts of mercury, 40-6
A lamp with 4 mg of mercury was shown to have suitable electrical properties. Lamps with more than 64 mg of mercury (having the same volume) showed arc instability, probably caused by convective forces.

The light emitting portion of the arc tube 1 of this embodiment has an almost elliptical shape. Its maximum inner diameter is about 20m
m and its length is about 35 mm. In other words,
The ellipsoidal shape has an aspect ratio between 2 and 3 (longitudinal length inside the arc tube per arc tube inner diameter).

It has been found that the vapor pressure of CeI ₃ is relatively low when compared to scandium (ScI ₃ ), one of the most common filling materials used in commercially available metal halide lamps. A relatively high cold spot temperature is required to obtain a suitable vapor pressure of CeI ₃ . In addition, the highest arc tube temperature should be lower than the lamp failure temperature (maximum allowable operating temperature) (failure includes glass breakage, glass devitrification, electrode damage and seal area leakage, etc.). Is included). At the same time, to give a relatively high coldest point temperature and a relatively low maximum arc tube temperature,
Nearly uniform temperature distribution is required. For this reason, the ellipsoidal shape of the arc tube is desirable because the shape of the arc itself is substantially elliptical. However, it has been found that the arc becomes unstable with any extremely thin or extremely thick arc tube.

Experiments have shown that the aspect ratio between 2 and 3 (length / diameter of the cross section of the ellipsoid) is perfect for the optimal molar ratio of NaI / CeI ₃ (3.5: 1). It was found to be the best in giving a stable arc of any shape. The optimal molar ratio of sodium iodide to cerium iodide is 3.5: 1 in this example. When the molar ratio of NaI / CeI ₃ is larger than 3.5, the intensity ratio of Na / Ce becomes larger. This reduces the contribution of Ce radiation to efficiency and results in a color shift to red. In some cases, large amounts of NaI will cause self-absorption of the Na line, thereby reducing luminous efficiency.
When the molar ratio of NaI is substantially smaller than 3.5, the intensity ratio of Ce / Na becomes larger. This means that the contribution of Na radiation to the luminous efficiency is reduced, and color shift in the green direction occurs. In some cases, large amounts of CeI ₃
In this case, the arc becomes unstable because Ce causes the arc to contract.

FIG. 3 shows experimental data as a function of the ratio of NaI / CeI ₃ . Here, CRI is a general color rendering index, and Tc is a color temperature. This data, for our preferred embodiment, is based on sodium halide (Na
X) and the cerium halide (CeX) have a molar ratio of 3 <
It shows that NaX / CeX ₃ <4.

The optimum total weight of the cerium iodide (CeI ₃ ) and sodium iodide (NaI) halide is 12 mg in this preferred embodiment. CeI ₃
If the total weight of NaI and NaI is greater than about 12 mg, the arc is in an unstable state, clearly caused by the convective force of the evaporating metal halide, and has a large amount of condensed liquid state. Will cover the side walls. Therefore, the convection force from the side wall portion toward the center of the arc is considerable. This leads to arc instability. In some cases, the condensed metal halide blocks light from the arc, which reduces luminous efficiency. If the total weight of CeI ₃ and NaI is extremely small, it is difficult to obtain consistent color characteristics over the entire service life due to material loss due to reaction with the vessel and sodium loss due to diffusion through the glass. It is.

FIG. 4 shows the experimental data as a function of the total weight of CeI ₃ and NaI. From the data, CeI ₃ and N
suitable range of the total weight of aI is can be seen that that is between the corresponding 5mg and 12mg between 0.3 mg / cm ³ and 0.7 mg / cm ³ of arc tube volume.

In the above example, the halide used was iodide. However, if the chemical reaction with the electrode can be prevented, the same effect of the present invention can be easily obtained for bromide or a mixture of iodide and bromide. Further, if the chemical interaction of Ce with PCA can be used at a practical level, an arc tube of polycrystalline alumina (PCA) can be used in addition to quartz. Various considerations are needed to select the arc tube material for a particular fill. PCA has a higher operating temperature, or Ce
, But the stability of CeO to AlO must be considered, among other factors. The introduction from the paper points out that thermodynamically advantageous for containing CeI ₃ in a PCA envelope.

In the above example, 32 torr of Ar was used for the starting gas, but neon (Ne), krypton (Kr), xenon (Xe) or mixtures thereof,
Still other gases are used to achieve the same effect.

In the above embodiment, a certain size arc tube was used, but the size of the arc tube depends on the wattage of the lamp. Thus, lower wattage and higher wattage lamps can also be designed according to the invention.

For example, the arc tube may be formed in a cylindrical shape, and a heating means may be provided in the end recess so as to increase the coldest point temperature in order to increase the vapor pressure of the halide. Alternatively, the arc tube may be formed in a substantially spherical shape so that the arc length between the two electrodes is shorter than the diameter of the container of the arc tube.

Obviously, other embodiments and modifications may be made within the spirit and scope of the present invention, but are intended to be limited by the scope of the appended claims. It is just that.

[0049]

As is apparent from the above, according to the present invention, it is possible to realize a metal halide light source which is more efficient than the currently used metal halide light source at the same power level.

[Brief description of the drawings]

FIG. 1 is a cross section of an arc tube of a metal halide lamp filled with NaI / CeI ₃ , and the shape of the lamp is indicated by oblique lines.

FIG. 2 is a spectral distribution diagram of relative intensity for the lamp of the preferred embodiment.

FIG. 3 shows experimental data as a function of the ratio of NaI / CeI ₃ .

FIG. 4 shows experimental data as a function of the total weight of the salt amounts of CeI ₃ and NaI.

[Explanation of symbols]

 Reference Signs List 1 arc tube 2 tungsten electrode 2a coil 2b rod 4 external conductor 10 molybdenum foil

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor John F. Weymouth 01945, Massachusetts, USA Marblehead Bennet Road 16

Claims (14)

[Claims] An arc tube in which a filling material is sealed inside a light-transmitting airtight container, and a pair of electrodes disposed at each end of the arc tube, wherein the filling material is mercury. , A rare gas, cerium halide (CeX ₃ ) and sodium halide (NaX)
Wherein the halide (X) is iodine or bromine, and the weight of the mercury is limited to 2.67 mg or less per cm ³ of volume of the arc tube. Metal halide lamp. 2. The metal halide lamp according to claim 1, wherein said arc tube has an ellipsoidal shape. 3. The arc tube has an elliptical shape, and an aspect ratio obtained by dividing a longitudinal length inside the arc tube by an inner diameter thereof is a value between 2 and 3. The metal halide lamp according to claim 1, wherein: 4. The molar ratio of the cerium halide (CeX ₃ ) and sodium halide (NaX) is 3 <
4. The metal halide lamp according to claim 1, wherein the relationship of NaX / CeX ₃ <4 is substantially satisfied. Wherein said cerium halide (CeX ₃₎ and sodium halide (NaX) and each yaw cerium (CeI ₃₎ and sodium iodide (Na
I), and the total weight of these cerium iodide (CeI ₃ ) and sodium iodide (NaI) is 0.3 mg /
cm ³ and 0.7 mg / cm ³ and a metal halide lamp of claim 1, characterized in that a value between. 6. The metal halide lamp according to claim 1, wherein said arc tube is made of fused quartz (SiO ₂ ). 7. The metal halide lamp according to claim 1, wherein said arc tube has a heat retaining element at least around one end. 8. The metal halide lamp according to claim 1, wherein said arc tube is disposed inside an outer jacket having a vacuum. 9. The arc tube is made of polycrystalline alumina (PC).
2. The metal halide lamp according to claim 1, wherein the metal halide lamp is made of A) material. 10. The arc tube has an ellipsoidal shape, and the aspect ratio of the ellipsoid is 2 or less or 3 or more, and the cerium halide (CeX ₃ ) and sodium halide (NaX) Molar ratio (NaX / Ce)
2. The method according to claim 1, wherein X ₃ is 3 or more.
Metal halide lamp. 11. The arc tube is formed in a cylindrical shape, and has a heating means in an end recess so as to increase a coldest point temperature in order to increase a vapor pressure of a halide. The metal halide lamp according to claim 1, wherein 12. The arc tube is formed substantially spherical.
2. The metal halide lamp according to claim 1, wherein an arc length between the pair of electrodes is shorter than a diameter of a vessel of the arc tube. 13. An arc tube made of polycrystalline alumina (PC).
The metal halide lamp according to claim 11, wherein the metal halide lamp is formed using the material of (A). 14. The arc tube is made of polycrystalline alumina (PC).
13. The metal halide lamp according to claim 12, wherein the lamp is formed using the material of A).