JP3925249B2 - Metal halide lamp - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal halide lamp using a ceramic tube such as a polycrystalline alumina ceramic as an arc tube material.
[0002]
[Prior art]
In recent years, metal halide lamps using a translucent polycrystalline alumina ceramic tube have been actively developed and deployed in place of quartz that has been conventionally used as an arc tube material.
[0003]
The feature of this metal halide lamp using an alumina ceramic tube is that it has a high heat resistance of about 1200 ° C. compared to about 1000 ° C. of quartz, and the higher the heat resistance, the higher the wall load of the arc tube. Therefore, it is possible to obtain lamp characteristics with high efficiency and high color rendering properties compared to those using quartz.
[0004]
A metal halide lamp using such an alumina ceramic tube is mainly a so-called low wattage type lamp having a lamp wattage of 70 W to 150 W, and is mainly used in the interior interior lighting field in commercial spaces such as storefronts.
[0005]
FIG. 7 shows an arc tube of a metal halide lamp using a conventional alumina ceramic.
[0006]
The arc tube 24 includes an arc tube container 25 made of polycrystalline alumina ceramic, which includes a light emitting portion 26 and thin tube portions 27 and 28. That is, the light emitting portion 26 that becomes the discharge arc region and the thin tube portions 27 and 28 are provided at both ends of the light emitting portion 26, respectively, and the light emitting portion 26 and the thin tube portions 27 and 28 are made of a polycrystalline alumina ceramic material. ing.
[0007]
A pair of tungsten electrodes 29 and 30 are provided in the light emitting unit 26. The tungsten electrodes 29 and 30 are made up of tungsten electrode rods 31 and 32 and tungsten coils 33 and 34 provided at the tips of the tungsten electrode rods 31 and 32, respectively.
[0008]
Feeders 35, 36 made of niobium or conductive cermet are inserted into the thin tube portions 27, 28, and hermetically sealed by a frit 37. Tungsten electrode rods 31, 32 are provided at the discharge-side tips of the feeders 35, 36. Joined and held (Note that in the power feeding bodies 35 and 36 made of conductive cermet, an external lead wire made of niobium or the like may be joined and held at the other end, respectively). Here, the frit 37 is usually melted and filled up to the joining end portions of the tungsten electrode rods 31 and 32 in order to suppress the erosion caused by the high-temperature luminescent material when the lamp is turned on. In other words, it can be said that a metal halide lamp using an alumina ceramic was realized for the first time by such a specific configuration. In the gaps 38 and 39 between the narrow tube portions 27 and 28 and the tungsten electrode bars 31 and 32 that are inevitably formed, molybdenum coils 40 and 41 are usually provided in a form wound around the tungsten electrode bars 31 and 32. Yes.
[0009]
The arc tube _{24, DyI 3, TmI 3,} HoI 3, TlI, a light emitting substance 42 composed of a metal halide such as NaI, starting aid rare gas such as mercury and argon as a buffer gas are sealed.
[0010]
As a configuration of the completed lamp, the arc tube 24 is assembled and held in an outer tube glass bulb (not shown) in which nitrogen or the like is sealed, and finally the outer tube glass bulb has a base (not shown). Is attached.
[0011]
Typical dimensions of the conventional arc tube 24 include, for example, a 70 W type, the inner diameter φi of the center of the light emitting portion of the arc tube is 6.2 mm, the inter-electrode distance Le is 5.0 mm, and the inner total length of the light emitting portion 26. (Distance between end faces of thin tubes located in the light emitting portion) Li is 10.0 mm. From these dimensions, the so-called arc tube shape parameter Le / φi, which is a main parameter indicating the arc tube shape, is 0.80. Further, the tube wall load we is set to a relatively high value of 37 W / cm ² (provided that the lamp input Wla and the total inner surface area of the light emitting portion 26 are S, the tube wall load we = Wla / S). .
[0012]
As other typical dimensions of the 150 W type, the inner diameter φi of the central portion of the light emitting portion is 10.6 mm, the interelectrode distance Le is 10.0 mm, and the arc tube shape parameter Le / φi value is 0.94. And larger than the 70W type. And the inner full length Li of the light emission part 26 is 17.0 mm, and the tube wall load we is set to about 27 W / cm < ² >.
[0013]
In the 70W and 150W types having the above-described arc tube configuration, excellent lamp characteristics of an average color rendering index Ra85 or more are achieved with a lamp luminous flux of 6700 lm and 13500 lm, a lamp efficiency of 90 lm / W, respectively. Also, a rated life time of 6000 hrs equivalent to that of a conventional quartz tube metal halide lamp is obtained (however, the lamp life time is defined by the aging time when the luminous flux maintenance factor is 70% of the initial value). It should be noted that three types of color temperatures of 3000K, 3500K, and 4300K have been developed by changing the composition ratios of the luminescent materials 42 as lamp light colors.
[0014]
In addition, a 20 W to 250 W type so-called short arc type metal halide lamp using an alumina ceramic tube is disclosed in Japanese Patent Laid-Open No. 10-144261. In this lamp, the arc tube vessel is composed of a cylindrical discharge center portion and hemispherical tube end portions, and the arc tube shape parameter Le / φi value is defined in the range of 0.67 to 1.25. On the other hand, the tube wall load we is defined in a relatively high range of 25 to 35 W / cm ² . Note that the light-emitting substance, the conventional lamp similar to DyI ₃ in FIG. _{7, TmI 3, HoI 3,} TlI, metal halides NaI are sealed.
[0015]
[Problems to be solved by the invention]
In general, a metal halide lamp using an alumina ceramic tube has a metal halide lamp equipped with a conventional quartz light emitting tube in which an exhaust pipe chip is present on the central wall of the light emitting unit in addition to the high efficiency and high color rendering properties described above. Compared to a lamp (hereinafter referred to as a quartz lamp), the emission color variation due to the lamp lighting direction is small.
[0016]
In a conventional quartz arc tube, a thin tube is provided on the tube wall of the light emitting part during the manufacturing process, and the inside of the arc tube is evacuated through this thin tube. In general, an exhaust chip is present.
[0017]
For this reason, when the quartz lamp is lit horizontally, if the exhaust chip is used at a lower position, the luminescent material accumulates in the exhaust pipe chip, and the vapor pressure of the luminescent material is reduced compared to when the lit material is vertically lit. This means that the color temperature of the color rises from the standard value.
[0018]
Therefore, as for quartz lamps, vertical lamps are the mainstream, and in some horizontally-lit quartz lamps, the exhaust chip must be positioned at the top and used in the lamp instruction manual. It has been necessary to regulate the shape of the base so that the exhaust tip is always positioned and attached.
[0019]
In contrast, metal halide lamps using an alumina ceramic tube that does not have an exhaust tube tip in the light-emitting part, so-called free lighting direction, generally has no restrictions on the lighting direction, even if the product is equipped with an Edison base (E type). It is considered a form. Such a lamp having a free lighting direction can be said to be an extremely advantageous feature particularly for an indoor interior lighting lamp in which various lamp lighting directions are adopted depending on the subject.
[0020]
However, when the conventional metal halide lamp using the alumina ceramic tube shown in FIG. 7 is used in the market, a specific lighting is performed particularly in a 70 W type, for example, having a watt lower than 100 W, even though there is no exhaust chip in the light emitting part. It turned out that the emission color fluctuates depending on the direction, which causes a problem. That is, in the 70W type of the emission color 4300K, the actual emission color has a color temperature 4300K as the standard value in the vertical lighting direction, but the color temperature decreases to 3700K in the horizontal lighting direction. Such emission color fluctuations are clearly visible to the human eye. For example, the difference in emission color becomes a conspicuous problem when illumination is performed by combining vertical lighting and horizontal lighting.
[0021]
Here, as described above, in the conventional quartz lamp, the color temperature at the time of horizontal lighting is higher than that at the time of vertical lighting, whereas the 70 W type of metal halide lamp using a conventional alumina ceramic tube is used. In contrast, the color temperature during horizontal lighting is lower than that during vertical lighting. In other words, such emission color variation is a phenomenon peculiar to a metal halide lamp using an alumina ceramic tube.
[0022]
In the case of, for example, a 150 W type having a watt higher than 100 W, the color temperature fluctuation width ΔTc depending on the lighting direction (hereinafter, the color temperature difference in horizontal lighting is Tc (H), and the color temperature in vertical lighting is Tc (V). Then, ΔTc = Tc (H) −Tc (V)) is as small as + 200K, and it is confirmed that this is a fluctuation range that does not cause a problem in actual use. Therefore, it can be said that the luminescent color fluctuation which causes a problem is peculiar to a low watt type of 100 W or less.
[0023]
As described above, in the metal halide lamp using the low watt type alumina ceramic tube of 100 W or less, in order to substantially realize the advantageous feature of the lighting direction free form, the color temperature fluctuation range is about the emission color fluctuation. Finding means that can suppress ΔTc within + 200K or −200K is the first technical problem.
[0024]
Further, as a second technical problem, there is an increase in lamp life. In other words, the alumina ceramic tube is basically said to have higher corrosion resistance against high temperature luminescent materials than the conventional quartz tube, but the rated life time of the metal halide lamp using the alumina ceramic tube according to the prior art is the same as that of the conventional quartz lamp. Equivalent to 6000 hrs.
[0025]
The present invention finds an effective means that can suppress emission color variation due to a specific lighting direction, particularly in a low watt type metal halide lamp having a luminous tube made of a ceramic material such as polycrystalline alumina and having a power consumption of 100 W or less. The purpose of this is to provide a metal halide lamp with high efficiency and long life, which has a free lighting direction characteristic for indoor interior lighting.
[0026]
[Means for Solving the Problems]
The invention according to claim 1 includes a light emitting portion having a pair of electrodes inside and a light emitting tube made of a ceramic material each having a thin tube portion at both ends of the light emitting portion, and a gap is formed in the thin tube portion. The arc tube is filled with a metal halide containing at least one of dysprosium halide, thulium halide, holmium halide and cerium halide and sodium halide as an enclosure. A low watt type metal halide lamp, where the distance between the electrodes in the light emitting part is Le (mm) and the tube inner diameter of the central part of the light emitting part is φi (mm), the arc tube shape parameter Le / φi value Satisfies the range of 0.45 to 0.65, and the tube wall load we of the arc tube satisfies the range of 23 to 30 W / cm ² . Assuming that the electrode length is De (mm) and the lamp power is W (Watt), the structure satisfies the relational expression of 0.0093 × W + 1.3 ≦ De ≦ 0.0133 × W + 2 .
[0027]
Thus, according to vertical and horizontal lighting direction can be suppressed within becoming not color temperature variation width △ Tc + 200K or -200K that the emission color variation problems Rutotomoni and can improve the luminous flux maintenance factor at aging while maintaining high together lamp efficiency High-efficiency, long-life metal halide lamps with free lighting direction that are characteristic for indoor interior lighting can be obtained.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
[0033]
FIG. 1 and FIG. 2 show an arc tube of a 70 W type metal halide lamp and an overall lamp configuration according to an embodiment of the present invention. Here, the basic configuration of the arc tube according to the present embodiment is the same as that of the prior art shown in FIG.
[0034]
The arc tube 1 has an arc tube container 2 made of polycrystalline alumina ceramic, which includes a light emitting portion 3 and thin tube portions 4 and 5. Thin tube portions 4 and 5 (outer diameter 2.6 mm, inner diameter 0.8 mm, and total length 14.5 mm) are sintered at both ends of the light emitting portion 3.
[0035]
Tungsten electrodes 6 and 7 are inserted into the thin tube portions 4 and 5, respectively, and a pair of tungsten electrodes 6 and 7 are provided in the arc tube 1. The tungsten electrodes 6 and 7 are made of tungsten electrode rods 8 and 9 (outer diameter 0.35 mm, total length 15.0 mm) and tungsten coils 10 and 11, respectively.
[0036]
The tube portion 4 and 5, Al ₂ O ₃ -Mo based conductive cermet consisting feeder 12 (outer diameter 0.70 mm, total length 12.0 mm) are respectively hermetically sealed with frit 14. Tungsten electrode rods 8 and 9 are joined and held at the discharge-side tips of the power feeders 12 and 13, respectively. The frit 14 is limited and filled up to the vicinity of the junction between the power supply bodies 12 and 13 and the tungsten electrode rods 8 and 9 in order to suppress the erosion caused by the luminescent material when the lamp is turned on. In the gaps 15, 16 between the thin tube portions 4, 5 and the tungsten electrode rods 8, 9, molybdenum coils 17, 18 are provided so as to be wound around the tungsten electrode rods 8, 9. In the arc tube 1, a metal halide _{(DyI 3, TmI 3, HoI} 3, TlI, NaI) and light-emitting substance 19 made of, argon as mercury and starting aid rare gas as a buffer gas are sealed .
[0037]
As shown in FIG. 2, the complete lamp 20 includes the arc tube 1 held inside an outer tube bulb 21 made of hard glass in which 46.5 kPa of nitrogen is sealed, and a base 22 (E type). Equipped. Further, in the outer tube bulb 21, a quartz shield tube 23 is provided around the arc tube 1 to prevent damage to the outer tube bulb.
[0038]
In setting the detailed configuration of the arc tube 1 according to the present embodiment, the present inventor first investigated the cause of the emission color variation due to the specific lighting direction in the 70W type shown in FIG. As a result, particularly in the 70 W type, the color temperature of the emission color increased in the vertical lighting direction compared to the horizontal lighting direction because the coldest spot temperature location of the arc tube during vertical lighting was higher than that of the light emitting unit 3. It became clear that it originates in forming in the thin tube part 5 located in the lower side used as low temperature. Specifically, since the luminescent material 19 is accumulated in the gap 16 between the narrow tube portion 5 and the tungsten electrode rod 9 that are at a lower temperature, the vapor pressure is lower than that in the horizontal lighting direction. As a result, sodium radiation is attenuated, and the color temperature of the emitted color is increased.
[0039]
As described above, the formation of the gap 16 in the narrow tube portion 5 is indispensable for suppressing the erosion of the frit 14 in realizing the alumina ceramic tube metal halide lamp.
[0040]
Based on the above results, the inventor basically lowers the coldest spot temperature of the arc tube in the horizontal lighting direction in order to suppress the emission color variation due to the lighting direction, compared to the 70 W type according to the prior art, A method of equalizing the coldest spot temperature of the narrow tube portion 5 in the vertical lighting direction was examined. Specifically, the effect of suppressing the emission color variation due to the increase in the tube inner diameter φi with respect to the interelectrode distance Le of the arc tube 1, that is, the decrease in the arc tube shape parameter Le / φi value was investigated. In this case, first, the arc tube 1 is prepared in which the Le / φi value is changed in a range lower than the 0.80 of the 70 W type according to the prior art, and the emission color variation depending on the lighting direction of the lamp 20 having these is measured. did. In addition, a lamp wall 20 having a tube wall load we of 20 to 40 W / cm ² was also prepared, and lifetime characteristics such as luminous flux maintenance rate in aging were measured along with emission color variation. As the dimensions of the arc tube in these studies, the electrode length De (the length between the light emitting portion side end surface of the thin tube and the electrode rod end surface) in FIG. It was changed in a range of 0.0 to 10.0 mm and an interelectrode distance Le 4.0 to 7.0 mm.
[0041]
FIG. 3 shows the relationship between the arc tube shape parameter Le / φi value when the tube wall load we of the arc tube 1 is approximately 27 W / cm ² and the color temperature fluctuation width ΔTc depending on the vertical and horizontal lighting directions. Therefore, in order to suppress the emission color fluctuation within the color temperature fluctuation range ΔTc + 200K or −200K which does not cause a problem, the arc tube shape parameter Le / φi value may be specified in the range of 0.45 to 0.65. all right.
[0042]
In addition, as shown in FIG. 4, by setting the tube wall load we of the arc tube 1 in a range of 30 W / cm ² or less, it is possible to secure a luminous flux maintenance ratio of 70% or more even in aging of 6000 hrs to 9000 hrs. It has been found that a long life can be achieved. However, setting the we value to 23 W / cm ² or less is not appropriate because the lamp efficiency is about 86 lm / W or less, which is 4% or more lower than the conventional value of 90 lm / W. After all, in order to suppress the decrease in lamp efficiency and achieve a long lifetime, it is appropriate to define the we value in the range of 23 to 30 W / cm ² .
[0043]
From the above, as a 70W type arc tube configuration, firstly, by defining the arc tube shape parameter Le / φi value in the range of 0.45 to 0.65, the emission color variation due to the lighting direction can be suppressed. It was found that the lamp characteristics with high efficiency and long life can be obtained by setting the wall load we in the range of 23 to 30 W / cm ² .
[0044]
A 70W type typical lamp 20 according to the present invention was prepared, and confirmation of suppression of emission color variation depending on the lighting direction, and measurement of characteristics such as lamp efficiency and luminous flux maintenance rate due to aging were performed. In this case, the lamp has the basic structure shown in FIG. 1 and FIG. ) Li is 10.0 mm, electrode length De is 2.5 mm, interelectrode distance Le is 5.0 mm, tube inner diameter φi is 8.5 mm (tube outer diameter is 9.7 mm), and arc tube shape parameter Le / φi is 0.59 and tube wall load we were set to 27 W / cm ² , respectively. As a result, with the arc tube configuration according to the present invention, the emission color fluctuation can be suppressed within about -90K, and excellent lamp characteristics with a lamp efficiency of 89 lm / W and a lifetime of about 9500 hrs can be obtained. It was. In addition, a level of an average color rendering index Ra of about 90 was obtained at an average color temperature of 4280 K in the horizontal lighting direction of the lamp (however, each value is an average value of 10 lamps).
[0045]
It has been confirmed that the arc tube structure according to the present invention can be applied to at least a 100 W type other than the 70 W type of the present embodiment.
[0046]
Further, in order to suppress the emission color variation depending on the lighting direction, the electrode length De (mm) is 0.0093 × W + 1.3 ≦ De ≦ 0.0133 × W + 2 when the lamp power is W (watts). Preferably there is.
[0047]
As the shape of the light emitting portion of the arc tube, the light emitting portion as shown in FIG. 5 has a cylindrical shape or a spheroid shape as shown in FIG. 6 instead of a tapered shape at both ends of the light emitting portion as shown in FIG. You may be doing. Particularly in the case of a tapered shape and a spheroid shape, the effect of the configuration of the present invention becomes remarkable. This is because the arc tube with the conventional configuration having these shapes tends to have a low color temperature during horizontal lighting. However, in the spheroid light emitting portion, the value of the maximum inner diameter φi, max at the center of the tube is adopted instead of the inner diameter φi of the tube.
[0048]
In addition, even if the discharge arc tube portion and a pair of thin tube portions at both ends thereof are integrally formed as an alumina ceramic arc tube container, the arc tube configuration according to the present invention can be applied as it is.
[0049]
As a configuration in which the effects of the present invention can be obtained more remarkably, the ratio of sodium halide to the metal halide inside the arc tube is preferably between 10 wt% and 50 wt%.
[0050]
As described above, in a low-wattage type metal halide lamp of 100 W or less equipped with an alumina ceramic arc tube, by providing the arc tube configuration according to the present embodiment, the color temperature variation that does not basically cause the emission color variation. A metal halide lamp that can be suppressed within a width ΔTc + 200K or −200K, and that is characterized by high efficiency and long life for interior interior lighting is obtained.
[0051]
【The invention's effect】
According to the present invention, the arc tube vessel is used in a low watt type metal halide lamp of 100 W or less in which a discharge arc tube portion made of a ceramic material such as polycrystalline alumina and a pair of narrow tube portions at both ends thereof are used. In this case, the variation in the color of the emitted light depending on the lighting direction can be suppressed within the color temperature fluctuation range ΔTc + 200K or -200K, which does not cause a problem. A high-efficiency, long-life metal halide lamp with a certain lighting direction can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing an arc tube of a metal halide lamp according to an embodiment of the present invention. FIG. 2 is a diagram showing an overall configuration of a metal halide lamp according to an embodiment of the present invention. FIG. 4 is a diagram showing the relationship between arc tube shape parameters and emission color fluctuations in a metal halide lamp, which is a metal halide lamp. FIG. FIG. 5 is a diagram showing a light emitting tube of a metal halide lamp whose light emitting portion is a cylindrical shape. FIG. 6 is a diagram showing a light emitting tube of a metal halide lamp whose light emitting portion is a spheroid shape. FIG. 7 is a diagram showing a conventional alumina ceramic tube. Diagram showing arc tube of metal halide lamp used 【Explanation of symbols】
DESCRIPTION OF SYMBOLS 1 Light emission tube 2 Light emission tube container 3 Light emission part 4, 5 Narrow tube part 6,7 Tungsten electrode 8,9 Tungsten electrode rod 10,11 Tungsten coil 12,13 Feeder 14 Frit 15,16 Crevice 17,18 Molybdenum coil 19 Luminescent substance 20 Lamp 21 Outer tube bulb 22 Base 23 Quartz shield tube

Claims (1)

A light emitting portion having a pair of electrodes inside and a light emitting tube made of a ceramic material each having a thin tube portion at both ends of the light emitting portion, a gap is formed in the thin tube portion, and the inside of the light emitting tube Is a low watt type metal halide lamp in which a metal halide containing at least one of dysprosium halide, thulium halide, holmium halide, and cerium halide and sodium halide is enclosed. When the distance between the electrodes in the light emitting part is Le (mm) and the inner diameter of the tube at the center of the light emitting part is φi (mm), the arc tube shape parameter Le / φi is 0.45 to 0.65. The tube wall load we of the arc tube satisfies the range of 23 to 30 W / cm ² and the electrode length is De (mm). A metal halide lamp characterized by satisfying a relational expression of 0.0093 × W + 1.3 ≦ De ≦ 0.0133 × W + 2 when the lamp power is W (Watt) .

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