JP2003016997A - Metal halide lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an (NaI-TlI-InI) based metal halide lamp with excellent lamp efficiency and life property. SOLUTION: This metal halide lamp is provided with an arc tube formed of a translucent material with the metal halide of sodium, thallium and indium filled as a main component of a luminescent material. A sodium bromide (NaBr) is further contained as the main component of the luminescent material. Both lamp efficiency and life property are thereby improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high pressure discharge lamp, and more particularly to a metal halide lamp.

[0002]

2. Description of the Related Art Metal halide lamps, among high pressure discharge lamps, have been characterized by higher efficiency and higher color rendering properties than the high pressure mercury lamps that were invented and developed in the 1960s. It has been put to good use and is being widely used in place of the high pressure mercury lamp. The lamp characteristics of a metal halide lamp are basically defined by the type of metal halide selected as a light emitting substance enclosed in an arc tube, and lamps composed of various combinations of metal halides have been put into practical use. Among these, a sodium-thallium-indium (NaI-TlI-InI) -based lamp is mentioned as one of the particularly representative high-efficiency general lighting lamps. Since being put into practical use as early as around 1970, this lamp has been widely used for outdoor lighting such as in plazas and sports fields, and for indoor lighting such as factories and gymnasiums, and has reached the present.

The main problems in the conventional development of a (NaI-TlI-InI) lamp are (i) water (H ₂ O) emitted from a light emitting substance during the life of the lamp, a quartz material of an arc tube or the like.
Increase in lamp starting voltage and deterioration of luminous flux due to impurities such as
(Ii) Improvement of life characteristics such as light color change due to disappearance of sodium (Na) from inside the arc tube. These problems have been solved by thoroughly improving the arc tube manufacturing process to completely remove impurities and filling the outer tube gas to prevent sodium loss. Further, in order to improve the color rendering of the lamp, lithium iodide (LiI) which newly emits red radiation is added to the light emitting material. As a result, as the lamp characteristics including the typical life of the existing lamp, for example, in the transparent 250 W type, the initial luminous flux is 17,000 lm (value at a lamp aging time of 100 hours) and the lamp efficiency is 6
8 lm / W, general color rendering index (Ra) 65, and life time 9000 hours were obtained. Here, according to the measurement result of the present inventor, the average luminous flux maintenance factor of the lamp at the life time of 9000 hours is about 65% of the initial value. In the above lamp characteristics, the lamp efficiency value is
It can be said that the level has not improved much compared to the level at the beginning of development.

By the way, another high-efficiency type lamp for general lighting is sodium-scandium (NaI).
-ScI ₃ ) based lamp is the same as the above (NaI-TlI-In
It was put into practical use at about the same time as the I) type lamps, and both lamps have been popularized in the market in competition. Current (Na
The typical lamp characteristics of the I-ScI ₃ ) type lamp are:
The obtained values are 1500 lm, lamp efficiency 86 lm / W, general color rendering index (Ra) 65, and life time 9000 hours. In this case, the average luminous flux maintenance factor of the lamp at the life time of 9000 hours is about 50% of the initial value.

The above-mentioned (NaI-TlI-
And InI) based lamp, Comparing lamp characteristics of (NaI-ScI ₃₎ based lamp, as features of the former lamp, in particular a light flux maintaining rate during the life and the like to be superior to the latter. For example, the luminous flux maintenance factor of the former lamp at a life time of 9000 hours is 65% compared to 50% of the latter.
%. This is basically due to the difference in reaction ratio between the luminescent materials of both lamps and the high-temperature arc tube quartz. That is, especially scandium iodide of the latter lamp reacts with quartz more easily than sodium iodide (NaI), thallium iodide (TlI), and indium iodide (InI) of the former lamp.

On the other hand, the problem with the lamp characteristics of the (NaI-TlI-InI) system lamp is that the lamp efficiency is (N
It is lower than that of the aI-ScI ₃ ) system lamp. For example, in the 250 W type, the former lamp efficiency is 68 lm / W, which is about 20% lower than the latter lamp efficiency of 86 lm / W. Conventionally, (N
aI-TlI-InI) based lamp, the low level of such lamp efficiency, by supplementing a stable life characteristics with a high luminous flux maintenance factor of the, said to have been obtained compete with (NaI-ScI ₃₎ based lamp .

[0007]

However, (Na
In the (I-TlI-InI) type lamp, such low lamp efficiency is a big problem in adapting to the future energy saving era, and therefore, the improvement of the lamp efficiency is a major issue demanded by the market. There is. Further, another problem is that the life time is as short as 9000 hours as compared with 12000 hours of the conventional high pressure mercury lamp. This is a problem that is common to all metal halide lamps, but improvement in this life time has also been a problem that the market has requested since the introduction of the lamp. Then, due to the above two improvements in lamp efficiency and life time, (NaI-TlI
-InI) -based lamps have been redeveloped into high-pressure discharge lamps that are excellent in terms of both lamp efficiency and life characteristics, and as a main lamp for high-efficiency indoor / outdoor lighting, they will further contribute to energy saving in the future. Can be expected.

The present invention relates to a (NaI-TlI-InI) -based metal halide lamp, which solves its low lamp efficiency and short life time, is excellent in both lamp efficiency and life characteristics, and is sufficiently adapted to the future energy saving era. The object is to provide a metal halide lamp that can be used.

[0009]

In order to achieve the above object, the metal halide lamp of the present invention comprises an arc tube made of a translucent material in which metal halides of sodium, thallium and indium are encapsulated as main components of a luminescent substance. ,
It is characterized by further containing sodium bromide (NaBr) as a main component of the luminescent material. This improves both low lamp efficiency and short life time,
It is possible to obtain a metal halide lamp that is excellent in both lamp efficiency and life characteristics and that can be sufficiently applied in the future energy saving era.

In the metal halide lamp of the present invention, the metal halide of sodium is sodium iodide (NaI), and the content of sodium bromide (NaBr) with respect to the sodium iodide is NaBr in a mass ratio.
It is preferable that / NaI is in the range of 0.02 to 0.10. As a result, both a low lamp efficiency and a short life time are sufficiently improved, and it is possible to obtain a metal halide lamp which is more excellent in both lamp efficiency and life characteristics and which can be sufficiently adapted to the future energy saving era. If the sodium bromide content is less than 0.02, the vapor pressure of sodium becomes too high, self-absorption of sodium occurs, the luminous flux decreases, and the lamp efficiency decreases. On the other hand, when the sodium bromide content exceeds 0.10, although the lamp efficiency can be improved, the halogen cycle more activated during the life of the lamp causes severe erosion / deformation of the tungsten electrode and shortens the life of the lamp. Become.

Further, the metal halide lamp of the present invention is
The wall load (we) of the arc tube is 18 to 25 W / cm
It is characterized by a range of ² . As a result, in particular, the lamp efficiency is further improved, and it is possible to obtain a metal halide lamp which is excellent in both lamp efficiency and life characteristics and which can be sufficiently applied in the future energy saving era. The pipe wall load is 18
If it is less than W / cm ² , a high luminous flux cannot be obtained because the vapor pressure of the luminescent metal is insufficient. On the other hand, the pipe wall load is 2
If it exceeds 5 W / cm ² , the sodium vapor pressure is Na
When the lamp efficiency rises beyond the suppression effect of Br and the lamp efficiency rises, the luminous flux maintenance factor decreases due to the recrystallization of the arc tube quartz due to the rise in the tube wall temperature, and the target life of 12000 hours. I don't have the time.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
4 to FIG.

FIG. 1 and FIG. 2 are cross-sectional views showing the arc tube structure and the lamp structure of a 250 W type metal halide lamp according to an embodiment of the present invention, respectively. FIG. 3 is a diagram showing a lighting circuit configuration of the metal halide lamp.

As shown in FIG. 1, the container of the arc tube 1 is made of a quartz material, the main electrodes 2 and 3 made of a pair of tungsten coils are provided at both ends of the arc tube 1, and one end thereof is provided. An auxiliary electrode 4 made of a tungsten rod is provided. The main electrodes 2 and 3 and the auxiliary electrode 4 are external lead wires 8 and 9 made of molybdenum rods via molybdenum foils 5, 6 and 7 which are hermetically sealed at both ends of the arc tube 1, respectively.
And 10 are connected. The heat insulating films 11 and 12 containing boron nitride (BN) as a main component are applied and baked on the outer surfaces of both ends of the arc tube 1. Inside the arc tube 1, metal halides of sodium, thallium, and indium, and a light-emitting substance 13 containing sodium bromide as a main component are enclosed, and in addition, 40 to 60 mg of mercury 14 as a buffer gas and a starting aid. Neon / argon Penning gas (Ne + 0.5% Ar) as rare gas for use 1
5 is enclosed at about 10 kPa. The luminescent material has a typical composition of sodium iodide (NaI) of 78.6.
%, Thallium iodide (TlI) 4.5%, indium iodide (InI) 2.9%, lithium iodide (Li
I) 1.1%, sodium bromide (NaBr) 2.9%
(However, the composition is mass%) 13.8 mg
Is enclosed. In this case, lithium iodide is added according to the prior art to improve the lamp color rendering.

In the structure of the completed lamp, as shown in FIG. 2, the arc tube 1 is assembled by using a stem 19 made of hard glass in which a pair of lead wires 17 and 18 are hermetically sealed, and made of hard glass. Hold inside the outer tube valve 20,
is set up. In this case, the external lead wires 8 and 9 leading to the main electrodes 2 and 3 of the arc tube 1 are lead wires 17, respectively.
The external lead wire 10 which is connected to 18 and communicates with the auxiliary electrode 4 is connected to one of the lead wires 18 via a resistor 21 and a bimetal switch 22. Further, a zirconium-aluminum getter 23 is installed inside the outer tube valve 20, and the inside of the outer tube valve 20 is evacuated to a vacuum and is filled with nitrogen-neon gas (N ₂ + 60%).
Ne) is enclosed in about 53 kPa. Finally, a cap 24 is attached to the outer tube valve 20.

The completed lamp 16 is, as shown in FIG. 3, a simple reactance ballast 2 for a 250 W high pressure mercury lamp.
Illuminated by 5. This lighting operation includes (i) 2
When the 00V power supply 27 is applied, first, an auxiliary discharge is generated between the main electrode 2 and the auxiliary electrode 4, and (ii) by the action of sufficient initial electrons supplied from the auxiliary discharge, the main electrode 2,
The main discharge is started during 3, and (iii) about 1 minute after the start of the main discharge, the contact point of one of the bimetal switches 22 becomes the arc tube 1.
The heat is dissipated from the ON state to the OFF state, and the OFF state is continued during the subsequent steady lighting of the lamp.

Next, in such a 250 W type metal halide lamp, the arc tube inner diameter (φi) is 15 m.
m and a distance between electrodes (Ld) of 26.5 mm (Example 1) were manufactured, and the lamp characteristics including the life thereof were measured by downward lighting. At this time, the tube wall load (we) of the arc tube 1 was 18.2 W / cm ² . The tube wall load (we) is a value obtained by dividing the lamp watt by the inner surface area within the distance between the electrodes of the arc tube, that is, we = 250 / (0.0
It is a value obtained by 1πφiLd). As a result of the measurement,
The lamp characteristics of Example 1 are as follows: initial luminous flux 18400 lm, lamp efficiency 73.6 lm / W, general color rendering index (Ra) 6
5.4 and color temperature 4750K.

For comparison, the conventional (NaI-Tl
The typical composition of the light emitting material of the I-InI-based lamp is sodium iodide (NaI) 82.2%, thallium iodide (TlI) 11.7%, and indium iodide (InI) 4.0. %, Lithium iodide (LiI) 2.
A lamp (Comparative Example 1) having the same configuration as that of Example 1 except that a luminescent substance consisting of 1% (however, the composition is% by mass) was filled was manufactured, and an experiment was conducted in the same manner as in Example 1. As a result of the measurement, the lamp characteristic of Comparative Example 1 is that the initial luminous flux is 1750.
0 lm, lamp efficiency 70 lm / W, general color rendering index (R
a) 64.5 and color temperature 4750K.

FIG. 4 shows the luminous flux maintenance factor characteristics of the lamp manufactured in Example 1 during the life of Comparative Example 1 (conventional type).
Compared with the lamp of. As is clear from FIG.
The average life time of the lamp of Example 1 is 12000 hours (luminous flux maintenance rate 65%), and Comparative Example 1 (conventional type)
The lamp can maintain a luminous flux maintenance rate of 65% for about 8 hours.
The luminous flux maintenance factor after 800 hours and 12,000 hours of life is about 5
It was 7%. From the above results, the lamp of Example 1
Compared with the characteristics of the conventional 250 W type lamp, the lamp efficiency is increased by about 5% and the life time is also increased by about 40%, which shows that there is a sufficient effect of improving the lamp characteristics.

The reason why such a result is obtained is that in Comparative Example 1, the sodium D line (589.0 nm and 589.6 n) was used.
It is considered that this is because the luminous efficiency of radiation was reduced due to self-absorption of m) and spread to the longer wavelength side. this is,
It is basically due to the increase of sodium vapor pressure in the discharge arc. On the other hand, in Example 1, by adding sodium bromide (NaBr), it is considered that the self-absorption of sodium D line from the arc tube 1 and the spread to the long wavelength side were suppressed, and the lamp efficiency was improved. . Further, the action of bromine (Br) of the added sodium bromide (NaBr) makes the so-called halogen cycle more active, and the tungsten evaporated from the electrode and adhering to the inner surface of the arc tube is relatively quickly removed, It is considered that the life time is also improved.

In the present invention, the effect of sodium bromide (NaBr) added to the luminescent material is as follows. When the encapsulated sodium metal halide is sodium iodide (NaI), the content ratio of sodium bromide (NaBr), That is, the mass ratio of sodium bromide to sodium iodide Na
Closely related to Br / NaI. If the content ratio of sodium bromide is too low, the effect of improving the lamp efficiency and the life characteristics of the lamp is reduced. On the other hand, if the content ratio of sodium bromide is too high, the lamp efficiency can be improved, but the halogen cycle which is activated more during the life of the lamp causes severe erosion / deformation of the tungsten electrode and shortens the life of the lamp. As a result, sodium bromide (NaB) capable of obtaining a sufficient lamp characteristic effect and suppressing a short life.
The content ratio of r) was in the range of NaBr / NaI = 0.02 to 0.10 by mass ratio with respect to sodium iodide (NaI).

Next, in order to further improve the lamp efficiency, a lamp in which a luminous substance having the same composition as the above, to which sodium bromide (NaBr) is added, is enclosed in an arc tube having a higher tube wall load (we) (implementation) Example 2) was manufactured and the lamp characteristics were measured in the same manner as in Example 1. The typical structure of the arc tube is: inner diameter of arc tube (φi) 16 mm, distance between electrodes (Ld)
It was 25 mm, and the tube wall load (we) of the set arc tube in this case was 19.9 W / cm ² .

As a result, the lamp characteristics of Example 2 were as follows: initial luminous flux 19900 lm, lamp efficiency 79.6 lm / W, general color rendering index (Ra) 65.6 and color temperature 4720.
K, average life time 12100 hours (light flux maintenance rate 65%)
Met. Especially, the lamp efficiency is further increased to about 17% as compared with the conventional 250 W type lamp, and it has been improved to the level of 93% of the (NaI-ScI ₃ ) system lamp which is competing in the market. In addition, life time is also an objective 1
2000 hours had been achieved.

Generally, the lamp efficiency of a high pressure discharge lamp is
It is well known that as the wall load of the arc tube increases, it rises. However, the above-mentioned conventional (N
In the study on the aI-TlI-InI) lamp, as the tube wall load (we) increases, the sodium vapor pressure becomes higher, and the self-absorption of sodium D-ray and the spread to the long wavelength side increase, resulting in Moreover, the lamp efficiency is not improved so much. On the other hand, the sodium vapor pressure suppressing action of sodium bromide (NaBr) according to the present invention is sufficiently exhibited even in an arc tube having a high tube wall load, and the tube wall load (we)
That is, the increase in lamp efficiency commensurate with the increase in
That is, it can be said that the effect of improving the lamp efficiency by sodium bromide (NaBr) is greater in the arc tube structure having a higher tube wall load (we).

In the present invention, the tube wall load (we) at which the effect of sodium bromide becomes large is in the range of 18 to 25 W / cm ² , but conventionally, the arc tube of the (NaI-TlI-InI) type lamp is Tube wall load (we) is usually 15 W / cm ²
It is set within the range of less than 18 W / cm ² . When the tube wall load (we) value is higher than 25 W / cm ² , the sodium vapor pressure becomes higher than the suppression effect of sodium bromide, and the increase in lamp efficiency is saturated. Further, due to the recrystallization of the arc tube quartz due to the rise in the temperature of the tube wall, the luminous flux maintenance factor is lowered, and the target life time of 12000 hours cannot be obtained.

The luminescent material to which NaBr is added in the above embodiment may be further added with another metal halide such as cesium iodide (CsI) for stabilizing the discharge arc. Further, even when an arc tube made of a material such as alumina ceramic other than quartz is used, the same effect by sodium bromide (NaBr) can be obtained.

Further, the arc tube structure of the embodiment of the present invention is
The present invention can be applied to 300W type and 400W type other than the 250W type. Further, it can be applied to a so-called phosphor type metal halide lamp in which a phosphor is applied to the inner surface of the outer bulb. In this case, the general color rendering index (Ra) is about 7 in consideration of the red emission from the phosphor.
The lamp light color is improved to 0, while the color temperature is low at about 4300K.

As described above, (NaI-TlI-In
Regarding the I) type metal halide lamp, by providing the arc tube configuration as shown in the above-mentioned embodiment, both the low lamp efficiency and the short life time, which have been problems in the past, are improved, and both the lamp efficiency and the life characteristics are improved. It is possible to obtain an excellent metal halide lamp.

[0029]

As described above, according to the present invention,
In the (NaI-TlI-InI) -based metal halide lamp, by using as a main component a light emitting material to which NaBr is newly added, both the low lamp efficiency and the short life time, which are problems in the conventional lamp, are improved, It is possible to provide a metal halide lamp that is excellent in both efficiency and life characteristics and that can be sufficiently adapted to the future energy saving era. Therefore, its industrial value is great.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of an arc tube of a metal halide lamp according to this embodiment.

FIG. 2 is a cross-sectional view showing a configuration of a lamp of the metal halide lamp according to the present embodiment.

FIG. 3 is a diagram showing a configuration of a lighting circuit of the metal halide lamp according to the present embodiment.

FIG. 4 is a diagram showing the luminous flux maintenance factor characteristics during the life of the metal halide lamps of the present embodiment and the conventional example.

[Explanation of symbols]

1 arc tube A few main electrodes 4 auxiliary electrodes 5, 6, 7 molybdenum foil 8, 9, 10 External lead wire 11, 12 Moisturizing film 13 Luminescent substances 14 Mercury 15 Neon-Argon Penning Gas 16 Completed lamp 17,18 Lead wire 19 stems 20 outer tube valve 21 Resistance 22 Bimetal switch 23 Zirconium-Aluminum Getter 24 mouthpiece 25 ballast

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Claims (3)

[Claims] 1. A light emitting tube comprising a translucent material in which metal halides of sodium, thallium and indium are enclosed as a main component of a light emitting substance, and sodium bromide (NaBr) is further contained as the main component of the light emitting substance. A metal halide lamp characterized by that. 2. The metal halide of sodium is sodium iodide (NaI), and the content of the sodium bromide (NaBr) with respect to the sodium iodide is NaBr / NaI = 0.02 to 0.03 by mass ratio. The metal halide lamp according to claim 1, wherein the range is 10. 3. The tube wall load (we) of the arc tube is 18
The metal halide lamp according to claim 1 or 2, wherein the content is in the range of 25 W / cm ² .