JP2003059451A - High pressure discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a general indoor and outdoor high watt type highly efficient-long service life light transmissive ceramic tube discharge lamp capable of surely preventing the occurrence of a crack and damage in a frit sealing part of an alumina ceramic capillary part by lamp aging while maintaining a superior lamp characteristic. SOLUTION: This high pressure discharge lamp has an arc tube vessel having a discharge arc tube part composed of a light transmissive ceramic polycrystalline substance and the capillary part composed of a light transmissive ceramic polycrystalline substance continuously arranged in this discharge arc tube part, and has a power supply body having the sealing part sealed by frit in the capillary part of the arc tube vessel. The average crystal particle size of the light transmissive ceramic polycrystalline substance for forming the capillary part abutting to the sealing part is set smaller than the average crystal particle size of the light transmissive ceramic polycrystalline substance for forming the capillary part unabutting to the sealing part.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high pressure discharge lamp,
In particular, the present invention relates to a metal halide lamp including a ceramic arc tube such as a translucent alumina polycrystal (hereinafter, also referred to as “polycrystal alumina ceramic”).

[0002]

2. Description of the Related Art Recently, a new metal halide lamp using a polycrystalline alumina ceramic has been developed and developed as an arc tube material instead of the conventional quartz product. Alumina ceramic arc tubes are basically more heat resistant than quartz arc tubes, so a higher tube wall load design is possible.
Lamp characteristics with high efficiency and high color rendering can be obtained.

Alumina ceramic tube metal halide lamps, which have been developed and developed in the past, have a lamp wattage of 35 W or more.
The low wattage type of 150 W is the main type, and its rated life time is usually set to 6000 hours or more, and it is mainly used in the field of indoor lighting in commercial spaces such as stores.

The structure of the arc tube and the entire structure of the conventional typical alumina ceramic tube metal halide lamp are shown in FIGS. 3 and 4, respectively. An arc tube container 29 that constitutes the arc tube 28 is composed of a discharge arc tube portion 30 made of a polycrystalline alumina ceramic material, and a pair of thin tube portions 31 and 32 sintered at both ends thereof. The discharge arc tube portion 30 and the thin tube portions 31 and 32 have almost no crystal grain size in order to prevent cracks and damage near the sintered portion of the discharge arc tube portion 30 and the thin tube portions 31 and 32 during lamp aging. It is composed of equally homogeneous polycrystalline alumina ceramic material. This is a necessary condition for the construction of the arc tube container 29 used for the alumina ceramic tube metal halide lamp.

As the polycrystalline alumina ceramic material, in order to increase the luminous efficiency of the lamp as much as possible, the average crystal grain size is defined to be a relatively large range of 30 to 40 μm, and the light transmittance thereof is 95. % Or higher material is used. The average crystal grain size is controlled mainly by the alumina raw material A before firing the alumina ceramic.
It is performed by increasing or decreasing the amount of magnesium oxide (MgO) added to l ₂ O ₃ as a crystal growth suppressing substance, and adjusting the firing temperature and firing time in the hydrogen reducing atmosphere.

A pair of tungsten coil electrodes 33 and 34 are provided at both ends of the arc tube 28. The tungsten coil electrodes 33 and 34 are respectively composed of tungsten electrode rods 35 and 36 and tungsten coils 37 and 38. It consists of three parts. The arc tube thin tube portions 31, 3
2, the power feeders 39 and 40 made of niobium or a conductive cermet are hermetically sealed by a frit 41, and one end of each of the power feeders 39 and 40 is
The tungsten rods 35 and 36 are welded and held. In addition, in the power feeding bodies 39 and 40 made of a conductive cermet,
In some cases, an external lead wire made of niobium or the like is welded and held at the other end.

Here, the frit 41 is melted and filled up to the vicinity of the welding ends of the tungsten rods 35 and 36.
This prevents (a) erosion of the frit 41 due to the luminescent material when the lamp is lit, and (b) prevention of cracks and damage due to direct frit sealing of the arc tube thin tube portions 31, 32 with the tungsten electrode rods 35, 36. In order to achieve this, it is an indispensable means, and it can be said that this basically embodies the alumina ceramic tube metal halide lamp. The arc tube thin tube portion 31, which is inevitably formed with this,
In the gaps 42, 43 between the 32 and the tungsten rods 35, 36, molybdenum coils 44, 45 are usually provided so as to wind the tungsten electrode rods 35, 36.

Furthermore, in the light emitting tube 28, dysprosium iodide (DyI _3), iodide thulium (TmI _3), iodide holmium (HoI _3), thallium iodide (Tl
I), a luminescent material 46 selected from metal halides such as sodium iodide (NaI), mercury as a buffer gas, and a rare gas for starting assistance such as argon are enclosed.

As shown in FIG. 4, the entire structure of the lamp 47 equipped with the arc tube 28 is such that the arc tube 28 is installed inside an outer bulb 48 made of quartz or hard glass. The base 49 is attached. Further, a gas mainly containing nitrogen is contained in the outer tube valve 48 at about 70 kPa.
A sealed quartz tube 50 is provided around the arc tube 28 to prevent damage to the outer bulb bulb. The lamp 47 is usually lit by an electronic ballast or a copper-iron type inductance ballast with a built-in starter.

By the way, in order to expand the application field of the alumina ceramic tube metal halide lamp and to further promote energy saving in the lighting field, the present inventor, in addition to the conventional indoor lighting for stores, etc. High wattage type 200 that can be expected to grow for outdoor lighting
We have been working on the development of ~ 400W alumina ceramic tube metal halide lamps. The specific development goals of the lamp are higher lamp efficiency for further energy saving, and a rated life time of 90 or more equivalent to the conventional quartz arc tube metal halide lamp for general indoor and outdoor use.
Two of a long life of 00 hours or more, more preferably 12000 hours or more, is set.

[0011]

However, in developing the above-mentioned high watt type lamp, a thin tube sintered at both ends of the discharge arc tube portion 30 of the alumina ceramic arc tube container 29 shown in FIG. Parts 31, 32 are 1
Even during lamp aging which is a relatively short time of 000 hours or less, cracks occur and breakage occurs. And such an alumina ceramic thin tube portion 3
The cracks and damages 1 and 32 were concentrated at the frit sealing portion with the power feeding bodies 39 and 40 shown in FIG. This is because the diameter of the power supply body is basically increased due to the high wattage type, the lamp current is also higher, and the stress applied to the alumina ceramic thin tube portion at the frit sealing portion is increased accordingly. It is considered to be a thing.

Therefore, as a means for solving the above problems,
For example, studies were made on increasing the wall thickness of the alumina ceramic thin tube portion and reducing the temperature of the thin tube portion at the sealed portion when the lamp was lit. However, according to these means, the vapor pressure of the luminescent material is lowered due to the temperature drop at the end portion of the arc tube when the lamp is lit, which causes new problems such as a decrease in lamp efficiency.

Therefore, in order to realize a high efficiency and long life alumina ceramic tube metal halide lamp for indoors and outdoors, while maintaining excellent lamp efficiency and other lamp characteristics, the frit at both ends of the arc tube container is maintained. It is an important technical issue to reliably prevent cracking and damage of the alumina ceramic thin tube portion in the sealed portion.

The present invention has been made in order to solve the above-mentioned problems, and surely prevents the occurrence of cracks and damages in the frit sealing portion of the alumina ceramic thin tube portion due to lamp aging while maintaining excellent lamp characteristics. It is an object of the present invention to provide a high-pressure discharge lamp using a translucent ceramic arc tube of high efficiency and long life, which can be used for general indoors and outdoors.

[0015]

To achieve the above object, a high-pressure discharge lamp of the present invention comprises a discharge arc tube made of a translucent ceramic polycrystal and a translucent tube connected to the discharge arc tube. High-pressure discharge lamp having an arc tube container having a thin tube portion made of a porous ceramic polycrystal, and having a sealing portion formed by sealing a power supply member with a frit in the thin tube portion of the arc tube container. The average crystal grain size of the translucent ceramic polycrystalline body forming the thin tube portion that abuts the sealing portion is the average of the translucent ceramic polycrystalline bodies forming the thin tube portion that do not abut the sealing portion. It is characterized by being smaller than the crystal grain size.

As a result, it is possible to reliably prevent cracks and damages in the frit sealing portion of the translucent ceramic thin tube portion due to lamp aging while maintaining excellent lamp characteristics. It is possible to obtain high watt type alumina ceramic tube high pressure discharge lamp with high efficiency and long life.

In the high pressure discharge lamp, the translucent ceramic polycrystalline body forming the thin tube portion not in contact with the sealing portion has an average crystal grain size of 25 μm or more, and the sealing portion is The average crystal grain size of the translucent ceramic polycrystalline body forming the thin tube portion abutting on the
It is preferably not more than, and particularly preferably not more than 15 μm.

As a result, while maintaining excellent lamp characteristics, the occurrence of cracks and damages in the frit sealing portion of the alumina ceramic thin tube portion due to lamp aging,
The aging time can be reliably prevented for at least 9000 hours, and the desired high efficiency and long life alumina ceramic tube high pressure discharge lamp for general indoor and outdoor purposes can be obtained.

In the high pressure discharge lamp, the translucent ceramic polycrystal is preferably translucent alumina polycrystal.

[0020]

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

FIG. 1 and FIG. 2 are views showing an arc tube structure of a translucent ceramic tube metal halide lamp with a built-in starting device for a lamp watt 300 W, which is an embodiment of the present invention, and an overall lamp structure.

As the translucent ceramic polycrystal forming the arc tube, a translucent alumina polycrystal, a translucent yttrium-aluminum-garnet polycrystal, a translucent yttria polycrystal, or the like is used. You can Among them, the translucent alumina polycrystal is preferable because it has low reactivity with the light emitting substance.

The basic structure of the arc tube 1 is the same as that of the conventional alumina ceramic tube metal halide lamp shown in FIG. In the arc tube 1, the arc tube container 2 is composed of a discharge arc tube portion 3 made of a polycrystalline alumina ceramic material and a pair of thin tube portions 4 and 5 sintered at both ends thereof. Here, as the polycrystalline alumina ceramic material used for the discharge arc tube portion 3, a material having an average crystal grain size of about 28 μm that can obtain a light transmittance of 95% or more is used in order to improve the lamp efficiency. The raw material of the material is
Magnesium oxide (MgO) 0.15% (mass ratio) was added as a crystal growth inhibitor. Further, the arc tube 1 has dimensions such that the discharge arc tube portion 3 has an inner diameter φi of 17.0 mm and a wall thickness of 1.3 mm, and the thin tube portions 4 and 5 have an outer diameter R of 3.8 mm.
The hole diameter r was set to 1.3 mm, the length L was set to 15 mm, and the interelectrode distance Ld was set to 24.0 mm.

A pair of tongues is provided at both ends of the arc tube 1.
Ten coil electrodes 6 and 7 are provided.
Ten coil electrodes 6 and 7 are tungsten electrode rods, respectively.
8, 9 (wire diameter 0.7 mm) and tungsten coil 10,
2 of 11 (single wire diameter 0.2mm and 10 coil turns)
It consists of parts. The thin tubes 4 and 5 were
Luminium (Al₂O₃) / Molybdenum (Mo) = 50%
/ 50% (mass ratio) composition made of conductive cermet
The electric bodies 12 and 13 (diameter 1.2 mm) are oxidized dyspros
Umm (Dy₂O₃) / Aluminum oxide (Al₂O₃)/two
Silicon oxide (SiO ₂) Airtightly sealed by the system frit 14
Has been. Also, one of the power feeding bodies 12 and 13
The tungsten rods 8 and 9 are welded and held at the ends of the
Each of the outer ends is made of niobium at the other end.
Wires 15 and 16 (wire diameter 1.2 mm) are welded and held
ing.

The frit 14 is melted and filled up to the vicinity of the welding ends of the tungsten rods 8 and 9. Then, in the gaps 17 and 18 between the arc tube thin tube portions 4 and 5 and the tungsten rods 8 and 9 that are inevitably formed with this, molybdenum coils 19 and 20 (wire diameter 0.25 mm) are provided in the tungsten electrode rods 8 and 8. It is provided in the form of being wound around 9. In the arc tube 1, 13.5 mg of a metal halide luminescent material 21 having a composition of 40% by mass of cesium iodide (CeI ₃ ) and 60% by mass of sodium iodide (NaI), and 45 mg of mercury (Hg) as a buffer gas. , And a rare gas for assisting starting, which is composed of neon / argon Penning gas (Ne + 0.5% Ar).

As shown in FIG. 2, the entire structure of the lamp 22 provided with the arc tube 1 is installed inside an outer bulb 24 made of hard glass, in which the arc tube 1 and a starting device 23 are combined. . Further, in order to further reduce the lamp starting voltage, a starting auxiliary conductor 25 made of molybdenum wire is attached along the discharge arc tube portion 3 of the arc tube container 2. Further, nitrogen gas 70 is provided inside the outer pipe valve 24.
A shield quartz tube 26 is provided around the arc tube 1 in which kPa is enclosed and which prevents damage to the outer bulb. Finally. The base 27 is attached to the outer bulb 24, and the lamp 2
2 is completed. The lamp 22 is lit by a simple conventional copper-iron type inductance stabilizer for a high pressure mercury lamp 300W.

Next, the translucent ceramic polycrystal forming the thin tube portion of the high pressure discharge lamp of the present invention will be described.
In this embodiment, a translucent alumina polycrystal is described as an example, but the present embodiment is not limited to this.

First, as the polycrystalline alumina ceramic material of the thin tube portions 4 and 5 which are sintered on both ends of the discharge arc tube portion 3 of the arc tube container 2, the average crystal grain size of 28 μm, which is the same as that of the discharge arc tube portion 3, is used. A trial lamp 22 using the above material was prepared and its lamp aging test was conducted. As a result, two of the 20 test lamps were subjected to a relatively short lamp aging of 600 to 950 hours, so that the thin tube portions 4 and 5 were frit-sealed with the power feeding bodies 12 and 13 made of a conductive cermet. There was a problem of cracking and damage, which led to the end of life. Analysis of this cause revealed that the diameter of the power supply was basically increased due to the high wattage type, and the lamp current was also higher. Therefore, the stress applied to the polycrystalline alumina ceramic thin tube portions 4 and 5 at the frit sealing portion was increased. It was found to be due to the increase.

Next, various investigations were made on means for preventing the occurrence of cracks and damages in the frit sealing portions of the polycrystalline alumina ceramic thin tube portions 4 and 5. as a result,
As a material configuration of the thin tube portions 4 and 5 made of a polycrystalline alumina ceramic material, in the sintered portion with the discharge light emitting tube portion 3, the average crystal grain size thereof is made of the same material as that of the discharge light emitting tube portion 3,
On the other hand, the average crystal grain size of so-called thin tube portions 4 and 5, which is made of a material having smaller average crystal grains and higher mechanical strength in the frit seal portion with the power feeding bodies 12 and 13, is partially different in the frit seal portion. It has been found that a means of using a polycrystalline alumina ceramic material set to be small is effective.

Therefore, based on the above knowledge, the arc tube 1 provided with the thin tube portions 4 and 5 made of a polycrystalline alumina ceramic material whose average crystal grain size is set smaller in the sealed portion than in the sintered portion is prepared. Then, a similar aging test was performed on the lamp 22 using this, and the rate of occurrence of cracks / damages depending on the aging time was examined.

In this test, the average crystal grain size of the polycrystalline alumina ceramics in the sintered parts as the thin tube parts 4 and 5 is
The thickness was set to about 28 μm, which is equivalent to that of the discharge arc tube unit 3, and the average crystal grain size was changed stepwise in the range of 7 to 24 μm by gradually reducing the amount of magnesium oxide (MgO) that is a crystal growth inhibitor in the sealed portion. Samples of various types were prepared, and arc tubes 1 for 20 lamps each equipped with the sample were prepared (Examples 1 to 1).
5). For comparison, a lamp provided with thin tube portions 4 and 5 having an average crystal grain size of 28 μm in the sealed portion was simultaneously tested. The above results are summarized in Table 1.

The average crystal grain size of the polycrystalline alumina ceramic is a value obtained by enlarging an electron micrograph of a fracture surface and calculating the average grain size from the number of grains present at a certain distance.

[0033]

[Table 1]

As a result, as shown in Table 1, (a) the occurrence of cracks and breakages which are particularly problematic is that the average crystal grain size of the polycrystalline alumina ceramics in the frit sealing portions of the thin tube portions 4 and 5 becomes small. Accordingly, it was confirmed that it was effectively suppressed as a whole. Further, it was confirmed that (b) the aging time at which cracking / damage begins to occur increases as the average crystal grain size decreases. Then, (i) in order to achieve the target rated life time of at least 9000 hours or more in the present invention, the average crystal grain size of the frit-sealed portion should be 2
Specified within the range of 0 μm or less, and (ii) longer 1200
It was found that the average crystal grain size should be 15 μm or less in order to obtain the rated life time of 0 hours or more.

Next, a lamp 22 provided with an arc tube 1 composed of alumina ceramic thin tube portions 4 and 5 in which the average crystal grain size of the frit sealing portion was set to a small value of 10 μm was prepared, and its initial lamp characteristics were prepared. (Lamp aging time: 1
00 hours) and life characteristics were measured.

As a result, at a lamp input of 300 W, the lamp luminous flux is 36500 lm and the lamp efficiency is 121.7 lm /
With W, excellent lamp characteristics of general color rendering index Ra72 were obtained. It was also confirmed that even after the aging time of 12000 hours, the thin tube portions 4 and 5 at the frit sealing portion in question did not crack or break.

As described above, the greatest feature of the means according to the present invention is that cracks and damages can be reliably prevented while maintaining lamp characteristics such as lamp efficiency at a high level.

[0038]

As described above, according to the present invention, in a high pressure discharge lamp, particularly a metal halide lamp, the average crystal grain size of the translucent ceramic polycrystalline body forming the thin tube portion abutting the sealing portion is controlled by The translucent ceramic thin tube portion by lamp aging is made smaller by making it smaller than the average crystal grain size of the translucent ceramic polycrystalline body forming the thin tube portion which is not in contact with the attachment part, and increasing its mechanical strength. It is possible to reliably prevent the occurrence of cracks and damages in the frit-sealed portion while maintaining excellent lamp characteristics. Therefore, it is possible to provide a high-wattage, high-efficiency, long-life ceramic tube high-pressure discharge lamp for general indoors and outdoors.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an arc tube used in an alumina ceramic tube metal halide lamp according to an embodiment of the present invention.

FIG. 2 is a front view of an alumina ceramic tube metal halide lamp according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of an arc tube used in a conventional alumina ceramic tube metal halide lamp.

FIG. 4 is a front view of a conventional alumina ceramic tube metal halide lamp.

[Explanation of symbols]

1 Alumina ceramic arc tube 2 arc tube container 3 discharge arc tube 4,5 thin tube section 6,7 Tungsten electrode 8,9 Tungsten electrode rod 10,11 Tungsten coil 12,13 Power supply 14 Frits 15, 16 External lead wire 17,18 gap 19,20 molybdenum coil 21 Luminescent substance 22 lamps 23 Starter 24 Outer pipe valve 25 Starting auxiliary conductor 26 Shielded quartz tube 27 base 28 Alumina ceramic arc tube 29 Arc tube container 30 discharge arc tube 31,32 thin tube 33,34 Tungsten electrode 35,36 Tungsten electrode rod 37,38 Tungsten coil 39,40 power supply 41 Frits 42,43 gap 44,45 molybdenum coil 46 Luminescent substances 47 lamps 48 outer tube valve 49 mouthpiece 50 shield quartz tube

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masanori Higashi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Takashi Maniwa             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Kazuo Takeda             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 5C043 AA14 CC03 CD01 DD03 EA19                       EB16 EC03

Claims (3)

[Claims] 1. An arc tube container having a discharge arc tube part made of a translucent ceramic polycrystal and a thin tube part made of a translucent ceramic polycrystal connected to the discharge arc tube part. A high-pressure discharge lamp having a sealing portion formed by sealing a power supply member with a frit in a thin tube portion of a tube container, the transparent ceramic polycrystalline body forming the thin tube portion contacting the sealing portion. A high-pressure discharge lamp, wherein an average crystal grain size is smaller than an average crystal grain size of the translucent ceramic polycrystalline body forming the thin tube portion that is not in contact with the sealing portion. 2. The thin tube portion portion abutting the sealing portion, wherein the translucent ceramic polycrystalline body forming the thin tube portion portion not abutting the sealing portion has an average crystal grain size of 25 μm or more. The high-pressure discharge lamp according to claim 1, wherein the translucent ceramic polycrystalline body forming the particles has an average crystal grain size of 20 µm or less. 3. The high pressure discharge lamp according to claim 1, wherein the translucent ceramic polycrystalline body is a translucent alumina polycrystalline body.