JP2001345070A - High-pressure vapor discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact high-pressure vapor discharge lamp with a long life wherein a light translucent alumina tube is used for a light emission tube, and a sealing part leak is especially prevented in the lamp with middle or high wattage. SOLUTION: In the high-pressure vapor discharge lamp wherein the light emitting tube consisting of the light translucent alumina tube encloses at least metal halides, mercury and inert gas, and wherein the light emitting tube is incorporated into an outer globe while a gap between an electro-conductive body and the alumina tube is sealed up with a brazing material for ceramic sealing at the both end parts, the light emitting tube has a central part and narrow tube parts whose outer diameter is thinner than that of the central part in both ends of the central part, and the narrow tube parts are both consisted of a thick wall part and a thin wall part. The thick wall part exists in the central part side of the light emitting tube, and the thin wall part exists in the end part of the light emitting tube.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure vapor discharge lamp using a translucent alumina tube as an arc tube.

[0002]

2. Description of the Related Art Translucent alumina tubes have been used in arc tubes of high-pressure sodium lamps, taking advantage of the property of being stable against alkali metals. In recent years, lamps using this translucent alumina tube as an arc tube of a metal halide lamp in which a metal halide is sealed have been commercialized as lamps of 150 W or less.

The advantage of using an alumina tube for a metal halide lamp is that it is more chemically and thermally stable with respect to a metal halide as an enclosure than quartz glass generally used in conventional metal halide lamps. Further, the disadvantage that the lamp life is shortened due to the chemical reaction between the filling and the quartz glass as in a conventional quartz metal halide lamp can be suppressed, and the life characteristics can be expected to be improved.

[0004] Further, the design of a lamp with high efficiency utilizing the characteristic that the use limit temperature is higher than that of quartz glass has been realized.
Since the quartz glass arc tube has high reactivity, there is an advantage that alkali metal that cannot be sealed can be sealed.

FIG. 4 shows an example of a conventional arc tube structure of a lamp. FIG. 4 is disclosed in Japanese Patent Application Laid-Open No. 6-196131. An alumina tube constituting an arc tube has a large diameter at a central portion 1 and narrow tubes 2 at both ends thereof. The thickness of the alumina tube in the central portion 1 and the narrow tube portion 2 is substantially uniform. A conductor 3 having an electrode 5 is inserted into the thin tube portion 2, and is sealed by a ceramic sealing brazing material 4 at an end opposite to the electrode pole core. The conductor 3 has an electrode at the tip, and a niobium wire or a tantalum wire is used for a sealing portion.

[0006]

When a conventional arc tube structure is applied to a lamp of a medium / high wattage, a leak may occur in a sealing portion. This is considered to be due to the difference between the expansion rates of alumina as the sealing member and the conductor and brazing material for ceramic sealing. The conductor such as a niobium wire or a tantalum wire present on the innermost side in the sealing portion has a smaller expansion coefficient than the alumina tube present on the outermost side, for example, due to a temperature difference from a high temperature to a low temperature when the lamp is turned off. ,
The ceramic sealing brazing material present in the middle of the sealing portion receives thermal stress in the direction of the inner conductor. Low wattage lamps with small conductor linearity have low thermal stress, so sealing
No cracking occurs, but in the case of a medium / high watt lamp with a large linear conductor, thermal stress increases, so cracks occur in the ceramic brazing filler metal and the alumina tube itself, and the sealing portion leaks. It is thought to lead. The probability of occurrence of leakage tends to increase as light-on / light-off is repeated more often.

In order to solve the leakage at the sealing portion, there is a method of reducing the temperature of the sealing portion by lengthening the narrow tube portion.
If the length of the thin tube portion is increased, the heat capacity of the arc tube is increased and the lamp characteristics are degraded, and the length of the arc tube is increased and the lamp size is increased. There is also a method of reducing the thermal stress and preventing leakage by reducing the thickness of the alumina tube. However, when the thickness is reduced, the mechanical strength of the alumina tube is reduced, and the center portion and the narrow tube portion are vibrated during lamp operation. There was a break between.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a high-pressure vapor discharge lamp using a translucent alumina tube as described above. This is to prevent leakage.

In order to achieve the above object, the present invention is characterized by having the following configuration. That is, in the high-pressure vapor discharge lamp of the present invention, at least a metal halide, mercury, and an inert gas are sealed in an arc tube made of a translucent alumina tube, and a gap between the conductor and the alumina tube is ceramic-sealed at both ends. In a lamp in which an arc tube hermetically sealed with a brazing material is incorporated in the outer bulb, the arc tube has a central portion and narrow tube portions having an outer diameter smaller than the central portion at both ends of the central portion, and both the thin tube portions are thick. And a thin portion, wherein the thick portion is located at the center of the arc tube, and the thin portion is located at the end of the arc tube.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the high-pressure vapor discharge lamp of the present invention, at least a metal halide, mercury and an inert gas are sealed in an arc tube made of a translucent alumina tube, and a conductor and an alumina tube are sealed at both ends. An arc tube whose gap is hermetically sealed with a ceramic sealing brazing material is incorporated in the outer sphere, and the arc tube has a narrow tube portion whose outer diameter is smaller than the center portion at both ends, and both the narrow tube portions are on the center side of the arc tube. And a thin portion at the arc tube end. By doing so, it is possible to provide a long-life, compact high-pressure vapor discharge lamp that uses a translucent alumina tube for the arc tube and that prevents leakage at the sealing portion, especially in a medium / high wattage lamp. it can.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a diagram showing the arc tube structure according to the first embodiment.
1 is a central portion of an alumina tube, 2 is a thin tube portion existing at both ends of the central portion, 3 is a conductor made of a niobium wire for conducting electricity to electrodes, 4 is a brazing material for ceramic sealing, and 5 is an electrode.
The thin tube portion 2 has a thick portion 21 at the center and a thin portion 22 at the end of the alumina tube. The outer diameter of the center portion 1 of the alumina tube 1 is 18 mm, the inner diameter is 16 mm, the outer diameter of the large diameter portion and the outer diameter of the thin tube portion are 4 mm and 3.4 mm, respectively.
0 mm. The thickness of the alumina tube is 1 mm at the center 1,
The thick part of the thin tube part is 1 mm, and the thin part is 0.7 mm.
The total length of the alumina tube is 74 mm, and the length between the electrodes is 25 mm. In the arc tube, dysprosium iodide 20
mg, thallium iodide 4 mg, sodium iodide 2 mg, mercury 16 mg, and argon gas 10 kPa are sealed.

The thickness of the alumina tube mainly affects the lamp luminous flux in the center portion, and needs to be carefully designed in the narrow tube portion in order to determine the mechanical strength of the arc tube. Considering the lamp luminous flux and mechanical strength, the thickness is most preferably about 1 mm. Therefore, in the first embodiment, the thickness of the thick portion 21 of the central portion 1 and the thin tube portion 2 which is most likely to be broken by an impact or the like is 1 mm. The thin portion 22 of the thin tube portion 2 that is hard to be broken by an impact or the like is 0.7 mm.
And

FIG. 2 is a view showing a structure of an arc tube according to a second embodiment.
1, a taper portion 12, and an end straight portion 13. The outer diameter of the central straight part is 18 mm, the inner diameter is 16 mm,
The outer diameter of the end straight portion 13 is 12 mm. Reference numerals, dimensions, and configurations other than the center portion 1 of the alumina tube are the same as those shown in FIG. The arc tube structure shown in FIG. 2 is suitable for a medium / high watt lamp which generates a large amount of heat during lamp operation. When the lamp is started or turned off, the thermal stress of the alumina tube increases near the electrode where the temperature change is large, and a crack may occur in the alumina tube itself. The structure shown in FIG. 2 increases the mechanical strength of the alumina tube near the electrode in order to solve this problem.

FIG. 3 is a view showing a structure of an arc tube according to a third embodiment, in which a central portion 1 of an alumina tube and a thin tube portion 2 are integrally formed together with a taper portion 6. Reference numerals, dimensions, and configurations other than the shape of the alumina tube main body are the same as those shown in FIG. In the structure shown in FIG. 3, since the heat capacity of the alumina tube is small, the temperature of the arc tube during lamp operation can be easily increased and the temperature of the arc tube can be made uniform. Therefore, it is suitable for a high color rendering lamp.

The arc tube constructed as described above is incorporated in the outer bulb, and the lamp power of 300 shown in FIG.
W, lamp power 400 W in FIG. 2 shown in the second embodiment,
In FIG. 3 shown in the third embodiment, five lamps were turned on for 6000 hours at a lamp power of 400 W. The lighting conditions are 5.
Lighting for 5 hours and turning off for 0.5 hours were repeated. In all the structures, it was confirmed that there was no problem such as leakage of the sealing portion even after elapse of 6000 hours, and the lighting was satisfactory.

The reason why such a good result was obtained is that by reducing the thickness of the alumina tube in the sealing portion, the alumina tube, the brazing material, and the conductor in the sealing portion are generated when the lamp is turned on and off. It is considered that the thermal stress to be applied was reduced, and the leakage of the sealing portion could be prevented.

[0017]

As described above, according to the present invention, a light-transmitting alumina tube is used for an arc tube, and particularly in a lamp of a medium / high wattage, a leak at a sealing portion is prevented and a long life and compact structure is achieved. A high pressure vapor discharge lamp is provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an arc tube structure according to a first embodiment of the present invention.

FIG. 2 is a view showing an arc tube structure according to a second embodiment of the present invention.

FIG. 3 is a view showing an arc tube structure according to a third embodiment of the present invention.

FIG. 4 is a diagram showing an example of a conventional arc tube structure of a lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Alumina tube center part 2 Alumina tube thin tube part 3 Conductor 4 Ceramic sealing brazing material 5 Electrode 6 Alumina tube taper part 11 Center straight part 12 Tape part 13 End straight part 21 Thin part thick part Part 22 Thin tube part Thin part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jiro Honda 1st Nishino-Sho Ino Babacho, Kichijo-in, Minami-ku, Kyoto, Kyoto Prefecture Within Nippon Battery Co., Ltd. (72) Inventor Shigeyuki Mori, Kichijo-in, Minami-ku, Kyoto, Kyoto No. 1 Nishinosho Inomabacho F-term (reference) in Nihon Battery Co., Ltd. 5C043 AA02 AA06 AA14 CC03 CD01 DD03 DD11 DD17 EA03

Claims (1)

[Claims] At least a metal halide, mercury and an inert gas are sealed in an arc tube made of a translucent alumina tube, and a gap between a conductor and the alumina tube is sealed at both ends with a ceramic sealing brazing material. In a high-pressure vapor discharge lamp in which a sealed arc tube is incorporated in an outer bulb, the arc tube has a central portion and narrow tube portions having an outer diameter smaller than the central portion at both ends of the central portion, and both the narrow tube portions are thick portions. A high-pressure vapor discharge lamp comprising a thin portion, wherein the thick portion is located at the center of the arc tube, and the thin portion is located at the end of the arc tube.