JPH05334992A - Metallic vapor electric discharge lamp - Google Patents

Abstract

PURPOSE:To provide a long-life metallic vapor electric discharge lamp whose emission characteristics such as color rendering properties and emission efficiency are improved and are not much changed with the elapse of time by sealing specific metal iodides in a translucent alumina tube in a specific ratio. CONSTITUTION:Indium iodide, thallium iodide, lithium iodide and dysprosium iodide are sealed, together with mercury and starting rare gas, in a translucent alumina tube 1 by 0.05 to 0.6mg, 0.1 to 1.6mg, 0.02 to 1.4mg, and 0.01 to 2.0mg per 1 cm<2> of the content volume of the arc tube 1, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vapor discharge lamp having an arc tube made of translucent alumina, and more particularly to improvement of a metal halide sealed in the arc tube.

[0002]

2. Description of the Related Art A metal vapor discharge lamp using a quartz arc tube, which is used indoors and outdoors as a light source for general illumination,
Radiation concentrated in the yellow-blue region of the emission spectrum is obtained by the metal halide enclosed in the arc tube.
It is well known that the color rendering is poor due to the low red emission.

Therefore, by appropriately controlling the amount of the metal halide of the arc tube and the operating temperature of the arc tube, it becomes possible to encapsulate the metal halide having a high vapor pressure, thereby improving the color rendering property and the luminous efficiency. It became possible. As a highly practical discharge lamp improved in this way, a discharge lamp containing dysprosium iodide or thallium iodide in an arc tube or a discharge lamp containing sodium iodide, thallium iodide or indium iodide is used. Are known.

[0004]

However, even in the above-mentioned discharge lamp, its emission spectrum does not substantially have a strong emission line in the red portion. In particular, in the case of the former discharge lamp containing dysprosium iodide, by increasing the temperature at the end of the arc tube, there is a close linear spectrum or band spectrum with a narrow half-value width, which is characteristic of molecular emission. It is possible to generate a continuous spectrum with a wide range, but the arc tube temperature must be raised further, and quartz, which is the material of the arc tube, is thermally affected, resulting in a shorter life and variations in its emission color. There are drawbacks such as being easy.

Further, in the latter discharge lamp, since it is an atomic spectrum emission type, it is not necessary to raise the temperature at the end of the arc tube as much as in the former case, but since there is no spectrum of the metal halide emitting in the red part, sodium iodide is used. Since the color temperature is lowered by the emission of light, the color rendering property is low. Therefore,
When lithium iodide having a strong emission spectrum at 610 nm and 670 nm is enclosed in order to improve the color rendering of this type of discharge lamp, lithium ions permeate the quartz of the arc tube material and the lithium emission disappears in a short time. Finally, there is a drawback that the arc tube leaks.

On the other hand, in order to deal with these problems, quartz is used as the arc tube material, and a translucent alumina tube used as the arc tube material of the high pressure sodium lamp is used.
There is known an arc tube having a structure in which conductive end caps are hermetically sealed at both ends thereof with a halogen-resistant sealing material. An electrode made of tungsten is fixed to the inner surface of the cap, a lead rod is fixed to the outer surface of the cap, and mercury and a rare gas for starting are enclosed in the arc tube together with the metal halide.

[0007] Regarding such an enclosure of a metal vapor discharge lamp using a translucent alumina tube as an arc tube, Japanese Patent Publication No.
7-49385, JP-B-49-15414, JP-B-51-33360, JP-B-57-36711, JP-A-1-137555 and the like.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a predetermined amount of iodine is used as a metal halide in an arc tube hermetically sealed with an electrically conductive cermet cap at the end of a translucent alumina tube. Indium iodide, thallium iodide,
By encapsulating lithium iodide and dysprosium iodide, not only can the emission characteristics such as color rendering and emission efficiency in the atomic spectrum type discharge lamp having red emission be improved, but also the emission characteristics can be improved. It is an object of the present invention to provide a long-life discharge lamp with little change over time.

[0009]

In the metal vapor discharge lamp according to the present invention, the arc tube is filled with a predetermined amount such that all the amounts of iodide of indium, thallium, lithium and dysprosium and mercury are evaporated during lighting, It has a well-balanced emission output of red, green, and blue components, and can maintain good emission characteristics throughout the life of the discharge lamp.

Here, by adding lithium iodide, the atomic spectra of lithium at 610 nm and 670 nm are added to the atomic spectra of indium iodide and thallium iodide, and the chromaticity coordinates are substantially from the blue side of the blackbody locus. As the color shifts to the white side, a discharge lamp with excellent color rendering can be obtained. Furthermore, by adding dysprosium iodide, the molecular emission of dysprosium iodide is superimposed over the entire wavelength range of visible light, and the luminous efficiency is improved without impairing the color rendering property. Also, the addition of dysprosium iodide has the effect of thinning the discharge arc and lowers the inner wall temperature of the arc tube, so the translucent alumina, which is the material of the arc tube, emits light as compared with the discharge lamp without addition. The translucency is not impaired by reacting with the tube-filled material and becoming cloudy.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, reference numeral 1 denotes an arc tube made of a translucent alumina tube, and end caps 2 and 2 of a conductive cermet made of alumina-tungsten are hermetically sealed at both ends with a sealing material 3 between the end caps. Electrodes 4 and 4 wound with a tungsten coil are embedded and fixed at the center of the arc tube, and external lead rods 5 and 5 made of tungsten, molybdenum, etc. are embedded and fixed to the outside thereof. The arc tube is filled with a predetermined amount of metal halide consisting of indium iodide, thallium iodide, lithium iodide and dysprosium iodide, mercury, and argon as a rare gas for starting.

Here, the iodide is the arc tube inner volume 1c.
0.05-0.6 mg indium iodide per m ³ ,
0.1-1.6 mg thallium iodide, 0.02-1.
Although it is defined as 4 mg of lithium iodide and 0.01 to 2.0 mg of dysprosium iodide, the amount of each enclosure will be described. First, lithium iodide is 0.02
If it is less than mg, good color rendering properties cannot be obtained in practical use.
If it exceeds 4 mg, the reaction between the alumina tube, which is a constituent material of the arc tube, the sealing material and the cermet cap becomes excessive, and the desired life cannot be maintained, resulting in arc tube leakage. Also, if the content of thallium iodide is less than 0.1 mg, the balance with the spectral intensity due to other inclusions becomes poor, causing a practical problem, and if it exceeds 1.6 mg, it moves to the green region on the chromaticity coordinate. Then, the luminous efficiency increases but the light source color becomes green. Furthermore, indium iodide is 0.05m
If it is less than g, the color change of the arc tube is severe, and if it exceeds 0.6 mg, the blue emission intensity is increased and the luminous efficiency is reduced. When the amount of dysprosium iodide is less than 0.01 mg, the effects of increasing the luminous efficiency and suppressing the reactivity of alumina are not recognized, and when the amount of dysprosium iodide exceeds 2.0 mg, the atomic emission intensity of lithium decreases. The color temperature decreases and the color rendering deteriorates.

As described above, by defining the amount of each metal halide enclosed within the above range, it is possible to maintain good luminescent properties such as color rendering properties and luminescent efficiency, as well as the chemical reaction of the arc tube constituent materials. It is possible to obtain a discharge lamp that is suppressed and has stable life characteristics.

Next, specific examples of the present invention will be described together with comparative examples. Arc tube inner diameter 10.0 mm, arc length 7.5
0.25 mg of indium iodide, 0.4 mg of thallium iodide, 0.3 mg of lithium iodide, 1.0 dysprosium iodide in an arc tube having a volume of 0.7 mm and an internal volume of 0.7 cc.
argon gas together with 50 mg and mercury 9.0 mg
The spectral distribution characteristics of the discharge lamp filled with rr and turned on with a tube input of 150 W were as shown by the solid line in FIG.

The initial luminous flux of this discharge lamp is 12,000 lm.
The luminous efficiency was 80.0 lm / W and the average color rendering index (Ra) was 88. The change in the spectral distribution characteristic after lighting for 1,700 hours was small, and the luminous flux maintenance factor was 87%.

For comparison, in an arc tube having the same shape as that of the above-mentioned embodiment, as an additive, indium iodide containing no dysprosium iodide, thallium iodide, lithium iodide and mercury, and argon gas in the same amount as above. The spectral distribution characteristics of the enclosed discharge lamp turned on with a tube input of 150 W were as shown by the broken line in FIG.

The initial luminous flux of this discharge lamp is 8,900 lm, the luminous efficiency is 59.0 lm / W, and its average color rendering index (R
a) 76. The luminous flux maintenance factor after lighting for 1,700 hours was 75%.

Therefore, Table 1 shows various characteristics of the embodiment and the conventional example. In Table 1, R output is 650 in the spectral distribution chart.
The output integrated value in the ˜695 nm region, the G output represents the integrated output value in the 520 to 560 nm region in the spectral distribution map, and the B output represents the integrated output value in the 435 to 475 nm region in the spectral distribution map.

[0019]

[Table 1]

Next, FIG. 3 shows changes with time in the light emission characteristics of the discharge lamp according to the present invention with the lighting time. The lighting condition of this discharge lamp is based on a blinking experiment of lighting for 150 minutes and extinguishing for 30 minutes. Also, R output in the figure is 650 to 650 in the spectral distribution chart.
The output integrated value in the 695 nm region, the G output represents the output integrated value in the 520 to 560 nm region in the spectral distribution map, and the B output represents the output integrated value in the 435 to 475 nm region in the spectral distribution map.

As is apparent from FIG. 3, the luminous flux maintenance factor of the total luminous flux and the R, G, B components after the lapse of 1,700 hours is 80.
% Or more.

[0022]

As is apparent from the above description, the metal vapor discharge lamp according to the present invention contains a predetermined amount of indium iodide, thallium iodide, lithium iodide and dysprosium iodide as an arc tube additive. By encapsulating, a well-balanced emission output of the three primary colors can be obtained, and not only the color rendering is high and the emission efficiency is excellent, but also a long-life discharge lamp with little change in emission characteristics over time can be obtained.

[Brief description of drawings]

FIG. 1 is a partially longitudinal side view of an arc tube according to the present invention.

FIG. 2 is a spectral distribution characteristic diagram of a discharge lamp according to the present invention and a conventional example.

FIG. 3 is a diagram showing changes in light emission characteristics of the discharge lamp according to the present invention with the passage of lighting time.

[Explanation of symbols]

 1 Translucent alumina arc tube 2 Conductive cermet end cap 3 Sealing material 4 Electrode 5 External lead rod

Claims (1)

[Claims] [Claim 1] A translucent alumina tube, an arc tube volume 1 cm ³ per with mercury and starting rare gas 0.05 to 0.
Metal vapor containing 6 mg of indium iodide, 0.1 to 1.6 mg of thallium iodide, 0.02 to 1.4 mg of lithium iodide and 0.01 to 2.0 mg of dysprosium iodide. Discharge lamp.