JP2596019B2 - Metal vapor discharge lamp - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a metal vapor discharge lamp having an arc tube made of a translucent alumina tube, and more particularly to an improvement in a metal halide sealed in the arc tube.

[Prior Art] Conventionally, a metal vapor discharge lamp using a quartz arc tube used indoors and outdoors as a light source for general illumination uses a metal halide sealed in the arc tube to emit yellow-blue light in the emission spectrum. It is well known that a concentrated radiation is obtained in a region and the color rendering is poor due to a small amount of red emission.

Therefore, by appropriately controlling the amount of metal halide in the arc tube and the operating temperature of the arc tube, it is possible to encapsulate a metal halide having a high vapor pressure, thereby improving both color rendering properties and luminous efficiency. I got it.

As a highly practical discharge lamp improved in this way,
Discharge lamps in which dysprosium iodide and thallium iodide are sealed in an arc tube, discharge lamps in which sodium iodide, thallium iodide and indium iodide are sealed, and the like are known.

[Problems to be Solved by the Invention] However, even in the above-described discharge lamp, the emission spectrum thereof does not essentially have a strong light emission line in the red part. In the case of electric lamps, by increasing the temperature at the arc tube end, it is possible to have a narrow linear spectrum or band-like spectrum with a narrow half-width specific to the molecular emission form, and to generate a very wide continuous spectrum in the red part. Will be possible,
The temperature of the arc tube must be increased, and the quartz, which is the material of the arc tube, is thermally affected, and thus has a shortcoming such as a shortened life and a variation in the luminescent color.

Also, in the latter case, it is not necessary to increase the arc tube end temperature as compared with the former, because it is an atomic spectrum emission type, but there is no spectrum of a metal halide emitting in the red part, and the color temperature is increased by the emission of sodium iodide. Although the efficiency has been reduced, the color rendering properties have been reduced. Therefore, in order to enhance the color rendering of this type of discharge lamp, 610 nm and 670 nm
When lithium iodide, which has a strong emission spectrum in the nm range, is encapsulated, lithium ions penetrate the quartz of the arc tube material, and the lithium emission disappears in a short time to change the emission characteristics, or quartz and lithium easily react. There is a drawback that arc tube leakage finally occurs.

Therefore, as shown in FIG. 5, a translucent alumina tube 51 used as an arc tube material of a high-pressure sodium lamp is used instead of quartz, and conductive end caps are provided at both ends.
An arc tube having a structure in which 52 is hermetically sealed via a halogen-resistant sealing material 53 is used. An electrode 54 made of tungsten is sealed and fixed to the inner surface of the cap.
A lead bar 55 is fixed to the outer surface thereof. A metal halide, mercury and a starting gas are sealed in the tube.

As described above, the enclosure of a metal vapor discharge lamp using a translucent alumina tube as an arc tube is disclosed in JP-B-47-49385.
No., JP-B-49-15414, JP-B-51-33360, JP-B-57
-36711 and the like.

[Means for Solving the Problems] The present invention has been made in view of the above points, and has been made in consideration of the above problem. A predetermined amount of a metal halide is contained in an arc tube in which a conductive cermet cap is sealed to an end of a translucent alumina tube. By encapsulating indium iodide, thallium iodide and lithium iodide, not only are the emission characteristics such as the color rendering properties and the luminous efficiency of an atomic spectrum type discharge lamp having essentially red emission excellent, but also the arc tube It is an object of the present invention to provide a long-life discharge lamp free from the risk of leakage and the like.

[Operation] The metal vapor discharge lamp according to the present invention contains a certain amount of iodide of indium, thallium, and lithium and mercury in the arc tube so that the entire amount sealed when the discharge lamp is turned on becomes vapor, and further emits light by lithium. Excess indium and thallium are sealed in order to measure thermodynamic stability against erosion of the tube sealing portion.

When the atomic spectrum of lithium at 610 nm and 670 nm is added to the atomic spectrum of indium iodide and thallium iodide, the chromaticity coordinates shift from the blue side of the black body locus to the substantially white side, and the discharge lamp has excellent color rendering properties. Is obtained.

Further, a predetermined amount of the metal halide discharge lamp according to the present invention, indium iodide in the arc tube volume 1 cm ³ per 0.05Mg～0.6Mg, also 0.05mg~1.6mg of thallium iodide, also 0.02mg~1.4mg Consisting of lithium iodide. Further, a mercury of 2.0 mg to 18.0 mg per 1 cm ^{3 of the} inner volume of the arc tube and a rare gas such as an argon gas as an ionizable starting auxiliary gas are used.

Embodiment An embodiment according to the present invention will be described below with reference to FIG.

In the figure, reference numeral 1 denotes an arc tube in which an end portion of a translucent alumina tube 2 is hermetically sealed with a conductive cermet end cap 3 made of alumina and tungsten via a sealing material 4. An electrode mandrel 5 made of tungsten with a tungsten coil wound at the tip is embedded and fixed at the center, and a lead rod 6 made of tungsten, molybdenum or the like is embedded and fixed to the outer surface of the cap.

A predetermined amount of indium iodide, thallium iodide, lithium iodide and mercury are sealed in the arc tube,
Also, a predetermined amount of argon gas is sealed as a starting rare gas.

Here, the predetermined amount of metal halide is described.

First, if the amount of lithium iodide is less than 0.02 mg, practically good color rendering properties cannot be obtained. Excessive reaction with the adhering material and the cermet cap makes it impossible to maintain a desired life, and causes a short arc due to arc tube leakage and the like.

Further, if the amount of thallium iodide is less than 0.1 mg, the balance with the spectral intensity of other inclusions is deteriorated and a practical problem occurs.If the amount exceeds 1.6 mg, it moves to the green region in the chromaticity coordinates. Although the luminous efficiency increases, the light source color becomes green.

Further, when the amount of indium iodide is less than 0.05 mg, a problem of chemical reactivity occurs, and the color change during the life of the lamp increases. When the amount exceeds 0.6 mg, the blue emission intensity increases and the emission efficiency decreases.

As described above, by setting the amount of each metal halide to be outside the predetermined range, the luminous characteristics such as the color rendering property and the luminous efficiency are maintained well, and the alumina tube, the sealing material, and the cermet, which are the constituent materials of the luminous tube. The chemical equilibrium with the cap can be stably maintained.

Next, specific examples according to the present invention will be described.

The inner diameter of the arc tube is 8.4 mm, the arc length is 15 mm, and the inner volume is about 1.2 cc.
g, thallium iodide 0.2 mg, lithium iodide 0.2 mg, lithium metal 0.1 mg and mercury 9.0 mg together with argon gas 60 to
Or, when the enclosed discharge lamp was lit at a tube input of 150 W, its spectral distribution characteristics were as shown in FIG.

The initial luminous flux of this discharge lamp is 8,000 lm and the luminous efficiency is 53.3 lm /
w, its average color rendering index (Ra) was 78. And 5,0
There was little change in the spectral distribution characteristics after lighting for 00 hours, and the luminous flux maintenance factor was 75%.

Also, 0.2 mg of indium iodide, 0.6 mg of thallium iodide, and 0.4 m of lithium iodide were placed in an arc tube configured as described above.
g, indium metal 0.1 mg, and mercury 9.0 mg and a discharge lamp filled with argon gas at 60 toor at a tube input of 150 W. The spectral distribution characteristics were as shown in FIG.

The initial luminous flux of this discharge lamp is 9,800 lm and the luminous efficiency is 65.3 lm /
w, its average color rendering index (Ra) was 71. And 5,0
There was little change in the spectral distribution characteristics after lighting for 00 hours, and the luminous flux maintenance ratio was 72%.

Further, as described above, indium iodide 0.6 mg, thallium iodide 1.2 mg, lithium iodide 0.3 mg, indium metal 0.1 m
g and 9.0 mg of mercury together with a discharge lamp filled with 90 tor of argon gas at a tube input of 150 W.
It was as shown in the figure.

The initial luminous flux of this discharge lamp is 9,300 lm and the luminous efficiency is 62.0 lm /
w, its average color rendering index (Ra) was 67. And 5,0
There was little change in the spectral distribution characteristics after lighting for 00 hours, and the luminous flux maintenance factor was 80%.

[Effects of the Invention] As is clear from the above description, the metal vapor discharge lamp according to the present invention has a high color rendering property and a high luminous efficiency by enclosing a predetermined amount of indium iodide, thallium iodide and lithium iodide. In addition to being excellent, a discharge lamp using an arc tube comprising a translucent alumina tube and a conductive cermet cap having a long life can be obtained, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a partially longitudinal side view showing an arc tube of a discharge lamp showing an embodiment according to the present invention. FIGS. 2 to 4 are spectral distribution characteristic diagrams of the discharge lamp of the embodiment according to the present invention. FIG. 5 is a partially longitudinal side view showing a luminous tube of a conventional discharge lamp.

Claims (1)

(57) [Claims] 1. An arc tube in which the end of a light-transmitting alumina tube is sealed with a conductive cermet cap, together with mercury and a rare gas for starting aid, 0.05 to 0.6 mg of indium iodide, 0.1 to 0.1 mg / cm ^{3 in the} arc tube. ~ 1.6 mg thallium iodide and 0.02 ~
A metal vapor discharge lamp containing 1.4 mg of lithium iodide.