JPH11154490A - Metal halide lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal halide lamp having a stable light source color through a life time, having little change of color temperature at an early stage, and having a color rendering index Ra of 90 or more. SOLUTION: In a metal halide lamp 1, cesium halide is filled in an arc tube 1 having electrodes 2, 3 at both end portions together with starting rare gas and mercury, and terbium halide of 0.15 mg/cc to 5.0 mg/cc is also filled. When the filling amount of the terbium halide is A micro mole, the cesium halide, B micro mole, the terbium halide and the cesium halide are filled so as to satisfy the relationship, 0.3<=B/A<=1.3, to obtain a metal halide lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide lamp containing terbium halide and cesium halide.

[0002]

2. Description of the Related Art A metal halide lamp is formed by enclosing a starting rare gas such as a metal halide, mercury and argon gas in an arc tube having electrodes at both ends.
Such a metal halide lamp obtains a lamp suitable for the purpose by utilizing an emission spectrum determined by an enclosed metal halide. The life is determined by the reaction between the metal halide in the high temperature and high pressure state at the time of lighting and the quartz glass or alumina ceramic used as the electrode or arc tube material.
000 hours, 9000 hours of vertical lighting is common.

A high color rendering metal halide lamp (Ra 90 or more) having a color temperature of 9500 to 12000 K and a peak of spectral distribution intensity from 420 nm to 480 nm is used as a Dy-In-Cs halide or sealed character. ing.

[0004]

However, since the metal halide lamp using such an enclosure is of a three-element type, the change in color temperature during the life thereof is large, and the temperature is 10,000 K.
Changed by lighting for about 1000 hours up to 6000K. In the initial stage, the change in color temperature was large because of the three-element system, and there was an error of about ± 1000K when the set color temperature was 10,000K. In most cases, Ra was also lower than 90.

The present invention provides a metal halide lamp which is stable throughout the life of the light source color, has a small variation in color temperature even in the initial stage, and has a color rendering index Ra of 90 or more.

[0006]

According to the metal halide lamp of the present invention, a cesium halide is sealed together with a starting rare gas and mercury in an arc tube having electrodes at both ends, and terbium halide is 0.15 mg / cc. ~ 5.0mg
/ Cc enclosed metal halide lamp, when the amount of terbium halide enclosed is A micromol and the amount of cesium halide enclosed is B micromol, the relationship of 0.3 ≦ B / A ≦ 1.3 is satisfied. Terbium halide and cesium halide.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In a metal halide lamp according to the present invention, at least terpium halide, cesium halide and mercury are sealed as an enclosure, a rare gas is sealed as a starting gas, and the amount of terbium halide is reduced. When A micromol and cesium halide are encapsulated in B micromol, these are encapsulated so as to satisfy the relationship of 0.3 ≦ B / A ≦ 1.3. By doing so, it is possible to obtain a lamp in which the color of the light source is stable throughout the life, the fluctuation of the color temperature is small even in the initial stage, and the color rendering index Ra is 90 or more.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows a 150 W metal halide lamp that is lit horizontally, according to a first embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes an arc tube made of quartz glass having an inner diameter of 12 mm and an internal volume of about 2.9 cc, and a pair of electrodes 2 and 3 are sealed at both ends. Reference numeral 4 denotes a cylindrical outer tube made of quartz glass having an inner diameter of 20 mm and an outer diameter of 23 mm, and has a structure in which both ends are sealed to keep the arc tube airtight. Reference numeral 5 denotes a white heat insulating film provided on the outer surfaces of both ends of the arc tube 1.

In order to investigate the relationship between the ratio of the amount of cesium halide to terbium halide and the lamp characteristics, the arc tube of FIG.
g, 19 mg of mercury and 25 torr of argon gas were used to produce a total of 40 lamps in which CsX / TbX ₃ was changed from 0.1 to 1.6. Table 1 shows the measurement results after aging for one hour.

[0010]

[Table 1] In Table 1, when the encapsulation amount ratio is 0.9 or more, the efficiency decreases as the ratio increases. This is because cesium halide has a lower excitation voltage than terbium halide, and the luminous efficiency increases as the encapsulation amount ratio increases. This is because the emission of cesium halide having a low victory is superior, and the practical range was found to be 1.3 or less.

On the other hand, the amount of terbium halide enclosed is related to the continuous emission intensity in the visible region. If the amount is too small, the emission of mercury increases. If the amount is too large, terbium halide adheres to the arc tube and the emission is absorbed. This leads to a decrease in efficiency and is not preferred as a lamp.

Therefore, an appropriate range of the terbium halide filling amount is 0.15 mg / cc ≦ TbX ₃ ≦ 5.0 mg / cc.

Next, in order to examine the life characteristics of the product of the present invention,
The lamps in Table 1 were lit horizontally at 150 W, and CsX / Tb
We examined the relationship between the X ₃ and the luminous flux maintenance factor. Table 2 shows the results after lighting for 6000 hours.

[0014]

[Table 2] As can be seen from Table 2, the higher the cesium halide encapsulation ratio, the higher the luminous flux maintenance factor. This is because cesium halide stabilizes the arc and suppresses the reaction between the enclosure and quartz glass. It seems to be. Considering that the luminous flux maintenance rate of 60% or more with a lighting time of 6000 hours is a practical level, 0.3 ≦ CsX / TbX ₃ is required. Therefore, an appropriate CsX / TbX ₃ encapsulation ratio is 0.3 ≦ CsX / TbX ₃ ≦ 1.3.

As can be seen from Tables 1 and 2, the variation in color temperature after aging for one hour in the above range is 300K or less, and the variation in color temperature during the lifetime is 50K.
It was found that the change was suppressed to 0K or less.

In the above embodiment, a horizontal lighting lamp having an outer bulb made of quartz glass has been described.
The lighting direction and outer sphere shape to which the present invention can be applied are not limited thereto.

Since the metal halide lamp of the present invention uses a two-element halide of Tb-Cs instead of a three-element halide of Dy-In-Cs as an enclosure, the color of the light source is stable throughout its life. The color temperature change during the life is ± 500 when the set color temperature is 10,000K.
I was able to make it within K. In addition, since the initial stage is a two-element system, the variation in color temperature is small and the set color temperature is 10
When it was 000K, the error was within ± 300K.
The peak of the spectral distribution intensity was from 420 nm to 480 nm, and the color rendering index Ra of 90 or more could be secured.

[0018]

As described above, according to the present invention, a two-element halide of Tb-Cs is used instead of a three-element halide of Dy-In-Cs as an enclosure. By enclosing the amount so as to satisfy a certain relational expression, the light source color is stable throughout the life, the fluctuation of the color temperature is small even at the initial stage, and the peak of the spectral distribution intensity is from 420 nm to 480 nm,
In addition, a metal halide lamp having a color rendering index Ra of 90 or more can be provided, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a metal halide lamp of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz glass arc tube 2 Electrode 3 Electrode 4 Quartz glass outer tube 5 White heat insulating film

Claims (1)

[Claims] 1. A cesium halide is sealed together with a starting rare gas and mercury in an arc tube provided with electrodes at both ends, and terbium halide is contained in an amount of 0.15 mg / cc to 5.0.
In a metal halide lamp filled with 0 mg / cc,
When the encapsulation amount of terbium halide is A micromol and the encapsulation amount of cesium halide is B micromol, terbium halide and cesium halide satisfy the relationship of 0.3 ≦ B / A ≦ 1.3. A metal halide lamp characterized by encapsulation.