JPH05151932A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To provide a lamp of good color rendering performance with reduced flicker and less change in the color in lighting, with which the lighting direction is selectable any as desired, by encapsulating ScI3, NaI, TlI, LiI in respective specified amounts in a light emission tube as additives. CONSTITUTION:Together with mercury and an inert gas, at least four substances are encapsulated in a light emission tube as additives in respective amounts specified as LiI/ScI3(mg) <=1.1, 0.12<=TlI/LiI(mg) <=0.50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in metal halide lamps, and more particularly to improvements in lamp lighting characteristics.

[0002]

2. Description of the Related Art Currently, metal halide lamps are used for many purposes, and especially Sc-Na as an additive in the arc tube.
System metal halide lamps are other types of lamps, for example
Compared with high color rendering type metal halide lamps such as Dy-Tl-Na, Dy-Tl-Cs, and Nd-Dy, inexpensive mercury ballasts can be used, and they are highly efficient and have a long life. There is.

However, it is known that Sc-Na type metal halide lamps having such characteristics may cause flicker particularly when vertically lit in a 50 Hz region. This is because the vertical distribution of the additive in the arc tube becomes asymmetrical when vertically lit, and the peak height of the light output waveform in one cycle differs due to the distortion of the alternating current as shown in FIG. I feel it.

Conventionally, as a method for improving the flicker, it is considered to use a dedicated ballast of high frequency type or DC type, but it is not possible to use an inexpensive ballast for mercury lamp which is a feature of this type of lamp. Become.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a mercury lamp ballast can be used without particularly limiting the lighting direction of the lamp, which reduces the flicker of the lamp and the light during lighting. Sc-N with little color change and good color rendering
It provides a-type metal halide lamps.

[0006]

The present inventor believes that the composition of the iodide sealed in the arc tube should be reexamined in order to reduce the flickering of the Sc-Na-based lamp regardless of the lighting direction. Various additives that contribute to the improvement were investigated.

In-Tl-Na type and Dy-Tl type metal halide lamps have maximum luminous output in green with high luminous efficiency, and TlI, which has a high vapor pressure as iodide, alleviates the vertical asymmetry of the light emission of the arc tube. It was presumed that there was a function of this, and a small amount of TlI was added to the Sc-Na lamp and sealed. However, the addition of TlI shifts the lamp light color from the white region to the yellowish green region, which is not practical and requires adjustment of the light color.Furthermore, when LiI is added, flicker and color rendering are It will be improved.

According to the present invention, main electrodes are sealed at both ends of the arc tube, and at least ScI ₃ , NaI, and T are contained inside together with mercury and an inert gas.
In a metal halide lamp in which lI and LiI are added and enclosed, as an additive, LiI (mg) / ScI ₃ (mg) ≦ 1.1,0.
12 ≦ TlI (mg) / LiI (mg) ≦ 0.50 is encapsulated.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a 250 W Sc-Na based metal halide lamp according to the present invention. In the figure, reference numeral 1 denotes an arc tube in which a pair of main electrodes (not shown) are sealed at both ends of a quartz glass tare, and ScI ₃ , NaI, TlI and LiI are added and sealed inside together with mercury and argon gas. . A heat insulating film 2 is applied to the outer surface of the end of the arc tube. Such an arc tube includes a pair of arc tube columns 3a, 3
It is mechanically supported via 3b and electrically connected by a wire 4.

Next, an experimental example compared with a conventional lamp will be described. In the lamp with the structure shown in Fig. 1, a conventional lamp, that is, Sc in an arc tube with an internal volume of 8cc and an arc length of 33mm
A lamp (a) in which ₃ mg of Na 3, 23 mg of NaI and predetermined amounts of mercury and argon were added and enclosed, a lamp (b) in which 0.1 mg of TlI was added to a, a lamp (c) in which 0.2 mg of TlI was added to a,
Lamp (d) in which 0.4 mg of TlI was added to a, and TlI of 0.4 was added to a.
A lamp (e) containing 8 mg was experimentally manufactured with five types of specifications, and flicker and changes in emission characteristics were measured. The evaluation of flicker is based on the difference between the peaks of the optical output in the waveform diagram shown in FIG.
Fractionated Fp values were used. The results are shown in Table 1.

[0011]

[Table 1]

As is clear from Table 1, the flicker is TlI.
It is clear that the larger the amount, the smaller it becomes, and if only the flicker is improved, a sufficient effect is recognized. However, since the chromaticity points on the black body locus also move at the same time, the white lights of a, b, and c are no longer yellow-green lights, which is a practical problem. Further, a and b are values exceeding Fp value of 2% where ordinary people do not feel flicker, and improvement of flicker cannot be recognized. Therefore, it is estimated that the chromaticity point can be corrected to the white region by adding LiI, and when 2,4,8,16,32 times the TlI amount is added in the arc tube specifications of c, d, and e. Table 1 shows the results of trial production with the arc tube specifications. According to this, the emission color is almost in the white region, and the Fp value is 2% or less when the weight ratio is TlI / LiI = 0.5 to 0.12.
Further, since the luminous flux value decreases as the LiI amount increases and the luminous flux value of 20000 lm is set as the target value, LiI needs to be 1.1 times or less in relation to the added ScI ₃ amount.

[0013]

The metal halide lamp according to the present invention has a predetermined amount of ScI ₃ , NaI, TlI and
By encapsulating LiI, it is possible to have any lighting posture, and a mercury lamp ballast can be used as a ballast, which has the advantages of reduced lamp flicker, less change in light color, and good color rendering. .

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a lamp waveform diagram showing a change in light output.

FIG. 3 is a waveform diagram of a lamp current of a conventional lamp.

[Explanation of symbols]

 1 arc tube 2 heat insulating film 3 support 4 wire 5 base 6 outer bulb

Claims (1)

[Claims] 1. A pair of main electrodes are sealed at both ends of a quartz glass arc tube, and at least mercury and an inert gas are contained inside.
In a metal halide lamp in which ScI ₃ , NaI, TlI and LiI are added and enclosed, LiI (mg) / ScI ₃ (mg) ≦ 1.1, 0.12 ≦ TlI (mg) / LiI (mg) ≦ 0.50 A metal halide lamp characterized by: