JPH10208693A - High-pressure metallic vapour discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-pressure metallic vapour discharge lamp with a good life characteristic and initial characteristic by decreasing an initial current peak value directly after the starting of a lamp and by decreasing maximum temperature in an electrode. SOLUTION: An arc tube 1 is provided with a luminous unit 1a which seals mercury, inert gas and metal halide inside and a sealing unit 1b which is connected to its both ends. The sealing unit 1b is an electric power lead-in body in which a double coil 2a, a tungsten bar 2b, a metallic foil 3 and an external lead wire 4 are connected successively, and the double coil 2a is sealed in the lumious unit 1a. In the arc tube 1, W/A=84, where, initial current peak value which flows in a lamp is A (A), and lamp power is W (W). An electrode 2 is provided with the tungsten bar 2b of which diameter ϕE=0.4(mm) and double coil 2a of which diameter ϕK=0.225(mm) and a protruded part 2c of the tungsten bar 2b protruded from the double coil 2a is d=10(mm).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure metal vapor discharge lamp.

[0002]

2. Description of the Related Art Heretofore, the main cause of deterioration of the luminous flux of a metal halide lamp, which is a high-pressure metal vapor discharge lamp, is that tungsten, which is an electrode material, scatters in the arc tube and the inner surface of the arc tube is blackened. As a cause of the scattering of tungsten, a metal halide sealed in an arc tube and high-temperature quartz as a material of the arc tube react during stable operation of the lamp to generate a silicon halide compound (SiX). The silicon halide compound moves to the arc near the electrode by convection in the arc tube, dissociates into halogen (X) and silica (Si) in the high-temperature arc, and forms a low melting point alloy of silica and electrode tungsten ( WSi). (WS
Since i) has a low melting point, during the stable operation of the lamp or immediately after the start of the lamp when the electrode reaches the maximum temperature, the vapor easily evaporates and tungsten adheres to the inner surface of the arc tube, so that the arc tube is blackened.

Hitherto, as a measure for reducing the luminous flux deterioration, the tube wall load of the arc tube has been optimized or the reactivity with quartz has been low for the purpose of suppressing the reaction between quartz, which is a material for the arc tube, and a metal halide. It is known to encapsulate metal halides.

[0004]

In the conventional methods for reducing the luminous flux deterioration, the method of optimizing the tube wall load of the arc tube and the method of encapsulating a metal halide having low reactivity with quartz,
There is a problem that the vapor pressure of the metal halide in the arc tube changes, and satisfactory initial light emission characteristics cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. By reducing the initial current peak value immediately after the lamp is started, the maximum temperature of the electrode is reduced, and a high-pressure electrode having good life characteristics and initial characteristics is obtained. A metal vapor discharge lamp is provided.

[0006]

A high-pressure metal vapor discharge lamp according to the present invention includes an arc tube having electrodes at both ends and containing a metal halide and a buffer gas therein, and the lamp power of the arc tube is reduced. W (W), when the initial current peak value flowing through the lamp is A (A), the lamp has a configuration satisfying the range of 80 ≦ W / A ≦ 90.

This has the effect of lowering the electrode maximum temperature at the time of startup and suppressing the evaporation of (WSi).

The electrode may be made of tungsten or
It consists of a thorium-containing tungsten electrode rod and a double coil provided on the electrode rod, and has a diameter of φ _E
(Mm), the diameter of the filament to be the double coil is φ _K (mm), the portion of the electrode rod protruding from the double coil toward the center of the arc tube is d (mm), and the lamp of the arc tube is When the power is W (W) and the initial current peak value flowing through the lamp is A (A), 0.0017 × W + 0.1
8 ≦ φ _E ≦ 0.0017 × W + 0.38 and A × Δd /
It has a configuration that satisfies the range of (φ _E + φ _K ) ≧ 12.

This has the effect that the life characteristics are good and the variation in the initial characteristics can be reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 shows an embodiment 1 of the present invention.
00W metal halide lamp (hereinafter referred to as the present invention)
An arc tube 1 made of quartz glass is provided with a light emitting portion 1a in which an appropriate amount of mercury, an inert gas and a metal halide are sealed, and sealing portions 1b connected to both ends of the light emitting portion 1a, The sealing portion 1b includes a double coil 2a and a power introduction body formed by sequentially connecting a tungsten rod 2b serving as an electrode rod, a metal foil 3 made of molybdenum, and an external lead wire 4 to each other. It is sealed so as to be located in the light emitting section 1a.

The arc tube 1 is housed in an outer tube (not shown) whose inside is evacuated. In the arc tube 1, when the initial current peak value flowing through the lamp is A (A) and the lamp power W (W) is W / A = 84.

The electrode 2 shown in FIG. 2 has a diameter φ _E = 0.4
(Mm) tungsten rod 2b and diameter φ _K = 0.22
The protruding portion 2c of the tungsten rod 2b protruding from the double coil 2a is set to d = 1.0 (mm).

FIG. 3 shows the luminous flux maintenance ratio when the 100 W metal halide lamp of this embodiment is operated for 9000 hours, and the stabilization time from the start to the stable state. FIG. 3 also shows the luminous flux maintenance ratio and stabilization time when W / A is used as a parameter. From FIG. 3, by setting W / A ≧ 80, the current density flowing to the electrode at the time of starting becomes small,
The electrode temperature is reduced, the scattering of tungsten, which is an electrode material, can be reduced, and the luminous flux maintenance factor during lighting for 9000 hours is 70%.
As described above, good characteristics can be obtained. On the other hand, W /
By setting A ≦ 90, it was confirmed that the vapor pressure of the metal halide in the arc tube after the start-up was increased quickly, stabilized within 6 minutes after the start-up, and good characteristics were obtained.

When W / A ≦ 80, 900
The luminous flux maintenance rate at the time of lighting for 0 hours is reduced to 70% or less. Also, when W / A ≧ 90, it was confirmed that the stabilization time after starting took 6 minutes or more.

Thus, by setting 80 ≦ W / A ≦ 90, it is possible to provide a metal halide lamp having a good luminous flux maintenance factor and an excellent stability time.

Next, 70W, 100W, 150W, 250
W, the metal halide lamp according to the present invention was manufactured, and the diameter φ of the electrode rod of the tungsten rod 2b of each lamp was determined.
_{Using E} as a parameter, the luminous flux maintenance factor during lighting for 9000 hours was measured. Table 1 shows the results. At this time, W / A =
80.

[0018]

[Table 1]

FIG. 4 shows the relationship between the lamp power W (W) and the optimum electrode diameter from Table 1. From FIG. 4, the optimum electrode diameter is φ _E = 0.0017 using the lamp power W (W) as a parameter.
× W + 0.28, confirming that an optimum value exists. If the diameter phi _E of the electrode rod is too thin, the electrode temperature during starting and stable lighting becomes high, scattering of tungsten which is an electrode material that is severely was confirmed. On the other hand, if the electrode rod diameter φ _E is too large, a bright spot of the discharge arc is generated at the tip of the electrode rod, and the temperature of the bright spot is locally high, and it is confirmed that the scattering of tungsten is promoted. Was done.

As shown in FIG. 4, 0.0017 × W +
By satisfying the range of 0.18 ≦ φ _E ≦ 0.0017 × W + 0.38, it becomes possible to provide a lamp having a good luminous flux maintenance factor.

Next, an electrode rod diameter phi _E and the electrode coil diameter phi _K of the present invention product as parameters, was tested for the presence of the coil discharge generation.

In each of the ten tests, if at least one coil was discharged, it was determined that there was coil discharge. In Table 2, Y indicates the value of A × Δd / (φ _E + φ _K ), all the circles in the evaluation column indicate normal discharge, and the cross indicates that coil discharge has occurred. At this time, W / A = 84, which is always constant. FIG. 5 shows a normal discharge when the lamp is stably turned on, and FIG. 6 shows a discharge state of the coil discharge when the lamp is stably turned on.

[0023]

[Table 2]

As is clear from Table 2, A × √d /
(φ _E + φ _K) when is 12 or more, the coil discharge does not occur. Further, the smaller the value of A × ／ d / (φ _E + φ _K ), the higher the probability of occurrence of coil discharge (see FIG. 7). The occurrence of coil discharge is related to the current density at the start and the temperature of the tip of the electrode rod, and the lower the current density or the lower the tip temperature, the higher the probability of the occurrence of coil discharge. When the coil discharge occurs, the discharge arc length increases, and the lamp voltage increases. As a result, the correlated color temperature changes and the lamp extinguishes early. That is, by setting A × √d / (φ _E + φ _K ) to 12 or more, a metal halide lamp having good life characteristics and initial characteristics can be provided.

[0025]

As described above, according to the present invention, an effective effect of obtaining a high-pressure metal vapor discharge lamp having good life characteristics and initial characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional front view of an arc tube of a 100 W metal halide lamp according to an embodiment of the present invention.

FIG. 2 is a sectional front view of the same electrode.

FIG. 3 is a diagram showing a luminous flux maintenance ratio characteristic and a stabilization time when W / A is used as a parameter.

FIG. 4 is a diagram showing a relationship between lamp power (W) and electrode rod diameter (φ _E ).

FIG. 5 is a diagram for explaining a normal discharge.

FIG. 6 is a diagram for explaining coil discharge;

FIG. 7 is a diagram showing a coil discharge probability when A × √d / (φ _E + φ _K ) is used as a parameter;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc tube 2a Double coil 2b Tungsten rod 3 Metal foil 4 External lead wire

Continuation of the front page (72) Inventor Takashi Yamamoto 1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd.

Claims (2)

[Claims] 1. An arc tube having electrodes at both ends and having a metal halide and a buffer gas sealed therein. The lamp power of the arc tube is W (W), and the initial current peak value flowing through the lamp is A. (A) A high-pressure metal vapor discharge lamp characterized by satisfying a range of 80 ≦ W / A ≦ 90. 2. The electrode comprises an electrode rod made of tungsten or thorium-containing tungsten and a double coil provided on the electrode rod, and has a diameter of φ _E (m
m), the diameter of the filament to be the double coil is φ _K
(Mm), a portion of the electrode rod protruding from the double coil toward the center of the arc tube is d (mm), the lamp power of the arc tube is W (W), and the initial current peak value flowing through the lamp is A. In the case of (A), 0.0017 × W + 0.18 ≦
φ _E ≦ 0.0017 × W + 0.38 and A × √d / (φ _E
2. The high-pressure metal vapor discharge lamp according to claim 1, wherein a range of + φ _K ) ≧ 12 is satisfied.