JP2000188086A - Metallic vapor discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a metallic vapor discharge lamp excellent in optical characteristics, such as luminous efficiency, a mean color rendering index, and so on, with an arc tube having sufficient pressure withstand strength in the low-watt metallic vapor discharge lamp having a rated lamp electric power consumption of 100 W or less wherein even a minute heat loss largely concerns the luminous efficiency. SOLUTION: This metallic vapor discharge lamp having a rated lamp electric power of 100 W or less includes an arc tube made of transparent quartz glass having a tube central part and sealing parts 3 formed at both ends of the tube central part; a pair of electrodes oppositely disposed in a discharge space of the arc tube; mercury, a metal (or a metal halide) and a rare gas sealed in the arc tube; and an outer tube having a bulb base at an end and holding the arc tube. A wall thickness(t) (mm) of a light emission part 1 of the arc tube is regulated to 0.5<=t<=0.8.

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 in which mercury, a metal or a metal halide, and a rare gas are sealed in an arc tube made of quartz glass, and more particularly to a metal vapor discharge lamp having a rated lamp power of 100 W or less. The improvement of the arc tube.

[0002]

2. Description of the Related Art Metal vapor discharge lamps are more efficient than incandescent lamps and halogen lamps, and have excellent color rendering properties and several types of correlated color temperatures. Because of its high economical efficiency, it is used not only for outdoor lighting but also for indoor lighting.
In particular, low-wattage metal vapor discharge lamps having a rated lamp power of 100 W or less are used for lighting ceiling lights and shop windows in stores.

[0003] Metal vapor discharge lamps have luminous efficiency several times higher than incandescent lamps and halogen lamps. Normally, lumen (lm) is used as a unit of the brightness of the lamp, but this unit of brightness (lm) is used.
Divided by the lamp power (W) is defined as luminous efficiency and is expressed in lumens / watt (lm / W).

The luminous efficiency of an incandescent lamp, a halogen lamp and a metal vapor discharge lamp is usually 10 to 15 (lm).
/ W), 20 to 30 (lm / W), 60 to 100 (lm
/ W). Thus, a metal vapor discharge lamp is
Compared with incandescent lamps and halogen lamps, these lamps have sufficiently high efficiency.

Generally, the wall thickness of the arc tube of a low-wattage metal vapor discharge lamp having a rated lamp power of 100 W or less is 1 unit.
mm is used. As the thickness of the arc tube decreases, the total weight of the arc tube decreases and the heat capacity of the arc tube decreases, so that the heat loss of the arc tube decreases. Therefore, the thinner the thickness of the arc tube, the smaller the heat loss of the arc tube, the greater the conversion efficiency to light in the arc tube,
The luminous efficiency of the lamp can be increased.

[0006]

However, if the thickness of the arc tube is too thin, the pressure resistance of the arc tube is reduced, so that the arc tube may be damaged or burst while the lamp is lit, or the lamp may be transported. The arc tube may be damaged by vibration such as inside. In addition, there is also a problem that the arc tube is deformed during processing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems in a metal vapor discharge lamp having a thin arc tube, and in particular, a rated lamp power of 100 W or less, which greatly affects luminous efficiency even with a small heat loss. It is an object of the present invention to provide a low-wattage metal vapor discharge lamp of the type described above, in which the pressure resistance of the arc tube is sufficient and the luminous efficiency and the optical characteristics such as the average color rendering index are good.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a light-transmitting quartz glass having a light-emitting portion at the center of a tube and sealing portions formed at both ends thereof. An arc tube, and a pair of electrodes disposed opposite to each other in a discharge space of the arc tube, and mercury, a metal or a metal halide, and a rare gas are sealed in the arc tube; In a metal vapor discharge lamp having a rated lamp power of 100 W or less and held in an outer tube having a base at one end, when the thickness of the light emitting portion of the arc tube is t (mm), 0.5 ≦ t
This is a metal vapor discharge lamp including an arc tube with ≦ 0.8.

According to a second aspect of the present invention, there is provided the metal vapor discharge lamp according to the first aspect, wherein a quartz sleeve is arranged on the outer periphery of the arc tube and is integrally held in the outer tube.

According to the first aspect of the present invention, the rated lamp power which greatly affects the luminous efficiency even with a small heat loss is 10%.
In an arc tube of a metal vapor discharge lamp of 0 W or less, when the thickness of the light emitting portion of the arc tube is t (mm), 0.5 ≦ t
By setting ≦ 0.8, it is possible to obtain a metal vapor discharge lamp in which the pressure resistance of the arc tube is sufficient and the luminous efficiency and the optical characteristics such as the average color rendering index are good.

According to the second aspect of the present invention, by arranging a quartz sleeve around the arc tube, the arc tube is kept warm, the optical characteristics such as the average color rendering index are improved, and the light is emitted by any chance. This is useful for preventing the arc tube from scattering when the tube ruptures.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a sectional view of an arc tube of a metal vapor discharge lamp showing one embodiment of the present invention. In the discharge space of the light emitting portion 1 of the arc tube, a pair of electrodes 2 are arranged to face each other, and the sealing portions 3 formed at both ends of the light emitting portion 1 of the arc tube are connected to the electrodes 2 by welding. The molybdenum foil 4 is connected to the external lead bar 5 by welding similarly to the molybdenum foil 4. The hatched portion in FIG. 1 is the thickness t of the light emitting portion of the light emitting tube.

Tables 1, 2 and 3 show that the rated lamp power is 7
In each of the 0 W, 100 W, and 150 W lamps, optical characteristics and pressure resistance characteristics were measured using the thickness t (mm) of the light emitting portion of the light emitting tube as a parameter. Here, the measurement of the pressure resistance characteristics is performed by using a high-pressure gas (air or nitrogen gas) from an exhaust pipe connected to exhaust the arc tube after sealing the electrodes.
Is measured when the pressure is supplied.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

In the results of Tables 1 to 3, the light emitting portion of the light emitting tube having a thickness t of 0.3 mm was too thin.
The arc tube was greatly deformed during arc tube processing, and could not be formed into a lamp. However, in the arc tube with a rated lamp power of 70 W, the arc tube was greatly deformed, but the arc tube was sealed, so only the withstand voltage was measured.

From the results of Tables 1 to 3, it is understood that the luminous efficiency increases as the thickness t of the light emitting portion of the arc tube decreases. In particular, if the rated lamp power is 1
In an arc tube of 00 W or less, the difference in luminous efficiency is large when the thickness t of the luminous portion of the arc tube is 0.8 mm and 1.0 mm, and there is a range of change in luminous efficiency. It can be seen that there is almost no change in luminous efficiency when the lamp power is 150 W.

This is because if the rated lamp power is increased so as to exceed 100 W, the heat loss from the arc tube does not become a factor having a significant effect on the luminous efficiency, but as the rated lamp power decreases. It is speculated that even minute heat loss from the arc tube may be a factor that greatly affects luminous efficiency.

As described above, if the thickness t of the light emitting portion of the arc tube is excessively reduced, the workability of the arc tube becomes extremely poor, and the arc tube may not be formed as described above. When the thickness t of the light emitting portion of the arc tube is 0.3 mm, the withstand voltage is 25 at.
m, and the pressure in the arc tube is normally about 6 atm to 10 atm when the lighting of the metal vapor discharge lamp is stable. Therefore, it can be said that there is no problem in a normal lighting state. However, considering the degree of safety, the pressure resistance required for the arc tube is required to be 50 atm or more. Therefore, it is difficult to say that an arc tube with a thickness t of 0.3 mm in the light emitting portion of the arc tube is safe.

Therefore, in a metal vapor discharge lamp having a rated lamp power of 100 W or less, the thickness t (mm) of the light emitting portion of the light emitting tube in which the pressure resistance of the light emitting tube is 50 atm or more and the luminous efficiency is increased is 0.1 mm. It can be said that the range is 5 ≦ t ≦ 0.8.

FIG. 2 is a block diagram of a metal vapor discharge lamp having a rated lamp power of 100 W showing an embodiment of the present invention. The light emitting tube 6 made of translucent quartz glass has an inner volume of 1.2 c.
At c, a pair of electrodes 7 are sealed at both ends of an arc tube 6 made of translucent quartz glass with an arc length (distance between electrodes) of 15 mm. Then, sodium (Na), scandium (Sc), iodide of mercury, and the like are filled in the light emitting tube 6 made of translucent quartz glass in a total weight of 8 mg, mercury of 11.0 mg, and argon gas of 16000 Pa, respectively. ing. The light-emitting tube 6 made of translucent quartz glass is provided with a heat insulating film 8 and is incorporated in a hard glass outer tube 9 together with a quartz sleeve 10, a filament holder 11, and a getter 12.

In a metal vapor discharge lamp having a rated lamp power of 70 W, a light-transmitting quartz glass arc tube has an inner volume of 0.7 cc and an arc length (distance between electrodes) of 10 m.
m, the total weight of sodium (Na), scandium (Sc) and mercury iodide is 5 mg, and the weight of mercury is 6.5 m
g.

The quartz sleeve disposed on the outer circumference of the arc tube is used for keeping the arc tube warm and preventing the arc tube from bursting. Due to the quartz sleeve, the additives in the arc tube are sufficiently evaporated, and the luminous efficiency and the optical characteristics such as the average color rendering index are improved. Even if the arc tube ruptures, the outer tube of the lamp will not be damaged.

[0025]

As described above, according to the present invention, in a luminous tube of a metal vapor discharge lamp having a rated lamp power of 100 W or less, which greatly affects luminous efficiency even with a small heat loss, the luminous portion of the luminous tube When the thickness is t (mm), by setting 0.5 ≦ t ≦ 0.8, the metal having sufficient pressure resistance of the arc tube and good optical characteristics such as luminous efficiency and average color rendering index is obtained. A vapor discharge lamp is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of an arc tube of a metal vapor discharge lamp showing one embodiment of the present invention.

FIG. 2 shows a rated lamp power of 10 according to an embodiment of the present invention.
It is a lineblock diagram of a metal vapor discharge lamp of 0W.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Emitting part of arc tube 2 Electrode 3 Sealing part 4 Molybdenum foil 5 External lead rod 6 Arc tube 7 Electrode 8 Heat insulation film 9 Outer tube 10 Quartz sleeve 11 Filament holder 12 Getter

Claims (2)

[Claims] 1. A light-transmitting quartz glass light-emitting tube having a light-emitting portion at the center of a tube and sealing portions formed at both ends thereof, and a pair of light-emitting tubes disposed opposite to each other in a discharge space of the light-emitting tube. A mercury, a metal or metal halide and a rare gas are sealed inside the arc tube, and the rated lamp power is 100 W or less, which is held in an outer tube having a cap at one end. A metal vapor discharge lamp, comprising: a vapor discharge lamp, wherein when a thickness of a light emitting portion of the arc tube is t (mm), 0.5 ≦ t ≦ 0.8. 2. The metal vapor discharge lamp according to claim 1, wherein said arc tube has a quartz sleeve disposed on an outer periphery thereof and is integrally held in an outer tube.