JPH0982280A - Low-pressure mercury vapor electric discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mercury vapor electric discharge lamp of low pressure type capable of holding stable and high germicidal beam output maintaining ratio until the end of a service life. SOLUTION: A metal oxide film such as Al2 O3 is formed on the internal surface of a light emitting tube 1 made of quartz glass to thickness between 0.01μm and 5μm, and stays 4a and 4b to support tungsten filaments 3a and 3b and positive electrodes 7a and 7b are flame sprayed to both ends of the light emitting tube 1. Also, 2.9×10<-2> mg/cc of mercury and 1Torr of argon gas are sealed into the light emitting tube 1 with an inter-electrode distance kept at 920mm, thereby forming a 65W mercury vapor pressure electric discharge lamp of low-pressure type.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pressure mercury vapor discharge lamp capable of maintaining a stable high sterilization line output maintenance rate until the end of its life.

[0002]

2. Description of the Related Art Conventionally, low-pressure mercury vapor discharge lamps that output ultraviolet rays have been widely used for purification of various gases and liquids and various sterilization. These low pressure mercury vapor discharge lamps
Lamp power (lamp load) per unit light emission length is 0.3 W
It is known from low load type of about 10 / cm to high load type of about 10 W / cm.

[0003]

However, with any lamp load, especially with a lamp load of 0.5 W / cm or more, mercury ions enter the quartz glass arc tube as the lighting time elapses. It is immobilized and causes the arc tube to be colored. Therefore, the amount of mercury that contributes to light emission is reduced, and at the end of the life, the amount of mercury is less than that required to obtain an appropriate mercury vapor pressure, the ultraviolet ray output is sharply reduced, and finally lighting failure occurs. Therefore, there is a considerable excess of mercury (2.9 mg / cc
It becomes necessary to enclose it in a degree). However, when mercury is excessively sealed in this way, although a sharp decrease in ultraviolet light output and lighting failure at the end of life can be prevented, a large amount of mercury adheres to the inner wall surface of the arc tube light emitting part in a particulate form, The balance of the mercury vapor pressure in the tube is deteriorated, causing unevenness of light emission, and ultraviolet rays are absorbed by the attached mercury, so that the ultraviolet ray output is reduced. Also, from the viewpoint of environmental protection, it is not preferable to use a large amount of mercury.

The present invention has been made to solve the above-mentioned problems in the conventional low-pressure mercury vapor discharge lamp, and provides a low-pressure mercury vapor discharge lamp which can maintain a stable high sterilization line output maintenance rate until the end of its life. The purpose is to

[0005]

In order to solve the above-mentioned problems, the present invention encloses mercury in a quartz glass arc tube having electrodes sealed at both ends, and a lamp load of 0.5 W / cm to 10 W / cm.
In a low-pressure mercury vapor discharge lamp with cm, a metal oxide film is formed on the inner surface of the arc tube, and the amount of mercury enclosed per unit volume is 4.0 × 10 ^-3 mg / cc to 2.7 mg / cc. is there.

In this way, the lamp load is 0.5 W / cm to 10
By forming a metal oxide film on the inner surface of the arc tube which is easily colored by mercury ions of W / cm, the penetration of mercury ions into the glass constituting the arc tube is prevented and the reduction of mercury is suppressed. Therefore, the amount of mercury enclosed per unit volume should be 4.0 × 10 ^-3 mg / cc to 2.7 mg / cc, and a stable high germicidal radiation output maintenance rate should be maintained until the end of life without enclosing excess mercury. Is possible. Note that the amount of mercury enclosed is set as above because
If it is less than 4.0 × 10 ^-3 mg / cc, it will be below the amount of mercury required to obtain an appropriate mercury vapor pressure, and normal lighting cannot be maintained. If the amount of enclosed mercury exceeds 2.7 mg / cc, a large amount will be produced. This is because the liquid mercury adheres to the inner wall surface of the arc tube in the form of particles, and the balance of the mercury vapor pressure inside the tube is deteriorated, causing uneven light emission, and the adsorbed mercury absorbs ultraviolet rays to reduce the output.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, examples will be described. FIG. 1 shows a first low-pressure mercury vapor discharge lamp according to the present invention.
FIG. 2 is a sectional view showing a state before chip-off of the exhaust pipe of the embodiment, and FIG. 2 is a sectional view showing a completed low-pressure mercury vapor discharge lamp of the first embodiment. In FIG. 1, reference numeral 1 denotes an arc tube made of a quartz glass tube having a diameter of 18 mm, the inner surface of which is made of Al ₂ O ₃
The metal oxide film 2 having a thickness of 0.01 to 5 μm is formed by the sol-gel method or the CVD method. At both ends of the arc tube 1, tungsten filaments 3a, 3b coated with an electron-emissive substance made of an oxide such as Ba, Ca, Sr in the form of carbonate are used as filament supports 4a, 4b which also serve as lead wires. The columns 4a and 4b are continuously sealed to the external lead wires 6a and 6b of the arc tube 1 through the molybdenum foils 5a and 5b. Anodes 7a and 7b are welded to the filament columns 4a and 4b, and the filaments 3a and 3b and the anodes 7a and 7b form electrodes.

The distance between the electrodes is 920 mm, and the negative glow region and the Faraday dark part are from the electrode to the part about 20 mm,
Therefore, the effective light emitting area is 20 mm inward from both electrodes, and the effective light emitting length is 880 mm. Also, the arc tube 1 has about 20 mm from the tips of the electrode filaments 3a and 3b.
Then, the exhaust pipe 8 is connected to a position other than the region which becomes the effective light emitting portion.

As described above, the inside of the arc tube 1 is evacuated by using a vacuum pump through the exhaust tube 8 provided in any one of the parts other than the effective light emitting part of the arc tube 1, and then the entire arc tube 1 To degas and heat tungsten filament 3
By applying current to a and 3b through the lead wires 6a and 6b for resistance heating, the tungsten filament 3
Carbonate gas applied to a and 3b is decomposed by heating to release carbon dioxide gas, and exhausted to discharge tungsten filaments 3a,
An oxide of Ba, Ca, Sr, which is an electron emitting substance, is formed on 3b.

Next, about 1 torr of starting gas and about 5 mg of mercury are filled through the exhaust pipe 8 and then the exhaust pipe 8 is chipped off. As a result, a low pressure mercury vapor discharge lamp as shown in FIG. 2 is obtained. The low-pressure mercury vapor discharge lamp of this embodiment has a lamp input of 65 W and a lamp load of 0.7 W /
In cm, the amount of mercury enclosed is 2.9 × 10 ^-2 mg / cc.

Next, an experiment conducted for setting the amount of mercury enclosed in the present invention will be described. In the low-pressure mercury vapor discharge lamp having the configuration shown in the above example, six types of lamps (No. 1 to No. 6) in which only the amount of enclosed mercury was changed to 2.5 × 10 ⁻³ mg / cc to 2.9 mg / cc were used. A prototype was made and a life test was conducted for 16000 hours.
The results shown in Table 1 were obtained for 000 hours).

[0012]

[Table 1]

As can be seen from Table 1 above, the amount of mercury enclosed is
In the range of 4.0 x 10 ^-3 mg / cc to 2.7 mg / cc, the sterilization line output maintenance rate is 70% or more. And 4.0 × 10 ^-3 mg /
If it is less than cc, it is below the amount of mercury required to obtain an appropriate mercury vapor pressure, and normal lighting cannot be maintained. If it exceeds 2.7 mg / cc, a large amount of liquid mercury emits particles. The mercury adheres to the inner wall surface of the tube, the balance of the vapor pressure of mercury inside the tube is deteriorated, and uneven light emission is caused. Further, ultraviolet rays are absorbed by the adhered mercury and the output is reduced.

Further, the same experiment was conducted with a lamp power of 0.5 W /
When a lamp of cm to 10 W / cm was used, the same result as above was obtained. Therefore, in the present invention,
The amount of mercury enclosed is set to 4.0 x 10 ^-3 mg / cc to 2.7 mg / cc.

FIG. 3 shows the lamp of the above embodiment (No. 3 in Table 1).
(Corresponding to the lamp of No. 1) and a conventional low-pressure mercury vapor discharge lamp not provided with a metal oxide film. In FIG. 3, the curve A shows the sterilization line output maintenance rate of the low-pressure mercury vapor discharge lamp in which the mercury filling amount was 2.9 × 10 ⁻² mg / cc according to this example, and the curve B is the inner surface of the arc tube. Without forming a metal oxide film, the amount of mercury enclosed is 2.9 × 10 ^-2 mg /
The sterilization line output maintenance rate of a conventional low-pressure mercury vapor discharge lamp is shown as cc, and curve C is the same as the conventional low-pressure case in which a metal oxide film is not formed on the inner surface of the arc tube and an excess amount of mercury of 2.9 mg / cc is enclosed. The sterilization line output maintenance rate range of a mercury vapor discharge lamp is shown.

When a metal oxide film is not formed on the inner surface of the arc tube, the amount of mercury normally enclosed is about 80 as shown by the curve B.
After 00 hours, the sterilization line output maintenance rate dropped sharply,
Lighting failure occurs in 12000 hours. Further, when mercury is excessively filled, as shown in the curve C, the lamp is normally turned on for about 16000 hours, but the sterilization line output maintenance rate is significantly lowered. On the other hand, the low-pressure mercury vapor discharge lamp according to this embodiment in which the metal oxide film is formed on the inner surface of the arc tube has a normal mercury filling amount of about 16,000.
It was confirmed that the lamps turned on normally for a certain period of time and the sterilization line output maintenance rate was improved by about 45 points compared with the case where mercury was excessively enclosed.

From the above results, a metal oxide film was formed on the inner surface of the arc tube and the amount of mercury enclosed was 4.0 × 10 ⁻³ mg / cc to 2.7 mg / cc.
It was confirmed that by setting to, it is possible to realize a stable germicidal line output stroke with little attenuation until the end of life.

FIG. 4 is a sectional view showing the second embodiment.
When the distance between the electrodes is relatively short, or when the arc tube diameter is small, etc., when it is necessary to reduce the amount of enclosed mercury, the mercury particles in liquid mercury become small and encapsulation becomes difficult. In these cases, a minute amount of mercury can be enclosed by installing a mercury dispenser such as a titanium-mercury alloy in the arc tube. In the second embodiment shown in FIG. 4, mercury dispensers 9a and 9b made of titanium-mercury alloy are installed on the anodes 7a and 7b.

[0019]

As described above on the basis of the embodiments,
According to the present invention, mercury is reduced by the penetration of mercury ions into the arc tube, unevenness of light emission due to adhesion of mercury particles to the inner wall surface and absorption of ultraviolet rays are eliminated, and the amount of mercury that can maintain normal lighting is enclosed. Therefore, it is possible to realize a low-pressure mercury vapor discharge lamp that maintains a stable high germicidal ray output maintenance rate until the end of its life.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state before chip-off of an exhaust pipe in a first embodiment of a low-pressure mercury vapor discharge lamp according to the present invention.

FIG. 2 is a sectional view showing a completed state of the first embodiment shown in FIG.

FIG. 3 is a diagram showing a germicidal line output stroke of a low-pressure mercury vapor discharge lamp.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 1 arc tube 2 metal oxide film 3a, 3b tungsten filament 4a, 4b filament support 5a, 5b molybdenum foil 6a, 6b lead wire 7a, 7b anode 8 exhaust pipe 9a, 9b mercury dispenser

Claims (1)

[Claims] 1. A mercury lamp is sealed in a quartz glass arc tube having electrodes sealed at both ends, and a lamp load is 0.5 W / cm to 10 W /.
In a low pressure mercury vapor discharge lamp with cm, a metal oxide film was formed on the inner surface of the arc tube, and the amount of mercury enclosed per unit volume was set to 4.0 × 10 ^-3 mg / cc to 2.7 mg / cc. Characteristic low-pressure mercury vapor discharge lamp.