JPH10125283A - Low-pressure mercury vapor discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the temperature rise by the heat reaching a filament through filament support columns and increase ultraviolet ray radiation efficiency by reducing the length and surface area of a pinch seal section. SOLUTION: Molybdenum foils 6a, 6b must be shortened in length to reduce the size of a pinch-sealed portion. The knife edge faces of the molybdenum foils 6a, 6b are installed perpendicularly to filament support columns 4a, 4b and molybdenum leads 7a, 7b, and the filament support columns 4a, 4b and molybdenum leads 7a, 7b are connected to both ends of the molybdenum foils 6a, 6b. A pinch seal forming mold is pressurization-machined by a mold longer than the width of the molybdenum foils 4a, 4b by 3-5mm to obtain a small pinch seal section 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the decomposition of organic matter by disinfection or photo-oxidation of water, air, foodstuff packaging materials, medical equipment, etc. by emitting an ultraviolet emission spectrum having a wavelength of 185 nm or 254 nm. The present invention relates to a low-pressure mercury vapor discharge lamp used for cleaning ozone and the like, and particularly to an improvement in an electrode mounting structure.

[0002]

2. Description of the Related Art A conventional low-pressure mercury vapor discharge lamp has a structure in which an ultraviolet ray transmitting glass or a quartz glass transmitting an ultraviolet wavelength of 300 nm or less is used as a material of an arc tube, and electrodes are provided at both ends thereof through lead wires as electrodes. Thus, a filament coated with an electron-emitting material is sealed, and mercury and a rare gas are sealed in the arc tube. As a method of filling mercury, there is a method of filling a liquid or a titanium-mercury alloy, and a method of using amalgam of mercury for a lamp operating at a high temperature in order to prevent a decrease in luminous efficiency at a high temperature. Argon is generally used as the rare gas, but a mixed gas such as krypton or neon may be used depending on the structure and type of the lamp.

The principle of light emission is that electrons accelerated by applying a voltage between the two electrodes collide with mercury ions, and the mercury atoms are excited by absorbing their kinetic energy.
Emit when returning to the low energy ground state. This radiation is mainly emitted from a part called the positive column,
It is constituted by resonance radiation of mercury atoms at wavelengths of 185 nm and 254 nm. In particular, the wavelength of 254 nm substantially coincides with the wavelength at which the wavelength of the germicidal action is maximized, and is called a germicidal line.

There are generally two types of methods for sealing a quartz glass tube and an electrode. One is a method of melting and sealing a stem to which an electrode is fixed and a quartz glass tube. There is a glass or a graded seal of hard glass and quartz glass. Another method is to directly pinch seal the arc tube and the electrode mount. In this pinch seal, an electrode mount is fixed to both ends of a quartz glass tube, and the quartz glass is melted while being blown with an inert gas, and is pressed with a pinch seal mold.

FIG. 4 shows the structure of an electrode mount which is pinch-sealed on quartz glass. The electrode mounts are sealed at both ends of a quartz glass tube 11 and hold a filament 13 holding an electron-emitting substance 12 and filament support columns 14a and 14a.
b, glass bridge 15, molybdenum foil 16a, 16
b, molybdenum leads 17a and 17b. The filament is fixed by caulking at both ends of a filament support column fixed at both ends by a glass bridge, and the filament support column and the molybdenum lead are welded and joined to both ends of the molybdenum foil. The electrode mount is fixed by sealing a portion indicated by a hatched portion 18.
Molybdenum foil has almost the same coefficient of thermal expansion as quartz glass, and its edge in the longitudinal direction has a knife-edge structure, so that there is no gap between quartz glass and molybdenum foil. It is kept airtight.
Therefore, a method of sealing the lead of the quartz glass and the electrode using a molybdenum foil is generally performed.

The electron-emitting substance applied on the filament is an alkaline earth metal (B) dispersed in an organic solvent.
a, Sr, Ca, etc.) as a main component, and is obtained by decomposing into an alkaline earth metal oxide that emits electrons with a low work function by applying electric current to the filament during the evacuation step. This reaction formula is shown in Formula 1. (Ba, Sr, Ca) CO ₃ → (Ba, Sr, Ca) O + CO ₂ (Equation 1) It is said that the appropriate temperature for the reaction to obtain the alkaline earth metal oxide is 800 to 1000 ° C. .

In the method of directly pinch-sealing the electrode mount to the quartz glass tube, the end of the quartz glass tube is melted at about 1600 ° C. at the time of pinch sealing, so that heat is rapidly transmitted from the filament support column near the seal portion. As the temperature of the filament rises, the oxidation of the filament and the peeling-off and deterioration of the electron-emitting material applied on the filament have caused the lamp not to turn on and have a short life due to a decrease in the emission of the electron-emitting material. .

[0008]

SUMMARY OF THE INVENTION A low-pressure mercury vapor discharge lamp,
In particular, the size of the pinch seal portion in a small lamp having a short light emission length of about 4 to 30 W is determined by the length of the molybdenum foil, and is generally 7 to 10 mm. Also, to fix the filament support columns and molybdenum leads,
The length of the pinch seal portion needs to be about 10 to 15 mm, and the smaller the lamp, the larger the length of the pinch seal portion with respect to the entire length of the lamp. As a result, the length of the positive column is shortened, and wavelengths of 185 nm and 254 nm are not efficiently radiated.

In order to solve the above problems, the present invention is intended to prevent the filament from being oxidized due to a rapid rise in the filament temperature due to heat conduction at the time of pinch sealing, which is a factor of non-lighting and short life, and peeling and deterioration of the electron emitting material. It is another object of the present invention to provide a low-pressure mercury vapor discharge lamp in which a positive column is secured for a long time to increase the ultraviolet radiation efficiency.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to the claimed invention reduces the amount of heat absorbed by quartz glass by reducing the length and surface area of the pinch seal portion, thereby reducing the pinch seal. The time for self-radiation of the pinch seal afterwards becomes shorter, the temperature rise due to the heat reaching the filament through the filament support column can be suppressed, and the positive column can be secured longer, so the ultraviolet radiation efficiency can be increased. You can do it.

[0011]

Next, an embodiment will be described. FIG. 1 shows an embodiment of an electrode mount for a low-pressure mercury vapor discharge lamp according to the present invention. A pinch seal portion is formed at the end of the quartz glass tube 1, and the filament 3 holding the electron-emitting substance 2 and the filament support column 4
a, 4b, glass bridge 5, molybdenum foil 6a, 6
b, molybdenum leads 7a and 7b. The filament is fixed by caulking at both ends of a filament support column fixed at both ends by a glass bridge, and the lower portion of the filament support column and the molybdenum lead are welded and joined to both ends of the molybdenum foil. The knife edge portion, which is the longitudinal end of the molybdenum foil, is installed perpendicularly to the filament support column and the molybdenum lead and sealed. The hatched portion 8 indicates a portion to be pinch-sealed.

FIGS. 2 and 3 are enlarged views of the electrode mount and FIG.
FIG. 4 shows a cross-sectional view taken along the line A ′. In order to reduce the size of the portion to be pinched and sealed, it is necessary to shorten the length of the molybdenum foil. However, in order to maintain the airtightness between the quartz glass and the molybdenum foil, it is necessary that the length d shown in FIG. 4 has a width of at least 4 to 6 mm. And molybdenum leads are installed vertically and the electrode structure is such that filament support pillars and molybdenum leads are connected to both ends of the molybdenum foil, and the pinch seal forming mold is pressed with a mold 3 to 5 mm longer than the width of the molybdenum foil. By processing, a small pinch seal portion having a pinch seal width of 5 to 6 mm is obtained.

Specifically, a molybdenum foil support having a diameter of 0.4 mm and a molybdenum lead having a diameter of 0.5 mm are placed at 0.5 mm from both ends of a molybdenum foil having a width of 2 mm and a length of 4 mm at the knife edge of the molybdenum foil. It is arranged perpendicularly, and is welded with a platinum foil of 1 mm ² as a binder.
In addition, a small seal shape having a pinch seal width of 5 to 6 mm can be obtained by using a pinch seal mold having a width of 5 mm.

[0014]

The electrode mount for a low-pressure mercury discharge lamp according to the present invention is pinch-sealed compared to a conventional electrode mount structure in which a knife edge surface of a molybdenum foil is welded on the same straight line of a filament support pillar or a molybdenum lead. The size of the part can be reduced to about 6 mm, preventing the filament from oxidizing due to the rapid rise of the filament temperature due to heat conduction during pinch sealing, which is the cause of non-lighting and short life, peeling of the electron emitting material, deterioration In addition, it is possible to provide a low-pressure mercury vapor discharge lamp that secures a long positive column and increases ultraviolet radiation efficiency.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of an electrode mount for a low-pressure mercury vapor discharge lamp according to the present invention.

FIG. 2 is an enlarged view of a molybdenum foil portion of the electrode mount for a low-pressure mercury vapor discharge lamp according to the present invention.

FIG. 3 is a sectional view taken along line A-A ′ of FIG. 2;

FIG. 4 is an enlarged view of a molybdenum foil portion of the electrode mount for a low-pressure mercury vapor discharge lamp according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz glass tube 2 Electron emission material 3 Filament 4a, 4b Filament support pillar 5 Bridge 6a, 6b Molybdenum foil 7a, 7b Molybdenum lead 8 Pinch seal part 11 Quartz glass tube 12 Electron emission material 13 Filament 14a, 14b Filament support pillar 15 Bridge 16a, 16b Molybdenum foil 17a, 17b Molybdenum lead 18 Pinch seal part

Claims (1)

[Claims] 1. A low-pressure mercury vapor discharge lamp in which pinch seals are formed at both ends of an arc tube and an electrode mount is sealed to the seals, and a knife edge surface of molybdenum foil as a part of the electrode mount. A low-pressure mercury vapor discharge lamp characterized by reducing the length and surface area of a pinch seal portion by vertically installing and sealing a filament support column and a molybdenum lead.