JPH04306551A - Discharge lamp - Google Patents

Abstract

PURPOSE:To prevent the ultraviolet deflection of a bulb and improve the safety of a discharge lamp under high operating pressure by sealing a hydrogen gas of a specified value or more by the sealing mole ratio to a rare gas, metal or halogen into a quartz glass bulb. CONSTITUTION:A hydrogen gas of 3X10<-4> or more by the sealing ratio to a determined amount of a rare gas is sealed in a quartz glass bulb 1. The hydrogen gas may be directly sealed, or adsorbed by a getter material adhered to the getter line 41 of an anode 4 followed by discharging at a high temperature by lighting. When a lamp is lighted, the hydrogen gas activated by ultraviolet ray is reacted with quartz glass to produce SiOH in the bulb, and this suppresses the ultraviolet deflection of the quartz glass. In case of a low pressure mercury lamp, a reduction in ultraviolet transmission of the bulb is suppressed to minimize the output reduction of ultraviolet rays with short wavelengths, and in case of an xenon discharge lamp or super-high pressure mercury lamp having a high operating pressure, the danger of bulb breakage is reduced, and the safety can be ensured.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp equipped with a bulb made of quartz glass, and more particularly to a discharge lamp with less distortion of the bulb by ultraviolet rays.

0002

[Prior Art] Long-arc low-pressure mercury lamps and high-pressure mercury lamps, short-arc xenon discharge lamps and ultra-high-pressure mercury lamps, and even metal halide discharge lamps are widely used in industry depending on their characteristics. However, a pair of electrodes are placed facing each other inside a quartz glass bulb, and rare gases such as mercury, xenon, and argon,
A predetermined amount of halogen and additive metals are sealed as necessary, and arc discharge occurs between both electrodes. Ultraviolet and visible light emitted from the arc are used, but it is known that if the lamp is left on for a long time, the ultraviolet rays will be absorbed by the quartz glass bulb, causing ultraviolet distortion in the bulb. Additionally, along with this, the bulb transmittance of short-wavelength ultraviolet rays decreases, and for example, in the case of low-pressure mercury lamps that emit ultraviolet rays with wavelengths of 185 nm and 254 nm, which are used for cleaning with ultraviolet rays, the output decreases. Put it away. Furthermore, in the case of xenon discharge lamps and ultra-high-pressure mercury lamps, where the pressure inside the bulb reaches several tens of atmospheres when lit, there is an increased risk that the bulb will be damaged due to ultraviolet distortion.

0003

[Problems to be Solved by the Invention] Conventionally, one method for preventing ultraviolet distortion of this quartz glass bulb is to
The inner surface of the bulb is coated with a UV-absorbing film to prevent UV rays from being absorbed by the bulb. However, this method cannot be used in the case of discharge lamps that utilize ultraviolet light because the output of ultraviolet light, which is the original purpose, will be reduced. In addition, in order to coat the ultraviolet absorbing film, it is necessary to apply an alcoholate solution such as titania by dipping and then bake it, which requires time and effort.
There are problems such as moisture generated from the ultraviolet absorbing film during lighting, oxidizing the electrodes, and adversely affecting lamp characteristics. Therefore, the present invention uses a simple method that reduces the decrease in short-wavelength ultraviolet transmittance, prevents ultraviolet distortion of a bulb made of quartz glass even under high operating pressure, and eliminates the risk of bulb damage caused by ultraviolet distortion. The purpose is to provide a highly safe discharge lamp.

0004

[Means for Solving the Problems] In order to achieve the above object, the discharge lamp of the present invention has a bulb made of quartz glass filled with a filler selected from rare gases, metals, halogens, etc. Hydrogen gas is sealed at a molar ratio of 3 x 10-4 or more to the hydrogen gas.

[0005]

[Operation] In order to achieve the above-mentioned object, the present inventor has conducted extensive research and found that hydrogen gas is effective, and has completed the present invention. That is, when hydrogen gas is sealed inside the bulb and the bulb is turned on for several tens of hours, the hydrogen gas and quartz glass are activated by ultraviolet rays, and the next reaction proceeds. H2 +SiO2 +hν+heat → SiOH In other words,
Hydrogen is introduced into the quartz glass, and S generated inside the bulb
It is speculated that iOH prevents ultraviolet distortion. Therefore, in the case of low-pressure mercury lamps that utilize short-wavelength ultraviolet rays, a decrease in ultraviolet transmittance is prevented, and in the case of xenon discharge lamps and ultra-high pressure mercury lamps, which have high operating pressures, accidents such as bulb breakage can be prevented. In order to obtain such an effect, the amount of hydrogen gas sealed must be at a molar ratio of 3 x 10-4 or more with other rare gases, metals, halogens, etc. However, if the amount of hydrogen gas is too large, the valve Since problems such as early blackening and deterioration of lamp characteristics occur, it is preferable to set it to 5×10 −3 or less.

[0006]

EXAMPLES The present invention will be specifically explained below based on examples shown in the drawings. FIG. 1 shows a short arc xenon discharge lamp as an example of a discharge lamp. The center of the bulb 1 made of quartz glass is a spherical light-emitting space surrounding part 2, and a sealing tube part 5 extends from both sides of the light-emitting space surrounding part 2, and a cap 6 is attached to the tip of the sealing tube part 5. There is. A cathode 3 and an anode 4 are disposed facing each other within the light emitting space surrounding section 2. The anode 4 is made of tungsten containing thorium oxide, and a getter wire 41 to which a getter material such as zirconium, tantalum, or a mixture of zirconium and tantalum is attached is wound around the outer periphery. Further, hydrogen gas is sealed in the bulb 1 at a filling ratio of 3×10 −4 or more to a predetermined amount of xenon gas. Hydrogen gas may be directly sealed together with xenon gas,
Alternatively, it may be made to be adsorbed to the getter material and released from the getter material when it is turned on and reaches a high temperature. Note that discharge lamps are not limited to short arc xenon discharge lamps,
Any discharge lamp may be used as long as it is equipped with a bulb made of quartz glass, and the amount of hydrogen sealed is 3× in molar ratio to the total amount of rare gases, metals, halogens, etc. that are filled at the same time. It is sufficient if it is 10-4 or more.

[0007] When such a discharge lamp is turned on, as described above, the hydrogen gas activated by ultraviolet rays reacts with the quartz glass, and SiOH is generated within the bulb. This SiOH suppresses the ultraviolet distortion of the silica glass. Therefore, in the case of low-pressure mercury lamps that emit short-wavelength ultraviolet rays, the decrease in UV transmittance of the bulb is suppressed and there is little decrease in the output of short-wavelength ultraviolet rays; Safety is ensured by reducing the risk of damage.

Next, by changing the amount of hydrogen to be sealed,
The results of measuring valve distortion will be explained based on FIG. 2. The discharge lamp used was a short arc xenon discharge lamp shown in Fig. 1, and the amount of hydrogen filled was 0, 1 x 10-4, 3 x 10-4, and 1 x 10-3 in molar ratio with xenon. There are four levels. Then, the distortion of the bulb after each discharge lamp was lit for 1000 hours was measured. As a result, when the amount of hydrogen enclosed is 0, the distortion is approximately 270 kgf/cm2.
However, at 3 x 10-4, it is approximately 160 kgf/c
m2, and even if it increases to 1 x 10-3, it remains about 150 kgf/cm2. That is, 3×10
The amount of distortion changes critically around -4, and it is extremely effective to prevent distortion if the amount of hydrogen enclosed in the molar ratio with xenon is 3 x 10-4 or more. In the case of xenon discharge lamps and ultra-high pressure mercury lamps, where the pressure inside the bulb is tens of atmospheres while lit, the amount of distortion of the bulb to ensure safety is 30
It is said that less than 0 kgf/cm2 is required, and it can be seen that if the amount of hydrogen enclosed is 3 x 10-4 or more, the integrity is greatly improved.

Furthermore, the changes in ultraviolet transmittance caused by changing the amount of hydrogen to be sealed will be explained based on FIG. The discharge lamp used was a low-pressure mercury lamp, and the amount of hydrogen filled was:
The molar ratio of mercury and noble gas is 0, 1 x 10-4
, 3x10-4, and 1x10-3. Then, the spectral transmittance of each discharge lamp was measured after being lit for 1000 hours. It can be seen from this that the higher the amount of hydrogen enclosed, the less the decrease in the transmittance of short wavelength ultraviolet rays, but when compared with the wavelength of 254 nm, which is used for cleaning with ultraviolet rays, the transmittance before lighting is about 78%. If the amount of hydrogen filled is 0, the amount will decrease to about 47% after 1000 hours of lighting. On the other hand, the amount of hydrogen enclosed is 3×10-4
, it is about 58%. In other words, the transmittance after 1000 hours of lighting increases by about 10%, and the decrease in the output of short wavelength ultraviolet rays can be significantly reduced.

[0010] Note that if the amount of hydrogen enclosed is too large,
Since getter materials such as zirconium and tantalum cause hydrogen embrittlement, causing early blackening of the bulb and deterioration of lamp characteristics, it is preferable to set it to 5×10 −3 or less.

[0011]

[Effects of the Invention] As explained above, the discharge lamp of the present invention has hydrogen gas sealed in a quartz glass bulb at a molar ratio of 3 x 10-4 or more to rare gases, metals, halogens, etc. Therefore, SiOH is generated on the wall inside the bulb, thereby preventing the bulb from being distorted by ultraviolet light. Therefore, it is possible to provide a highly safe discharge lamp with little decrease in ultraviolet transmittance and no risk of bulb damage caused by ultraviolet distortion even when operating pressure is high.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a short arc type xenon discharge lamp.

FIG. 2 is a diagram showing the relationship between the amount of hydrogen sealed in the arc tube and distortion.

FIG. 3 is an explanatory diagram of spectral transmittance when the amount of hydrogen enclosed is changed.

[Explanation of symbols]

1 Valve 2　　　Light emitting space surrounding part 3 Cathode 4 Anode 5 Sealed tube section 6 Base

Claims (1)

[Claims] [Claim 1] A filler selected from a rare gas, a metal, a halogen, etc. is sealed in a bulb made of quartz glass, and hydrogen gas is sealed at a molar ratio of 3 x 10-4 or more to these fillers. A discharge lamp characterized by: