JPH04345743A - Low-pressure mercury-vapor discharge lamp - Google Patents

Abstract

PURPOSE:To provide a low-pressure mercury-vapor discharge lamp capable of restraining the blackening of a glass wall produced when input electric power is increased. CONSTITUTION:This discharge lamp is a low-pressure mercury-vapor discharge lamp, in which electrodes 3 and 4 are sealedly mounted on both the end parts of a light emitting tube 1 and also mercury and a rare gas are sealed in the light emitting tube, and which is lit by an input to a unit inner surface area of 0.3W/cm<2> or more. The light emitting tube is composed of a glass material having a volume resistivity at 150 deg.C of 1X10<15>OMEGA.cm or more, and moreover its luminous part cross section is formed in a noncircular shape. Composing the light emitting tube with the glass material having a volume resistivity of 1X10<15>(OMEGA.cm) or more, which is considered to effect a crystal condition, causes preventing blackening due to the diffusion of mercury into a glass inside, resulting in restraining the lowering of ultraviolet ray output.

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 used, for example, as a light source for ultraviolet chemical reactions.

0002

[Prior Art] Electrodes are sealed at both ends of an arc tube made of quartz glass or the like that transmits ultraviolet rays, and mercury and rare gas are sealed inside the arc tube, and when the electrodes are energized, a discharge is generated within the arc tube. A low-pressure mercury vapor discharge lamp, which ionizes and excites mercury atoms to emit ultraviolet light mainly in the mercury resonance lines of 185 nm and 254 nm, is used as an ultraviolet light source for photochemical reaction devices, etc. .

[0003] That is, the above-mentioned low-pressure mercury vapor discharge lamp is, for example, a photo-CVD (Chemical Vapor Depth)
It is an indispensable ultraviolet light source for semiconductor manufacturing, including the synthesis of Si thin films using the photoposition method, photocuring of resists, photoashing, and photocleaning, as well as for water purification, sterilization, and food sterilization. It is also widely used as a light source that irradiates short wavelength ultraviolet rays. Recently, there has been a demand for faster photochemical processing, and there is a demand for an improvement in the output of ultraviolet rays emitted from low-pressure mercury vapor discharge lamps.

0004

[Problems to be Solved by the Invention] By the way, when the input power is increased in order to improve the ultraviolet output emitted from the above-mentioned low-pressure mercury vapor discharge lamp, the glass wall forming the arc tube becomes black. There was a phenomenon in which the blackening progressed as the lighting time increased, resulting in a significant drop in ultraviolet output.

[0005] Although the reason for this is not clear,
It is assumed that when the input power is increased, the arc generated between the electrodes approaches the glass wall, and as a result, the mercury ions sealed in the arc tube diffuse into the glass, causing blackening. be done.

The present invention was made based on the above circumstances, and its purpose is to provide a low-pressure mercury vapor discharge lamp that can suppress the blackening of the glass wall that occurs when input power is increased. It is something to do.

[Configuration of the invention]

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the low-pressure mercury vapor discharge lamp according to claim 1 has electrodes sealed at both ends of the arc tube, and mercury and a rare gas inside the arc tube. is enclosed, and the input per unit internal surface area is 0.
The arc tube is lit at 3 W/cm2 or more, and the volume resistivity at 150°C is 1 x 1015 (Ω・
cm) or more.

The low-pressure mercury vapor discharge lamp according to claim 2 further includes an anode and a cathode sealed at both ends of the arc tube, and mercury and a rare gas sealed in the arc tube,
The light is turned on when the input per unit internal surface area is 0.3 W/cm2 or more, and the cross section of the light emitting part of the arc tube is formed into a non-circular shape, and the volume resistivity at 150°C is 1 x 1.
It is characterized by being made of a glass material with a resistance of 0.015 (Ω·cm) or more.

0010

[Function] According to the invention as claimed in claim 1 and claim 2, the volume resistivity, which is estimated to have an effect on the crystal structure of glass, is 1×1015 (Ωcm) at 150°C.
) Since the arc tube is made of the above glass materials, it is thought that it is possible to reduce the diffusion of mercury inside the glass, thereby suppressing the blackening of the glass wall.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the low-pressure mercury vapor discharge lamp according to the present invention. , a stem 2 is sealed, and an anode 3 and a hot cathode 4 are supported on the stem 2, respectively. Each anode 3 is a hot cathode 4
The anode 3 is formed of a circular coil, cylinder, or annular plate, and the hot cathode 4 is formed of a filament coil.

[0013] If the anode 3 and cathode 4 are respectively sealed at both ends of the arc tube 1 as described above, when the discharge current is increased, the cathode 4 can be made smaller to reduce loss due to heat radiation. On the other hand, the anode 3 can be made large to promote heat dissipation.

The arc tube 1 has a non-circular cross section, for example, a substantially flat square shape as shown in FIG. 2, and the ratio X/Y of the short side X to the long side Y is 0.2 to 0.2. It is formed to be about 0.8. In this example, the short side X is 15 mm, and the long side Y
is 30 mm, and the cross-sectional area of this arc tube is approximately 4.5 cm2.

[0015] Inside this arc tube 1, a pressure of 0.5 to 13 Pa is applied.
of mercury and a rare gas such as argon of 13 to 267 Pa are sealed.

The low pressure mercury vapor discharge lamp constructed as described above is connected to an AC power source via the lighting circuit device 10. This lighting circuit device 10 includes, for example, a step-up transformer 11 and a heater transformer 12.
are connected to the anode 3 of the lamp, and the heater transformers 12 are connected to the hot cathode 4, respectively. Therefore, the hot cathode 4 always generates heat and emits thermoelectrons.

The lighting circuit device 10 is configured to supply, for example, an input power of 500 W from a commercial power source to a low-pressure mercury vapor discharge lamp, so that the low-pressure mercury vapor discharge lamp has a discharge current of 7 A during discharge. is set so that the input per unit internal surface area is 0.3 W/cm2 or more, and the tube wall temperature of the arc tube in this case is 100 to 15
It reaches 0°C.

Here, the inventors investigated the blackening phenomenon of the arc tube by variously changing the glass material constituting the arc tube 1 of the low-pressure mercury vapor discharge lamp constructed as described above, and found that 150℃, which was often used in low-pressure mercury vapor discharge lamps.
The volume resistivity at is 1×1011 (Ω・cm), 1×
1014 (Ω・cm) glass material has a significant blackening during its life, whereas the volume resistivity at 150°C is 1×1015 (Ω・cm) and 1×1018
It was found that arc tubes made of quartz glass material with a diameter of (Ω・cm) exhibited almost no blackening during their lifetime. Although the reason for this has not been completely investigated at present, as mentioned above, the input power per unit internal surface area is 0.3 W/cm2.
When the light is turned on under the above conditions, a large number of mercury ions with high energy will be present near the tube wall, and the above-mentioned glass with a low volume resistivity will noticeably diffuse mercury into the interior of the glass. It is assumed that. In other words, electrical conduction in glass is generally caused by ionic conduction,
As the alkali content inside the glass increases, its volume resistivity decreases. On the other hand, an increase in the alkali content causes an increase in the number of non-bridging oxygen atoms in the glass, which means that the network structure of the glass crystal becomes loose. It is assumed that this is due to the promotion of

From the above experimental results, the volume resistivity of the glass material forming the arc tube is 1×1015 at 150°C.
(Ω·cm) or more, it is possible to prevent blackening caused by diffusion of mercury into the glass even if the input per unit internal surface area is 0.3 W/cm 2 or more.

In the above embodiments, the arc tube has a non-circular cross section, where the arc and the tube wall are likely to come close to each other, and blackening due to the diffusion of mercury into the glass becomes noticeable. As described above, for example, when the arc tube has a circular cross section, the arc and the tube wall are relatively separated, so that blackening can be further prevented.

[0021]Also, in the above embodiment, an arc tube in which an anode and a cathode are sealed at both ends of the arc tube is explained, but the present invention also applies to an arc tube in which a pair of electrodes are sealed at both ends of the arc tube. It has been confirmed that the same effect as in the example is obtained.

Furthermore, in the above embodiments, the arc tube has a U-shape, but the arc tube may be formed in other shapes other than the straight arc tube. .

[0023]

[Effects of the Invention] As explained above, according to the present invention,
The volume resistivity, which is thought to affect the crystalline state, is 1×101
Since the arc tube is made of a glass material with a resistance of 5 (Ω cm) or more, it is possible to prevent blackening caused by the diffusion of mercury into the interior of the glass, thereby providing a low-pressure mercury vapor discharge lamp that can suppress a decrease in ultraviolet output. .

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of a low-pressure mercury vapor discharge lamp according to the present invention.

FIG. 2 is a sectional view taken along line II in FIG. 1.

[Explanation of symbols]

1... Arc tube 2...
Stem 3...Anode 4...Cathode 10...
・Lighting circuit device 11...Step-up transformer 1
2... Heater transformer

Claims (2)

[Claims] [Claim 1] A low-pressure mercury vapor discharge device in which electrodes are sealed at both ends of an arc tube, and mercury and rare gas are sealed inside the arc tube, and the lamp is lit at an input of 0.3 W/cm2 or more per unit internal surface area. It is an electric light, and the arc tube has a temperature of 150°C.
A low-pressure mercury vapor discharge lamp characterized in that it is made of a glass material having a volume resistivity of 1×10 15 Ω·cm or more. [Claim 2] A low-pressure lamp in which an anode and a cathode are sealed at both ends of the arc tube, and mercury and a rare gas are sealed in the arc tube, and the lamp is lit at an input per unit internal surface area of 0.3 W/cm2 or more. A low-pressure mercury vapor discharge lamp, characterized in that the light emitting portion of the arc tube has a non-circular cross section and is made of a glass material having a volume resistivity of 1×10 15 Ω·cm or more at 150° C. discharge lamp.