JPH0586617B2 - - Google Patents

Description

Detailed description of the invention [Technical field to which the invention pertains] The present invention relates to a water treatment device used in the production of pure water for semiconductor manufacturing or a low-pressure sterilization device used in the production of soft drinks and for cleaning containers thereof. Concerning improvements to mercury lamps.

[Prior art and its problems] In recent years, conventional high-pressure mercury lamps have been replaced with short wavelength ( For example, 254, 248,
It has been proposed to use a low-pressure mercury lamp that emits ultraviolet light (240, 236, 230, 194, 185 nm, etc.).

Conventionally, when sterilizing liquids such as water to be treated,
In order to irradiate a liquid with ultraviolet rays, a device called an internal illumination type as shown in FIG. 1 is used. In the figure, reference numeral 1 denotes a low-pressure mercury lamp made of straight quartz glass, electrodes 3a and 3b are sealed at both ends, and mercury and rare gas are sealed inside.
This low-pressure mercury lamp is fitted into the main body of the water treatment apparatus (not shown). As an example, as shown in FIG. 1, it is installed in an ultraviolet-transparent cylindrical body 5 in which water to be treated 6 such as water is circulated.

However, due to the need to speed up or increase the capacity of pure water production, etc., the conventional distance between electrodes per cm
There has been a demand for the use of higher output low-pressure mercury lamps than those of about 0.7W.

As an example of such a high-output low-pressure mercury lamp,
As shown in FIG. 1, a low-pressure mercury lamp has been proposed as a cooling means for increasing output, which is configured to bring the low-pressure mercury lamp into direct contact with an ultraviolet-transparent cylinder 5 for cooling.

However, it has been found that in a water treatment apparatus having such a configuration, uneven light emission and blackening of the tube wall of the low-pressure mercury lamp tend to occur early in the low-pressure mercury lamp.

This uneven light emission is thought to occur as follows.

In other words, when a low-pressure mercury lamp is turned on, due to the initial state of mercury in the tube, the mercury emits a large amount of light in the areas where mercury is present, but in the areas where mercury is not present, only rare gas is discharged, resulting in an overall This causes uneven light emission. From this, it seems that uneven light emission will not occur if the mercury is uniformly distributed in the tube at the beginning, but if the straight tube-shaped low-pressure mercury lamp 1 and the tubular body 5 are spread over the entire light-emitting part of the mercury lamp, It is difficult to make surface or line contact, and point contact and control of the contact point become impossible. As a result, the part that is in contact with the lighting center point, for example, point C, becomes the coldest point, and mercury condenses there.

Then, while the mercury emits a large amount of light at the contacting part, as the distance from the contacting part increases, only the rare gas is discharged, which causes uneven light emission.

Further, the blackening of the tube wall is caused by the absence of mercury near the electrode periphery. That is, in such a case, the discharge in the area around the electrode is a discharge of only the rare gas, and as a result, the electrode material is violently scattered and attached to the tube wall. As this phenomenon progresses, the starting voltage of the discharge lamp increases and eventually the lamp cannot be lit. The same result will occur even if scattering occurs on one of the electrodes.

[Objective of the Invention] The present invention has been made in view of the above points, and provides a high-output type low-pressure light source with less uneven luminescence over the entire arc tube throughout the lighting period, less blackening of the arc tube wall, and less decrease in ultraviolet output. The purpose is to provide mercury lamps.

[Structure and operation of the invention] Hereinafter, one embodiment of a high-output low-pressure mercury lamp according to the present invention will be described while comparing it with a conventional example.

FIG. 1 is a partially vertical side view of a conventional example. In the same figure, 2 is an arc tube of a low-pressure mercury lamp 1 that emits ultraviolet rays, and electrodes 3a and 3b are sealed at both ends, and an appropriate amount of mercury is contained inside. 4 and a rare gas are sealed. This arc tube is installed so as to be in contact with the inner surface of an ultraviolet-transparent cylinder 5 made of quartz glass or the like. Reference numeral 6 indicates water to be treated that is circulated around the outer periphery of the cylindrical body 5.

In such a low-pressure mercury lamp, the mercury sealed in the arc tube is unevenly distributed in the arc tube as shown in the figure. When such a low-pressure mercury lamp is turned on, in the A part of the arc tube where mercury is unevenly distributed, 1×10 ² to 1×10 ³
It exhibits the appearance of a low-pressure mercury lamp under torr of mercury. On the other hand, in part B, since there is no mercury supplied, it takes on the appearance of a low-pressure discharge lamp filled with only rare gas. Then, when the lamp is lit as it is, the electrode 3b on the side becomes like a low-pressure discharge lamp using only rare gas.
As the electrode material evaporates and scatters, the starting voltage increases, the arc tube becomes black, and eventually the lamp cannot be lit.

Furthermore, even if there is mercury in part B of the arc tube 2 from the beginning, the contact point C between the arc tube 2 and the cylindrical body 5 will be the coldest part during lighting, so it will not be possible after several hundred hours of lighting time. The mercury 4 sealed in the arc tube moves to point C,
It will condense and give the same result as above.

In this way, in conventional low-pressure mercury lamps, it is difficult to make line contact between the cylinder body 5 and the arc tube 2, resulting in evaporation and scattering of the electrode material as described above, blackening of the arc tube wall, increase in starting voltage, and lighting. It becomes impossible.

FIG. 2 is a partially longitudinal side view of a high-output low-pressure mercury lamp according to the present invention. As in FIG. 1, the arc tube 22 is arranged so as to be in contact with the inner surface of the ultraviolet-transparent cylindrical body 5. The arc tube 22 is formed into a straight tube shape, and has a large diameter in at least two portions. By using an arc tube having such a shape, the arc tube and the ultraviolet-transparent cylindrical body come into contact at two points _{, point} C1 and point _C2 , of the large outer diameter D.
This means that points _C1 and _C2 are at the same temperature and are lower in temperature than the part with the outer diameter d of the light emitting part, so the mercury 4 sealed in the arc tube is diffused throughout the arc tube during the lighting period. This makes it possible to supply mercury that contributes to luminescence. Other parts that are the same as those in Figure 1 are given the same numbers.

The present invention can take the embodiments described below.

First, the input per 1 cm of the distance between the electrodes of the arc tube is
It is preferable to set it as 3-12W. If it is less than 3W, the temperature of the arc tube will not rise, so there is no need to adopt a cooling structure as in the present invention. This is because the temperature is higher than the temperature at which the optimal mercury vapor pressure is obtained in a low-pressure mercury lamp, and therefore less radiation is effective for the above purpose.

Next, the effects of the present invention are recognized in the case of a low-pressure mercury lamp whose arc tube has a light emission length of 500 mm or more.

This is because when the emission length is 500 mm or less, a sufficient amount of mercury can be supplied even if the arc tube and the cylindrical body are in contact at only one point.

Further, the difference (D-d) between the outer diameter D of the large diameter portion and the outer diameter d of the small diameter portion is 1 to 4 mm. If _the temperature is 1 mm or less, the temperature balance between the arc tube and the cylindrical body is slightly different due to vertical lighting, etc., the temperature at the large diameter _part and the small diameter part. Because the difference is small, mercury diffuses better from the large-diameter part to the small-diameter part, so migration occurs to either C ₁ or C ₂ , whichever is cooler, and as with conventional low-pressure mercury lamps, uneven light emission and Darkening of the tube wall occurs.

On the other hand, if it exceeds 4 mm, the output in the axial direction of the arc tube will be extremely lower than that of the large diameter portion in contact, as shown in FIG. In addition, Fig. 4 shows the output of the small diameter portion of the arc tube with respect to the maximum value of light distribution in the axial direction of the arc tube.
It is the output ratio with d) as a parameter. As shown in FIGS. 3 and 4, when D-d exceeds 4 mm, the overall output decreases. This is thought to be because the temperature difference between the large-diameter and small-diameter walls of the arc tube is large, which prevents mercury vapor from diffusing.

Furthermore, the length (l) of the large diameter part of the arc tube is 5 to 30 cm.
It is better to If the distance is less than 5 cm, sufficient cooling effect will not be obtained and the effective radiation will decrease;
If the length is longer, a cooling effect can be obtained, but it becomes difficult to control the position of mercury throughout the lighting period, and mercury vapor will not diffuse throughout the arc tube.

The distance (L) between at least two or more large diameter portions is set to within 2/3 of the light emission length.

This is because if it is made larger than 2/3, the mercury at the cooling point in the large diameter portion will not diffuse to the part farthest from the cooling point.

[Effect of the invention] As is clear from the above explanation, according to the present invention,
Even in the case of long low-pressure mercury lamps with a luminescence length of 500 cm or more, mercury may remain near the electrodes sealed at both ends of the arc tube throughout the lighting period, resulting in uneven light emission, blackening of the arc tube wall, and It has a long lifespan and there is no problem of not being able to turn it on. Further, since the output of the portion where the arc tube and the cylindrical body are in contact increases, the overall output also increases.

[Brief explanation of the drawing]

Fig. 1 is a partially longitudinal side view showing a conventional low-pressure mercury lamp, Fig. 2 is a partially longitudinal side view showing an embodiment of the present invention, and Fig. 3 shows the illuminance of the low-pressure mercury lamp in the tube axis direction. FIG. 4 is a characteristic diagram showing the relative output of the lamp using the difference in outer diameter (D-d) of the light emitting portion as a parameter.

Claims (1)

[Claims] 1. A UV-transparent tubular body 5 is installed around a straight low-pressure mercury lamp 21 that emits ultraviolet rays, and a liquid is passed through the outer periphery of the cylindrical body to emit ultraviolet rays into the liquid. The low-pressure mercury lamp is characterized in that the low-pressure mercury lamp has a straight tube-shaped light-emitting portion having a large diameter at least at two places, and the large-diameter portion is brought into contact with the cylindrical body. 2. The low-pressure mercury lamp according to claim 1, wherein the input power per 1 cm of distance between electrodes of the low-pressure mercury lamp is 3 to 12 W/cm. 3. The low-pressure mercury lamp according to claim 1 or 2, wherein the low-pressure mercury lamp has a light emission length of 500 mm or more. 4. Claim 1, wherein the difference in outer diameter (D-d) between the large diameter part and the small diameter part of the low pressure mercury lamp is 1 to 4 mm.
The low-pressure mercury lamp according to any one of items 1 to 3. 5. The low-pressure mercury lamp according to any one of claims 1 to 4, wherein the length (l) in the tube axis direction of the large diameter portion of the low-pressure mercury lamp is 5 to 30 cm. 6. The low pressure according to any one of claims 1 to 5, wherein the distance (L) in the tube axis direction of at least two large diameter parts of the low pressure mercury lamp is within 2/3 of the light emission length. Mercury lamp.