JPS60143554A - High-output low-pressure mercury lamp - Google Patents

Abstract

PURPOSE:To prevent any luminous nonuniformity as well as any blackening of the tube wall by forming at least three mercury reservoirs on the innter surface of an emission tube radiating ultraviolet rays and by igniting the emission tube after mercury is filled in reservoirs located near the ends of the tube to disperse and evaporate mercury homogeneously in the tube. CONSTITUTION:An emission tube 1 radiating ultraviolet rays is installed in an ultraviolet-ray permeable water-cooled jacket 2 so that the emission tube 1 is cooled with cooling water thereby making a high-output low-pressure mercury lamp. Three or more mercury reservoirs 3a-3d including those located near the ends of the emission tube 1 are formed on the inner surface of the emission tube 1. After mercury is filled in the reservoirs 3a and 3d located near the ends of the tube 1, the emission tube 1 is ignited while being maintained at a constant temperature of 30-50 deg.C to homogeneously disperse and evaporate mercury. Then the emission tube 1 is suppressed to cause mercury to homogeneously adhere to the reservoirs 3a-3d. Therefore it is possible to prevent any luminous nonuniformity by preventing any maldistribution of mercury. Besides it is also possible to prevent any blackening of the tube wall.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a high-output low-pressure mercury lamp used for surface sterilization of foods or containers and packaging materials thereof.

[Prior art]

Conventionally, air-cooled low-pressure mercury lamps with an inter-electrode distance of 1 cTn and an input of less than IW have been used for general sterilization.

However, multiple sterilization of foods or their containers and packaging materials, etc.

Due to the need for high-performance killing, the distance between the electrodes is 1cfn when returning to work.
High-output low-pressure mercury lamps that require 2 to 8 W8 degrees of human power per unit are coming into use. As an example of such a low-pressure mercury lamp, a low-pressure mercury lamp has been proposed in which a quartz arc tube that emits ultraviolet rays is housed in a water cooling jacket that is transparent to external radiation, and the entire outer surface of the arc tube is directly cooled by cooling water. .

However, it has been found that such low-pressure mercury lamps with a negative composition have disadvantages in that uneven light emission and early blackening of the arc tube wall tend to occur during lighting. Among the above-mentioned drawbacks, uneven light emission is thought to be caused in the following manner. In other words, when a discharge lamp is turned on, due to the initial distribution of mercury in the arc tube, the luminescence of mercury is large in the area where mercury was present, while the emission of rare gas is large in the area where mercury was not present. This results in discharge in only a small atmosphere, resulting in uneven light emission as a whole. This uneven luminescence will not occur if the mercury is uniformly distributed within the arc tube from the beginning, but since mercury has the property of becoming granular due to surface tension, when enclosing mercury, the mercury is distributed uniformly within the arc tube. It is difficult to do so.

Further, early blackening of the arc tube wall is caused by the absence of mercury in the peripheral area of the electrode. That is, in such a case,
The discharge at the electrode occurs in an atmosphere containing only a rare gas, and as a result, the electrode material is violently scattered and attached to the wall of the arc tube. As this phenomenon progresses, the starting voltage of the discharge lamp increases, and eventually the lamp cannot be lit.

[Purpose of the invention]

The purpose is to provide

[Structure and operation of the invention]

The present invention provides three low-pressure mercury lamps in which the arc tube is housed in a water-cooling jacket and the outer surface of the arc tube is directly cooled with cooling water. In addition to forming the above mercury reservoir S, mercury is sealed only in the mercury reservoirs near both ends of the arc tube, and the entire outer surface of the arc tube is uniformly heated with cooling water maintained at a constant temperature within the range of 30 to 50 degrees Celsius. When the arc tube is turned on while being cooled, the mercury sealed only in the vicinity of both ends of the arc tube is uniformly dispersed and evaporated within the arc tube, and even when the arc tube is turned off, mercury remains in each mercury reservoir within the arc tube. This is based on the discovery that it coagulates and adheres evenly.

Hereinafter, the structure of the high-output low-pressure mercury lamp according to the invention will be explained while comparing it with that of a conventional high-output low-pressure mercury lamp.

FIG. 1 is a sectional view of a conventional high-output low-pressure mercury lamp.

In the figure, reference numeral 1 denotes an arc tube of a low-pressure mercury lamp that emits ultraviolet rays, and electrodes 2a and 2b are sealed at both ends, and a suitable amount of mercury and rare gas are sealed inside. The arc tube 1 is housed in a water-cooled jacket 3 that transmits ultraviolet light, and its outer surface is directly cooled with cooling water 4. Low pressure water 4! In a lamp, the mercury sealed in the arc tube 1 is unevenly distributed in the arc tube, partly as large particles and partly as fine particles, as shown in the figure.

When such a discharge lamp is turned on, mercury emission is seen around parts B and n of the arc tube 1 where mercury is present, but light emission of mercury is seen around parts A and 0 where mercury is not present. In some cases, the discharge occurs in a rare gas atmosphere. In other words, 'rf at part B and part D
:, I X 10''-I X 101 Torr of mercury vapor pressure.
In the 1 and 0 groups, since there is no mercury to be supplied, the lamp behaves like a low-pressure discharge lamp filled with only rare gas. If the lamp continues to be lit, parts A and D, where the electrodes 2a and 2b are located, will become hot, and part B will also become hot due to the mercury arc, and the mercury in the arc tube will gradually diffuse to 0 parts. , mercury does not diffuse into part A, and even if a small amount of mercury exists in AJ, the mercury on the contrary decreases.

As a result, not only is there a shortage of mercury, which contributes to light emission, in part A, but the electrode material is also scattered, causing blackening of the wall of the arc tube.Furthermore, the starting voltage increases and the resulting inability to light up. This leads to the invitation of Furthermore, in the discharge lamp with the structure shown in Fig. 1, the mercury in the arc tube 1 tends to clump together into large particles, so the mercury particles can move freely within the arc tube during transportation or handling of the discharge lamp. However, when the discharge lamp is turned on, the distribution of mercury within the arc tube is extremely uneven, which has the drawback of causing uneven light emission and blackening of the tube wall.

FIGS. 2 and 3 are cross-sectional views of a high-output low-pressure mercury lamp according to the present invention. FIG. 2 shows an arc tube 1 that emits ultraviolet rays, which is housed in an ultraviolet-transparent water cooling jacket 2.
In a low-pressure mercury lamp, the outer surface of the arc tube 10 is directly cooled with cooling water.
Mercury reservoirs 3a, 3 are located at three or more locations including near both ends.
b, 3c, and 3d, and water roots are sealed in the mercury reservoirs 3a, 3d near both ends of the arc tube 1, or in the vicinity of these, and the arc tube 1 is placed in the range of 30 to 50 υ. The mercury is uniformly dispersed and evaporated in the arc tube 1 by lighting it while being uniformly cooled with cooling water maintained at a constant temperature within the arc tube 1t, and when the arc tube 1t is turned off, each of the mercury reservoirs 3a, 3b, 3c, and 3d are coated with mercury by condensation almost evenly. As the mercury reservoirs 3a, 3b, 3c, and 3d formed on the inner surface of the arc tube 10, for example, as shown in FIG. 5, an annular protrusion 3 formed over the entire inner circumference of the arc tube 1 is suitable.

Further, the number of mercury reservoirs is required to be at least three, one each near both ends of the arc tube and one near the center of the arc tube, but more than that may be δ. In addition, add 30 arc tubes
In order to uniformly cool the cooling water with the cooling water maintained at a constant temperature within the range of ~50° C., for example, the cooling water may be circulated by a circulation device and a temperature control device rtft may be provided in the middle of the circulation path. In this way, when lighting the arc tube while cooling the outer surface of the arc tube with cooling water at a constant temperature, unlike the case where cooling water is simply fed along the temperature side, the wall of the arc tube is The temperature becomes almost uniform. As a result, even if mercury is initially filled only in a part of the arc tube, for example, near both ends, the mercury will be dispersed and evaporated uniformly within the arc tube, and even when the arc tube is turned off, each of the mercury reservoirs will be filled with mercury. Condensation adheres almost evenly to the surface.

The same state will be maintained even when the light is turned on or off thereafter. In addition, maintaining the temperature of the cooling water within the range of 30 to 50℃ is less than 30υ.
This is because the mercury in the arc tube may not evaporate sufficiently and the luminous efficiency may not increase.On the other hand, if the mercury exceeds 50υ, the luminous efficiency will decrease as heat loss increases. FIG. 3 shows another embodiment of the present invention, in which mercury reservoirs 3a and 3b of the arc tube 1 are shown.
, 3c, 3d, . . ., 6-concave grooves y as shown in FIG. 6 are used. Such a groove y has the advantage of being easier to form than the annular protrusion 3 shown in FIG.

It goes without saying that the groove 1 and the annular protrusion 3 may be used in combination.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, even if mercury is initially sealed only near the end of the arc tube, the mercury can be uniformly dispersed and evaporated within the arc tube, and almost all of the mercury can be evaporated in each mercury reservoir. It can be evenly set and deposited. Therefore, it is not only easy to manufacture, but also prevents uneven light emission and blackening of the wall of the arc tube during lighting. When a discharge lamp is turned off, the mercury condenses and adheres almost evenly to each mercury reservoir, making it difficult to form large particles.Mercury moves within the arc tube during transportation and handling of the discharge lamp, resulting in uneven distribution. It will never happen. Furthermore, when an annular protrusion as shown in Fig. 5 is used as the mercury reservoir in the arc tube, the annular protrusion prevents blackening of the tube wall due to impure gases mixed into the arc tube during manufacturing. It does not spread any further and has the advantage of keeping the center of the arc tube clear.

FIG. 4 shows the working characteristics of ultraviolet output of a high-output low-pressure mercury lamp according to the present invention and a conventional low-pressure mercury lamp.

[Brief explanation of drawings]

5 and 6 are partially enlarged sectional views of the low-pressure mercury lamps shown in FIGS. 2 and 3, respectively. In Figures 2 and 3, 1... arc tube, 2
・・・・・・Water cooling jacket), 3a, 3b, 3a,
3d...Mercury reservoir. 53 Figure 5 1 Figure 6 ヱ Procedural amendment (method) % formula % 2. Title of the invention High-output low-pressure mercury lamp 3. Person making the amendment Relationship to the case Patent applicant (dispatch) (Japanese: March 27, 1982) 5. Subject of amendment Ming IllI4

Claims (3)

[Claims] (1) A low-pressure mercury lamp configured to house the arc tube (1) of a low-pressure mercury lamp that emits ultraviolet rays in an ultraviolet-transparent water cooling jacket (2), and to directly cool the outer surface of the arc tube (1) with cooling water. In a mercury lamp, mercury droplets 5 (3a), (3b), j (3d), etc. are present on the inner surface of the arc tube (1) at three or more locations including near both ends of the arc tube (1). ...
..., mercury is sealed in the mercury reservoirs (3a), (3d) near both ends of the arc tube (1), or the vicinity thereof, and the arc tube (1) is heated at 30-50°C. By turning on the light while uniformly cooling it with cooling water maintained at a constant temperature within the range, the mercury is uniformly dispersed and evaporated in the arc tube (1) circle, and when the arc tube is completely turned off, each mercury reservoir is Parts (3a), (3b)...(3d)...
A high-output low-pressure mercury lamp characterized by almost uniform condensation coating. (2) Mercury reservoir (3a), (3b)...(3d).
. . . The high-output low-pressure mercury lamp according to claim 1, wherein the lamp has an annular protrusion. (3) Mercury reservoir (,3a1.(3t+)...(3d)
. . . The high-output low-pressure mercury lamp according to claim 1, wherein the lamp has a concave groove.