JP2021034365A - Low pressure mercury lamp unit - Google Patents

Abstract

To realize a low pressure mercury lamp unit having a long life.SOLUTION: A low pressure mercury lamp unit according to the present invention includes a surface-irradiating low-pressure mercury lamp in which an electrode is arranged on one side, and an arc tube repeatedly bends in a U-shape a predetermined number of times in the length in the axial direction of the lamp, and a reflector that reflects and directs the light emitted from the arc tube toward an object to be irradiated, and the coldest portion is formed in the vicinity of an electrode portion of the arc tube.SELECTED DRAWING: Figure 1

Description

The present invention relates to a low pressure mercury lamp unit.

The low-pressure mercury lamp is a discharge lamp that utilizes the light emission of an arc discharge in mercury vapor having a mercury vapor pressure of 100 Pa or less during lighting. A rod-shaped glass tube is mainly used for the arc tube, and a rare gas such as Ar (argon) and mercury or its amalgam (alloy of mercury and another metal) are sealed therein. The low-pressure mercury lamp is mainly used in a running water sterilizer, an ultraviolet oxidized water treatment device, and the like. Further, it is also used as a data erasing light source of an IC memory called an ultraviolet erasing EPROM (Ultra-Violet Erasable Programmable ROM).

Patent No. 2820623 "Lighting Equipment" (Publication date: 1998.11.05) Applicant: Kajima Corporation Japanese Patent Application Laid-Open No. 7-240173 "Discharge Lamp and Lamp Device" (Publication Date: September 12, 1995) Applicant: Toshiba Lilac Co., Ltd. Japanese Patent Application Laid-Open No. 10-208698 "Mercury steam discharge lamp" (Publication date: 1998.08.07) Applicant: Iwasaki Electric Co., Ltd.

Currently, in the low-pressure mercury lamp unit used for running water sterilization, ultraviolet oxide water treatment, data erasure of IC memory, etc., the shape of the arc tube is formed so that surface irradiation is possible. Conventionally, such a low-pressure mercury lamp unit for surface irradiation has a problem that the lamp life is extremely short.

Therefore, an object of the present invention is to realize a low-pressure mercury lamp unit having a long life.

In view of the object of the present invention, in the low pressure mercury lamp unit according to the present invention, an electrode is arranged on one side on one surface, and the arc tube repeats bending in a U shape a predetermined number of times to a predetermined lamp axial length. A low-pressure mercury lamp unit provided with a low-pressure mercury lamp capable of surface irradiation and a reflecting plate that reflects and directs the light emitted from the arc tube toward the object to be irradiated. It forms a cold part.

Further, in the low-pressure mercury lamp unit, the reflector is formed with a plurality of openings through which cooling air passes, and the aperture ratio in the vicinity of the electrode portion of the reflector is locally increased to increase the amount of cooling air. However, the cooling effect may be enhanced.

Further, in the low-pressure mercury lamp unit, the opening near the electrode portion of the reflector may be oval, and the other openings may be circular.

Further, in the low-pressure mercury lamp unit, the opening near the electrode portion of the reflector may be larger in size than the other openings.

Further, in the low-pressure mercury lamp unit, the tube diameter in the vicinity of the electrode portion of the arc tube may be formed to be relatively large.

Further, in the low-pressure mercury lamp unit, the reflector may partially reduce the aperture ratio in the vicinity of the U-shaped portion or may not provide an opening to relatively prevent the U-shaped portion of the arc tube from being cooled. ..

According to the present invention, a long-life low-pressure mercury lamp unit can be realized.

FIG. 1 is a diagram showing a low-pressure mercury lamp unit according to the present embodiment, the upper diagram is a plan view, and the lower diagram is a front view. FIG. 2A is a diagram illustrating that the diameter of the arc tube in the vicinity of the electrode portion of the arc tube is relatively large with respect to the arc tube shown in the front view of the low-pressure mercury lamp unit of FIG. FIG. 2B is a diagram for explaining that the aperture ratio of the portion near the electrode portion of the reflector is relatively high with respect to the reflector shown in the front view of the low-pressure mercury lamp unit of FIG. FIG. 3 is a graph of surface temperatures measured at a plurality of positions in the longitudinal direction of the low-pressure mercury lamp unit according to the present embodiment, and data of a conventional low-pressure mercury lamp unit is also plotted as a comparative example. FIG. 4A is a diagram showing the position of the coldest portion of the conventional low-pressure mercury lamp unit. FIG. 4B is a diagram showing the position of the coldest portion of the low-pressure mercury lamp unit according to the present embodiment. FIG. 5A is a diagram illustrating a flow of cooling air when erasing data in an ultraviolet erasing IC memory using the low-pressure mercury lamp unit according to the present embodiment. FIG. 5B is a diagram illustrating a usage example of another low-pressure mercury lamp unit according to the present embodiment. FIG. 6 is data on the lighting time (lamp life) of the low-pressure mercury lamp unit according to the present embodiment. FIG. 7 is data showing the transition of the illuminance until the end of the life of the low-pressure mercury lamp unit according to the present embodiment. FIG. 8 is data showing the transition of the illuminance until the end of the life of the low-pressure mercury lamp unit according to the present embodiment. FIG. 9 is data showing the transition of the illuminance until the end of the life of the low-pressure mercury lamp unit according to the present embodiment.

Hereinafter, embodiments of the low-pressure mercury lamp unit according to the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are given to the same elements, and duplicate explanations will be omitted.

[Low pressure mercury lamp unit]
(overall structure)
FIG. 1 is a diagram showing a low-pressure mercury lamp unit according to the present embodiment, the upper diagram is a plan view, and the lower diagram is a front view. As shown in the front view, in the low-pressure mercury lamp unit 10, the arc tube 4 is installed on the reflector 6.
The arc tube 4 is typically formed of quartz glass, and is encapsulated with mercury as an inclusion and typically argon as a rare gas.

FIG. 2A is an enlarged view of the arc tube shown in the front view of FIG. 1, and explains that a thick tube diameter 4a near the electrode portion of the arc tube and a relatively thin tube diameter 4b on the U-shaped portion side portion are shown. It is a figure. The difference in pipe diameter is exaggerated for ease of understanding. The left end of the arc tube 4 is an electrode portion 4a containing the electrodes 2a and 2b, and the right end is a bent portion (U-shaped portion) 4b. As shown in the plan view of FIG. 1, the arc tube 4 extends in the longitudinal direction from the portion containing one electrode 2a (first stage), is bent at the first U-shaped portion 4b1, and is bent in the direction of the electrode 2a. It is folded back and extends in the longitudinal direction (second step), and when it reaches the vicinity of the electrode 2a, it is folded back into a U shape again and extends in the longitudinal direction (third step), and is bent at the second U-shaped portion 4b2. The shape is such that it is folded back in the electrode 2a direction and extends in the longitudinal direction (fourth step), and this is repeated a predetermined number of times to return to the electrode 2a side and terminate at the end portion containing the other electrode 2b.
The shape of the arc tube 4 enables surface irradiation of an object to be irradiated (also referred to as a "work").

Each part of the arc tube 4 is close to the adjacent part, and the lamp axis directions are parallel to each other. Each part of the arc tube is designated by the reference code "Te" for the arc tube portion on the electrode portion side and the reference symbol "Tu" for the arc tube portion on the U-shaped portion side with reference to the center line CL of the longitudinal length. I will explain.

The reflector 6 is typically made of, but is not limited to, aluminum. The reflector 6 is formed with a plurality of openings (holes) 9 through which cooling air passes. The arrangement of the openings 9 is typically in a regular grid pattern. However, the arrangement of openings is not limited to this. The rows of adjacent openings may be arbitrary, such as a mosaic shape in which the rows of adjacent openings are offset by a half grid.

As seen from the front view of FIG. 1, the light emitted from the arc tube 4 irradiates the object to be irradiated (not shown) by the light emitted upward and the light emitted reflected by the reflector 6 and directed upward.

Here, the terms used in the application documents are defined. A low-pressure mercury lamp having such a shape is simply referred to as "a low-pressure mercury lamp capable of surface irradiation in which an electrode is arranged on one side and the arc tube is repeatedly bent into a U-shape a predetermined number of times in the length in the axial direction of the lamp". Refer to.
The "low-pressure mercury lamp" refers to an arc tube and its inclusions, and the "low-pressure mercury lamp unit" refers to related parts such as a low-pressure mercury lamp and a reflector.
There is also a U-shaped part of the arc tube (the part that connects the 2nd and 3rd stages, the 4th and 5th stages, ...) On the electrodes 2a and 2b side, but for the sake of simplicity, FIG. Looking at the center line CL, the right half Tu is referred to as the "U-shaped portion side", and the left half Te is referred to as the "electrode portion side".
Further, in the arc tube 4, the arc tube portion close to the electrodes on the uppermost side (first stage in the example of the figure) and the lowermost side (eighth stage) is referred to as "near the electrode portion of the arc tube".
Further, in the reflecting portion 6a of the reflecting plate 6, the area of the reflecting plate corresponding to the vicinity of the electrode portion of the arc tube is referred to as "a portion near the electrode portion of the reflecting plate".

(Means for changing the position of the coldest part)
In general, in a metal discharge lamp such as a low-pressure mercury lamp, the enclosed metal vapor pressure changes according to the temperature of the coldest part of the lamp. The ultraviolet output of a low-pressure mercury lamp depends on the mercury vapor pressure in the arc tube when the lamp is lit. The coldest portion of the conventional low-pressure mercury lamp was located in the rightmost area (see FIG. 4A) on the U-shaped portion side. Encapsulations such as mercury tend to stay in this coldest part.

When the lamp is lit, the inclusions that should originally contribute to light emission move to the right end area on the U-shaped part side and accumulate, causing a local rare gas light emission phenomenon (argon light emission phenomenon when argon is filled). I have something to do. When rare gas emission occurs, sufficient illuminance (ultraviolet output) cannot be obtained, and the lamp illuminance becomes uneven and the uniformity deteriorates. In the local light emission, the deterioration of the electrode is promoted, the electrode material is sputtered and adheres to the inner wall of the arc tube near the electrode, and the overall illuminance is lowered. In addition, the lamp life is extremely short. Due to the poor initial lighting characteristics, the lamp life will be reached sooner.

As a countermeasure, the present inventors have decided to improve the lamp life by changing the position of the coldest portion from the right end area on the U-shaped portion side to the vicinity of the electrode portion. The coldest part has the property of accumulating inclusions. When the lamp is lit, the lamp temperature gradually rises from the vicinity of the electrodes, but if the coldest part is on the U-shaped side away from the electrodes, the inclusions that originally contribute to light emission cannot be completely evaporated, and the lamp voltage drops and the lamp drops. The illuminance decreases. By providing the coldest part near the electrode, the inclusions that contribute to light emission are evaporated, so that the decrease in lamp voltage and lamp illuminance is suppressed, and the lamp life can be expected to be extended.

As a means for changing the position of the coldest portion, the following configuration was adopted in order to form a portion having a temperature lower than that of the coldest portion located on the conventional U-shaped portion in the vicinity of the electrode portion of the arc tube.
Configuration 1: With respect to the reflector, the aperture ratio of the arc tube (= total area of all openings / area of the reflector) is partially increased in order to further cool the vicinity of the electrode portion. For example, the aperture ratio in the vicinity of the electrode portion of the reflector is locally increased to increase the amount of cooling air to enhance the cooling effect.
Configuration 2: Regarding the arc tube, the tube diameter in the vicinity of the electrode portion of the arc tube is increased as compared with other parts, the surface area exposed to the cooling air is increased, and the cooling effect is enhanced.
Configuration 3: With respect to the reflector, the aperture ratio on the U-shaped portion far from the electrode is partially lowered, or no opening is provided, and the U-shaped portion of the arc tube is relatively prevented from cooling.

With respect to the configuration 1, various configurations can be adopted in order to locally increase the aperture ratio in the vicinity of the electrode portion of the reflector. For example, as shown in FIG. 2B (A), openings located near the electrode portion of the reflector may be connected to each other to form one oval opening. As shown in FIG. 2B (B), the opening located in the vicinity of the electrode portion of the reflector may be made larger in size. In FIG. 2B, the deformed opening is drawn with a thick line for easy viewing. In addition, the number of openings located near the electrode portion of the reflector may be increased.

First, an experiment was conducted to confirm the advantages and effects of this example. In this experiment, in each case, an in-house manufactured arc tube having a large diameter in the vicinity of the electrode portion of the arc tube of the configuration 2 was used as the arc tube. As for the reflector, a lamp unit using an in-house reflector that locally increases the aperture ratio in the vicinity of the electrode portion of configuration 1 and does not provide an opening on the U-shaped portion side of configuration 3 is defined as an "example", and other companies A comparative experiment was conducted using a lamp unit using a reflector made of steel as a "conventional example". Through preliminary experiments, it has been found that the effect of the difference in the aperture ratio of the reflectors of configurations 1 and 3 is relatively large as compared with the configuration 2 with respect to the means for changing the position of the coldest portion. This is because we needed the difference data.

The specifications of the lamp unit (example) used in the experiment and the unit (conventional product) used for comparison are as follows.

As shown in Table 1, with respect to the opening of the reflector of the configuration 1, in the embodiment, the shape shown in FIG. 2B (A) is adopted, the circular opening 9 of the reflector is set to φ6.5 mm, and the portion near the electrode portion is formed. The located openings 9 were connected to each other to form an oval opening (short axis 6.5 mm and long axis φ82.5 mm). In the conventional product, the opening 9 is φ6.5 mm. Regarding the arc tube of the configuration 2, in both the embodiment and the conventional product, the thick tube diameter 4a near the electrode portion is φ10 mm, and the relatively thin tube diameter 4b on the U-shaped portion side portion is φ9 mm. Regarding the opening of the reflector of the configuration 3, in the embodiment, as shown in FIG. 2B, the opening 9 is not provided on the U-shaped portion side (6a, 6b) far from the electrode of the reflector, and is supplied to the U-shaped portion side. The amount of cooling air is reduced, and the conventional product has an opening of φ6.5.

(Change of coldest part position)
FIG. 3 shows surface temperature data (◯) measured at a plurality of positions along the lighting lamp axis direction of the example of the low-pressure mercury lamp unit according to the present embodiment, and is data (◯) of a conventional product as a comparative example. ●) is also displayed.
As shown in the lamp shown at the bottom, the measurement positions on the horizontal axis of the graph are 1 and 3 with the vicinity of the electrodes as "position 1", the central part as "position 3", and the vicinity of the U-shaped part as "position 5". The middle is "position 2" and the middle between 3 and 5 is "position 4".

Looking at the graph as a whole, the coldest part of the conventional product is in the U-shaped part at position 5. On the other hand, in the embodiment, the coldest portion is converted to the vicinity of the electrode portion at position 1. Further, the surface temperature of 41 ° C. at the coldest portion position 5 of the conventional product is raised to 54 ° C. by using a reflector having no opening in the embodiment, and it is ensured that the surface temperature does not become the coldest portion. Further, the surface temperature of the examples tends to be relatively low as compared with the surface temperature of the conventional product. The average surface temperature of both is about 15 ° C lower.

4A and 4B are diagrams schematically showing the coldest portion. As shown by the broken line frame in FIG. 4A, the coldest portion 11a of the conventional product was in the U-shaped portion. However, after the position of the coldest portion is changed, as shown by the broken line frame in FIG. 4B, the coldest portion 11b of the embodiment is changed to the vicinity of the electrode portion.

(Application example of low-pressure mercury lamp unit)
FIG. 5A is a diagram illustrating a flow of cooling air when data erasure of an ultraviolet erasing EPROM is performed using the low-pressure mercury lamp unit 10a according to the present embodiment. A low-pressure mercury lamp unit 10a is arranged above the tray 22a in which the EPROM 22a is housed so that the light emitting surface faces downward. The entire device is covered with a hood 24. When the fan 23a operates, an intake flow Fin and an exhaust flow Fout are generated to cool the low-pressure mercury lamp unit 10a.

5B is a diagram illustrating a usage example of another low-pressure mercury lamp unit 10b according to the present embodiment, FIG. 5B is a schematic plan view of the apparatus, and FIG. 5B is a schematic front view. A low-pressure mercury lamp unit 10b is arranged above the tray 22b in which the irradiated product (work) is housed, with the light emitting surface facing downward, and is lit by the ballast 32. In this application example, a plurality of upper and lower two-stage axial fan fans 23b and 23c are operated to cool the low-pressure mercury lamp unit 10b.

(Life of low-pressure mercury lamp unit)
The life data of the lamp units of the first embodiment and the second embodiment were displayed using two samples selected from the lamps satisfying the specifications of the examples in Table 1. Similarly, the conventional product is the life data of two samples selected from the lamps satisfying the specifications of the conventional product in Table 1.

FIG. 6 shows the data of the lighting time (lamp life) of the embodiment, and also displays the data of the conventional product as a comparative example. The lamp life was set to a point below 80% of the initial illuminance.
The two lamps of the example maintained approximately 80% of the initial illuminance even when the lighting time exceeded 6,000 hours. On the other hand, the conventional product has reached the end of its life with a lighting time of about 200 hours. It was confirmed that the lamp according to this embodiment was able to achieve a life extension of nearly 30 times that of the conventional product.

FIG. 7 is data showing the transition of the illuminance at the end of the life of the example. As a comparative example, the data of the conventional product is also displayed by a broken line. As shown in Fig. 6, the life of the conventional product expires after a lighting time of about 200 hours, but as shown by the broken line in Fig. 7, the illuminance at the end of the life was about ^{6.8 mW / cm 2.} On the other hand, the two lamps of the example ^{maintained approximately 8.0 mW / cm 2} (80% of the initial illuminance) even at the end of the service life. Therefore, it was confirmed that the example was a long-life lamp and that the desired illuminance could be maintained even at the end of the life.

8 and 9 are data showing the transition of the illuminance at the end of the life of the low-pressure mercury lamp unit according to the present embodiment, which was further tested using another lamp. As a comparative example, the data of the conventional product is also displayed by a broken line. The two lamps maintained approximately 80% of the initial illuminance even at the end of their lifespan. Therefore, it was confirmed that the example was a long-life lamp and that the desired illuminance could be maintained even at the end of the life.

[Advantages / Effects of the present embodiment]
(1) As described in the present embodiment, by increasing the aperture ratio in the vicinity of the electrode portion of the reflector, the position of the coldest portion is moved from the vicinity of the U-shaped portion to the vicinity of the electrode portion as shown in FIG. I was able to convert.
(2) By forming the diameter of the arc tube near the electrode portion relatively large, the cooling efficiency near the electrode portion is improved, and the position of the coldest portion is changed from the vicinity of the U-shaped portion to the vicinity of the electrode portion. Can promote that.
(3) As shown in FIG. 3, the surface temperature of the lamp of the example could be relatively lowered as compared with the conventional product.
(4) As shown in FIG. 6, by changing the position of the coldest part, the lamp life of the examples could be extended by nearly 30 times as compared with the conventional product.
(5) As shown in FIGS. 7 to 9, it was confirmed that the lamp of the example had little decrease in illuminance at the end of the life by changing the position of the coldest part.

[Summary]
Although the embodiment of the low-pressure mercury lamp unit according to the present invention has been described above, the present invention is not limited thereto. The technical scope of the present invention is defined by the description of the appended claims.

2a, 2b: Electrode, 4: arc tube, 6: reflector, 9: opening, 10: low pressure mercury lamp unit, 11a, 11b: coldest part, 23a: fan, 23b, 23c: axial fan, 24: hood , 32: Stabilizer,

Claims (6)

A low-pressure mercury lamp capable of surface irradiation in which an electrode is arranged on one side and the arc tube repeatedly bends in a U shape a predetermined number of times in the length in the axial direction of the lamp, and the light emitted from the arc tube is reflected toward the object to be irradiated. In a low-pressure mercury lamp unit equipped with a reflector that points toward
A low-pressure mercury lamp unit having a coldest portion formed in the vicinity of the electrode portion of the arc tube. In the low-pressure mercury lamp unit according to claim 1,
A plurality of openings through which cooling air passes are formed in the reflector, and the aperture ratio in the vicinity of the electrode portion of the reflector is locally increased to increase the amount of cooling air and enhance the cooling effect. A low-pressure mercury lamp unit featuring. In the low-pressure mercury lamp unit according to claim 2.
A low-pressure mercury lamp unit in which the opening near the electrode portion of the reflector is oval, and the other openings are circular. In the low-pressure mercury lamp unit according to claim 2 or 3.
A low-pressure mercury lamp unit in which the opening near the electrode portion of the reflector is larger in size than the other openings. In the low-pressure mercury lamp unit according to any one of claims 1 to 4.
A low-pressure mercury lamp unit characterized in that the diameter of the tube in the vicinity of the electrode portion of the arc tube is formed to be relatively large. In the low-pressure mercury lamp unit according to any one of claims 2 to 5.
The reflector is a low-pressure mercury lamp unit in which the aperture ratio in the vicinity of the U-shaped portion is partially lowered or no opening is provided to relatively prevent cooling of the U-shaped portion of the arc tube.

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