JPH08124526A - Mercury vapor electric discharge lamp and lighting device therefor, and ultraviolet irradiation device using the lamp and device - Google Patents

Abstract

PURPOSE: To provide a mercury vapor electric discharge lamp, a lighting device therefor and an ultraviolet radiation device using the lamp and the device capable of preventing the blackening of a tube wall for keeping an ultraviolet radiation maintenance factor at a high level, regarding a mercury vapor electric discharge lamp of medium pressure type. CONSTITUTION: Regarding the mercury vapor electric discharge lamp 1 with mercury sealed over the range of 0.1 to 3.0mm/g per unit capacity in a silica light emitting tube 10 having an electrode 13 sealed for lighting under a tube wall load equal to 10W/cm<2> or less, a translucent protection film 14 of metallic oxide is formed on the internal surface of the tube 10. The film formed on the internal surface of the tube 10 acts to prohibit the contact of mercury with silica and prevents mercury ions from being implanted in the defective grill of the silica. As a result, the occurrence of tube wall blackening can be prevented, and a high ultraviolet radiation performance can be maintained over a long term.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mercury discharge lamp of a medium pressure class having a mercury vapor pressure during lighting of 0.1 atm to less than 5 atm, a lighting device therefor, and an ultraviolet ray using the mercury discharge lamp as a light source. Irradiation device.

[0002]

2. Description of the Related Art A low-pressure mercury vapor discharge lamp operated at a mercury vapor pressure of about 10 ^-5 atm during lighting is in a short wavelength range, for example, 2
Although it has a high UV radiation efficiency of 54 nm, it is extremely difficult to realize a discharge lamp with a large capacity. On the other hand, a mercury discharge lamp of a medium pressure class (hereinafter referred to as a medium pressure mercury discharge lamp) whose mercury vapor pressure during lighting is 0.1 atm or more and less than 5 atm is a discharge lamp having a larger capacity than a low pressure mercury discharge lamp. Since it has been obtained and has a higher ultraviolet radiation efficiency in a short wavelength region than a high pressure mercury discharge lamp, it has come to be used for sterilization and purification of water.

In particular, as a mercury discharge lamp used for sterilizing and purifying water, a discharge lamp that uniformly illuminates a relatively wide area has a higher light utilization rate than a compact and high-intensity discharge lamp. The wall load is 10 W / cm ² or less, and a mercury discharge lamp having a mercury filling amount per unit volume of approximately 0.1 to 3.0 mg / cc is used.

However, this type of mercury discharge lamp has a problem that the tube wall made of quartz is blackened as the lighting time elapses. Conventionally, Japanese Patent Publication No. 49-42751 has been proposed from the viewpoint of preventing blackening of the tube wall.
According to this publication, a means for applying a transparent refractory refractory material such as thorium oxide, magnesium oxide, titanium oxide, zirconium oxide, and aluminum oxide to the inner surface of an arc tube made of quartz is proposed. By applying a high-melting-point refractory, it is possible to prevent the contact between mercury and quartz and prevent the occurrence of blackening.

However, the technique disclosed in the above publication relates to a mercury discharge lamp in which the bulb wall load of the arc tube is 12 W / cm ² or more, and the cause of blackening on the bulb wall is mercury encapsulation. It has no relation to the quantity.

[0006]

However, the inventors of the present invention have determined that the load on the tube wall is 10 W / cm ² or less, and the amount of mercury enclosed per unit volume is 0.1 to 3.0 mg / cc. It was discovered that a remarkable blackening occurred in the discharge lamp.

That is, the medium-pressure mercury discharge lamp according to the present invention refers to a lamp whose vapor pressure during lighting is 0.1 atm or more and less than 5 atm, and the amount of mercury enclosed per unit volume is 0.
It is 1 to 3.0 mg / cc, and the light is turned on when the tube wall load is 10 W / cm ² or less. Such a medium-pressure mercury discharge lamp is effective in sterilizing and purifying water because it can realize a discharge lamp having a large amount of ultraviolet rays in a short wavelength range with respect to the input power and having a large capacity as described above. .

However, it has been found that this type of medium-pressure mercury discharge lamp is prone to blackening of the tube wall. The reason why the blackening is likely to occur in the medium-pressure mercury discharge lamp is considered as follows. That is, in the medium-pressure mercury discharge lamp, as described above, the amount of enclosed mercury is 0.1 to 3.0 per unit volume.
Since it is as low as mg / cc, the evaporation amount of mercury during lighting is relatively small, and therefore the mercury vapor pressure is relatively low. Therefore, it is considered that the mean free path of the mercury ions becomes large and the motion velocity of the mercury ions attracted by the electric field becomes high. Therefore, when the mercury ions collide with quartz, they collide with a large amount of energy, and hence the implantation into quartz is increased. .

An object of the present invention is to provide a mercury discharge lamp capable of preventing blackening of a tube wall in a medium-pressure mercury discharge lamp and thereby increasing an ultraviolet emission maintenance rate, its lighting device, and its lighting device. It is intended to provide an ultraviolet irradiation device using the.

[0010]

According to a first aspect of the present invention, a quartz arc tube in which electrodes are sealed contains mercury in a range of 1.0 to 3.0 mg / cc per unit volume, and a tube wall is provided. Load is 1
A mercury discharge lamp that is turned on at 0 W / cm ² or less is characterized in that a transparent protective film made of a metal oxide is formed on the inner surface of the arc tube.

According to a second aspect of the invention, mercury is contained in a quartz arc tube in which electrodes are sealed in an amount of 0.1 to 3.0 mg per unit volume.
In the mercury discharge lamp that is enclosed in the range of / cc and the wall load is 10 W / cm ² or less, the inner surface of the arc tube is
It is characterized in that a transparent protective film for preventing implantation of mercury is formed.

According to a third aspect of the invention, the translucent protective film is
An oxide selected from 4A group, 3B group and 2A group of the periodic table of elements, which is colorless and harmless and is selected from at least one of zirconium oxide, hafnium oxide, boron oxide, aluminum oxide, magnesium oxide and calcium oxide. It is characterized by

According to a fourth aspect of the present invention, the translucent protective film is
The film thickness is 0.1 μm to 2.5 μm. The invention of claim 5 comprises the mercury discharge lamp according to any one of claims 1 to 4, and a lighting circuit for lighting the discharge lamp. Is. A sixth aspect of the present invention is an ultraviolet irradiation device using the mercury discharge lamp according to any one of the first to fourth aspects as a light source.

[0014]

According to the invention of claim 1, the amount of mercury enclosed is 0.1 to 3.0 mg / cc per unit volume, and the tube wall load is 10
In a so-called medium-pressure mercury discharge lamp that is lit at W / cm ² or less, a transparent protective film made of metal oxide is formed on the inner surface of the arc tube, and this protective film prevents contact between mercury and quartz. However, mercury ions are prevented from being implanted into the lattice defects of quartz. In particular, in a medium-pressure class mercury discharge lamp with a relatively small amount of enclosed mercury, the average free path of mercury ions is long and the velocity of mercury ions is high. The action works effectively.
Therefore, the blackening of the tube wall is prevented.

Also in the case of the second aspect of the invention, since the light-transmitting protective film for preventing the implantation of mercury is formed on the inner surface of the arc tube, it is possible to prevent the mercury ions from being implanted into the lattice defect of quartz, and the tube wall. To prevent blackening.

According to the invention of claim 3, the light-transmitting protective film is zirconium oxide which is an oxide selected from the 4A group, 3B group and 2A group of the periodic table, and is colorless and harmless.
Formed with at least one of hafnium oxide, boron oxide, aluminum oxide, magnesium oxide, and calcium oxide, these substances effectively block the contact between mercury and quartz, and mercury ions are implanted into the defect lattice of quartz. Prevent. Moreover, since it is colorless and harmless, it excels in transmitting ultraviolet rays and can be used with confidence.

According to the invention of claim 4, since the thickness of the light-transmitting protective film is set to 0.1 μm to 2.5 μm, contact between mercury and quartz is effectively prevented, and mercury ions are defective in quartz. Prevents hitting the grid. That is, when the film thickness of the light-transmitting protective film is less than 0.1 μm, the function as the protective film is not satisfied, the initial purpose of forming the protective film cannot be achieved, and the film of the light-transmitting protective film is not achieved. When the thickness exceeds 2.5 μm, even though the protective film is colorless, the absorption rate of ultraviolet rays is high, the radiation performance of ultraviolet rays is deteriorated, and when the film thickness is large, peeling easily occurs.

According to a fifth aspect of the present invention, there is provided a mercury discharge lamp lighting device comprising the mercury discharge lamp according to any one of the first to fourth aspects and a lighting circuit for lighting the discharge lamp. Therefore, it is possible to provide a lighting device in which the blackening of the tube wall is suppressed and the ultraviolet irradiation maintenance rate is high.

According to the invention of claim 6, since it is an ultraviolet irradiation device using the mercury discharge lamp according to any one of claims 1 to 4 as a light source, blackening of the tube wall is suppressed, and ultraviolet irradiation is carried out. An ultraviolet irradiation device having a high maintenance rate can be provided.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. The drawing shows an ultraviolet irradiation device used as a water sterilization device, and in the drawing, 1 is a mercury discharge lamp as a light source. The mercury discharge lamp 1 includes an arc tube 10.
And the outer tube 20 surrounding the same forms a double tube structure.

The arc tube 10 is an elongated bulb 1 made of quartz.
Sealing portions 12 and 12 are formed at both ends of the electrode 1, and electrodes 13 and 13 are sealed in the sealing portions 12 and 12, respectively. The arc tube 10 is filled with a predetermined amount of mercury and a rare gas such as argon. The amount of mercury enclosed is 0.1 to 3.0 mg per 1 cc of the inner volume of the arc tube. Further, this arc tube 10 has a wall load of 10 W /
It is designed to be illuminated at cm ² or less. Therefore,
This mercury discharge lamp is a medium pressure class mercury discharge lamp.

A transparent protective film 14 is formed on the inner surface of the arc tube 10.
Are formed. The light-transmitting protective film 14 is an oxide selected from the 4A group, 3B group and 2A group of the periodic table of elements, and is colorless and harmless, zirconium oxide ZrO ₂ , hafnium oxide HfO ₂ and boron oxide BO. ₂ , aluminum oxide Al ₂ O ₃ , magnesium oxide MgO, and calcium oxide CaO. In this example, aluminum oxide Al ₂ O ₃ is used. The thickness t of the transparent protective film 14 is 0.1 μm to 2.5 μm.
It is set to μm.

As a concrete example, in the case of a mercury discharge lamp having a rated input of 5 kW, the inner diameter d of the arc tube 10 is 23 mm, the distance L between the electrodes is 1620 mm, and the surface area S facing the discharge space of the arc tube 10 is S. Is about 1170 cm ² and the internal volume is about 673 cc.

Therefore, the tube wall load obtained by dividing the input W by the surface area S is 4.27 W / cm ² . Such an arc tube 1
670 mg of mercury is enclosed in 0, and thus 1.0 mg / cc is enclosed per unit volume.

The arc tube 10 is housed in the outer tube 20. The outer tube 20 is made of quartz glass, and has a lower end closed and an upper end sealed by a stem 21. The inside of the outer tube 10 is maintained in a vacuum or an atmosphere of an inert gas.

A pair of conductive supports 22a and 22b are hermetically penetrated through the stem 21. The conductive tube holders 23, 23 are attached to the conductive supports 22a, 22b.
Are electrically insulated and fixed, and both ends of the arc tube 10 are mechanically attached to the arc tube holders 23, 23.

The one electrode 13 is connected to the one conductive support 22a through the conductive wire 24a,
The other electrode 13 is connected to the other conductive support 22b via a conductive wire 24b. The pair of conductive supports 22a and 22b is connected to a lighting circuit 25 including a ballast outside the mercury discharge lamp 1, and the lighting circuit 25 is connected to a power supply 26.

The mercury discharge lamp 1 having such a structure is immersed in the photochemical reaction tank 3 in which the liquid 2 to be treated flows. In this case, the cooling tube jacket 4 is immersed in the photochemical reaction tank 3, and the mercury discharge lamp 1 is housed in the cooling tube jacket 4 for use.

The operation of the photochemical reaction device having such a structure and the mercury discharge lamp for emitting ultraviolet light used as the light source will be described. When the mercury discharge lamp 1 is turned on, the mercury enclosed in the arc tube 10 evaporates, and the mercury atoms are ionized and excited to emit ultraviolet rays. The ultraviolet rays pass through the arc tube 10 and the outer tube 20, pass through the cooling tube jacket 4, and irradiate the liquid 2 to be treated in the photochemical reaction tank 3. Therefore, the sterilization and purification of the water 2 is promoted.

In the mercury discharge lamp 1, since the transparent protective film 14 made of colorless and harmless metal oxide is formed on the inner surface of the arc tube 10, the protective film 15 is composed of the bulb 11 made of mercury and quartz. Prevents contact and prevents mercury ions from being driven into the lattice defects of quartz.

Particularly, 0.1 to 3.0 mg / c per unit volume
In a mercury discharge lamp that is c and that is lit at a tube wall load of 10 W / cm ² or less, the so-called medium pressure class mercury discharge lamp has a lower mercury vapor pressure during lighting than the high pressure mercury discharge lamp and Since the mean free path of ions is large and the velocity of mercury ions is fast, the ratio of mercury ions being driven into quartz lattice defects is large and premature blackening is likely to occur. Since the protective film 14 is provided, the protective film 14 prevents the implantation of mercury ions into quartz and suppresses the occurrence of blackening.

As the light-transmitting protective film 14, zirconium oxide, hafnium oxide, boron oxide, aluminum oxide,
Since these substances are formed of at least one of magnesium oxide and calcium oxide, these substances can effectively prevent the contact between mercury and quartz.

The film thickness t of the translucent protective film 14 is 0.
Since the thickness is 1 μm to 2.5 μm, the contact between mercury and quartz is effectively prevented. The film thickness t of the translucent protective film 14 is 0.
When it is less than 1 μm, the function as a protective film is not satisfied,
If the initial purpose of providing the protective film cannot be achieved, and if the film thickness t of the protective film exceeds 2.5 μm, the protective film absorbs ultraviolet rays and the ultraviolet radiation performance deteriorates, and when the film thickness becomes thick, it easily peels off. It causes problems such as becoming. For this reason, when the translucent protective film 15 as in the embodiment is provided, the blackening of the tube wall is prevented, the transmission of ultraviolet rays is not hindered, and the ultraviolet irradiation maintenance rate can be kept high for a long period of time. it can.

FIG. 2 shows the film thickness t as the translucent protective film 15.
₂ shows the results of measuring the ultraviolet irradiation maintenance rate of a mercury discharge lamp with a rated input of 5 kW when using aluminum oxide Al ₂ O ₃ having a thickness of 1.0 μm. The lamp having the translucent protective film 15 maintains the ultraviolet irradiation maintenance rate of 80% or more even after 1000 hours of lighting, but the lamp not having the translucent protective film 15 causes early blackening. Due to this, after 5000 hours of lighting, the UV irradiation maintenance rate drops to 50% or less, and after 10,000 hours, the UV irradiation maintenance rate drops to 30% or less. Therefore,
The effectiveness of the translucent protective film 15 was confirmed.

In the mercury discharge lamp lighting device including the mercury discharge lamp 1 and the lighting circuit 25, the blackening of the tube wall can be suppressed for a long period of time, and the ultraviolet irradiation maintenance rate can be kept high. it can.

Further, in the ultraviolet irradiation device using such a mercury discharge lamp 1 as a light source, blackening of the tube wall is suppressed for a long period of time,
An ultraviolet irradiation device having a high ultraviolet irradiation maintenance rate can be provided.
In the above embodiment, the mercury discharge lamp 1 having a double tube structure including the outer tube 20 is described as an example of the structure housed in the cooling tube jacket 4, but the outer tube 20 and the cooling tube jacket 4 are not always necessary. For example, the outer tube 20 may be omitted and the arc tube may be directly housed in the cooling tube jacket 4, or the cooling tube jacket 4 may be omitted and the outer tube 20 may be directly contacted with water. It may be a structure dipped in. Further, the mercury discharge lamp of the present invention is not limited to being applied to an ultraviolet irradiation device, and can be implemented by a mercury discharge lamp for general lighting.

[0037]

As described above, according to the invention of claim 1, the amount of mercury enclosed is 0.1 to 3.0 mg / c per unit volume.
c, and the wall load is turned on at 10 W / cm ² or less,
In so-called medium-pressure mercury discharge lamps, the mean free path of mercury ions is large and the velocity of mercury ions is fast, which tends to cause premature blackening. Since the film is formed, this light-transmitting protective film prevents contact between mercury and quartz and prevents mercury ions from being implanted into lattice defects of quartz. Therefore, the blackening of the tube wall is suppressed, high ultraviolet radiation performance can be maintained for a long time, and the life characteristics are improved.

Also in the case of the second aspect of the present invention, since the light-transmitting protective film for preventing the implantation of mercury is formed on the inner surface of the arc tube, it is possible to prevent mercury ions from being implanted into the lattice defects of quartz and to prevent the tube wall. Blackening is prevented.

According to the invention of claim 3, the light-transmitting protective film is zirconium oxide, which is an oxide selected from the 4A group, the 3B group and the 2A group of the periodic table, and is colorless and harmless.
Formed with at least one of hafnium oxide, boron oxide, aluminum oxide, magnesium oxide, and calcium oxide, these substances effectively block the contact between mercury and quartz, and mercury ions are implanted into the defect lattice of quartz. Prevent. Moreover, since it is colorless and harmless, it excels in transmitting ultraviolet rays and can be used with confidence.

According to the fourth aspect of the invention, since the thickness of the light-transmitting protective film is 0.1 μm to 2.5 μm, the contact between mercury and quartz is effectively prevented, and the mercury ions are defective in quartz. Prevents hitting the grid. That is, when the film thickness of the light-transmitting protective film is less than 0.1 μm, the function as the protective film is not satisfied, the initial purpose of forming the protective film cannot be achieved, and the film of the light-transmitting protective film is not achieved. When the thickness exceeds 2.5 μm, even though the protective film is colorless, the absorption rate of ultraviolet rays is high, the radiation performance of ultraviolet rays is deteriorated, and when the film thickness is large, peeling easily occurs.

According to a fifth aspect of the present invention, there is provided a mercury discharge lamp lighting device comprising the mercury discharge lamp according to any one of the first to fourth aspects and a lighting circuit for lighting the discharge lamp. Therefore, it is possible to provide a lighting device in which the blackening of the tube wall is suppressed and the ultraviolet irradiation maintenance rate is high.

According to the invention of claim 6, since it is an ultraviolet irradiation device using the mercury discharge lamp according to any one of claims 1 to 4 as a light source, the blackening of the tube wall is suppressed and the ultraviolet irradiation is carried out. An ultraviolet irradiation device having a high maintenance rate can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a mercury discharge lamp used in a water sterilizer according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between lighting time and ultraviolet radiation maintenance factor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mercury discharge lamp 2 ... Treatment liquid 3 ... Photochemical reaction tank 4 ... Cooling tube jacket 10 ... Arc tube 11 ... Valve 12 ... Sealing part 13 ... Electrode 14 ... Translucent protective film 20 Outer tubes 22a, 22b ... Support 23 … Arc tube holder 25… Lighting circuit

Claims (6)

[Claims] 1. A quartz arc tube in which electrodes are sealed is filled with mercury in a range of 0.1 to 3.0 mg / cc per unit volume, and the tube wall load is turned on at 10 W / cm ² or less. The mercury discharge lamp is characterized in that a light-transmitting protective film made of a metal oxide is formed on the inner surface of the arc tube. 2. A quartz arc tube having electrodes sealed therein, in which mercury is enclosed in a range of 0.1 to 3.0 mg / cc per unit volume, and a tube wall load is turned on at 10 W / cm ² or less. The mercury discharge lamp is characterized in that a light-transmitting protective film for preventing implantation of mercury is formed on the inner surface of the arc tube. 3. The transparent protective film is 4A of the periodic table of elements.
Zirconium oxide, hafnium oxide, which is a colorless and harmless oxide selected from Group 3B, 2A
The mercury discharge lamp according to claim 1 or 2, comprising at least one of boron oxide, aluminum oxide, magnesium oxide, and calcium oxide. 4. The transparent protective film has a thickness of 0.1 μm.
To 2.5 μm, the mercury discharge lamp according to any one of claims 1 to 3. 5. A lighting device for a mercury discharge lamp, comprising: the mercury discharge lamp according to claim 1; and a lighting circuit for lighting the discharge lamp. 6. An ultraviolet irradiation device comprising the mercury discharge lamp according to any one of claims 1 to 4 as a light source.