JP2016225037A - Double tube type microwave discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double tube type microwave discharge lamp which is capable of realizing a long-lifetime UVC radiation light source of which the UVC radiation light power density is extremely high even with a discharge tube having a length of 20 to 30 cm and conversion efficiency of 20 to 30%, is capable of downsizing a device to be integrated, facilitates maintenance and is advantageous in terms of cost.SOLUTION: The double tube type microwave discharge lamp comprises: an outer tube and an inner tube that are formed from quartz tubes and coaxially disposed while having a space in which a buffer gas and a little mercury are encapsulated; a rod-like antenna which is inserted into the inner tube via a matching element that is disposed in an opening end of the inner tube, and connected to a microwave oscillation source; and a metal mesh body that is disposed to cover an outer peripheral side of the outer tube and has predetermined radiation light transmissivity. The metal mesh body is formed from a net-like metal mesh or a thin metal wire mesh in which thin metal wires are disposed in parallel, and its radiation light transmissivity is set equal to or higher than 80%.SELECTED DRAWING: Figure 3

Description

  The present invention excites the discharge gas in the space by forming a space between the outer tube and the inner tube, inserting an antenna inside the inner tube, and supplying microwaves from the microwave oscillation source to the antenna. The present invention relates to a double-tube microwave discharge lamp that is discharged in this manner.

  Conventionally, a discharge lamp such as a low-pressure mercury lamp has been widely used as a UVC radiation light source having a strong sterilizing effect in a water purifier or a sterilizer. In this discharge lamp, tungsten filaments having emitters applied to both ends of a discharge tube formed in a cylindrical shape are arranged as electrodes, and a trace amount of mercury is enclosed in the discharge tube together with argon gas as a buffer gas. Then, by supplying AC or DC electric power to the electrode, the discharge tube discharges in a predetermined manner. For example, Patent Document 1 is disclosed as a double tube discharge lamp.

JP 2000-173542 A

  However, in such a discharge lamp, the efficiency of converting electric power into UVC radiation light power (hereinafter referred to as UVC radiation light conversion efficiency) generally increases as the lighting power is lower and the lamp length is longer. However, data has been published that the conversion efficiency is 50% when the lamp length is about 1 m. However, since the UVC light radiation power per unit length of the discharge tube (hereinafter referred to as UVC radiation light power density) is low and the lamp life is long, it is several thousand hours. When used in the apparatus, the apparatus itself is increased in size, and replacement of a discharge lamp that has caused a lighting failure becomes troublesome, which is disadvantageous in terms of cost.

  The present invention has been made in view of such circumstances, and the object thereof is, for example, a discharge tube having a length of 20 to 30 cm and a conversion efficiency of 20 to 30%, but the UVC radiation light power density is markedly higher than that of the conventional product. Another object of the present invention is to provide a double tube type microwave discharge lamp that realizes a long-life UVC radiation light source, enables downsizing of an incorporated apparatus, is easy to maintain, and is cost-effective.

  In order to achieve such an object, the invention according to claim 1 of the present invention is an outer tube and an inner tube made of quartz tubes arranged coaxially with a space in which a buffer gas and a small amount of mercury are enclosed. A rod-like or pipe-like antenna having one end supported by a coaxial connector or the like disposed at the opening end of the inner tube and inserted into the inner tube and connected to a microwave oscillation source; and the outer tube And a metal mesh body having a predetermined radiated light transmittance disposed so as to cover the outer peripheral side.

  The invention according to claim 2 is characterized in that the coaxial connector or the like is provided with a cooling medium supply unit capable of supplying a cooling medium into the inner pipe. Further, in the invention according to claim 3, the metal mesh body is formed of a mesh metal mesh or a thin metal mesh in which a plurality of metal fine wires are arranged in parallel, and the emitted light transmittance thereof Is 80% or more.

  Furthermore, the invention described in claim 4 is characterized in that a mercury reservoir is provided in the outer tube. At this time, it is preferable that the mercury reservoir is detachably provided on the outer peripheral surface or the bottom surface of the outer tube as in the invention described in claim 5. According to a sixth aspect of the present invention, the outer tube and the inner tube are inserted into a quartz tube having a closed end, and the quartz tube is incorporated in a container having a water inlet and a water outlet in an airtight state. It is characterized by that.

  According to the first aspect of the present invention, a rod-shaped or pipe-shaped antenna connected to the microwave oscillation source is inserted into the inner tube, and a predetermined shape is provided so as to cover the outer peripheral side of the outer tube. Since a metal mesh body having a radiated light transmittance is arranged, a microwave transmission line having a coaxial tube structure can be formed by the antenna and the metal mesh body, and leakage of microwave power from the antenna to the outside of the lamp is suppressed. At the same time, the discharge plasma does not touch the antenna and operates as an electrodeless discharge lamp. Moreover, by reducing the tube wall temperature of the double tube by cooling so as to be in the low pressure mercury discharge mode, for example, the conversion efficiency is 20-30% in a double discharge tube having a length of 20-30 cm, but the UVC radiation light power A long-life UVC radiation source having a density much higher than that of the conventional product can be realized, and the apparatus incorporating the UVC radiation source can be miniaturized and its maintenance can be easily performed.

  Further, according to the invention described in claim 2, in addition to the effect of the invention described in claim 1, a cooling medium is provided inside the inner tube to a coaxial connector or the like that electrically connects the antenna and the microwave oscillation source. Since a cooling medium supply unit that can be supplied is provided, for example, by supplying cooling air from the cooling medium supply unit into the inner tube, the antenna inside the inner tube can be cooled, and in combination with cooling of the outer tube, Lights in low-pressure mercury discharge mode can be realized.

  According to the invention of claim 3, in addition to the effect of the invention of claim 1 or 2, the metal mesh body is formed of a mesh-like metal mesh or a plurality of fine metal wires are arranged in parallel. Since the radiated light transmittance is 80% or more, the desired UVC radiation is suppressed while suppressing leakage of the microwave supplied to the antenna to the outside of the double discharge tube substantially completely. Light can be easily obtained.

  Further, according to the invention described in claim 4, in addition to the effects of the invention described in claims 1 to 3, since the outer tube is provided with the mercury reservoir, the mercury is stored in the mercury reservoir so that the discharge tube Without receiving strong heat, the mercury vapor pressure in the space between the outer tube and the inner tube is set to a predetermined pressure, so that, for example, air cooling of the discharge tube is unnecessary, and a high UVC radiation light power density can be maintained.

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 4, since the mercury reservoir is detachably provided on the outer peripheral surface or the bottom surface of the outer tube, the mercury reservoir is connected to the discharge tube. When the amount of mercury enclosed in the space is determined, the mercury reservoir can be separated, and a double discharge tube can be made compact and a discharge lamp excellent in usability can be obtained.

  According to the invention described in claim 6, in addition to the effect of the invention described in claim 1 or 3, the outer tube and the inner tube are inserted into the quartz tube whose tip is closed, and this quartz tube is inserted into the water inlet. Since it is built in an airtight state in a container having a water outlet, water can be sterilized by circulating water through the water inlet and water outlet, and the discharge lamp can be suitably used in a water purifier. can do.

The conceptual diagram which shows 1st Embodiment of the double tube | pipe type microwave discharge lamp concerning this invention. Front view showing an embodiment of the double discharge tube AA line sectional view of FIG. Sectional view similar to FIG. 3 showing a modification of the double discharge tube Sectional view similar to FIG. 3 showing another modification of the double discharge tube Enlarged view of part B in Fig. 5 Enlarged view of part C in Fig. 5 The figure which shows the relationship between the microwave incident power, UVC radiation light conversion efficiency, and UVC radiation light power The figure which shows the relationship between other microwave incident power and UVC radiation light power The figure which shows the relationship between other microwave incident power and UVC radiation light conversion efficiency The figure which shows the relationship between other incident electric power, UVC radiation light power, UVC radiation light power density, and UVC radiation light throughput. The conceptual diagram similar to FIG. 1 which shows 2nd Embodiment of the double tube | pipe type microwave discharge lamp concerning this invention. Conceptual diagram showing the modification Conceptual diagram showing another modification The conceptual diagram which shows 3rd Embodiment of the double tube | pipe type microwave discharge lamp concerning this invention. Sectional view showing the specific embodiment of the same

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
1 to 3 show a first embodiment of a double tube microwave discharge lamp of the present invention. As shown in the conceptual diagram of FIG. 1, a double-tube microwave discharge lamp 1 (hereinafter referred to as a discharge lamp 1) includes an inner tube 2a and an outer tube 2b made of a quartz tube forming a double discharge tube 2, A rod-shaped antenna 3 inserted into the inner tube 2a from the opening of the inner tube 2a and a metal mesh body 4 arranged so as to cover the outer periphery of the outer tube 2b are provided.

  The antenna 3 is a microwave oscillation source that oscillates a microwave of 2.45 GHz, for example, via a coaxial connector 5 disposed in the opening of the inner tube 2a and a coaxial cable 6 connected to the coaxial connector 5. Are electrically connected to the microwave oscillator 7. At this time, as the coaxial connector 5, a coaxial connector with a matching element (slag tuner) is used.

  The inner tube 2a and the outer tube 2b are coaxially arranged, and a sealed space 8 is formed between them. The space 8 is filled with argon gas or xenon gas as a buffer gas, and low pressure mercury. A small amount of mercury that operates in the discharge mode is enclosed. The metal mesh body 4 is formed in a substantially cylindrical shape and is disposed so as to cover the entire outer peripheral surface of the outer tube 2b coaxially.

  The antenna 3 is formed of a metal rod having a predetermined length, its distal end is located near the bottom surface of the inner tube 2a, and its proximal end is supported (connected) by the coaxial connector 5. The antenna 3 is not limited to a metal rod. For example, a metal pipe or several metal wires may be bundled in a cylindrical shape so that the microwave is evenly distributed on the surface of the inner tube 2a. good.

  2 and 3 show a specific embodiment of the double discharge tube 2 of the discharge lamp 1. Hereinafter, the same parts as those in the conceptual diagram of FIG. The same applies to the following embodiments and modifications. The inner tube 2a of the double discharge tube 2 is formed in a bottomed cylindrical shape that is open at one end and closed at the front end (bottom surface), and the outer tube 2b has a bottom surface and one end opens from the inner tube 2a. It is integrated with the outer peripheral surface of the end. Thereby, the said space 8 of the fixed state of the fixed width | variety is formed between the outer peripheral surfaces of the inner tube | pipe 2a and the outer tube | pipe 2b, and both bottom surfaces.

  Further, a net-like metal mesh 4a as the metal mesh body 4 is wound around the outer peripheral surface of the outer tube 2b, for example, around the outer peripheral surface of the outer tube 2b. 2b and the inner tube 2a (antenna 3) are arranged coaxially. The mesh-shaped metal mesh 4a has its upper end fixedly supported on the coaxial connector 5 by a metal ring 9 or the like, and its lower end opened.

  The mesh metal mesh 4a is fixed when the outer diameter of the discharge lamp 1 (the outer diameter of the double discharge tube 2) is larger than the outer diameter of the coaxial connector 5 (for example, 20 mm). The mesh metal mesh 4a is fitted into the coaxial ring 5 and the upper end of the mesh metal mesh 4a is fitted into the coaxial connector 5. The mesh metal mesh 4a is fixed to the coaxial connector 5 with a ring clasp or nut so that the mesh metal mesh 4a is not detached. When the outer diameter of the discharge lamp 1 is smaller than the outer diameter of the coaxial connector 5, a cylindrical mesh metal mesh 4a is attached to the coaxial connector 5 and fixed with a clasp or nut. The mesh metal mesh 4a has a radiated light transmittance of 80% or more.

  The coaxial connector 5 attached to the opening of the inner tube 2a is integrated with a matching element (slag tuner). For example, a metal main body 5a having an axial hole communicating with the inner tube 2a. And a cable connecting portion 5b fixed to the base end side of the main body portion 5a. In the case of this embodiment, the dimensions of the double discharge tube 2 shown in FIG. 3 are set to L1 = 200 mm, L2 = 190 mm, t = 5 mm, φ1 = 32 mm, and φ2 = 18 mm.

  As described above, the discharge lamp 1 configured in this manner encloses, for example, argon gas and a small amount (μg to ng) of mercury in the space 8 in order to enter a low-pressure mercury discharge mode when turned on, and the coaxial connector 5 And a microwave oscillator 7 are connected by a coaxial cable 6. When the microwave oscillator 7 is operated in this state and the microwave is supplied to the antenna 3 through the coaxial cable 6 and the coaxial connector 5, the sealed gas in the space 8 is ionized by the microwave electric field to form plasma. . The spectrum of emitted light from this plasma is strongly dependent on the type of encapsulated gas and its pressure and microwave incident power. For example, when a trace amount (μg to ng) of mercury is sealed in about 1 kPa of argon, a UVC radiation low-pressure mercury lamp having a strong bactericidal action is realized.

  In particular, in the case of the discharge lamp 1, the substantially cylindrical mesh metal mesh 4a is disposed on the outer peripheral surface of the outer tube 2b, so that the mesh metal mesh 4a and the antenna 3 are coaxial and have a coaxial tube structure micro. A wave transmission line can be formed. As a result, useless radiation of the microwave incident power from the antenna 3 is suppressed, and the microwave electric field between the mesh metal mesh 4a and the antenna 3 is strengthened to facilitate discharge. At the same time, since the net-like metal mesh 4a eliminates external radiation, the leakage of microwaves can be suppressed to a nearly complete state.

  By the way, in the UVC radiation low-pressure mercury lamp, UVC radiation having a bactericidal effect is emitted when the mercury atom at the first excitation level is deexcited. Since this is the resonance light of the mercury atom, it has the property of easily absorbing the mercury atom at the ground level, which is called self-absorption. In the mercury lamp, it is important that mercury atoms at the first excitation level generated during discharge are emitted outside the discharge tube without being self-absorbed. Since a mercury lamp that strongly emits UVC radiation needs to have low self-absorption, it is inevitably turned on with low-pressure mercury, and is therefore called a low-pressure mercury mode.

  In addition, since the lamp wall temperature rises during operation of the mercury lamp, the mercury vapor pressure in the lamp rises, and if the mercury vapor pressure becomes too high, self-absorption occurs significantly, and the UVC radiation is attenuated. Considering the above, it can be seen that optimization of mercury vapor pressure is important for lighting an efficient UVC radiation low-pressure mercury lamp. Under such circumstances, sometimes a process such as cooling of the lamp wall temperature is required.

  FIG. 4 shows a modification of the double discharge tube 2 to which such a cooling structure is added. The double discharge tube 2 of this modification is provided with a cooling gas supply port 5c as a cooling medium supply portion on the peripheral wall of the main body portion 5a of the coaxial connector 5, and the cooling gas supply tube 10 connected to the cooling gas supply port 5c. The cooling gas (including cooling air) can be supplied into the inner tube 2a of the double discharge tube 2 through the hole in the main body 5a.

  As a result, as shown by an arrow A in FIG. 4, the cooling gas is supplied from the cooling gas supply pipe 10 into the inner pipe 2a through the cooling gas supply port 5c, and this gas is supplied from the opening end of the inner pipe 2a. The antenna 3 is cooled by being discharged outside the heavy discharge tube 2, that is, the cooling gas flows (circulates) through the inner tube 2a. According to this configuration, the cooling of the antenna 3 can suppress the heat generation of the antenna 3 when the microwave is supplied, and the inner wall 2a heated by the heat generation from the discharge plasma can be simultaneously cooled. As a result, the temperature rise of the tube wall of the double discharge tube 2 due to the supply of microwaves can be suppressed, the rise of mercury vapor pressure can be suppressed, and the tube wall temperature of the double discharge tube 2 can be easily set to 40 to 50 ° C. It can be stably maintained, and low-pressure mercury discharge can be performed efficiently.

  5 to 7 show other modified examples of the double discharge tube 2. The feature of this modification is that the metal mesh body 4 is not the mesh metal mesh 4a but a fine metal mesh 4b composed of a plurality of metal fine wires 4b1 arranged in parallel along the axis of the double discharge tube 2. It is in the point formed. That is, by arranging the fine metal wires 4b1 having a predetermined diameter along the longitudinal direction (axial direction) on the outer peripheral surface of the outer tube 2b in parallel, the outer peripheral surface of the outer tube 2b is covered with each metal thin wire 4b1 in a substantially cylindrical shape. The coaxial connector 5 side of each metal thin wire 4b1 is fixedly supported by a metal ring 9 or the like in the same manner as the mesh metal mesh 4a1. Moreover, the diameter of the opening end of the thin metal mesh 4b is set small by narrowing the lower end part of the metal thin wire 4b1 from the outer tube 2b and connecting it with the metal ring 11. Note that the thin wire metal mesh 4b can be designed to have a discharge light transmittance of 90% or more, for example.

  In the case of this modification, the diameter of the substantially cylindrical thin metal mesh 4b can be arbitrarily adjusted (for example, increased), and the discharge light transmittance of the metal mesh body 4 can be set to, for example, the mesh metal mesh 4a. It can be increased by at least 10%, and the UVC radiation conversion efficiency can be further improved. In this modification, the discharge light transmittance may be 90% or more by appropriately changing the diameter and cross-sectional shape of the metal thin wire 4b1.

  8 to 10 show experimental results of UVC radiation light power and UVC radiation light conversion efficiency with respect to microwave incident power in the embodiment. Among these, FIG. 8 shows the case where the outer diameter φ1 of the double discharge tube 2 is 32 mm and the length L1 is 30 cm, with the cooling structure added and without the cooling structure. 9 and 10 show the relationship between the UVC radiation light power and the UVC radiation light conversion efficiency with respect to the microwave incident power when the outer diameter φ1 of the double discharge tube 2 is 10 mm and the length L1 is 15 cm. The case where the pressure in the space 8 of the heavy discharge tube 2 is 133 Pa, 266 Pa, 665 Pa, and 1330 Pa is shown.

  FIGS. 11A to 11C show two types of the double discharge tube 2 according to the present invention having an outer diameter of 32 mm and 10 mm and a length of 20 cm and 15 cm, and an outer diameter of 32 mm and a length of 1 m. The discharge tube (Comparative Example 1) and the discharge tube (Comparative Example 2) having an outer diameter of 15 mm and a length of 21 cm are subjected to UVC radiation light power, UVC radiation light power density and UVC radiation light treatment for input (incident power). Indicates the amount. The two types of double discharge tubes 2 are microwave inputs, and Comparative Examples 1 and 2 are AC / DC inputs. Also from FIG. 11, it can be seen that the UVC radiation light power density and the UVC radiation light processing amount by the two types of double discharge tubes 2 are significantly different from those of Comparative Examples 1 and 2. This is because, when the double discharge tube 2 of the present invention is lit in the low-pressure mercury discharge mode, the conversion efficiency is not as high as 20 to 30%, but a large UVC radiation light power density is obtained.

  As described above, according to the discharge lamp 1 of the above-described embodiment, the microtube is placed inside the inner tube 2a of the double discharge tube 2 in which the buffer gas and a small amount of mercury are sealed in the space 8 between the inner tube 2a and the outer tube 2b. The rod-shaped antenna 3 connected to the wave oscillator 7 is inserted, and the metal mesh body 4 having a predetermined radiated light transmittance is disposed so as to cover the outer periphery of the outer tube 2b of the double discharge tube 2. The discharge light from the discharge lamp 1 does not touch the antenna 3 and operates as an electrodeless discharge lamp. For example, the double discharge tube 2 having a length L1 of 20 to 30 cm has a UVC radiation conversion efficiency of 20 to 30%. However, it is possible to realize a long-life discharge lamp 1 whose UVC radiation light power density is much higher than that of the conventional product, and to make it possible to reduce the size of the apparatus incorporating the discharge lamp 1 and to easily maintain the apparatus. Can do.

  Further, since the metal mesh body 4 is formed of a mesh-like metal mesh 4a or a fine-line metal mesh 4b and has a radiated light transmittance of 80% or more, the microwave double discharge tube 2 supplied to the antenna 3 is externally provided. Desired radiated light can be easily obtained while suppressing leakage to the. Further, if the coaxial connector 5 that electrically connects the antenna 3 and the microwave oscillator 7 is provided with a cooling gas supply portion 5c capable of supplying a cooling gas inside the inner tube 2a of the double discharge tube 2, For example, the cooling gas can be supplied from the cooling gas supply unit 5c into the inner tube 2a to cool the antenna 3 inside the inner tube 2a, thereby suppressing the heat generation of the antenna 3 and the like and being heated by the heat generated from the discharge plasma. The inner wall of the inner pipe 2a can be cooled at the same time. As a result, the cooling effect of the outer tube becomes effective, the double tube lamp wall temperature can be lowered, and the mercury vapor pressure inside the discharge tube can be maintained at a value suitable for the low pressure mercury discharge mode.

  Further, since the discharge lamp 1 is configured to be discharged by the excitation of the antenna 3, an electrodeless structure that does not require a pair of electrodes can be obtained, and the life of the discharge lamp 1 itself can be extended and further compact. Can be achieved.

  FIGS. 12-14 has shown 2nd Embodiment of the discharge lamp 1 concerning this invention. The feature of the discharge lamp 1 of this embodiment is that a mercury reservoir 13 (mercury reservoir) is provided outside the outer tube 2 b of the double discharge tube 2. That is, in the discharge lamp 1 shown in FIG. 12, the mercury reservoir 13 is disposed on the outer peripheral surface of the outer tube 2 b of the double discharge tube 2 through the quartz tube 14. At this time, when the shape of the double discharge tube 2 has the dimensions shown in FIG. 3, the quartz tube 14 has, for example, an outer diameter φ3 of 15 mm, a length L3 of 50 mm, and the mercury reservoir 13 has a height h of 20 mm. The diameter φ4 is set to 60 mm.

  In the case of this discharge lamp 1, the temperature of the mercury reservoir 13 is controlled to, for example, 25 to 30 ° C. in a state where a small amount of mercury is sealed in the mercury reservoir 13, thereby being affected by the heat generated by the double discharge tube 2. Accordingly, the mercury in the mercury reservoir 13 can be supplied into the space 8 of the double discharge tube 2 through the quartz tube 14. In this case, the mercury vapor pressure is mainly determined by the difference between the temperature of the mercury reservoir 13 and the wall surface temperature of the double discharge tube 2, and the wall surface temperature of the double discharge tube 2 is equal to the mercury vapor pressure in the space 8. Therefore, it is possible to maintain high UVC radiation light conversion efficiency while making the cooling structure of the double discharge tube 2 unnecessary.

  In the case of the discharge lamp 1 having the mercury reservoir 13, by controlling the temperature of the mercury reservoir 13 and the temperature of the double discharge tube 2, the mercury in the mercury reservoir 13 is transferred to the double discharge tube 2 from the low-pressure mercury discharge conditions. Move a lot. Thereafter, when the double discharge tube 2 is subjected to microwave discharge while maintaining the temperature of the mercury reservoir 13 at room temperature, the lamp wall rises and the mercury vapor pressure increases, and the mercury moves to the mercury reservoir 13 on the low temperature side, The mercury vapor pressure inside the double discharge tube 2 gradually decreases.

  When the mercury vapor pressure falls below a predetermined threshold value, the medium pressure mercury discharge that has been used so far changes to a mode of low pressure mercury discharge. If the double discharge tube 2 is subjected to microwave discharge under these conditions, the UVC radiation light conversion efficiency is 20 to 30%, but a low-pressure mercury lamp with a high UVC radiation light power density can be realized. The temperature of the mercury reservoir 13 may be controlled by appropriate temperature control means such as a ribbon heater (not shown) wound around the mercury reservoir 13 as necessary.

  FIG. 13 shows a modification of the discharge lamp 1 shown in FIG. 12, in which the mercury reservoir 13 is disposed outside the bottom surface of the double discharge tube 2 via an axial quartz tube 14. Also in this configuration, the same effect as the discharge lamp 1 shown in FIG. 12 can be obtained, and the mercury reservoir 13 is arranged in the axial direction of the double discharge tube 2, so The protruding portion is eliminated, and the outer shape of the discharge lamp 1 can be made compact.

  Further, the discharge lamp 1 shown in FIG. 14 is provided with a small-diameter portion 14a narrowed so as to have an inner diameter of about 2 mm at a substantially intermediate portion in the longitudinal direction of the quartz tube 14 shown in FIG. At the time when the radiant light power reaches the maximum, the quartz tube 14 and the mercury reservoir 13 are separated while the small diameter portion 14a is heated and melted with a gas burner, for example, and shrink-sealed.

  By the way, a difficult point in the development of a UVC radiation low pressure mercury lamp is optimization of the amount of mercury enclosed in the lamp. Although the amount of mercury depends on the lamp capacity, it is a trace amount on the order of ng to μg. Since it is difficult to enclose such a trace amount of mercury in a lamp, an amalgam containing a trace amount of mercury is used. It is also difficult to calculate the amount of mercury enclosed analytically. However, in the case of the discharge lamp 1 shown in FIG. 14, it can be solved by attaching the mercury reservoir 13 to the double discharge tube and lighting it, and separating the mercury reservoir 13 at the small diameter portion 14a when the low pressure mercury discharge mode occurs. That is, if the mercury reservoir 13 is disconnected when the UVC radiation becomes maximum, a UVC light-emitting lamp that operates in the low-pressure mercury discharge mode can be easily obtained.

  Further, in the discharge lamp 1 of this modified example, the same operation effect as that of the discharge lamp 1 shown in FIG. 13 can be obtained, and by separating the mercury reservoir 13, the double discharge tube 2 can be made more compact and easy to use. A discharge lamp 1 can be obtained. Needless to say, the configuration in which the detachable small diameter portion 14a is provided in the quartz tube 14 can also be applied to the quartz tube 14 of the discharge lamp 1 shown in FIG. An appropriate configuration that can seal the separation end face can be employed.

  15 and 16 show a third embodiment of the discharge lamp 1 according to the present invention. A feature of the discharge lamp 1 of this embodiment is that the double discharge tube 2 shown in FIGS. 2 and 3 is inserted into a quartz tube 15 so as to be immersed in water. That is, as shown in the conceptual diagram of FIG. 15, the double discharge tube 2 is disposed in an airtight state in a container 16 such as a water tank having a water inlet 16a and a water outlet 16b, and water circulating in the container 16 is discharged. Sterilize.

  Specifically, as shown in FIG. 16, the double discharge tube 2 is inserted into a quartz tube 15 having one open end, and this quartz tube 15 is built in a container 16 having a water inlet 16a and a water outlet 16b. . At this time, by attaching the open end of the quartz tube 15 to a mounting hole 16 c provided in the container 16 in a sealed state, the double discharge tube 2 is incorporated in the container 16 in an airtight state, and the quartz tube 15 is discharged from the discharge lamp 1. Thus, water is sterilized (purified) by the radiated light radiated into the container 16.

  In the discharge lamp 1 of this embodiment, in addition to obtaining the same effect as the above embodiment, the quartz tube 15 in which the double discharge tube 2 is inserted is housed in a sealed state in the container 16, The double discharge tube 2 can be easily immersed in water without adversely affecting the radiation of UVC radiation, and the discharge lamp 1 can be suitably used, for example, for water purification in a water purifier.

  In each of the above embodiments, the coaxial connector 5 with a matching element is used to connect the microwave oscillator 7 and the double discharge tube 2, but the present invention is not limited to this, for example, the two-dot chain line in FIG. As shown, the matching element 17 (slag tuner) may be connected between the microwave oscillator 7 and the coaxial connector 5 separately from the coaxial connector 5.

  In each of the above embodiments, the solid-state microwave oscillator 7 is used as the microwave oscillation source and connected to the antenna via the coaxial cable 6 and the coaxial connector 5. For example, a magnetron is used as the microwave oscillation source, It is of course possible to feed the magnetron microwaves to the antenna via a rectangular waveguide and a matching element. Further, the configuration of the metal mesh body 4, the antenna 3, and the mercury reservoir 13 in each of the embodiments is an example, and an appropriate configuration can be employed without departing from the gist of each invention according to the present invention. .

  The present invention is not limited to a double tube microwave discharge lamp used as a low-pressure mercury lamp or the like, but can be used for, for example, a versatile sulfur lamp, fluorescent lamp, or metal halide lamp.

1. Double tube type microwave discharge lamp 2. Double discharge tube 2a ... Inner tube 2b ... ··· Outer tube 3 ········· Antenna 4 ·········· Metal mesh body 4a ························ Fine wire metal mesh 4b1 ... Metal fine wire 5 ... Coaxial connector 5a ... Body part 5b ... Cable connection part 5c ... Cooling gas supply port 6 ... Coaxial cable 7 ... Microwave oscillator 8 ... Space 9, 11. Metal ring 10 ... Cooling gas supply tube 13 ... Mercury reservoir 14 ... Quartz tube 14a ...・ ・Diameter 15 ... Quartz tube 16 ... Container 16a ... Water inlet 16b ... Drain 17 ... ..Matching elements

Claims (6)

  Supported by an outer tube and an inner tube made of a quartz tube arranged coaxially with a space in which a buffer gas and a small amount of mercury are enclosed, and a coaxial connector or the like disposed at the open end of the inner tube. A rod-shaped or pipe-shaped antenna inserted into the inner tube and connected to the microwave oscillation source, and a metal mesh having a predetermined radiated light transmittance disposed so as to cover the outer peripheral side of the outer tube A double tube type microwave discharge lamp.   The double tube type microwave discharge lamp according to claim 1, wherein a cooling medium supply unit capable of supplying a cooling medium to the inside of the inner tube is provided in the coaxial connector or the like.   The metal mesh body is formed of a mesh metal mesh or a thin metal mesh in which a plurality of metal fine wires are arranged in parallel, and the emitted light transmittance is 80% or more. The double tube microwave discharge lamp according to claim 1 or 2.   4. The double tube microwave discharge lamp according to claim 1, wherein a mercury reservoir is provided in the outer tube.   5. The double tube microwave discharge lamp according to claim 4, wherein the mercury reservoir is detachably provided on an outer peripheral surface or a bottom surface of the outer tube.   4. The outer tube and the inner tube are inserted into a quartz tube whose tip is closed, and the quartz tube is incorporated in a container having a water inlet and a water outlet in an airtight state. The double-tube microwave discharge lamp described.

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