Low-pressure ultraviolet lamp unit

Abstract

To provide a low-pressure UV lamp unit capable of suppressing the variation of position in which the coolest portion is formed.SOLUTION: The low-pressure UV lamp unit includes a light-emitting tube that is nearly-U-shaped and has a discharge space in which a rare gas and mercury are sealed, electrodes provided on each of the end portions on both sides of the light-emitting tube, and a block having recesses provided in the vicinity of the end portions on each side of the light-emitting tube that is nearly-U-shaped and salients provided inside the recesses and located between vicinities of end portions on each side of the light-emitting tube that is nearly-U-shaped.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a low-pressure ultraviolet lamp unit. [Background technology]

[0002] Low-pressure ultraviolet lamps are one type of lamp that emits ultraviolet light. For example, so-called low-pressure mercury lamps are used to generate ultrapure water for use in the manufacture of semiconductor devices, and for surface modification and cleaning of organic materials. When a low-pressure mercury lamp is turned on, some of the mercury sealed inside the arc tube vaporizes due to the heat generated by lighting. When electrons collide with the vaporized mercury, ultraviolet rays with a peak wavelength of about 254 nm are generated. In this case, if the mercury vapor pressure is too low, the ultraviolet irradiance will be insufficient, and if the mercury vapor pressure is too high, the generated ultraviolet rays will be absorbed by the mercury, and the ultraviolet irradiance will be attenuated.

[0003] The vapor pressure of mercury is affected by the temperature of the arc tube. In addition, while a low-pressure mercury lamp is on, mercury condenses at the coldest point of the arc tube (the coldest part). Therefore, by controlling the temperature of the coldest part of the arc tube, the vapor pressure of mercury, and therefore the irradiance of ultraviolet light, can be kept within an appropriate range.

[0004] For example, a metal block can be attached to the end of the arc tube to form a coldest spot, and the temperature of the coldest spot can be controlled by cooling the metal block. However, the location where the coldest spot is formed can vary within the area where the metal block is attached, depending on the contact position between the arc tube and the metal block and the tightness of the fastener that secures the arc tube to the metal block. If the location where the coldest spot is formed varies, the distance between the coldest spot and the heat source, such as the electrode or positive column, can vary, which can make it difficult to obtain an appropriate temperature for the coldest spot, and ultimately an appropriate UV irradiance. Therefore, there has been a demand for the development of a low-pressure ultraviolet lamp unit that can suppress variations in the position where the coldest spot is formed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-266759 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a low-pressure ultraviolet lamp unit that can suppress variations in the position where the coldest spot is formed. [Means for solving the problem]

[0007] The low-pressure ultraviolet lamp unit according to the embodiment comprises: a substantially U-shaped arc tube having a discharge space filled with rare gas and mercury; electrodes provided at both ends of the arc tube; and a substantially U-shaped arc tube. The aforementioned On both sides of the arc tube The aforementioned a recess in which the vicinity of the end is provided, and a recess provided inside the recess and on both sides of the arc tube The aforementioned a block having a protrusion located between the ends; The length of the convex portion is shorter than the length of the concave portion in a direction perpendicular to the direction in which the vicinities of the ends on both sides of the arc tube are arranged. [Effects of the Invention]

[0008] According to an embodiment of the present invention, it is possible to provide a low-pressure ultraviolet lamp unit that can suppress variations in the position where the coldest spot is formed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a low-pressure ultraviolet lamp unit according to an embodiment of the present invention; [Figure 2] 2 is a schematic cross-sectional view of the low-pressure ultraviolet lamp unit in the direction of line AA in FIG. 1. FIG. [Figure 3] 2 is a schematic cross-sectional view of the low-pressure ultraviolet lamp unit in FIG. 1 taken along line BB. [Figure 4] FIG. 2 is a schematic cross-sectional view of a lamp. [Figure 5] FIG. 2 is a schematic diagram for illustrating a main electrode. [Figure 6] FIG. 2 is a schematic perspective view of a block. [Figure 7] 10 is a table illustrating the relationship between the distance L (mm) and the relative illuminance of ultraviolet light. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be illustrated with reference to the drawings. In the drawings, like components are designated by like reference numerals and detailed descriptions thereof will be omitted where appropriate. FIG. 1 is a schematic diagram illustrating a low-pressure ultraviolet lamp unit 1 according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the low-pressure ultraviolet lamp unit 1 in FIG. 1 taken along the line AA. FIG. 3 is a schematic cross-sectional view of the low-pressure ultraviolet lamp unit 1 in FIG. 1 taken along the line BB. As shown in FIGS. 1 to 3, the low-pressure ultraviolet lamp unit 1 includes, for example, a lamp 2, a block 3, a temperature control section 4, and a fixing section 5.

[0011] FIG. 4 is a schematic cross-sectional view of the lamp 2. As shown in FIG. 4, the lamp 2 includes, for example, an arc tube 20 and electrodes 21. The arc tube 20 may be, for example, a cylindrical tube having a substantially U-shape. The arc tube 20 is formed from a material that transmits ultraviolet light. The arc tube 20 may be formed from, for example, quartz glass. The size of the arc tube 20 may be changed as appropriate depending on the application of the lamp 2. For example, the outer diameter (tube diameter) of the arc tube 20 may be about 30 mm, the inner diameter may be about 28 mm, and the arc length (the distance from one end of the arc tube 20 to the other end) may be about 500 mm.

[0012] The internal space of the arc tube 20 serves as a discharge space, which can be filled with gas and mercury.

[0013] The gas may be a rare gas. Examples of rare gases include argon, krypton, and xenon. In this case, the gas may be one type of rare gas or a mixture of two or more types of rare gases. The gas may also contain a halogen such as mercury iodide. The pressure (filled pressure) of the gas at 25°C in the discharge space may be, for example, approximately 10 Pa to 5 kPa. In other words, the lamp 2 is a low-pressure ultraviolet lamp. The pressure (filled pressure) of the gas at 25°C in the discharge space may be determined from the standard state of the gas (SATP (Standard Ambient Temperature and Pressure): temperature 25°C, 1 bar).

[0014] The amount of enclosed mercury can be, for example, about 1 mg to 1000 mg. The mercury may be contained as an amalgam. When the lamp 2 is turned on, heat is generated at the electrodes 21, causing part of the mercury sealed in the discharge space to turn into mercury vapor.

[0015] The discharge space may further contain metals (e.g., iron, tin, indium, bismuth, thallium, manganese, etc.) to generate ultraviolet rays or extend the lamp life. That is, the lamp 2 may be a metal halide lamp containing mercury, metals, or halogens.

[0016] A pair of electrodes 21 can be provided, one at each end of the arc tube 20 on both sides. Each of the pair of electrodes 21 includes, for example, a main electrode 21a, an auxiliary electrode 21b, a stem 21c, and three outer leads 21d.

[0017] FIG. 5 is a schematic view illustrating the main electrode 21a. As shown in FIG. 5, the main electrode 21a includes, for example, a filament coil 21a1, two leads 21a2, and an insulating portion 21a3.

[0018] The filament coil 21a1 is provided inside (discharge space) of the light-emitting tube 20. The filament coil 21a1 is, for example, a wire-shaped member wound in a spiral shape. The wire-shaped member contains, for example, tungsten or a renium-tungsten alloy. The filament coil 21a1 can be a so-called double filament coil in which the wire-shaped member is wound twice, or a so-called triple filament coil in which the wire-shaped member is wound three times.

[0019] One lead 21a2 electrically connects one end of filament coil 21a1 to one outer lead 21d. The other lead 21a2 electrically connects the other end of filament coil 21a1 to the other outer lead 21d. Lead 21a2 is a linear member containing, for example, tungsten or a tungsten-reinforced tungsten alloy.

[0020] The insulating portion 21a3 is, for example, cylindrical and made of an insulating material. The insulating portion 21a3 can be made of, for example, quartz glass. The insulating portion 21a3 passes through the interior of the filament coil 21a1. The lead 21a2 passes through the insulating portion 21a3. This makes it possible to prevent a short circuit between the lead 21a2, which passes through the interior of the filament coil 21a1, and the filament coil 21a1.

[0021] The auxiliary electrode 21b is provided inside (discharge space) of the arc tube 20. The auxiliary electrode 21b is provided on the side of the filament coil 21a1 opposite to the outer lead 21d side. The auxiliary electrode 21b is provided spaced apart from the main electrode 21a. The outer lead 21d that is not connected to the main electrode 21a is electrically connected to the auxiliary electrode 21b. The auxiliary electrode 21b contains, for example, tungsten or a tungsten-reinforced tungsten alloy. In lamp 2 according to this embodiment, a discharge occurs between auxiliary electrode 21b provided at one end of arc tube 20 and main electrode 21a provided at the other end of arc tube 20. A discharge also occurs between auxiliary electrode 21b provided at the other end of arc tube 20 and main electrode 21a provided at one end of arc tube 20.

[0022] Furthermore, discharges occur alternately between the auxiliary electrode 21b and the main electrode 21a in the lamp 2. For example, at a certain point in time, a discharge occurs between the auxiliary electrode 21b provided at one end of the arc tube 20 and the main electrode 21a provided at the other end of the arc tube 20, and at another point in time, a discharge occurs between the auxiliary electrode 21b provided at the other end of the arc tube 20 and the main electrode 21a provided at one end of the arc tube 20.

[0023] When electrons generated by such discharge collide with mercury atoms, the mercury atoms receive the energy of the electrons, generating ultraviolet light with a peak wavelength of about 254 nm. The generated ultraviolet light is irradiated onto the outside of the arc tube 20.

[0024] The stem 21c is provided at each of the opposite ends of the arc tube 20. The stem 21c is provided inside the arc tube 20 (discharge space), and one end is welded to the arc tube 20. Three outer leads 21d are sealed inside the stem 21c. The stem 21c holds the main electrode 21a and the auxiliary electrode 21b, and also seals the inside of the arc tube 20 (discharge space) so as to be airtight. The stem 21c includes, for example, quartz glass.

[0025] The end of outer lead 21d opposite to main electrode 21a and the end opposite to auxiliary electrode 21b are exposed to the outside of arc tube 20. The end of outer lead 21d exposed to the outside of arc tube 20 is electrically connected to, for example, a power source provided outside lamp 2. Furthermore, a terminal, a connector, a base, etc. may also be provided to the end of outer lead 21d exposed to the outside of arc tube 20. Outer lead 21d may be a linear member containing, for example, tungsten or a tungsten-reinforced tungsten alloy.

[0026] As shown in FIG. 1, the block 3 is provided near the end of the arc tube 20. As shown in FIGS. 2 and 3, the block 3 is, for example, plate-shaped and has a recess 3a that opens on one side. The recess 3a is provided inside the recess 3a near both ends of the substantially U-shaped arc tube 20. The outer surface of the arc tube 20 is in contact with the inner wall of the recess 3a. For example, the outer surface of the arc tube 20 is in contact with the bottom surface 3a1 of the recess 3a. For example, the outer surface of the arc tube 20 may be in contact with the side surface 3a2 of the recess 3a, or there may be a small gap between the outer surface of the arc tube 20 and the side surface 3a2 of the recess 3a.

[0027] The block 3 holds the lamp 2 (the end of the arc tube 20) and transfers the heat generated in the lamp 2 to the temperature control unit 4. For this reason, the block 3 is made of a material with high thermal conductivity, such as a metal. The block 3 can be made of, for example, stainless steel, an aluminum alloy, or a copper alloy.

[0028] The temperature control unit 4 is provided on the side of the block 3 opposite to the side where the lamps 2 are provided. The temperature control unit 4 controls the temperature of the block 3, and therefore the temperature of the coldest spot, which will be described later. The temperature control unit 4 is made of a material with high thermal conductivity, such as metal. The temperature control unit 4 can be made of, for example, stainless steel, an aluminum alloy, or a copper alloy.

[0029] 2 and 3, holes 4a for allowing a refrigerant to flow can be provided inside the temperature control unit 4. By allowing a refrigerant to flow inside the temperature control unit 4, it becomes easier to control the temperature of the block 3, and thus the temperature of the coldest part, which will be described later. For example, by controlling the flow rate, flow velocity, temperature, etc. of the refrigerant, it is possible to control the temperature of the block 3, and thus the temperature of the coldest part, which will be described later. There are no particular limitations on the type of refrigerant. For example, the refrigerant can be water. Although the example has been given in which the block 3 and the temperature control unit 4 are provided separately, the block 3 and the temperature control unit 4 can also be formed integrally.

[0030] The fixing part 5 cooperates with the block 3 to hold the lamp 2 (the end of the arc tube 20). For example, the lamp 2 (the end of the arc tube 20) can be sandwiched between the fixing part 5 and the block 3. The fixing part 5 can be, for example, a metal band. The fixing part 5 can be fixed to the block 3 using a fastening member such as a screw.

[0031] Generally, low-pressure ultraviolet lamps are provided with a coldest part, which is the part of the arc tube 20 that has the lowest temperature while the lamp 2 is lit. If a coldest part is provided, some of the mercury vapor can be condensed into mercury. Since the low-pressure ultraviolet lamp unit 1 is provided with the block 3, the portion of the arc tube 20 that is provided with the block 3 becomes the coldest part.

[0032] Here, if the vapor pressure of the mercury is too low, the irradiance of the ultraviolet light will be insufficient, and if the vapor pressure of the mercury is too high, the generated ultraviolet light will be absorbed by the mercury, and the irradiance of the ultraviolet light will be attenuated. As mentioned above, the low-pressure ultraviolet lamp unit 1 is provided with the block 3 and the temperature control unit 4, so the temperature of the block 3 and, therefore, the temperature of the coldest part can be controlled by the temperature control unit 4. If the temperature of the coldest part can be controlled, the vapor pressure of the mercury and, therefore, the irradiance of the ultraviolet light can be kept within an appropriate range.

[0033] Furthermore, as shown in FIG. 1, when viewed from a direction perpendicular to the surface of block 3 where recess 3a opens, the side of block 3 on the filament coil 21a1 side is preferably arranged to overlap, for example, the end of filament coil 21a1 on the block 3 side.

[0034] As described above, the temperature of the block 3 can be controlled by the temperature control unit 4. Therefore, if the temperature-controllable block 3 is provided near the filament coil 21a1, the mercury vapor can be condensed near the filament coil 21a1.

[0035] Furthermore, if there is condensed mercury near the filament coil 21a1, the heat generated in the filament coil 21a1 is more easily transferred to the mercury. Therefore, temperature control by block 3 (temperature control unit 4) makes it easier to convert the mercury back into mercury vapor near the filament coil 21a1.

[0036] However, the contact position between the arc tube 20 and the inner wall of the recess 3a of the block 3 may vary depending on factors such as the degree of tightening of the fixing portion 5 that fixes the arc tube 20 to the block 3. If the contact position between the arc tube 20 and the inner wall of the recess 3a of the block 3 varies, the position of the coldest spot will also vary. If the position of the coldest spot varies, the distance between the coldest spot and the filament coil 21a1, which is the heat source, will also vary, which could make it impossible to obtain an appropriate mercury vapor pressure, and ultimately an appropriate ultraviolet irradiance.

[0037] Therefore, as shown in FIGS. 1 to 3, the block 3 is provided with a protrusion 3b. FIG. 6 is a schematic perspective view of the block 3. 2, 3, and 6, the protrusion 3b is provided inside the recess 3a. The protrusion 3b can be formed integrally with the block 3. The material of the protrusion 3b can be the same as the material of the block 3.

[0038] The convex portion 3b can be provided at approximately the center of the bottom surface 3a1 of the recess 3a in the direction in which the vicinity of both ends of the substantially U-shaped arc tube 20 are aligned. The convex portion 3b is located between the vicinity of both ends of the substantially U-shaped arc tube 20. The outer surface of the arc tube 20 and the side surface 3b1 of the convex portion 3b may be in contact with each other, or a small gap may be provided between the outer surface of the arc tube 20 and the side surface 3b1 of the convex portion 3b.

[0039] That is, the side surface 3b1 of the protrusion 3b is in contact with or close to the outer surface of the arc tube 20. Therefore, the temperature of the portion of the lamp 2 (arc tube 20) facing the protrusion 3b is likely to be lowered by the protrusion 3b. As a result, the coldest spot is likely to be formed in the portion of the lamp 2 (arc tube 20) facing the protrusion 3b.

[0040] Furthermore, the length of the convex portion 3b is shorter than the length of the concave portion 3a in a direction perpendicular to the direction in which the vicinity of the ends on both sides of the arc tube 20 are aligned. That is, the convex portion 3b is provided in a partial area of ​​the bottom surface 3a1 of the concave portion 3a. This makes it possible to narrow the area of ​​the lamp 2 (arc tube 20) where the coldest spot is formed. As a result, it is possible to prevent variation in the position where the coldest spot is formed.

[0041] 1, when viewed from a direction perpendicular to the surface of the block 3 where the recess 3a opens, the protrusion 3b is provided near the end of the recess 3a on the side opposite to the main electrode 21a (filament coil 21a1). When viewed from a direction perpendicular to the surface of the block 3 where the recess 3a opens, if the distance L (mm) between the protrusion 3b and the side of the block 3 on the filament coil 21a1 side is made too small, mercury vapor will be difficult to condense in the coldest spot. On the other hand, if the distance L (mm) is made too large, it will be difficult to convert the condensed mercury into mercury vapor.

[0042] FIG. 7 is a table illustrating the relationship between the distance L (mm) and the relative illuminance of ultraviolet light. In this case, the arc tube 20 was roughly U-shaped, had an outer diameter (tube diameter) of 30 mm, an emission length of 500 mm, and was made of synthetic quartz glass. The lamp voltage was 120 V, the lamp current was 4.5 A, and the lamp power was 500 W. The discharge space was filled with a rare gas such as xenon and mercury, and the filling pressure was 100 Pa. The width W (mm) of the block 3 was 50 mm. The width W1 (mm) of the protrusion 3b was 10 mm. The protrusion 3b was formed integrally with the block 3, and the material of the block 3 and the protrusion 3b was stainless steel. When viewed from a direction perpendicular to the surface of the block 3 where the recess 3a opens, the side of the block 3 on the filament coil 21a1 side is arranged to overlap the end of the filament coil 21a1 on the block 3 side. Water at 20° C. was allowed to flow through the hole 4a of the temperature control section 4.

[0043] As can be seen from Figure 7, the relative illuminance of ultraviolet light can be improved by setting the distance L (mm) ≥ 25 mm. This means that the coldest spot can be formed in an appropriate position and the variation in the position where the coldest spot is formed can be suppressed.

[0044] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0045] 1 low-pressure ultraviolet lamp unit, 2 lamp, 3 block, 3a recess, 3a1 bottom surface, 3a2 side surface, 3b protrusion, 3b1 side surface, 4 temperature control section, 5 fixing section, 20 arc tube, 21 electrode, 21a main electrode, 21a1 filament coil

Claims

1. a substantially U-shaped arc tube having a discharge space filled with rare gas and mercury; Electrodes provided at both ends of the arc tube; a block having a recessed portion provided in the vicinity of the end portions on both sides of the substantially U-shaped arc tube, and a protruding portion provided inside the recessed portion and positioned between the vicinity of the end portions on both sides of the arc tube; Equipped with A low-pressure ultraviolet lamp unit, wherein the length of the convex portion is shorter than the length of the concave portion in a direction perpendicular to the direction in which the vicinities of the ends on both sides of the arc tube are aligned.

2. The electrode has a filament coil provided inside the discharge space, 2. The low-pressure ultraviolet lamp unit according to claim 1, wherein, when viewed from a direction perpendicular to the surface of the block where the recess opens, the side of the block facing the filament coil overlaps with the end of the filament coil facing the block.

3. 3. The low-pressure ultraviolet lamp unit according to claim 2, wherein the position where the coldest spot is formed is determined by the distance between the convex portion and the side of the block on the side of the filament coil.

4. 4. The low-pressure ultraviolet lamp unit according to claim 1, wherein the side surface of the convex portion is in contact with the outer surface of the arc tube or is close to the outer surface of the arc tube.

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