KR20090015809A - Discharge lamp - Google Patents

Abstract

A discharge lamp is provided to prevent the hole of atmosphere by forming the low-melting point glass in the axial direction of the penetration hole. The discharge vessel is formed by consecutively setting up the sealed tube(2) in both ends of the arc tube. The anode and the cathode consisting of tungsten are disposed in the arc tube. The inside of the discharge vessel is filled with the luminescent material and the buffer gas for the starting assistance. The inner lead is installed according to the pipe shaft of the inside of the sealed tube. One end of the outer lead(9) is supported by the glass member. The outer lead of the diameter 6mm is inserted into the hole.

Description

Discharge Lamps {DISCHARGE LAMP}

This invention relates to the discharge lamp used for the light source of exposure apparatuses, such as a liquid crystal, a semiconductor, and a printed circuit board. In particular, it is related with the discharge lamp of the foil seal structure in which the seal part was sealed by the metal foil which consists of molybdenum (Mo).

As a power supply structure of a discharge lamp, it is known that an electrode is connected to the metal foil embedded in the seal tube, and an external lead is connected to the other end of the metal foil, and it takes electrical conduction. The discharge lamp having the seal portion of such a thin seal structure has the outer circumference of the seal tube and the outer lead due to the difference in the expansion coefficients of the molybdenum (Mo) or the tungsten (W) constituting the seal tube and the quartz glass constituting the seal tube. Fine gaps are formed between them. Since such a gap exists, there exists a problem that air | atmosphere penetrates into the surface of a metal foil or an external lead, and the oxidation of a metal foil and an external lead is greatly promoted at the time of lighting. As a result, cracks generate | occur | produce in the seal tube, metal foil melted, etc., and the lifetime of the discharge lamp was shortened.

As a means to solve this problem, the technique shown in Unexamined-Japanese-Patent No. 2004-319177 is known. In the discharge lamp which is used for a liquid crystal projector as shown in Fig. 6, the gap formed on the outer periphery of the seal tube 2 and the outer lead 9 and the metal foil (5), consisting of rubidium oxide (Rb ₂ O) The sealing material 22 is filled, and the low melting-point glass 20 which has a boron oxide and bismuth oxide as a main component is attached to the outer end part of the seal pipe 2. By such a structure, the inflow opening of the atmosphere of the outer end surface of the seal pipe 2 can be blocked, the outer lid 9 and the metal foil 5 can be cut off from external air, and the heat resistance temperature of a seal part can be improved. In addition, it is possible to extend the service life under the exposure to high temperatures.

[Patent Document 1: Japanese Patent Application Laid-Open No. 2004-319177]

However, the sealing material 22 is filled in the large discharge lamp used for the light source of an exposure apparatus, the above-mentioned structure, ie, the clearance gap formed in the outer periphery of the seal tube 2, the outer lead 9, and the metal foil 5. And even if the structure which affixes the low melting glass 20 to the outer end surface of the seal pipe 2 was applied, the problem that the invasion of air | atmosphere cannot be prevented. Since the discharge lamp used for the light source of an exposure apparatus is large compared with the discharge lamp used for liquid crystal projectors, the clearance gap formed in the outer periphery of the outer lead 9 is also large. Moreover, in the discharge lamp used for the light source of the exposure apparatus, the outer end surface of the seal tube 2 is separated from the electrode, and the temperature does not increase that much even when the discharge lamp is lit. Therefore, the low melting glass 20 is maintained at a temperature below the softening point even during the lighting of the discharge lamp, and microcracks are generated on the surface.

In the large discharge lamp used for the light source of an exposure apparatus, since a micro crack exists in the surface of the low melting glass 20, only by attaching the low melting glass 20 to the outer end surface of the seal tube 2, The gap formed on the outer circumference of the outer lead 9 is not completely blocked, and the metal foil 5 is oxidized by the inflow of external air.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a discharge lamp capable of blocking an inflow port of the atmosphere with low melting glass and blocking a metal foil from outside air in a discharge lamp used for a light source of an exposure apparatus.

The 1st invention of this application is the discharge container by which the seal tube is continuously provided in the both ends of a light emitting tube, the electrode arrange | positioned inside the said light tube, the glass member arrange | positioned inside the said seal tube, and the said glass member A discharge lamp having a metal foil disposed on an outer circumferential surface and an outer lead electrically connected to the metal foil and inserted into a through hole of an outer quartz tube, the discharge lamp having an inner circumferential surface between a through hole of the outer quartz tube and an outer circumferential surface of the outer lead. It is characterized by having a recessed part provided with the low melting glass in the clearance gap formed in this, and extending the said through hole in the outer end of the said through hole.

Moreover, in this invention of 2nd this application, in the 1st invention of this application, the said recessed part is formed by the taper surface extended to the opening side of the said through hole, It is characterized by the above-mentioned.

Moreover, in the 3rd invention of this application, in the 1st invention of this application, the said recessed part is formed by providing an edge part in the inner surface of the said through hole. It is characterized by the above-mentioned.

In addition, according to the fourth invention of the present application, in the first invention of the present application, the low-melting-point glass is a donut-shaped solid material, and the external lead penetrates and is disposed on the outer end surface of the external quartz tube. In the state, it is formed by heat melting.

In addition, in the fifth invention of the present application, in the first invention of the present application, the low-melting-point glass is a donut-shaped solid material, in which the external lead penetrates and is disposed inside the concave portion. It is characterized by being formed by heat melting.

In addition, according to the sixth invention of the present application, in the first invention of the present application, the seal tube is formed to protrude in the tube axis direction from the outer end surface of the outer quartz tube, so that the outer circumferential wall of the outer quartz tube is formed. It features.

Moreover, the 7th invention of this application is the 1st invention of this application WHEREIN: The winding foil is formed in the site | part corresponded to the said gap as an outer peripheral surface of the said external lead, It is characterized by the above-mentioned.

According to the discharge lamp which concerns on the 1st invention of this application, it has a recess provided in the outer end of a through hole to enlarge the through hole, and is formed in the clearance gap formed between the inner peripheral surface of the through hole of an outer quartz tube, and the outer peripheral surface of the said external lead. The low melting point glass can be inserted, the air inlet port can be blocked, and the metal foil in the current collector plate and the welded portion thereof can be blocked from the outside air to prevent oxidation.

According to the discharge lamp which concerns on 2nd or 3rd invention of this application, by forming a recessed part by the taper surface which spreads to the opening side of a through hole, or the edge part provided in the inner surface of a through hole, the low melting glass is extended in the axial direction of a through hole. It can form, and it can reliably block the air intrusion port, can block the metal foil in a collector plate and the welding part with it from external air, and can prevent oxidation.

According to the discharge lamp which concerns on 4th invention of this application, an external lead can be made to pass through a donut-shaped solid material, and it can arrange | position to the outer end surface of an external quartz tube, and it can position easily, and it heats and melts in this state, and is a clearance gap. The opening of can be surely blocked by low melting glass.

According to the discharge lamp which concerns on 5th invention of this application, since the low melting glass is previously filled with low melting glass by heat-melting the low melting glass in the recessed part of a discharge lamp, a clearance can be reliably prevented by low melting glass.

According to the discharge lamp which concerns on 6th invention of this application, it forms so that it may protrude in a tube-axis direction rather than the outer end surface of an outer quartz tube, and forms the outer peripheral wall of an outer quartz tube, and when the low melting glass is heated and melted, it will go out of a seal tube No outflowing dripping occurs.

According to the discharge lamp which concerns on 7th invention of this application, as an outer peripheral surface of an external lead, winding foil is formed in the site | part corresponded to a clearance gap, and the external quartz tube which consists of quartz glass, and the external lead which consists of tungsten (W) directly contact. There is no work. Although the linear expansion rate differs between a quartz glass and an external lead, buffering can mutually be suppressed by winding foil.

A first embodiment of the present invention will be described. 1 is a cross-sectional view showing an outline of the configuration of a discharge lamp.

The discharge lamp is made of a light-transmitting material such as quartz glass, for example, and includes a discharge container 1 having a generally spherical light emitting tube 3 and a seal tube 2 extending outwards continuously at both ends thereof. In the light emitting tube 3, an anode 6 and a cathode 7 each made of, for example, tungsten (W) are disposed to face each other. In the discharge container 1, mercury as a luminescent material and xenon gas, for example, as a buffer gas for starting assistance, are respectively encapsulated in a predetermined amount of encapsulation. The amount of mercury is contained, for example, in the range of 1 to 70 mg / cm 3, for example, 22 mg / cm 3, and the amount of xenon gas is, for example, in the range of 0.05 to 0.5 MPa. For example, it is 0.1 MPa.

In the discharge container 1, the inner lead 8 in which the positive electrode 6 or the negative electrode 7 is fixed to the tip is provided so that the inside of the seal tube 2 extends along the tube axis. The other end of the inner lead 8 is supported by a substantially cylindrical glass member 4 made of, for example, quartz glass provided in the seal tube 2. In addition, one end of the outer lead 9 provided to extend outward from the discharge vessel 1, that is, protrude outward from the outer end of the seal tube 2, is supported by the glass member 4.

On the outer circumferential surface of the glass member 4, mutually spaced apart in the circumferential direction, plural pieces, for example, six strip | belt-shaped metal foil 5 is provided in parallel with each other along the tube axis direction of a discharge lamp. The metal foil 5 may be made of, for example, a high melting point metal such as tungsten (W), tantalum (Ta), ruthenium (Ru), or rhenium (Re) or alloys thereof, but the ease of welding and the conductivity of welding heat It is preferable that it is comprised by the metal which has molybdenum (Mo) as a main component from the reason of this good thing. Each metal foil 5 is 0.02-0.06 mm in thickness, for example, and 6-15 mm in width. Moreover, the hole in which the external lead 9 of diameter 6mm is inserted is provided in the end surface of the glass member 4 by the outer quartz tube 13 side.

One end of each metal foil 5 is electrically connected to the inner lead 8, and the other end is electrically connected to the outer lead 9. And the sealing tube 2 and the glass member 4 in the discharge container 1 are welded through the metal foil 5, and the airtight seal structure is formed. The holding cylinder 10 is, for example, a tubular inner lead supporting member made of quartz glass that supports this in a state where the inner lead 8 is inserted, and includes a seal tube 2 in the discharge container 1. It is welded.

When the electrical connection state is demonstrated concretely, the internal lead 8 is supported by the state which inserted through the holding cylinder 10, the metal plate 11 is being fixed to the seal part side of the internal lead 8, and the metal foil The inner lead 8 and the metal foil 5 are electrically connected by welding the metal plate 11 to the metal plate 11. The outer lead 9 inserted into the glass member 4 is supported while being inserted into the outer quartz tube 13, and the current collector plate 12 covers the outer circumferential surface from the end face of the light emitting tube side of the outer quartz tube 13. This is provided, and the metal foil 5 is welded to the outer peripheral surface of the collector plate 12, and the external lead 9 and the metal foil 5 are electrically connected.

In this discharge lamp, a high voltage, for example, 20 kV, is applied between the electrodes of the anode 6 and the cathode 7 by a lighting source (not shown), so that dielectric breakdown occurs between the electrodes, and then a discharge arc is formed. For example, light containing i-line with a wavelength of 365 nm and g-line with a wavelength of 435 nm is emitted.

2 is an enlarged cross-sectional view showing the outer end side of the seal portion of the discharge lamp.

A cylindrical current collector plate 12 having a bottom opening outward is fixed to the external lead 9 in a state where the external lead 9 penetrates the bottom portion, and is fixed to the outer circumferential surface of the current collector plate 12. The other end of each metal foil 5 is welded and joined, and the external lead 9 and the metal foil 5 are electrically connected through the collector plate 12 by this. Here, as a material which comprises the collector plate 12, molybdenum (Mo) etc. are mentioned, for example. In the inner space of the current collector plate 12, a cylindrical external quartz tube 13 made of, for example, quartz glass is provided to support this in the state where the external lead 9 is inserted.

The outer circumferential surface of the current collector plate 12 and the metal foil 5 are electrically connected by welding with a spot welder or the like at the portions where the current collector plates 12 overlap each other. Since the metal foil 5 is pressed firmly at the time of welding, the metal foil 5 of a welding part may become thin. When the metal foil 5 of the welded portion is thinned, the passage of the current flowing through the metal foil 5 is narrowed, so that the metal foil 5 in the welded portion with the current collector 12 has a characteristic that the temperature is likely to rise. . In the high temperature part, the metal foil 5 is easy to oxidize, and since the cross-sectional area which can become a passage of electric current by the progress of oxidation also gradually decreases, electrical resistance becomes large and temperature becomes higher. Since this phenomenon arises, the metal foil 5 in the welding part with the collector plate 12 is the part which needs to suppress oxidation most.

The light emitting space and the external air space are divided by welding and sealing the seal pipe 2 and the glass member 4 through the metal foil 5. Since the outer end side is the outer air space from the glass member 4, the clearance gap 30 formed between the inner peripheral surface of the through-hole 16 of the outer quartz tube 13 and the outer peripheral surface of the outer lid 9 communicates with the outside. It is. Since the thermal expansion rate of metals such as tungsten (W) and molybdenum (Mo) and the thermal expansion rate of quartz glass differ by about one digit, a gap 30 is provided between the metal and the quartz glass to allow thermal expansion of the metal. Because you need to be. Further, the winding foil 15 made of molybdenum (Mo) is placed on the outer circumferential surface of the outer lead 9 so that the outer quartz tube 13 made of quartz glass and the outer lead 9 made of tungsten (W) do not directly contact each other. It is installed and inserted into the external quartz tube 13.

The through-hole 16 provided in the substantially center of the outer quartz tube 13 is provided with the taper surface 17 which spreads to the opening side. In the location where the tapered surface 17 is formed, the distance between the inner circumference of the outer quartz tube 13 and the outer circumference of the outer lead 9 increases, and the ring-shaped recess 14 provided by enlarging the outer end of the through hole 16 is provided. Becomes The recessed part 14 is formed along the outer periphery of the outer lead 9 in the axial direction, and the largest outer diameter is larger than the inner diameter of the through hole 16. A gap 30 extending in the axial direction of the outer lead 9 is formed between the inner circumferential surface of the through hole 16 of the outer quartz tube 13 and the outer circumferential surface of the outer lead 9, and the through hole 16 is formed. ) And the concave portion 14 is formed to enlarge the space of the gap 30 at the outer end of the through hole 16.

Since the air penetrates through the gap 30, the current collector plate 12, the metal foil 5, and the metal foil 5 in the welded portion thereof are prevented from being oxidized, so that the through hole of the outer quartz tube 13 ( The low melting point glass 20 is filled in the gap 30 formed between the inner circumferential surface of the 16 and the outer circumferential surface of the outer lead 9 so as to fill the recess 14 provided by enlarging the outer end of the through hole 16. It is. Since the low-melting-point glass 20 aims at suppressing the inflow of external air, the seal tube 2 is closed so as to close the gap 30 formed between the inner circumferential surface of the through hole 16 and the outer circumferential surface of the outer lead 9. It is densely installed in the cross section cut | disconnected in the radial direction of (). Low-melting-point glass 2P consists of a boron oxide and bismuth oxide as a main component, and the total weight of this main component becomes 70% or more of the weight of the whole.

The temperature of the outer end of the external quartz tube 13 at the time of lighting of a discharge lamp is 150-250 degreeC. Since the softening point of the low melting glass 20 is 420 degreeC, the low melting glass 20 does not have a viscosity even during lighting of a discharge lamp, and the microcracks exist in the surface. Due to the minute cracks forming the low melting point glass 20, the atmosphere flows between the outer end side of the outer quartz tube 13 and the inside of the gap 30, and the welded portion with the current collector plate 12. It should be formed so that the metal foil 5 can be prevented from being exposed to the outside air. Therefore, the low melting-point glass 20 must be formed thick enough with respect to the length in which a micro crack is formed, and it is necessary to form over the at least 2 mm in the axial direction of the through-hole 16.

The gap 30 formed between the inner circumferential surface of the through hole 16 of the outer quartz tube 13 and the outer circumferential surface of the outer lead 9 by having the concave portion 14 provided to enlarge the outer end of the through hole 16. ) Becomes larger at the outer end of the through hole 16, and the low melting glass 20 can be injected and inserted efficiently. According to the low melting point glass 20 injected into the gap 30, the air inlet port is blocked, and the metal foil 5 in the weld portion with the current collector plate 12 is blocked from the outside air to prevent oxidation. Can be.

Moreover, in the clearance gap 30 formed in the outer periphery of the glass member 4 and the external lead 9, the clearance gap 21 in which the low melting glass 20 is not provided is formed. By increasing the input power of the discharge lamp or shortening the length of the seal portion in the axial direction, if the lighting condition of the discharge lamp is severe, the outer end side of the external quartz tube 13 also tends to become high temperature. Under such conditions, when the low melting glass 20 is turned on, the temperature of 400 ° C. or more is increased as compared with when the low melting glass 20 is turned off, and thermal expansion of the amount corresponding to the temperature difference is performed. If the space | gap 21 is provided in advance around the low melting glass 20, the low melting glass 20 has the space allowance which can expand by thermal expansion in the outer periphery of the outer lid 9, and a glass member (4) or the surrounding low melting glass 20 is not loaded.

Moreover, even if a discharge lamp is lighted on such conditions, since the low melting glass 20 is only about 450 degreeC, even if it is high, although the low melting glass 20 softens, it does not melt. Therefore, the low melting glass 20 stays in the position where it was initially installed, and the space | gap 21 is not filled with the low melting glass 20 which melted.

FIG. 3 is an enlarged cross-sectional view showing the outer end side of the seal portion of the discharge lamp during the manufacture of the method for forming the low melting point glass 20. FIG. 3 shows a state where the donut-like solid material 24 is inserted into the external lead 9 in a discharge lamp in which the low melting point glass 20 is not formed in the gap 30.

The solid material 24 shape | molds solid low melting glass. When the donut-shaped solid material 24 is placed on the recess 14 and the solid material 24 is heated and melted, the low melting glass passes through the through hole 16 through which the outer quartz tube 13 passes from the outer end. Therefore, it is injected into the gap 30 formed. In the narrow gap 30 extending in the axial direction, it is difficult to densely install the low melting point glass in the radial section of the gap 30 to prevent the inflow of outside air. However, since the solid solid material 24 is arrange | positioned so that the cover of the clearance gap 30 may be melt | dissolved, it is easy to maintain the airtightness of low melting-point glass, and can reliably suppress the inflow of external air.

By forming the concave portion 14, the opening of the gap 30 passing along the through hole 16 from the outer end of the outer quartz tube 13 is widened, so that low melting glass is injected into the narrow gap 30. Easier The molten low melting point glass is selectively injected into the recessed part 14 lowered one step in the outer end surface 19 of the outer quartz tube 13. The external lead 9 is made to pass through the donut-shaped solid material 24, and it arrange | positions on the outer end surface 19 of the external quartz tube 13, and it can position easily, and it heats and melts in this state, and a clearance gap is carried out. The opening part of 30 can be reliably closed with low melting glass.

In addition, it is also possible to provide the low melting glass 20 without using the above-mentioned solid substance. For example, there is a method of injecting molten low-melting glass from the outer end face 19 of the seal tube 2 into the gap 30 formed on the outer circumference of the outer quartz tube 13 and the outer lead 9. In order to efficiently inject a liquid into a small gap, the low melting glass is dripped while the air in the gap 30 is taken out. When a sufficient amount of low melting point glass is injected and solidified by natural cooling, the low melting point glass 20 is filled in the gap 30 formed in the outer circumference of the outer quartz tube 13 and the outer lead 9.

Next, 2nd Embodiment of this invention is described. 4 is an enlarged cross-sectional view showing the outer end side of the seal portion of the discharge lamp.

Instead of the bottom-shaped cylindrical collector plate 12 which opens outward, the collector disk 18 in which the through-hole was formed in the center is used. The current collector disk 18 is disposed between the glass member 4 and the external quartz tube 13, and the external lead 9 is fixed by, for example, press-fitting into the through hole of the current collector disk 18. Examples of the material constituting the current collector disk 18 include high melting point metals such as tantalum (Ta), niobium (Nb), tungsten (W), and molybdenum (Mo). The thickness of the collector disk 18 is 1-5 mm, for example.

The outer peripheral surface of the current collector disk 18 is welded and electrically connected to the outer peripheral surface of each metal foil 5 by means of a spot welder or the like in a portion where the other ends thereof overlap each other. Since it joins by such a method, it has the characteristics that the metal foil 5 of a weld part becomes easy to become thin, and temperature rises easily. In the high temperature part, the metal foil 5 is easy to oxidize, and since the cross-sectional area which can become a passage of electric current by the progress of oxidation also decreases gradually, electrical resistance becomes large and temperature becomes higher. Since such a phenomenon occurs, even when conducting with the current collector disk 18, the metal foil 5 in the welded portion with the current collector disk 18 is the portion where the oxidation needs to be most suppressed.

The cap 23 which consists of cylindrical molybdenum (Mo) with a bottom is arrange | positioned so that the junction part of the collector disk 18 and the metal foil 5 and the outer end of the collector disk 18 may be covered. By providing the cap 23, the outer quartz tube 13 made of quartz glass and the current collector disk 18 made of metal are prevented from directly contacting each other, and the edge of the outer circumferential end face of the current collector disk 18 is sealed. Prevent contact with 2). Since the current collector disk 18 does not directly contact the outer quartz tube 13 or the seal tube 2, the occurrence of cracks in the quartz glass constituting the outer quartz tube 13 or the seal tube 2 is reduced. can do. In addition, the cap 23 is not fixed to the current collector disk 18 or the metal foil 5 by welding or the like, and is maintained so as not to move between the external quartz tube 13 and the current collector disk 18. .

An end portion 25 is formed in the inner surface of the through hole 16 provided in the center of the outer quartz tube 13. The diameter of the through hole 16 is about 0.5 mm larger than the diameter of the outer lead 9, but the diameter of the outer end side of the end 25 of the through hole 16 is 0.5 mm to 3 greater than the diameter of the through hole 16. Mm is large. On the outer end side of the through hole 16, the distance between the inner circumference of the outer quartz tube 13 and the outer circumference of the outer lead 9 is increased, and the outer end of the through hole 16 is enlarged to have a ring shape. It becomes the recessed part 14. The recessed part 14 is formed along the outer periphery of the outer lead 9 in the axial direction, and the outer diameter is larger than the inner diameter of the through hole 16. By expanding the through hole 16 to form the recess 14 between the inner circumferential surface of the through hole 16 of the outer quartz tube 13 forming the gap 30 and the outer circumferential surface of the outer lead 9, The clearance gap 30 in the outer end of the through-hole 16 is enlarged.

The gap 30 formed between the inner circumferential surface of the through hole 16 of the outer quartz tube 13 and the outer circumferential surface of the outer lead 9 by having the concave portion 14 provided to enlarge the outer end of the through hole 16. ) Becomes large at the outer end of the through hole 16, and the low melting glass 20 can be injected and inserted efficiently, blocking the air inlet port, and the metal foil 5 in the welding portion with the current collector disk 18. Can be blocked from outside air to prevent oxidation.

Next, the formation method of the low melting glass 20 is shown. The recessed part 14 in which the edge part 25 is formed in the inner surface of the through-hole 16 is large enough to arrange | position the solid material shape | molded the solid low melting-point glass in the inside of the recessed part 14. It can take a large space. Therefore, the discharge lamp in which the low melting point glass 20 is not formed in the clearance gap 30 can be arrange | positioned inside the recessed part 14 in the state which passed the donut-shaped solid material in the outer lead 9 in the state. have. As a solid product in which solid low melting glass is formed, a member whose outer diameter is slightly smaller than the diameter of the recess 14 and whose inner diameter is slightly larger than the diameter of the outer lead 9 is used. When the solid is placed and melted in the concave portion 14, the low melting point glass 20 fills the gap between the inner diameter of the concave portion 14 and the outer diameter of the outer lead 9 and lowers it. The melting point glass 20 is densely installed to prevent the inflow of outside air.

Since the opening of the gap 30 can be closed by the low melting glass 20 only by heating the solid material formed by molding the low melting glass to the extent that the other surface melts, the molten low melting glass 20 ) Outflow can be reduced. In addition, since the solid substance can be used as the low melting glass 20 in a state as it is without melting in portions other than the outer surface, the air can be effectively prevented from invading by the pore drilling generated during the heat melting. can do. Since the solid material is previously filled and melted in the inside of the recess 14 of the discharge lamp, the opening of the gap 30 can be reliably blocked by the low melting glass 20.

Next, a third embodiment of the present invention will be described. FIG. 5 is an enlarged cross-sectional view showing the outer end side of the seal portion of the discharge lamp formed so that the seal tube 2 protrudes in the tube axis direction from the outer end surface 19 of the outer quartz tube 13.

In the discharge lamp shown in the first embodiment, the outer tube is formed by extending the seal tube 2 outward in the tube axis direction and protruding in the tube axis direction from the outer end surface 19 of the outer quartz tube 13. The outer circumferential wall 26 of 13 is formed. The outer circumferential wall 26 has a function of an edge that fixes the fluid so that it does not flow out. Therefore, even if the solid material 24 is heat-melted in the state arrange | positioned at the outer end surface 19 of the outer quartz tube 13 by the method shown in FIG. 3, the solid material 24 will be carried out of the outer peripheral wall 26. FIG. Since it is arrange | positioned inside, the molten low melting glass 20 does not leak out over the outer peripheral wall 26, and dripping which the low melting glass 20 flows out of the seal tube 2 does not generate | occur | produce.

In addition, in order to reliably prevent the metal foil 5 from coming into contact with the atmosphere and oxidizing, a rubidium composite oxide is formed on the surface of the metal foil 5, particularly, the surface of the metal foil 5 in the weld portion with the current collector plate 12. and forming a sealing material 22 made of a (Rb ₂ MoO _4). Since the sealing material 22 is a rubidium composite oxide (Rb ₂ MoO ₄ ) containing rubidium (Rb) and molybdenum (Mo), and is a stable compound even at high temperatures, the sealing material 22 does not react with the metal foil 5 even when the discharge lamp is turned on. Does not erode In addition to the low-melting-point glass 20, the sealing material 22 is formed on the surface of the metal foil 5 in the welded portion with the current collector plate 12, whereby the metal foil 5 is effectively blocked from external air to oxidize. You can prevent it. The sealing material 22 is formed so that the space which becomes the space | gap 21 between the low melting glass 20 may be left.

The sealing material 22 made of rubidium composite oxide (Rb ₂ MoO ₄ ) can be provided as follows before the low melting glass 20 is formed in the gap 30.

The aqueous solution of rubidium nitrate (RbNo ₃ ) whose density | concentration was adjusted is dripped appropriately from the clearance gap 30 of the outer end surface 19 of the seal pipe 2. The discharge lamp in which the gap 30 is filled with the aqueous solution of rubidium nitrate is heated to about 150 ° C. and dried, whereby water evaporates to produce rubidium nitrate. The evaporated water is released to the outside of the discharge lamp. In addition, when heated with a hydrogen burner, NOx gas is released to generate rubidium oxide (Rb ₂ O), and reacted with a metal foil (5) made of molybdenum (Mo) at high temperature to seal the rubidium composite oxide (Rb ₂ MoO ₄ ). Ash 22 is produced.

In addition, an aqueous solution of rubidium nitrate (RbNo ₃ ) is formed by weighing pure water and rubidium nitrate so as to have a concentration of 2 mol / L, for example, by dissolving rubidium nitrate in pure water. Aqueous solution of rubidium nitrate may be injected to obtain a uniform coating, and may be further injected after drying when the amount is insufficient. By repeating injection and drying several times, a thick film of the sealing material 22 made of rubidium complex oxide (Rb ₂ MoO ₄ ) can be formed on the surface of the metal foil 5.

In addition, the figure used for the said description simplified the seal part of an actual discharge lamp, and exaggerates the thickness of the metal foil 5 etc. for the purpose of illustration. In addition, the seal shape using the collector plate 12 shown in FIG. 2, and the seal shape using the collector disk 18 shown in FIG. 4 can be selected freely.

Moreover, the discharge lamp of this invention can also be used in the temperature range beyond the softening point of the low melting glass 20. FIG. In the temperature range beyond the softening point, the microcracks of the low melting point glass 20 disappear and prevent the inflow of external air, so that the low melting point glass 20 works more effectively.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the outline of the structure of the discharge lamp of this invention.

2 is an enlarged cross sectional view showing an outer end side of a seal portion of the discharge lamp of the present invention;

3 is an enlarged cross-sectional view showing an outer end side of a seal portion of the discharge lamp of the present invention;

4 is an enlarged cross sectional view showing an outer end side of a seal portion of the discharge lamp of the present invention;

5 is an enlarged cross sectional view showing an outer end side of a seal portion of the discharge lamp of the present invention;

6 is an enlarged cross-sectional view showing an outer end side of a seal portion of a conventional discharge lamp.

<Description of the code | symbol about the principal part of drawing>

1: discharge container 2: seal

3: light emitting tube 4: glass member

5: metal foil 6: anode

7: Cathode 8: Internal lead

9: External lead 10: Maintenance cylinder

11: metal plate 12: current collector

13: Outside quartz tube 14: Concave part

15: Winding 16: Through hole

17: Tapered surface 20: Low melting point glass

21: gap 22: sealing material

Claims (7)

A discharge vessel formed by continuously sealing tubes at both ends of the light emitting tube, an electrode disposed inside the light emitting tube, a glass member disposed inside the seal tube, a metal foil disposed on an outer circumferential surface of the glass member, A discharge lamp having an external lead electrically connected to the metal foil and inserted through a through hole of an external quartz tube, A low melting point glass is provided in the gap formed between the inner circumferential surface of the through hole of the outer quartz tube and the outer circumferential surface of the outer lead, and the concave portion is provided at the outer end of the through hole to enlarge the through hole. Discharge lamp. The method according to claim 1, The said recessed part is formed by the taper surface extended to the opening side of the said through hole, The discharge lamp characterized by the above-mentioned. The method according to claim 1, The said recessed part is formed by providing the edge part in the inner surface of the said through-hole, The discharge lamp characterized by the above-mentioned. The method according to claim 1, The low melting glass is a donut-shaped solid material, characterized in that formed by heating and melting in a state in which the external lead penetrates and is disposed on an outer end surface of the external quartz tube. The method according to claim 1, The low-melting-point glass is a donut-shaped solid material, characterized in that the external lead penetrates and is formed by heat melting in a state arranged inside the recess. The method according to claim 1, The said seal tube is formed so that it may protrude in the tube axis direction rather than the outer end surface of the said outer quartz tube, The outer peripheral wall of the said outer quartz tube is formed, The discharge lamp characterized by the above-mentioned. The method according to claim 1, A discharge lamp, characterized in that a winding foil is formed at a portion corresponding to the gap as an outer circumferential surface of the external lead.

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