JP5080327B2 - Discharge lamp with sealing structure - Google Patents

Description

  The present invention relates to a sealing structure for a discharge lamp such as a short arc type discharge lamp, and more particularly to a sealing structure in which sealing tubes are stacked.

  In a short arc type discharge lamp, a glass sealing tube is integrally connected to both ends of an arc tube sealed with an electrode, and an electrode supporting rod for supporting the electrode is a cylindrical glass tube in the sealing tube. Held by. In the sealing structure using a metal foil, a molybdenum foil or the like is electrically connected to the electrode support rod through a metal ring or the like on which the electrode support rod is attached. In the sealing step, the diameter of the sealing tube is reduced by heat, and the sealing tube is welded to the glass tube. As a result, the metal foil is sealed, and the arc tube is hermetically sealed.

  In the semiconductor and liquid crystal manufacturing fields, in order to improve production efficiency, the power of short arc type discharge lamps is increasing. When the electric power is increased, excessive stress is applied to the sealing tube, and the sealing tube may be damaged, and the lamp may be destroyed. In order to prevent such destruction, there is known a discharge lamp whose strength is increased by a double sealing structure (see Patent Documents 1 and 2).

In a discharge lamp having a double sealing structure, a sealing tube is welded to a part (mounting part) including a glass tube and metal foil inserted into the sealing tube, and the sealing tube is further welded from the outside. In Patent Document 2, in order to prevent the end of the inner sealing tube from being exposed to the discharge space, the inner sealing tube is brought into contact with the end of the tapered glass tube having a diameter larger than that of the inner sealing tube. With this structure, the inner and outer sealing tubes can be welded at a time to provide a sealing structure, and the production efficiency is increased.
JP 2007-157513 A JP 2007-95328 A

  In the conventional double sealing structure, the inner sealing tube contracts during the sealing process, while the end of the glass tube having a large diameter is less likely to change due to its thickness. Therefore, the inner sealing tube may be welded by a complicated contraction operation on the contact surface at the tapered portion of the inner sealing tube and the glass tube, and a gap may remain on the contact surface. In particular, a gap is likely to occur due to the complicated shape of the end portion of the inner sealing tube.

  Stress concentration is likely to occur in the vicinity of the contact surface between the metal ring and the glass tube made of different materials, and cracks are likely to occur along a minute gap near the contact surface. The generated crack immediately proceeds along the radial direction to the adjacent inner sealing tube and further to the outer sealing tube. Due to the progress of such cracks, the sealing tube breaks, and further, the crack progresses to the arc tube, so that the lamp is broken or ruptured. Further, if the diameter of the end of the glass tube on the arc tube side is increased, stress concentration occurs at the welded portion with the outer sealing tube, which may become a rupture starting point when the lamp is turned on.

  On the other hand, in the case of a short arc type discharge lamp, it is required to shorten as much as possible the time to rise from the start of discharge to the rated lamp voltage which can be said to be a stable lighting state. However, if the diameter of the end of the glass tube on the arc tube side is large, the heat capacity of the end surface of the glass tube that touches the discharge space increases, and the glass tube is difficult to warm. As a result, mercury evaporation in the discharge space does not progress easily, it takes time to discharge at the rated voltage, and it is not possible to quickly shift to stable lighting.

  The discharge lamp of the present invention supports an electrode in an arc tube, and has a conductive electrode support rod disposed in an outer sealing tube connected to the arc tube, and holds the electrode support rod, and is welded to the outer sealing tube. A glass tube, a conductive annular member facing the glass tube and electrically connecting the metal foil and the electrode support rod disposed along the axial direction, and an inner side coaxially welded in the outer sealing tube A side sealing tube. For example, the glass tube is a cylindrical glass tube, and the electrode support rod is passed through and held. What is necessary is just to comprise an annular member with a metal ring, for example.

  In the present invention, the inner sealing tube extends from the annular member within the range of the outer sealing tube end. That is, it exceeds the annular member, does not extend in the axial direction to the arc tube side, and is separated from the contact surface between the annular member and the glass tube. And the diameter in the annular member side edge part of a glass tube is larger than the diameter in an arc tube side edge part.

  Since the contact surface between the annular member and the glass tube is away from the outer sealing tube and the inner sealing tube, cracks that are likely to occur on the contact surface are not easily transmitted to the outer sealing tube. Moreover, since the magnitude | size of the diameter in the arc tube side edge part of a glass tube is suppressed, it transfers to stable lighting rapidly. Furthermore, stress concentration on the arc tube side end of the glass tube is suppressed.

  In order to avoid stress concentration, at least a part of the glass tube is preferably formed in a tapered shape toward the end of the outer sealing tube. For example, it is preferable to form a cylindrical recess coaxially and insert the annular member into the recess so that the annular member side end of the glass tube surrounds the annular member. In particular, since the inner sealing tube is not adjacent to the annular member, the axial length of the annular member side end of the glass tube having a larger outer diameter than the annular member is desirably larger than the thickness of the annular member. . Moreover, it is good to make the diameter of an inner side sealing tube smaller than a 1st diameter so that the whole sealing tube may not be enlarged. For example, a tapered tapered portion may be formed on the glass tube toward the end of the sealing tube.

  The method for producing a discharge lamp according to the present invention comprises 1) forming a glass tube having a tapered portion and a cylindrical recess coaxially provided at a sealing tube side end portion having a diameter larger than that of the arc tube side end portion. 2) The conductive annular member holding the electrode support rod is inserted into the recess, and 3) the inner diameter is larger than the outer diameter of the conductive annular member, and the outer diameter is larger than the outer diameter of the end portion of the glass tube on the sealing tube side. Position the arc tube side end of the small inner seal tube against the end of the seal tube, and 4) enclose the mounting component including the inner seal tube and the conductive annular member in the outer seal tube. 5) The method includes a step of simultaneously reducing the diameter of the outer sealing tube, the inner sealing tube, and the arc tube side end of the glass tube by heating the outer sealing tube from the outside.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to ensure the discharge space reliably and providing the sealing structure which does not have a possibility of a rupture and a failure | damage, a stable lighting can be implement | achieved rapidly.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a short arc type discharge lamp according to this embodiment. FIG. 2 is a schematic cross-sectional view of the sealing tube on the anode side.

  The short arc type discharge lamp 10 includes an anode 14 and a cathode 16 in an arc tube 12 made of quartz glass, and coaxially sealed tubes 20 and 60 (hereinafter referred to as an outer seal tube) on both sides of the arc tube 12. Is formed. The outer sealing tubes 20 and 60 are quartz glass tubes integrally connected to the arc tube 12, and both ends thereof are closed with caps 80A and 80B.

  Each of the sealing tubes 20 and 60 is provided with parts (hereinafter referred to as “mounting parts”) 18A and 18B that support the anode 14 and the cathode 16 and seal and seal the discharge space 11 in the arc tube 12. ing. In the present embodiment, the discharge space 11 in the arc tube 10 is hermetically sealed by a double sealing structure. Mercury and discharge gas are enclosed in the discharge space 11.

  As shown in FIG. 2, an electrode support rod 22 that supports the anode 14 is provided inside the sealing tube 20, and extends in the axial direction inside the outer sealing tube 20. The electrode support rod 22 is inserted into a shaft hole 24A provided in a quartz glass tube (hereinafter referred to as an electrode side glass tube) 24, and the electrode side glass tube 24 welded to the outer sealing tube 20 is attached to the electrode support rod 22. Hold. A cylindrical hole 24 </ b> B is formed in an end portion (light emitting tube side end portion) 24 </ b> T <b> 2 facing the arc tube side of the electrode side glass tube 24 in order to reliably weld to the outer sealing tube 20.

  The electrode support bar 22 does not extend to the end of the outer sealing tube 20, and a metal lead bar 28 is coaxially disposed opposite the electrode support bar 22 at a predetermined interval. The electrode support rod 22 and the lead rod 28 are fitted into insertion holes 34A and 34B provided along the shafts at both ends of the quartz cylindrical glass member 34, and the glass member 34 attaches the electrode support rod 22 and the lead rod 28 to each other. Hold. The lead bar 28 is connected to a lead wire (not shown) connected to an external power supply unit (not shown).

  The rigid metal rings 26 and 32 are arranged so as to be in close contact with both ends of the cylindrical glass member 34, and the electrode support bar 22 and the lead bar 28 are inserted into the shaft holes 26A and 32B. A metal ring (hereinafter referred to as an inner metal ring) 26 close to the arc tube 12 is in contact with the other end 24T1 of the electrode side glass tube 24. The other metal ring (hereinafter referred to as an outer metal ring) 32 abuts on an outer glass tube ring 35 made of quartz. The metal rings 26 and 32 are welded to the electrode support rod 22 and the lead rod 28, respectively.

  Between the inner metal ring 26 and the outer metal ring 32, a plurality of strip-shaped metal foils 36 extend in the axial direction along the outer surface of the glass member 34 along the axial direction. The outer peripheral surface of the metal ring 32 is welded. The metal ring 32 electrically connects the lead bar 28 and the metal foil 36, and the metal ring 26 electrically connects the metal foil 36 and the electrode support bar 22.

  The inner sealing tube 38 made of quartz glass is welded to the inner surface of the outer sealing tube 20 and is disposed coaxially. The inner sealing tube 38 accommodates the cylindrical glass member 34 and the metal foil 36 and seals the inside of the sealing tube 20 by welding with the outer sealing tube 20. Note that the metal foil 36 is actually much thinner than the inner sealing tube 38, unlike the case shown in FIG. The quartz fixing ring 29 is inserted into the end of the outer sealing tube 20 and fixes the position of the inner sealing tube 38 along the axial direction.

  FIG. 3 is an enlarged cross-sectional view of the vicinity of the glass tube 24 of the outer sealing tube 20.

  In the vicinity of the end portion 24T1 of the electrode side glass tube 24, a tapered portion 24S that is tapered from the arc tube side toward the metal ring side is formed, and the outer sealing tube 20 is also tapered along the tapered portion 24S. It is formed in a shape. The tapered portion 24S is formed smoothly to prevent stress concentration.

  Due to the tapered portion 24S, the diameter D1 at the end 24T1 of the electrode side glass tube 24 is larger than the diameter D2 at the other end 24T2. A cylindrical recess 24N is coaxially formed at the end 24T1, and the inner metal ring 26 and the glass member 34 including the metal foil 36 on the outer peripheral surface are inserted into the recess 24N. That is, the end 24T1 surrounds the inner metal ring 26.

  The diameter D2 of the end 24T1 is larger than the outer diameter of the inner sealing tube 38. The axial length L of the end 24T1 having the diameter D2 is longer than the thickness L0 of the inner metal ring 26. That is, the end portion 38T1 of the inner sealing tube 38 is welded to the end portion 24T1 of the electrode side glass tube 24 at a position closer to the sealing tube end portion than the metal ring 36 along the axial direction.

  Furthermore, the end portion 24T1 of the electrode-side glass tube 24 is formed with a tapered portion 24U that is tapered toward the end portion of the sealing tube, and the diameter at the end surface of the end portion 24T1 that is welded to the inner sealing tube 38. D3 is smaller than the diameter D1.

  FIG. 4 is a schematic cross-sectional view before welding in which the mount component 18A is inserted into the inner sealing tube 38. FIG. FIG. 5 is a schematic cross-sectional view before welding in which the inner sealing tube 38 that houses the mount component 18 </ b> A is inserted into the outer sealing tube 20. The sealing process will be described with reference to FIGS.

  The inner sealing tube 38 shown in FIG. 4 shows a state before welding with a burner or the like, and the end 24T1 of the electrode side glass tube 24 has a shape before welding. The annular flange portion 24 </ b> V of the end portion 24 </ b> T <b> 1 has an inner diameter larger than the outer diameter of the inner metal ring 26 and an outer diameter larger than the outer diameter of the inner sealing tube 38. The inner diameter of the inner sealing tube 38 is larger than the outer diameter of the conductive annular member.

  In order to configure the mount component 18A, first, the inner metal ring 26 and the electrode support bar 22 are integrated by welding, and the electrode side glass tube 24 is inserted into the electrode support bar 22. Further, the electrode support rod 22 is press-fitted into the anode 14 and integrated. Further, the outer metal ring 32 and the lead bar 28 are integrated by welding.

  Next, the electrode support rod 22 welded to the inner metal ring 26 and the lead rod 28 welded to the outer metal ring 32 are inserted into the insertion holes 34 </ b> A and 34 </ b> B of the glass member 34. The inner metal ring 26 and the outer metal ring 32 are disposed at both ends.

  Further, a plurality of strip-shaped metal foils 32 are welded to the outer peripheral surface of the inner metal ring 26 and the outer peripheral surface of the outer metal ring 32, whereby the inner metal ring 26, the glass member 34, and the outer metal ring 32 are integrated. In the present embodiment, six metal foils are extended in the axial direction at equal intervals.

  This time, the inner metal ring 26 integral with the outer metal ring 32, the metal foil 32, and the glass member 34 is inserted into the recess 24 </ b> N of the electrode side glass tube 24. Then, the inner sealing tube 38 is put on the glass member 34. At this time, a slight gap is generated between the glass member 34 and the inner sealing tube 38.

  Further, the outer glass tube 35 is inserted into the lead rod 28, and the lead rod 28 is inserted while the fixing ring 29 is in contact with the inner sealing tube 38. The end 38T1 of the inner sealing tube 38 contacts the end 24T1 of the electrode side glass tube 24, and the other end 38T2 contacts the fixing ring 29. As a result, the inner sealing tube 38 is positioned and movement in the axial direction is suppressed.

  When the mount component 18A is mounted and the inner sealing tube 38 is attached, the mount component 18A is inserted into the outer sealing tube 20 this time. And the inside of the discharge space 11 is made into a negative pressure state, and the outer sealing tube 20 is heated by a burner or the like. The outer sealing tube 20, the inner sealing tube 38, and the electrode side end 24T2 of the electrode side glass tube are reduced in diameter by heating, and are welded to the electrode side glass tube 24, the glass member 34, and the outer glass tube 35. As a result, the mount component 18 </ b> A is sealed in the outer sealing tube 20.

  The cathode side sealing structure and the sealing process are the same as those on the anode side.

  As described above, according to the present embodiment, in the discharge lamp 10 having the double sealing structure, the end portion 24T1 of the electrode side glass tube 24 that holds the electrode support rod 22 is thickened toward the end portion of the sealing tube. A tapered portion 24S is formed. The diameter D1 of the end 24T1 is larger than the diameter D2 of the other end 24T2. That is, in the vicinity of the contact surface between the inner metal ring 26 and the glass tube 24, the diameter of the electrode-side glass tube 24 is larger than the diameter of other portions.

  Since the contact surface between the inner metal ring 26 and the glass tube 24 is a contact surface made of different materials, stress due to the internal pressure of the lamp or heat during use of the lamp is likely to be applied, and a gap is likely to occur. In this embodiment, the electrode side glass tube 24 surrounds the contact surface vicinity by inserting the inner metal ring 26 into the recess 24N of the glass tube 24. Therefore, generation of cracks from the vicinity of the contact surface is prevented, and damage to the outer sealing tube 20, and hence the arc tube 12, is prevented.

  Further, the welded portion between the inner sealing tube 38 and the end 24T1 of the electrode side glass tube 24 is away from the vicinity of the contact surface between the inner metal ring 26 and the electrode side glass tube 24, so this welded portion is the starting point. Generation of cracks can be prevented.

  On the other hand, the diameter D2 of the end portion 24T2 of the electrode-side glass tube 24 can be set to a size having substantially the same diameter as that of the single sealing structure. Thereby, the crack generation | occurrence | production in the thin welded part of the edge part 24T2 and the outer side sealing pipe | tube 20 and the failure | damage of the pipe | tube by stress concentration are prevented. In addition, the contact area with the discharge space 11 can be kept small, and it is possible to quickly shift from a lighting start to a stable rated voltage.

  Furthermore, a tapered portion 24U that is tapered is formed at the end 24T1 of the electrode side glass tube 24, and the outer diameter of the inner sealing tube 38 is smaller than the diameter D1 of the end 24T1 of the electrode side glass tube 24. This eliminates the need for increasing the diameter of the outer sealing tube 20.

  In addition, since the inner sealing tube 38 is positioned between the end 24T1 of the electrode side glass tube 24 and the fixing ring 29, the inner sealing tube 38 and the outer sealing tube 20 are used in the discharge lamp sealing process. Can be welded at a time, and a discharge lamp can be manufactured efficiently.

  In addition, it is not limited to a double sealing structure, Three or more types of sealing pipes having a predetermined strength shape may be stacked and welded. The inner sealing tube 38 may be disposed so as not to extend beyond the inner metal ring 26 to the arc tube side. Further, the shape of the tapered portion 24S of the glass tube 24T2 can be changed as necessary. Furthermore, the present invention can be applied to a discharge lamp sealing structure other than the short arc type.

It is a schematic sectional drawing of the short arc type discharge lamp which is this embodiment. It is a schematic sectional drawing of the sealing tube in the anode side. It is sectional drawing to which the glass tube vicinity of the outer side sealing tube was expanded. FIG. 6 is a schematic cross-sectional view before welding in which a mount component is inserted into the inner sealing tube. It is a schematic sectional drawing before the welding which has inserted the inner side sealing pipe | tube which accommodates mount components in an outer side sealing pipe | tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Discharge lamp 11 Discharge space 12 Light emission tube 20 Outer sealing tube 22 Electrode support rod 24 Electrode side glass tube (glass tube)
24T1 end (annular member side end)
24T2 end (arc tube side end)
24N recess 26 inner metal ring (annular member)
28 Lead rod 32 Outer metal ring 34 Glass member 36 Metal foil 38 Inner sealing tube D1 diameter (diameter at the end of the annular member)
D2 diameter (diameter at the arc tube side end)

Claims (7)

A conductive electrode support rod that supports the electrode in the arc tube and is disposed in the outer sealing tube connected to the arc tube;
A glass tube that holds the electrode support rod and is welded to the outer sealing tube;
A conductive annular member facing the glass tube and electrically connecting the metal foil disposed along the axial direction and the electrode support rod;
An inner sealing tube welded coaxially within the outer sealing tube and extending from the annular member within the outer sealing tube end;
The outer sealing tube has a shape along the outer surface of the annular member side end portion by welding with the glass tube in the vicinity of the annular member side end portion of the glass tube,
The discharge lamp according to claim 1, wherein a diameter of the glass tube at the end portion on the annular member side is larger than a diameter at the end portion on the arc tube side.   2. The discharge lamp according to claim 1, wherein at least a part of the glass tube is formed in a tapered shape with a taper toward the end of the outer sealing tube.   2. The discharge lamp according to claim 1, wherein an end of the glass tube on the side of the annular member has a cylindrical recess so as to surround the annular member.   2. The discharge lamp according to claim 1, wherein an axial length of an end of the glass tube having an outer diameter larger than that of the annular member is larger than an axial thickness of the annular member.   2. The discharge lamp according to claim 1, wherein a diameter of the inner sealing tube is smaller than a diameter at an end of the glass tube on an annular member side.   The discharge lamp according to claim 1, wherein the annular member is a metal ring that holds the electrode support rod in an axial manner. Forming a glass tube in which a tapered tapered portion and a cylindrical concave portion are provided coaxially at a sealing tube side end portion having a larger outer diameter than the arc tube side end portion;
Inserting a conductive annular member holding an electrode support rod into the recess,
The arc tube side end portion of the inner sealing tube having an inner diameter larger than the outer diameter of the conductive annular member and smaller than the outer diameter of the sealing tube side end portion of the glass tube is sealed with the glass tube. Position it against the end of the stop tube side,
Enclose mounting parts including the inner sealing tube, the glass tube, and the conductive annular member in an outer sealing tube;
And said outer sealing tube by heat the outer sealing tube from the outside, the inner sealing tube, at the same time reduced in diameter and a sealing tube end of the glass tube, outer sealing the mounting component A method for producing a discharge lamp , comprising sealing in a tube .

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