JP5733264B2 - High pressure discharge lamp - Google Patents

Description

  The present invention relates to a high pressure discharge lamp used, for example, as a light source for a projector apparatus, a light source for an exposure apparatus for manufacturing a semiconductor element or a liquid crystal display element, or a light source for an inspection apparatus using ultraviolet rays.

For example, a short arc type high-pressure discharge lamp is used as a light source of a projector device, a light source of an exposure device for forming a pattern on a semiconductor substrate, a liquid crystal substrate, a printed circuit board or the like, or a light source of an inspection device using ultraviolet rays. ing.
Some types of such high-pressure discharge lamps include, for example, a quartz glass arc tube composed of a light emitting portion and a sealing portion formed continuously at both ends of the light emitting portion, and an inside of the light emitting portion in the arc tube. For sealing made of, for example, molybdenum embedded in a sealing portion in which a pair of electrodes arranged to face each other along the tube axis direction of the arc tube and the other end of each electrode are electrically connected A foil, and an external lead rod made of, for example, tungsten, having one end electrically connected to the other end of the sealing foil and the other end protruding outside from the outer end surface of the sealing portion. The stop portion is formed by, for example, a shrink seal (see, for example, Patent Document 1).

Therefore, since tungsten as a material constituting the external lead rod has low workability, there is a problem that man-hours are required in the manufacturing process.
Therefore, the present inventors produced a high-pressure discharge lamp with a foil seal structure using, for example, a molybdenum alloy that is superior in workability to tungsten as a material constituting the external lead rod, and the following problems arise. It has been found. That is, when the lamp is turned on, the temperature of the seal portion rises, and when the sealing foil and the external lead rod reach a temperature of 350 ° C. or higher, for example, the surfaces of the sealing foil and the external lead rod are rapidly oxidized. For this reason, when the volume of the external lead rod expands, a crack is generated in the seal portion, or a stress that peels off the quartz glass constituting the seal portion and the sealing foil is generated and the foil floats. As a result, the seal portion is broken and the desired lamp life cannot be obtained. In addition, the external lead rod is easily oxidized because the rear end portion is exposed to the outside, for example, and the surface oxidation of the exposed portion is caused by the oxidation of the sealing foil in the seal portion and the surface of the external lead rod. It becomes a factor to make progress.

JP 2012-022780 A

  The present invention has been made based on the above circumstances, and in a high-pressure discharge lamp having a foil seal structure, it is possible to reliably prevent the occurrence of cracks in the glass at the seal portion and the occurrence of foil floating. An object of the present invention is to provide a high-pressure discharge lamp that can obtain a desired lamp life.

The high-pressure discharge lamp of the present invention includes a glass arc tube in which sealing portions are formed by heating and shrinking at both ends of the light emitting portion or by pinch seal, and the inside of the light emitting portion in the arc tube A pair of electrodes arranged opposite to each other along the tube axis direction of the arc tube, and the electrodes are electrically connected via a sealing foil made of molybdenum embedded in each of the sealing portions. In a high-pressure discharge lamp comprising an external lead rod protruding outside the sealing portion,
The external lead rod is made of molybdenum or molybdenum alloy,
The external lead rod has a buffer portion formed by covering at least an end portion including the inner end face with a foil material made of molybdenum .

  In the high-pressure discharge lamp of the present invention, the buffer portion may be formed by folding back a foil material constituting the sealing foil.

In the high-pressure discharge lamp of the present invention, the external lead rod and the sealing foil are welded and joined,
It is preferable that the buffer portion is configured to cover a weld region between the external lead bar and the sealing foil.

According to the high pressure discharge lamp of the present invention, for example, when the volume of the external lead rod increases due to oxidation of the surface of the external lead rod made of molybdenum or molybdenum alloy or due to thermal expansion of the external lead rod. Even so, in addition to the plastic deformation of the sealing foil, the volume increase of the external lead rod is moderately absorbed by the plastic deformation of the foil material constituting the buffer portion. Thereby, it can prevent reliably that a crack generate | occur | produces in the glass in a seal | sticker part, or foil float arises, and can obtain a desired lamp life.
In addition, since the external lead rod is made of molybdenum or a molybdenum alloy, the external lead rod has higher workability than that made of, for example, tungsten. Therefore, in the lamp manufacturing process, the external lead rod can be processed. Therefore, it is possible to avoid the problem that the number of manufacturing steps is increased.

It is sectional drawing along the tube axis | shaft of the arc_tube | light_emitting_tube which shows the outline of a structure in an example of the high pressure discharge lamp of this invention. It is an expanded sectional view which shows a part of high-pressure discharge lamp shown in FIG. It is a side view which shows a part of structure of the electrode mount provided with one electrode which operate | moves as a cathode in the high pressure discharge lamp shown in FIG. FIG. 4 is a perspective view showing the configuration of the electrode mount shown in FIG. 3 with a part thereof omitted. FIG. 4 is an enlarged cross-sectional view showing a part of the electrode mount shown in FIG. It is a side view which shows a part of other structural example of the electrode mount which concerns on the high pressure discharge lamp of this invention in a cross section. It is an expanded sectional view showing a part of electrode mount shown in Drawing 6, Comprising: (a) Axial direction sectional view, (b) AA line sectional view (width direction sectional view) in (a). It is a perspective view which abbreviate | omits one part and shows the further structural example of the electrode mount which concerns on the high pressure discharge lamp of this invention. It is an expanded sectional view which shows a part of electrode mount shown in FIG. 8 in the state arrange | positioned airtightly at the sealing part, Comprising: (a) Axial sectional view, (b) AA line cross section in (a) It is a figure (width direction sectional drawing). It is an expanded sectional view showing a part in other example of composition of an electrode mount concerning a high-pressure discharge lamp of the present invention, (a) Axial direction sectional view, (b) AA line sectional view in (a) ( It is width direction sectional drawing). It is a side view which shows a part in cross section the structure of the electrode mount provided with one electrode which operate | moves as a cathode in the high-pressure discharge lamp for a comparison which concerns on the comparative example 1. FIG.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a cross-sectional view taken along the tube axis of an arc tube showing an outline of the configuration of an example of a high-pressure discharge lamp according to the present invention. FIG. 2 is an enlarged view showing a part of the high-pressure discharge lamp shown in FIG. 3 is a side view showing a part of the configuration of an electrode mount including one electrode operating as a cathode in the high-pressure discharge lamp shown in FIG.
This high-pressure discharge lamp is driven to be lit by a direct current power source, for example, and is formed integrally with each of the light emitting part 11 having an outer shape that forms a discharge space therein and both ends of the light emitting part 11. The arc tube 10 is composed of one rod-shaped sealing portion 12a and the other sealing portion 12b that extend outward along the tube axis direction.

The arc tube 10 is made of, for example, quartz glass, and an appropriate luminescent material is sealed in the light emitting portion 11 of the arc tube 10. For example, in the case of constituting a high-pressure mercury lamp, for example, 0.05 mg / mm ³ or more of mercury is enclosed as a luminescent substance, and a rare gas, halogen, or the like is enclosed. Further, for example, when configuring a metal halide lamp, a metal such as gallium or iron is sealed in addition to these inclusions, and when configuring a xenon lamp, xenon gas is sealed as a luminescent material.

  In the light emitting section 11 of the arc tube 10, one electrode 21 that operates as a cathode and the other electrode 26 that operates as an anode are arranged so as to face each other along the tube axis direction of the arc tube 10.

One electrode 21 is an electrode body composed of a tapered portion 23 that expands from the front end to the rear end and an electrode shaft portion 24 that extends from the rear end of the tapered portion 23 toward one sealing portion 12a of the arc tube 10. 22 and a coil (not shown) wound spirally along the outer peripheral surface of the electrode body 22.
Examples of the material constituting each of the electrode body 21 and the coil include tungsten, thorium tungsten, molybdenum, and the like.
The maximum outer diameter of the electrode shaft portion 24 is, for example, φ0.6 to φ6 mm, and the outer diameter of the rear end portion 24a of the electrode shaft portion 24 is, for example, φ0.5 to φ2.0 mm.

The other electrode 26 includes a substantially cylindrical electrode head portion 27 and an electrode shaft portion 28 extending in the axial direction continuously to the rear end of the electrode head portion 27.
Examples of the material constituting the other electrode 26 include tungsten and thorium tungsten.
The maximum outer diameter of the electrode head 27 is, for example, φ2 to φ6 mm, and the outer diameter of the rear end portion 28a of the electrode shaft portion 28 is, for example, φ0.8 to φ2.0 mm.

One electrode mount 20 is disposed in an airtight manner on one sealing portion 12 a in the arc tube 10. One electrode mount 20 includes one electrode 21, a columnar external lead rod 45, and a rear end portion 24 a of an electrode shaft portion 24 of one electrode 21 electrically connected to one end and an external end to the other end. The leading end 46 of the lead bar 45 is electrically connected to the sealing foil 30 made of, for example, molybdenum. A binder 40 made of, for example, a tantalum wire is provided on a part of the outer peripheral surface (the lower surface in FIGS. 2 and 3) at the rear end portion 24a of the electrode shaft portion 24 of the one electrode 21. Is given.
The rear end portion 24a of the electrode shaft portion 24 of the one electrode 21 is welded and electrically connected to the front end portion of the one surface 30a of the sealing foil 30 that is hermetically embedded in the one sealing portion 12a. Thus, the rear end portion 24a of the electrode shaft portion 24 is embedded and held in one sealing portion 12a. On the other hand, as will be described in detail below, the front end portion 46 of the external lead bar 45 is welded and electrically connected to the rear end portion of the sealing foil 30.

The other electrode mount 25 is airtightly disposed on the other sealing portion 12 b of the arc tube 10. The other electrode mount 25 includes the other electrode 26, a columnar external lead rod 45, a rear end portion 28a of the electrode shaft portion 28 of the other electrode 26 at one end and an external end at the other end. The leading end 46 of the lead bar 45 is electrically connected to the sealing foil 30 made of, for example, molybdenum. A binder 40 made of, for example, a tantalum wire is applied to a rear end portion 28a of the electrode shaft portion 28 of the other electrode 26, and a binder processing of the electrode shaft portion 24 related to the one electrode mount 20 is performed. Binder processing is performed by being provided on the outer peripheral surface portion in the same direction as the portion.
The rear end portion 28a of the electrode shaft portion 28 of the other electrode 26 is welded and electrically connected to the front end portion of the one surface 30a of the sealing foil 30 that is hermetically embedded in the other sealing portion 12b. Thus, the rear end portion 28a of the electrode shaft portion 28 is embedded and held in the other sealing portion 12b. On the other hand, as will be described in detail below, the front end portion 46 of the external lead bar 45 is welded and electrically connected to the rear end portion of the sealing foil 30.
The other electrode mount 25 has the same configuration as that of the one electrode mount 20 except that the other electrode 26 is provided instead of the one electrode 21 in the one electrode mount 20, for example. The same components as those of the electrode mount 20 are denoted by the same reference numerals.

The external lead bar 45 is made of molybdenum or a molybdenum alloy.
Examples of the molybdenum alloy include alkali metals such as potassium (K); alkaline earth metals such as calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra); lanthanum (La) and cerium (Ce). Lanthanoids such as); actinides such as thorium (Th); transition metals such as yttrium (Y), and one or more metals selected from the group of these oxides contained (doped) in molybdenum Is preferred.
Moreover, it is preferable that content of metals other than molybdenum in a molybdenum alloy is 0.8-1.2 wt%, for example.
Since the external lead bar 45 is made of molybdenum or a molybdenum alloy, a stable current can be supplied and excellent workability can be obtained. In particular, since the outer lead rod 45 is made of a molybdenum alloy, deformation or breakage due to recrystallization of the outer lead rod 45 can be suppressed.
The outer diameter of the external lead rod 45 is, for example, φ0.8 to φ2.0 mm.

Thus, the high-pressure discharge lamp has a buffer portion 35 in which at least an end portion (tip portion 46) including the inner end surface (tip surface) of the external lead rod 45 is covered with a foil material.
The configuration of the buffer portion 35 in the illustrated example will be described in detail. As shown in an enlarged view in FIGS. 4 and 5, the sealing foil 30 is the rear end of the foil material constituting the sealing foil 30. The side portion is folded back in the axial direction via the first bending portion 31 and the second bending portion 32, and a stacking portion 33 is formed in which the minute gap S is interposed or closely stacked in a triple manner. For example, it has an S-shaped form in a side view. The distal end portion 46 of the external lead bar 45 is subjected to binder processing by providing a binder 41 formed by winding a wire made of tantalum in a coil shape, for example, on the outer peripheral surface. It welds and is electrically connected in the location where the other surfaces 30b of the foil material in the heavy part 33 face. As a result, a buffer portion 35 is formed in which the entire outer peripheral surface of the distal end portion 46 of the external lead rod 45 is covered with the foil material, and the distal end portion 46 of the external lead rod 45 is in direct contact with the glass constituting the arc tube 10. It is in a state not to do.

The buffer portion 35 is formed in a state in which the welding region W (the region where the binder processing is performed on the external lead rod 45) between the external lead rod 45 and the sealing foil 30 is covered, as in the illustrated example. Is preferred.
Due to such a configuration, when the lamp is lit, the welded portion between the external lead bar 45 and the sealing foil 30 is deformed, which causes cracks in the glass at the seal portion, It is possible to reliably prevent the foil floating.

The thickness of the foil material constituting the sealing foil 30 is, for example, 0.025 to 0.03 mm, and the widthwise dimension (the lateral dimension in FIG. 5B) is, for example, 3 to 6 mm.
Moreover, the outer diameter of the wire which comprises the binder 41 is (phi) 0.25- (phi) 0.5 mm, and the magnitude | size (axial direction length) of the welding area | region W is 1.2-3.5 mm, for example.
When the stacked portion 33 in the buffer portion 35 is formed with the minute gap S interposed, the size of the minute gap S is, for example, 0.010 to 0.015 mm.

  One sealing portion 12a and the other sealing portion 12b in the high-pressure discharge lamp described above are, for example, in a state where an electrode mount is inserted into a cylindrical arc tube forming material and disposed at an appropriate position. It is formed by heating and shrinking the end region of the forming material (the region surrounding the periphery of the sealing foil in the electrode mount) from the outer surface.

Thus, according to the high-pressure discharge lamp having the above-described configuration, the external lead rod 45 is made of molybdenum or a molybdenum alloy, so that the external lead rod 45 has higher workability than that made of, for example, tungsten. Therefore, it is possible to avoid the problem that the number of manufacturing steps is increased due to the processing of the external lead rod in the lamp manufacturing process. In particular, since the external lead rod 45 is made of a molybdenum alloy, the external lead rod 45 can be prevented from being recrystallized more than that made of tungsten, for example, so that, for example, when welding with a lead wire or a base. Even when an impact or vibration is applied, the deformation or breakage of the external lead rod 45 can be reliably prevented.
In addition, the rear end side portion of the foil material constituting the sealing foil 30 is folded back in the axial direction via the first curved portion 31 and the second curved portion 32, and the stacking portion 33 is overlapped in three layers. The leading end portion 46 of the lead bar 45 is welded and joined to the sealing foil 30, whereby the leading end portion 46 including the inner end face of the external lead rod 45 has a buffer portion 35 covered with a foil material. ing. By adopting such a configuration, the temperature of the seal portion (for example, the welded portion between the external lead bar 45 and the foil material (sealing foil 30)) becomes overheated, or the external lead bar 45 For example, when the surface oxidation of a portion exposed to the outside proceeds, it is possible to prevent or suppress the oxidation of the surface of the external lead bar 45 at the welding point. Even if the volume of the external lead rod 45 is increased by oxidizing the surface of the external lead rod 45, the foil constituting the buffer portion 35 in addition to the plastic deformation of the sealing foil 30. Since the material is plastically deformed and relaxed and absorbed, it is possible to reliably prevent the occurrence of cracks in the glass at the seal portion and the occurrence of foil floating. In addition, when the lamp is lit, the stress (compression strain generated in the glass) caused by the difference in thermal expansion coefficient between molybdenum or the molybdenum alloy constituting the external lead rod 45 and the glass causes the sealing foil 30 to be plastically deformed. In addition, the foil material constituting the buffer portion 35 is securely absorbed by being plastically deformed, thereby reliably preventing the glass at the seal portion from cracking or causing the foil to float. Thus, the desired lamp life can be obtained.
In addition, since the buffer portion 35 is formed in a state where the minute gap S is interposed, the above effect can be obtained more reliably.

As mentioned above, although one Embodiment of the high pressure discharge lamp of this invention was described, this invention is not limited to said form, A various change can be added.
For example, it is not necessary that both the external lead bar and the sealing foil are joined by welding using a binder. As shown in FIGS. 6 and 7, the external lead bar 45 and the sealing foil The foil 30 may be configured to be joined by so-called projection welding.
In this example, the external lead bar 45 of one of the electrode mounts 20 is covered with a rear end side portion of the sealing foil 30 so that a buffer portion 35 is to be formed, and a step portion is formed on the front end portion 47a. And a main body portion 47b having an outer diameter larger than that of the distal end portion 47a.
A plurality (two in this example) of projections (projections) 48 are formed on a part of the outer peripheral surface of the distal end portion 47a of the external lead bar 45 so as to be separated from each other in the axial direction. The protrusion 48 is welded and electrically connected to the other surface 30b of the foil material at the portion of the stacked portion 33 where the other surfaces 30b of the foil material face each other. As a result, the buffer portion 35 is formed in which the entire outer peripheral surface of the tip portion 47a of the external lead rod 45 is covered with the foil material, and the tip portion 47a of the external lead rod does not directly contact the glass constituting the arc tube 10. It is in a state.
The size of each protrusion 48 and the number of protrusions 48 are not particularly limited. For example, each protrusion 48 has an axial dimension of 0.3 to 0.7 mm and a width dimension. It is 0.8-2.0 mm, and the number of the protrusion parts 48 is 2-5 pieces.
Even in such a configuration, the same effect as described above can be obtained. Moreover, as described above, the external lead rod 45 is made of molybdenum or a molybdenum alloy, and therefore has excellent workability as compared with, for example, tungsten. Therefore, the protrusion 48 can be easily formed, and a sufficiently high welding strength can be obtained without using, for example, a binder. Therefore, an intended electrode mount can be easily manufactured. The incidental effect of being able to do is obtained.

Furthermore, the buffer portion in the high-pressure discharge lamp of the present invention is not limited to the configuration according to the above-described embodiment as long as the tip portion of the external lead rod is not in contact with the glass constituting the arc tube. For example, as shown in FIG. 8, the buffer portion 35 in the electrode mount is configured in a state where a part of the sealing foil 30 is wound around the outer peripheral surface of the distal end portion 46 of the external lead 45 to form a cylindrical shape. It may be. The sealing foil 30 in this example has a strip-shaped extending portion 34 extending outward in the width direction from one side edge at the rear end portion in the length direction of the strip-shaped foil material. Then, the extending part 34 of the sealing foil 30 is folded back in the width direction so that the one surfaces 30a face each other, and the end part in the width direction of the extending part 34 is further connected to the distal end part 46 of the external lead bar 45. Thus, the buffer portion 35 is formed. The distal end portion 46 of the external lead rod 45 is subjected to binder processing, and the inner end surface (front end surface) of the external lead rod 45 is, for example, axially outward from the inner end edge (front end edge) of the buffer portion 35. In the state of being positioned at, the tip end portion 46 is welded and electrically connected to the foil material. As a result, the entire outer peripheral surface of the distal end portion 46 of the external lead bar 45 is covered with the foil material.
In such an electrode mount, in the process of forming the sealing portion in the lamp manufacturing process, the portion of the foil material that protrudes from the front end surface of the external lead bar 45 is crushed, and as shown in FIG. The inner end surface (front end surface) of the lead bar 45 is in a state where the front end portion 46 is covered with a foil material.

  Furthermore, the buffer portion in the high-pressure discharge lamp of the present invention does not need to be constituted by a part of the foil material constituting the sealing foil. For example, as shown in FIG. 10, the buffer portion 35 may be configured by a buffer foil 38 made of a foil material different from the foil material that forms the sealing foil 30. In this example, the front end portion 46 of the external lead rod 45 subjected to, for example, binder processing is positioned on one surface 30a at the rear end portion of the foil material constituting the sealing foil 30, and the outer peripheral surface and The inner end face (tip face) is covered with a foil material constituting the buffer foil 38. In this state, the distal end portion 46 of the external lead bar 45 is welded and joined to each of the foil material constituting the sealing foil 30 and the foil material constituting the buffer foil 38, thereby the buffer portion 35. Is configured.

  Furthermore, the buffer portion in the high-pressure discharge lamp of the present invention is formed in a state in which the welded area W (the area where the binder is processed in the external lead bar 45) between the external lead bar 45 and the sealing foil 30 is covered. There is no need to be.

Furthermore, the high-pressure discharge lamp of the present invention may be configured to be driven by, for example, an AC power supply, or may be configured to have a sealing portion formed by a pinch seal.
Furthermore, the high-pressure discharge lamp of the present invention may have a configuration in which a base is provided on one or both of the sealing portions. In such a configuration, for example, the base is usually fixed to the arc tube with an adhesive, and the oxidation of the external lead rod is easily promoted by moisture contained in the adhesive. However, with the configuration having the buffer portion, it is possible to suppress or prevent the occurrence of cracks and the foil floating phenomenon due to the oxidation of the external lead rod in the seal portion.

<Example 1>
In accordance with the configuration shown in FIGS. 1 to 5, a total of 30 high-pressure discharge lamps having the following specifications were produced.
The arc tube (10) is made of quartz glass, the maximum outer diameter of the light emitting part (11) is 13 mm, the inner volume of the light emitting part (11) is 275 mm ³ , the outer diameter of the sealing part is 8 mm, and the axial length is 30 mm.
In the light emitting part (11) of the arc tube (10), 2 MPa of xenon gas was sealed at a static pressure.
The electrode body (22) of one electrode (21) is made of thorium tungsten and tungsten, the maximum outer diameter of the electrode shaft portion (24) is φ2 mm, the outer diameter of the rear end portion (24a) is φ0.8 mm, and the electrode shaft The total length of the part (24) is 5 mm.
The other electrode (26) is made of thorium tungsten and tungsten, the maximum outer diameter of the electrode head (27) is 3 mm, the length of the electrode head (27) is 18 mm, and the rear end of the electrode shaft (28) The outer diameter of (28a) is φ0.8 mm, and the length of the electrode shaft portion (28) is 6 mm. The interelectrode distance between one electrode (21) and the other electrode (26) is 1.5 mm.
The external lead rod (45) is made of a molybdenum alloy containing cerium, and has an outer diameter of 0.8 mm and a total length of 12 mm.
The binder (41) provided on the external lead rod (45) is a region in which a tantalum wire having a wire diameter of φ0.25 mm is wound in a coil shape, the number of windings is 2 turns, and the binder processing is performed. The size of (welding area W) is 1.5 mm.
The sealing foil (30) has a strip shape with an axial dimension of 20 mm (the length from the rear end of the electrode shaft portion to the tip of the external lead bar is 11 mm), a width dimension of 4 mm, and a thickness of 0.025 mm. Made of foil material. The buffer portion (35) is configured by being overlapped in a triple manner with the outer end portion of the foil material folded back and the minute gap (S) interposed, and the axial length of the stacked portion (33). Is 4 mm (in a state of covering the welding region W), and the size of the minute gap (S) is 0.01 mm in width.

For the 30 high-pressure discharge lamps described above, a 75 W power supply is supplied from a DC power source for 30 minutes, and then an operation for stopping the power supply for 30 minutes is performed 500 times in total, and a power supply of 500 times is performed. The number of high-pressure discharge lamps that did not light more than once was examined.
Further, a lighting / extinguishing test was performed in the same manner as described above except that the supplied power was changed to 150 W, 200 W, and 300 W, and the number of high-pressure discharge lamps that did not light more than once out of 500 power supplies was examined. The results are shown in Table 1.

<Comparative Example 1>
As shown in FIG. 11, it is the same as the electrode mount in the high-pressure discharge lamp according to Example 1 except that the joint between the external lead bar (45) and the sealing foil (30) does not have a buffer part. A total of 30 comparative high-pressure discharge lamps having the same configuration as the high-pressure discharge lamp according to Example 1 except that the electrode mount (20A) having the configuration was used were manufactured. These comparative high-pressure discharge lamps were subjected to a lighting / extinguishing test in the same manner as in Example 1. The results are shown in Table 1.

As is clear from the results in Table 1, it was confirmed that the high pressure discharge lamp according to Example 1 surely steadily lights up regardless of whether the supplied power is 75 W, 150 W, 200 W, or 300 W. Moreover, in any of the high pressure discharge lamps after the lighting / extinguishing test, no cracks or foil lifting were confirmed in the welded portion in the sealing portion.
On the other hand, in the high pressure discharge lamp for comparison according to Comparative Example 1, there is a lamp that does not steadily light even when the supplied power is 75 W, 150 W, 200 W, and 300 W. In these high pressure discharge lamps, In addition, it was confirmed that a crack occurred in the welded portion in the sealing portion or that a foil float occurred .

DESCRIPTION OF SYMBOLS 10 Light emission tube 11 Light emission part 12a One sealing part 12b The other sealing part 20, 20A One electrode mount 21 One electrode 22 Electrode main body 23 Tapered part 24 Electrode axial part 24a Rear end part 25 Other electrode mount 26 The other Electrode 27 electrode head portion 28 electrode shaft portion 28a rear end portion 30 sealing foil 30a one surface 30b other surface 31 first bending portion 32 second bending portion 33 stacking portion 34 extending portion 35 buffering portion 38 buffering foil 40 , 41 Binder 45 External lead rod 46 Tip portion 47a Tip portion 47b Main body portion 48 Protrusion portion S Micro gap W Welding region

Claims (3)

A light emitting tube made of glass in which sealing portions are formed by heating and shrinking at both ends of the light emitting portion or by pinch seal, and along the tube axis direction of the light emitting tube inside the light emitting portion in the light emitting tube A pair of electrodes arranged opposite to each other and a sealing foil made of molybdenum embedded in each of the sealing portions, and electrically connected to the electrodes, outside the sealing portion. In a high-pressure discharge lamp with a protruding external lead rod,
The external lead rod is made of molybdenum or molybdenum alloy,
A high-pressure discharge lamp comprising a buffer portion in which an end portion including at least an inner end face of the external lead rod is covered with a foil material made of molybdenum .   The high-pressure discharge lamp according to claim 1, wherein the buffer portion is formed by folding back a foil material constituting the sealing foil. The external lead bar and the sealing foil are joined by welding,
3. The high-pressure discharge lamp according to claim 1, wherein the buffer portion is formed in a state of covering a welding region between the external lead rod and the sealing foil.

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