JP2007115498A - Short-arc type discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a short-arc type discharge lamp with high reliability, of which the inner lead rod and the current collecting disc can be connected tightly by a welding method that uses laser beam irradiation or electron beam irradiation. <P>SOLUTION: A contact part of the current collecting disc 21 and an inner lead rod holding a cylinder-shaped body 16 is formed so as to reach a mixed layer 21a, in a manner with the contact part getting over across a crossing point (A) of the contact part and a boundary line (L) of an inside end face of the current collecting disc, the mixed layer, and the material constituting the current collecting disc. Strip-off stress is relaxed, by making a>b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a short arc type discharge lamp such as a high-pressure mercury lamp.

FIG. 5 is a cross-sectional view for explaining a short arc type discharge lamp.
In this discharge lamp, the bulb 10 is formed of quartz glass and has an elliptical spherical arc tube portion 11 surrounding the light emitting space S, and a cylindrical shape continuously connected to extend outward from both ends of the arc tube portion 11. A state in which a part of the sealing tube portion 12 is reduced in diameter at a location close to the luminous tube portion 11 of the sealing tube portion 12 following the luminous tube portion 11. The narrowing-down portion 12a is formed.
An anode 13 and a cathode 14 are arranged in the arc tube portion 11 of the bulb 10 so as to face each other, and each of them is made of, for example, tungsten extending from the sealing tube portion 12 to the arc tube portion 11 along the tube axis. The cylindrical internal lead bar 15 is fixed and supported at the tip. The arc tube portion 11 of the bulb 10 is filled with a noble gas such as xenon, argon, krypton or a mixture thereof, and a luminescent substance such as mercury. The proximal end portion of the internal lead bar 15 is connected to a current collecting disk 21 disposed between the internal lead bar holding cylinder 16 and the sealing glass member 17. At the center of the current collecting disc 21, a hole having an inner diameter that matches the outer diameter of the internal lead rod 15 is formed, and the internal lead rod is connected in an inserted state.
Inside the sealing tube portion 12 of the bulb 10, an internal lead rod holding cylinder 16 made of quartz glass having a cylindrical hole with an inner diameter matching the outer diameter of the internal lead rod 15 at a position close to the arc tube portion 11. However, the inner lead bar 15 is inserted and the outer peripheral surface of the inner lead bar holding cylinder 16 is welded to the inner surface of the narrowed portion 12a which is a part of the sealing tube portion 12, One end face 16 a of the internal lead bar holding cylinder 16 is exposed to the light emitting space S. A sealing glass member 17 is disposed on the outer end side of the inner lead bar holding cylinder 16 in the sealing tube portion 12. In the sealing glass member 17, the inner end portion 171 on the light emitting space S side is formed in a truncated cone shape having a diameter that increases toward the outer end. Following the inner end portion 171, a sealing tube portion is formed. A cylindrical body 172 having an outer diameter matching the inner diameter of 12 is formed. The sealing glass member 17 is formed with a bottomed hole 173 extending from the outer end surface along the axial direction. The bottomed hole 173 has an outer lead having an outer diameter matching the inner diameter. A rod 18 is inserted.
A plurality of strip-shaped metal foils 20 made of molybdenum are arranged on the outer peripheral surface of the sealing glass member 17 so as to be spaced apart from each other in the circumferential direction of the sealing glass member 17. The inner end portion is connected to the current collecting disk 21 and is electrically connected to the inner lead rod 15, while each outer end portion of the metal foil 20 is connected to the outer end surface of the sealing glass member 17. The glass member 17 extends along the outer lead rod 18 and extends from the inner end of the sealing glass member 17 toward the outer end. Further, the outer peripheral surface of the sealing glass member 17 is hermetically welded to the inner surface of the sealing tube portion 12 via the metal foil 20.
On the outer end side of the sealing glass member 17, a lead rod holding cylinder 19 made of quartz glass having a cylindrical hole that matches the outer diameter of the external lead rod 18 is inserted into the external lead rod 18. The outer peripheral surface of the lead bar holding cylinder 19 is air-tightly welded to the inner surface of the sealing tube portion 12.

  In the above description, the internal lead bar 15 and the current collecting disk 21 are joined by brazing or resistance welding. However, these means have various problems in terms of stability and reliability of the joined state or manufacturing cost. is there.

That is, when the internal lead bar and the current collecting disk are joined by brazing, there are the following problems.
(1) First, the brazing material is required to be a material that can withstand use at a high temperature of about 1000 ° C. for a long time from the temperature reached by the internal lead bar when the lamp is turned on. Furthermore, it is required that the material has good wettability with respect to both members so as to be used for joining the inner lead bar and the current collecting disk. The material of the internal lead bar is tungsten, which is the same as the electrode component material, and the current collector disc is often made of molybdenum from the viewpoint of workability and heat resistance, and has good wettability to these metals. In addition, platinum (Pt) is preferably used as a material having heat resistance.
Thus, platinum is a metal whose melting point is higher than the recrystallization temperature (˜1200 ° C.) of molybdenum, and when the internal lead bar and the current collector disk are heated above their melting point in the brazing process, the recrystallization of molybdenum. The current collecting disk becomes brittle and easily breaks. As a result, when an excessive load such as an electrode load is applied to the current collecting disk via the internal lead rod, brittle fracture may be caused.
(2) In a lamp with mercury enclosed in the arc tube, platinum reacts with mercury to form an alloy, which may lower the melting point, so the junction between the internal lead bar and the current collector disk can melt. There is sex.
(3) Further, in the brazing process, it is necessary to heat the internal lead bar and the entire current collecting disk to the melting point or higher of the brazing material. For this reason, an unbonded internal lead bar and a current collecting disk are set in a batch type furnace, the inside of the furnace is maintained in vacuum, heated to 1800 ° C. or higher, and brazed. At that time, a series of steps of heating, maintaining, and slow cooling takes a lot of time, and productivity is poor.

On the other hand, resistance welding has the following problems.
First, since the welding is performed on the side surface of the cylinder, the resistance value is not stable, and the joint strength is unstable. Furthermore, in order to ensure the reliability and mechanical strength of the electrical connection between the internal lead bar and the current collecting disk, multi-point welding is performed, but in resistance welding, the resistance value changes as the number of connection points increases. The joint strength becomes unstable. As a result, the strength of the joint is not stable, and as a result, it becomes easy to cause a welding failure. If the welding is lost, the contact area of the joint becomes smaller, resulting in a larger resistance value, increased resistance heat due to the current during lighting, overheating, and melt fracture, even without mechanical failure. To. In particular, the possibility of destruction due to overheating increases in a large-sized large-current type lamp.
Japanese Patent Laid-Open No. 2003-132828 JP 2003-323866 A Japanese Patent Laid-Open No. 2002-8586 Japanese Patent Laid-Open No. 11-342479

  From the above, it is desired to examine a method for connecting the current collecting disk and the internal lead bar by a method in place of conventional brazing or resistance welding. In view of such circumstances, the present inventors examined joining by melting of members to be joined, and as a specific means thereof, an internal lead bar and a current collecting disk by laser beam welding or electron beam welding. We conducted an intensive study on joining. Laser beam welding and electron beam welding are basically performed by heating the vicinity of the joining portion of the member to be joined to the melting point or higher without using other members, and by joining the materials together. It is considered that a strong bonding state can be obtained without using other substances.

  However, as a result of studies by the present inventors, it has been found that sufficient mechanical strength may not be obtained even when the current collecting disk and the internal lead bar are joined by these means.

Hereinafter, the phenomenon in which such a defect has occurred will be described in detail by taking a welded portion by a laser beam welding method as an example.
FIG. 6A is an explanatory cross-sectional view in which a joint portion between the internal lead bar 15 and the current collecting disk 21 by a laser beam welding method is cut along a cross section passing through the tube axis of the lamp.
As a result of detailed studies on the joint state of the internal lead rod 15 and the current collecting disk 21 by the laser beam welding method, the present inventors have found the following.

The current collecting disk plays two roles of (a) “supporting the weight of the electrode” and (b) “flowing current”. Since the investigation of the cause of the fracture will be examined here, the former (A) will be described in detail with reference to FIGS. 6 (a), 6 (b) and FIG.
The state of supporting the weights of the electrode 13 and the internal lead bar 15 is as shown in FIG. 6A. That is, the current collecting disk 21 is supported by the current collecting disk 21 supported by the internal lead bar holding cylinder 16. An internal lead rod 15 connected to the electrode 13 holds the electrode 13. As a result, a force F that pushes up the current collecting disk 21 upward in the drawing acts on the contact portion between the internal lead bar holding cylinder 16 and the current collecting disk 21.

A further enlarged view is shown in FIG. The internal lead rod 15 is pulled downward in the figure by the weight of the electrode (13), and the current collecting disk 21 and the holding cylinder contact portion (the minimum diameter at which the current collecting disk 21 is supported by the holding cylinder 16). Part) or the internal lead rod 15 generates a tension T.
As a result of being exposed to such a stress state, it is assumed that the welded portion is broken.

In FIG. 6B, the vicinity of the welded portion W surrounded by a circle is further enlarged and illustrated in FIG. In FIG. 7, the sealing glass member (17) located above is omitted for convenience.
In FIG. 7, a mixed layer 21 a is a layer in which two kinds of metals, tungsten constituting the internal lead rod 15 and molybdenum constituting the current collecting disk 21 are mixed. And the part shown with the code | symbol 21b in the figure is a recrystallized part of molybdenum partially formed by the high temperature at the time of welding, although it is comprised with molybdenum as a material. Reference numeral 21c denotes an initial molybdenum phase, which is a non-recrystallized portion. Recrystallization occurs in the weld zone in this way, which is a characteristic of welding between materials with different melting points, but the temperature is adjusted so that the metal with a higher melting point melts. This is because of recrystallization. The recrystallization temperature of tungsten is about 2000 ° C. and the recrystallization temperature of molybdenum is about 1200 ° C.

As a result, the mixed layer 21a forms a boundary L with the molybdenum recrystallized portion 21b. At this boundary L, the bonding force is weaker than other interfaces, and when stress (tension T) is applied in the tearing direction, It was found that a crack occurred in the direction of the arrow N and fractured along the boundary L.
Such a boundary such as L is similarly formed in a welded part by an electron beam welding method as well as a laser beam welding method.

  In view of the above, the problem to be solved by the present invention is that the internal lead bar and the current collecting disk can be firmly joined by a welding method by laser beam irradiation or electron beam irradiation, and a highly reliable short arc type An object is to provide a discharge lamp.

The short arc type discharge lamp according to the present invention is:
A bulb composed of an arc tube portion and a sealing tube portion connected to both ends of the arc tube portion;
A cathode and an anode disposed opposite to each other in the arc tube portion;
An internal lead bar having a cathode or anode at the tip;
A lead rod holding cylinder that is penetrated by the internal lead rod and arranged in the sealing tube portion of the valve;
A current collecting disk, which is disposed in the sealing tube portion along the outer end surface of the lead rod holding cylinder, and is connected to the lead rod insertion hole formed in the center thereof through the proximal end portion of the inner lead rod. When,
One end of the current collector disk is connected, and a metal foil embedded in a sealed tube portion in an airtight manner;
An external lead rod connected to the other end of the metal foil and led out of the sealing tube portion;
A short arc type discharge lamp comprising:
The current collecting disc and internal lead rod are mixed in the vicinity of the lead rod insertion hole on the inner end face of the current collecting disc by the laser beam welding method or the electron beam welding method. Is formed by joining,
At least a part of the contact portion between the current collecting disk and the inner lead rod holding cylinder is formed on the inner end face of the current collecting disk formed on the cross section passing through the lamp tube axis, the mixed layer, and the current collecting disk configuration It is characterized by being formed so as to reach the mixed layer beyond the intersection (A) where the boundary (L) of the material intersects.

Further, a bulb composed of a light emitting tube portion and a sealing tube portion connected to both ends of the light emitting tube portion;
A cathode and an anode disposed opposite to each other in the arc tube portion;
An internal lead bar having a cathode or anode at the tip;
A lead rod holding cylinder that is penetrated by the internal lead rod and arranged in the sealing tube portion of the valve;
A current collecting disk, which is disposed in the sealing tube portion along the outer end surface of the lead rod holding cylinder, and is connected to the lead rod insertion hole formed in the center thereof through the proximal end portion of the inner lead rod. When,
One end of the current collector disk is connected, and a metal foil embedded in a sealed tube portion in an airtight manner;
An external lead rod connected to the other end of the metal foil and led out of the sealing tube portion;
A short arc type discharge lamp comprising:
The current collecting disc and internal lead rod are mixed in the vicinity of the lead rod insertion hole on the inner end face of the current collecting disc by the laser beam welding method or the electron beam welding method. Is formed by joining,
In the section through the tube axis of the valve,
An imaginary half-line n starting from the intersection (A) of the inner end face of the current collecting disk and the boundary (L) of the mixed layer and the current collecting disk constituting material, and passing on the tangent line of the boundary (L);
An angle α formed by an imaginary half line m drawn in a direction perpendicular to the tube axis of the bulb from the intersection (A) toward the internal lead rod is less than 90 °.

Further, a bulb comprising a collecting and emitting tube portion and a sealing tube portion connected to both ends of the arc tube portion,
A cathode and an anode disposed opposite to each other in the arc tube portion;
An internal lead bar having a cathode or anode at the tip;
A lead rod holding cylinder that is penetrated by the internal lead rod and arranged in the sealing tube portion of the valve;
A current collecting disk, which is disposed in the sealing tube portion along the outer end surface of the lead rod holding cylinder, and is connected to the lead rod insertion hole formed in the center thereof through the proximal end portion of the inner lead rod. When,
One end of the current collector disk is connected, and a metal foil embedded in a sealed tube portion in an airtight manner;
An external lead rod connected to the other end of the metal foil and led out of the sealing tube portion;
A short arc type discharge lamp comprising:
The current collecting disc and internal lead rod are mixed in the vicinity of the lead rod insertion hole on the inner end face of the current collecting disc by the laser beam welding method or the electron beam welding method. It is joined by being formed in
In the section through the tube axis of the valve,
An imaginary half-line n starting from the intersection (A) of the inner end face of the current collecting disk and the boundary (L) of the mixed layer and the current collecting disk constituting material, and passing on the tangent line of the boundary (L);
The angle α formed with the virtual half-line m drawn in the direction perpendicular to the tube axis of the bulb from the intersection (A) toward the internal lead rod is 90 ° or less,
An angle β formed by the tangent line h drawn from the intersection (A) toward the inner surface of the current collecting disk in the mixed layer and the virtual half line m is greater than 0 °.

In the first aspect of the invention, the tensile stress applied to the boundary portion between the mixed layer and the current collecting disk constituent material can be reduced, and the mixed layer and the current collecting disk constituent material layer (molybdenum recrystallized phase) The force for peeling off the interface can be reduced.
According to the second or third aspect of the present invention, the tension is applied in a direction parallel to the surface of the current collecting disk, but the tangential direction of the boundary line between the mixed layer and the current collecting disk constituting material and the tension are applied. Since the angle α formed with this direction is less than 90 °, the force for peeling off the interface between the mixed layer and the current collecting disk constituting material layer (molybdenum recrystallized phase) can be reduced. If the magnitude of α is 35 ° or less, a sufficient effect can be obtained.
According to the present invention described above, the joint strength between the internal lead bar and the current collecting disk by laser beam welding or electron beam welding is formed so as to have any of the above structures, so that the joint strength is increased and high. A reliable short arc discharge lamp can be obtained.

  Hereinafter, embodiments of the present invention will be described. The basic structure of the short arc type discharge lamp according to the present invention is as described above with reference to FIG. 5, and will be described with reference to FIG.

[First Embodiment]
The first embodiment will be described with reference to FIGS. 1, 2, and 5.
First, the configuration of the entire lamp will be described with reference to FIG. This figure is a longitudinal sectional view of the lamp cut along the tube axis of the bulb.
In this discharge lamp, the bulb 10 is formed of quartz glass and has an elliptical spherical arc tube portion 11 surrounding the light emitting space S, and a cylindrical shape continuously connected to extend outward from both ends of the arc tube portion 11. Each of the sealing tube portions 12 is in a state where a part of the sealing tube portion 12 is reduced in diameter at a location close to the arc tube portion 11 of the sealing tube portion 12 following the arc tube portion 11. A narrowing portion 12a is formed.

  An anode 13 and a cathode 14 are arranged in the arc tube portion 11 of the bulb 10 so as to face each other, and each of them is made of, for example, tungsten extending from the sealing tube portion 12 to the arc tube portion 11 along the tube axis. The cylindrical internal lead bar 15 is fixed and supported at the tip. The arc tube portion 11 of the bulb 10 is filled with a noble gas such as xenon, argon, krypton or a mixture thereof, and a luminescent substance such as mercury.

Inside the sealing tube portion 12 of the bulb 10, an internal lead rod holding cylinder 16 made of quartz glass having a cylindrical hole with an inner diameter matching the outer diameter of the internal lead rod 15 at a position close to the arc tube portion 11. However, the inner lead bar 15 is disposed in a state where the inner lead bar 15 is inserted, and the outer peripheral surface of the inner lead bar holding cylinder 16 is welded to the inner surface of the narrowed portion 12a which is a part of the sealing tube portion 12. One end face 16 a of the lead rod holding cylinder 16 is exposed to the light emitting space S.
A sealing glass member 17 is disposed on the outer side of the inner lead bar holding cylinder 16 in the sealing tube portion 12. In the sealing glass member 17, the inner end portion 171 on the light emitting space S side is formed in a truncated cone shape having a diameter that increases toward the outer end. Following the inner end portion 171, a sealing tube portion is formed. A cylindrical body 172 having an outer diameter matching the inner diameter of 12 is formed.

The proximal end portion of the internal lead bar 15 is connected to a current collecting disk 21 disposed between the internal lead bar holding cylinder 16 and the sealing glass member 17. The internal lead rod 15 and the current collecting disc 21 are formed such that the inner lead rod 15 penetrates the lead rod insertion hole 211 formed in the current collecting disc 21 and the inner diameter portion of the lead rod insertion hole 211 and the internal lead. The outer peripheral part of the rod 15 is joined by a laser beam welding method, and the detailed configuration will be described later.
The sealing glass member 17 is formed with a bottomed hole 173 extending from the outer end surface along the axial direction. The bottomed hole 173 has an outer lead rod 18 having an outer diameter matching the inner diameter. Has been inserted.

A plurality of strip-shaped metal foils 20 made of molybdenum are arranged on the outer peripheral surface of the sealing glass member 17 so as to be spaced apart from each other in the circumferential direction of the sealing glass member 17. The inner end portion is connected to the current collecting disk 21 so that the metal foil 20 and the internal lead bar 15 are electrically connected. Each outer end portion of the metal foil 20 extends along the outer end surface of the sealing glass member 17 and is connected to the external lead rod 18, and extends from the inner end of the sealing glass member 17 toward the outer end. ing. Further, the outer peripheral surface of the sealing glass member 17 is hermetically welded to the inner surface of the sealing tube portion 12 via the metal foil 20.
An external lead rod holding cylinder 19 made of quartz glass having a cylindrical hole that matches the outer diameter of the external lead rod 18 is inserted into the outer end side of the sealing glass member 17. The outer lead surface 19 of the external lead rod holding cylinder 19 is hermetically welded to the inner surface of the sealing tube portion 12.

  FIG. 1 is a perspective view for explaining a state of a current collecting disk and an internal lead bar during laser beam welding. The current collecting disk 21 is a circular plate-like body, and has a thickness of 2 mm, an outer diameter φ20 mm, and an inner diameter φ6 mm, for example. The internal lead bar 15 has a total length of 100 mm and an outer diameter of 6 mm, and an electrode (anode) is fixed to a tip (upper end) (not shown). The rear end portion 15a of the inner lead rod 15 is fixed to the lead rod insertion hole 211 of the current collecting disc 21 with a chuck or the like, and a laser beam is irradiated in an argon gas atmosphere from the upper right direction on the paper surface. In the laser beam irradiation, the irradiation time of one time is, for example, 4 ms, and finally the entire circumference (360 °) direction is moved while relatively moving the position by 2 to 5 ° about the central axis of the internal lead rod 15 as a pivot. Irradiate. For example, 70 to 180 melt marks are formed discontinuously by the laser beam.

  Welding may be performed only on the inner end face of the current collecting disc 21 or on both faces. When welding is performed on both sides, it is desirable to form at least one discontinuous portion of welding so that gas accumulated between the outer peripheral surface of the inner lead bar 15 and the inner peripheral surface of the current collecting disc 21 is released. .

2 (a) and 2 (b) are cross-sectional views through the tube axis of the valve, showing an enlarged vicinity of the joint between the internal lead rod 15 and the current collecting disk 21. FIG.
Here, FIG. 2A is an enlarged view showing the vicinity of the anode 13 side internal lead rod 15 and the current collecting disk 21, and FIG. 2B is a portion surrounded by a circle in FIG. It is a figure expanding further. When the lamp tube axis is supported in the vertical direction as shown in FIG. 5, the sealing glass member 17 breaks down the welded portion in the current collecting disk 21 located on the upper side as shown in FIG. Since it is not involved in the mechanism, it is omitted in FIG.
In FIG. 2B, reference numeral 21 a is a mixed layer formed by melting tungsten constituting the internal lead rod 15 and molybdenum constituting the current collecting disk 21. Reference numeral 21b and reference numeral 21c are both made of the constituent material of the current collecting disk 21, but 21b is a recrystallized portion made of a recrystallized phase of molybdenum, and 21c is an initial molybdenum phase constituting the current collecting disk. Non-recrystallized phase. The boundary between the mixed layer 21a and the recrystallized portion 21b is indicated by a curve L as shown in the figure. In this specification, the point where the boundary L intersects the inner end surface of the current collecting disk 21 is defined as an intersection A. Called. Further, the distance between this point A and the surface of the internal lead bar 15 is a (mm).
Further, in the abutting portion where the inner lead rod holding cylinder 16 and the current collecting disc 21 are in contact, the portion closest to the inner lead rod 15 (that is, the smallest diameter portion) is indicated by B, The distance between this point B and the surface of the internal lead bar 15 is b (mm).

In the present invention, as shown in the figure, the minimum diameter portion B in the contact portion is located radially inward from the intersection A, and the above a (mm) and b (mm) are a> b Have the relationship. As described above, the contact portion between the current collecting disk 21 and the inner lead rod holding cylinder 16 has the inner end face of the current collecting disk 21, the mixed layer, and the boundary line (L) of the current collecting disk constituting material. Is formed so as to reach the mixed layer 21a beyond the intersecting point (A) where the crossing points intersect, so that the tension applied to the intersecting point A is relaxed, and the generation and progress of cracks at the boundary L are suppressed.
If the relationship of a> b is established in at least a part of each welded portion, it is effective in relaxing the stress to be peeled off and the strength can be increased. In particular, the maximum diameter portion at the intersection A is the holding cylinder 16. When held, since the moment is reduced, a great effect can be obtained in reducing the tension from the load of the internal lead bar.

  In this way, by joining the inner lead bar and the current collecting disk by the laser beam welding method having the above-mentioned structures, the joint strength between the inner lead bar and the current collecting disk is increased, and high reliability is achieved. A short arc type discharge lamp having the characteristics.

[Second Embodiment]
Subsequently, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view through the tube axis of the valve corresponding to the previous figure and FIG. 2B, and shows an internal lead bar (15), a current collecting disk (21), and an internal lead bar holding cylinder (16). ) Only enlarged. In this embodiment, the difference from the first embodiment described above is the welded portion structure, and the welding method (laser beam welding method) and other lamp configurations are all the same as in the first embodiment. The components described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 3, a straight line n indicated by a dashed line passes through a tangent line of the boundary line (L) between the mixed layer and the current collecting disk component material, and the intersection point where the boundary line (L) intersects the inner end face of the current collecting disk. It is a virtual half line starting from (A). Similarly, a straight line m indicated by a one-dot broken line is a virtual half line that passes through the end face on the inner side of the current collecting disk 21 with the intersection A as a starting point.

If the angle formed by the straight line m and the straight line n is α, in the present embodiment, α is configured in a range of less than 90 °.
As a result, the perpendicular direction of the tangent line n and the direction of the tension T do not coincide with each other at the intersection A, and the stress G is more dispersed than when α = 90 °, so The power to do becomes smaller. The smaller the angle α formed by the straight line m and the straight line n, the smaller the force acting in the direction perpendicular to the tangent line n, that is, the magnitude of the stress G to be peeled off. Although it is possible to suppress the progress of fracture, α is 10 to 60 °, preferably 20 to 45 ° because strength is obtained by forming a melted portion that spans both the internal lead rod 15 and the current collecting disk 21 during welding. More desirably, the angle is in the range of 30 to 35 °.

  In order to realize such a welded portion by the laser beam welding method or the electron beam welding method, the means for controlling the beam spot diameter and the converging angle, or the initial shape of the current collecting disk 21, An easily meltable part may be formed in advance, for example, by providing an annular protrusion on the inner edge, and a structure that can reduce the area to be heated (melted) may be provided. In short, the angle α formed by the straight line m and the straight line n may be finally made smaller than 90 °.

  As described above, by controlling the shape of the boundary L between the mixed layer 21a and the molybdenum recrystallized portion 21b, the stress to be peeled can be relaxed, and as a result, the occurrence and progress of cracks can be avoided. As a result, breakage of the welded portion can be suppressed and the joint strength can be increased.

[Third Embodiment]
Subsequently, a third embodiment of the present invention will be described with reference to FIG. 4 (a) is a drawing corresponding to the previous figure, FIG. 2 (b) or FIG. 3, and shows an internal lead bar (15), a current collecting disk (21), and an internal lead bar holding cylinder (16). It is only the figure expanded and shown. FIG. 4B is an explanatory diagram for explaining the stress state of FIG. In this embodiment, the difference from the previously described embodiment is the welded portion structure, and the welding method and other lamp configurations are all the same as those of the previously described embodiment. Therefore, the components described above are denoted by the same reference numerals, and detailed description thereof is omitted. The straight line m is a virtual half line that passes through the inner end face of the current collecting disk 21 starting from the intersection A, and the straight line n is on the tangent line of the boundary line (L) between the mixed layer and the current collecting disk constituting material. And a boundary line (L) is a virtual half line starting from the intersection (A) where the boundary line (L) intersects the inner end face of the current collecting disk.
In addition, an angle formed by the straight line m and the straight line n is α.

In the present embodiment, the molten metal flows into the lead rod insertion hole 211 of the current collecting disk 21 at the portion where the mixed layer 21a is formed, so that the thickness of the current collecting disk continuously decreases. A recess having a substantially C-shaped cross section is formed.
As shown in FIG. 4 (b), by changing the surface shape of the inner end face from a uniform planar state to a concave shape at a portion corresponding to the mixed layer, the direction in which the tension T acts on the surface of the mixed layer 21a changes, It tilts in the tangential direction indicated by the straight line h.
As a result, if the angle formed by the straight line m and the straight line h is β (°), if this is larger than 0 °, the tension α is 90 ° even if the angle α formed by the straight line m and the straight line n is 90 °. The direction of T and the vertical direction of the straight line n do not match, and the magnitude of the stress G applied in the direction of peeling the boundary L at the intersection A can be reduced. As a result, the occurrence and progress of cracks are suppressed, and the joint strength of the welded portion is increased.

In this way, by changing the surface of the mixed layer, the direction in which the tension is applied is changed, and the tangential direction of the boundary line between the mixed layer and the current collecting disk constituent material and the direction in which the tension is applied are changed to less than 90 °. (That is, the magnitude of α-β is less than 90 °), the magnitude of the tension T can be dispersed, and the stress acting in the direction perpendicular to the straight line n can be reduced.
Such a welded portion is formed by forming a gap K in the inner lead rod 15 and the lead rod insertion hole 211 of the current collecting disc 21 so that the melted liquid of both flows in and thins the melted portion. It can be easily realized.

As described above, various embodiments of the present invention have been described. If the current collector disk and the internal lead rod according to the present invention are welded by local heating between two members, a laser beam may be used. In addition to welding, it can also be applied to electron beam welding. It can also be realized in so-called hybrid welding in which both laser beam and TIG welding are used simultaneously.
Moreover, in the said embodiment, although the lead rod insertion hole was formed in the current collection disk and the base end part of the internal lead rod protruded and fixed to the said hole was demonstrated, it is an unnecessary part after welding. It is also possible to apply an excised material. It suffices that at least a part of the internal lead bar is inserted into the current collecting disk at the welding point.

It is a perspective view explaining the state of a current collection disc and an internal lead bar at the time of laser beam welding. BRIEF DESCRIPTION OF THE DRAWINGS (a), (b) It is sectional drawing which passes along the tube axis | shaft of the valve | bulb which expands and shows the vicinity of the junction part of an internal lead rod and a current collection disk explaining 1st Embodiment. It is sectional drawing which passes along the tube axis | shaft of the valve | bulb which expands and shows the junction part vicinity of the internal lead bar and current collection disc explaining 1st Embodiment. (A) is sectional drawing which passes along the valve tube axis | shaft which expanded and showed the internal lead rod, the current collection disk, and the cylinder for internal lead rod holding | maintenance, (b) is an explanation explaining the stress state of (a). FIG. It is sectional drawing for description of a short arc type discharge lamp. (A) Cross section for description which cut | disconnected the welding part in the cross section which passes along the tube axis | shaft of a lamp | ramp, (b) is the figure which expanded (a) further. FIG. 7 is an enlarged explanatory sectional view of the vicinity of a welded portion surrounded by a circle in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light emission tube 11 Light emission part 12 Sealing tube part 12a Narrowing part 13 Anode 14 Cathode 15 Internal lead rod 16 Internal lead rod holding cylinder 16a One end surface 17 Sealing glass member 171 Inner end portion 171a Bottomed hole 172 Body 173 Bottomed hole 18 External lead rod 19 External lead rod holding cylinder 20 Metal foil 21 Current collecting disk 21a Mixed layer 21b Molybdenum recrystallized portion 21c Molybdenum non-recrystallized portion 211 Lead rod insertion hole S Discharge space

Claims (3)

A bulb composed of an arc tube portion and a sealing tube portion connected to both ends of the arc tube portion;
A cathode and an anode disposed opposite to each other in the arc tube portion;
An internal lead bar having a cathode or anode at the tip;
A lead rod holding cylinder that is penetrated by the internal lead rod and arranged in the sealing tube portion of the valve;
A current collecting disk, which is disposed in the sealing tube portion along the outer end surface of the lead rod holding cylinder, and is connected to the lead rod insertion hole formed in the center thereof through the proximal end portion of the inner lead rod. When,
One end of the current collector disk is connected, and a metal foil embedded in a sealed tube portion in an airtight manner;
An external lead rod connected to the other end of the metal foil and led out of the sealing tube portion;
A short arc type discharge lamp comprising:
The current collecting disc and internal lead rod are mixed in the vicinity of the lead rod insertion hole on the inner end face of the current collecting disc by the laser beam welding method or the electron beam welding method. Is formed by joining,
At least a part of the contact portion between the current collecting disk and the inner lead rod holding cylinder is formed on the inner end face of the current collecting disk formed on the cross section passing through the lamp tube axis, the mixed layer, and the current collecting disk configuration A short arc type discharge lamp formed so as to reach the mixed layer beyond the intersection (A) where the boundary (L) of the material intersects. A bulb composed of an arc tube portion and a sealing tube portion connected to both ends of the arc tube portion;
A cathode and an anode disposed opposite to each other in the arc tube portion;
An internal lead bar having a cathode or anode at the tip;
A lead rod holding cylinder that is penetrated by the internal lead rod and arranged in the sealing tube portion of the valve;
A current collecting disk, which is disposed in the sealing tube portion along the outer end surface of the lead rod holding cylinder, and is connected to the lead rod insertion hole formed in the center thereof through the proximal end portion of the inner lead rod. When,
One end of the current collector disk is connected, and a metal foil embedded in a sealed tube portion in an airtight manner;
An external lead rod connected to the other end of the metal foil and led out of the sealing tube portion;
A short arc type discharge lamp comprising:
The current collecting disc and internal lead rod are mixed in the vicinity of the lead rod insertion hole on the inner end face of the current collecting disc by the laser beam welding method or the electron beam welding method. Is formed by joining,
In the section through the tube axis of the valve,
An imaginary half-line n starting from the intersection (A) of the inner end face of the current collecting disk and the boundary (L) of the mixed layer and the current collecting disk constituting material, and passing on the tangent line of the boundary (L);
A short arc type discharge lamp characterized in that an angle α formed with an imaginary half line m drawn in a direction perpendicular to the tube axis of the bulb from the intersection (A) toward the internal lead rod is less than 90 °. . A bulb composed of a collector tube part and a sealing tube part provided continuously at both ends of the arc tube part;
A cathode and an anode disposed opposite to each other in the arc tube portion;
An internal lead bar having a cathode or anode at the tip;
A lead rod holding cylinder that is penetrated by the internal lead rod and arranged in the sealing tube portion of the valve;
A current collecting disk, which is disposed in the sealing tube portion along the outer end surface of the lead rod holding cylinder, and is connected to the lead rod insertion hole formed in the center thereof through the proximal end portion of the inner lead rod. When,
One end of the current collector disk is connected, and a metal foil embedded in a sealed tube portion in an airtight manner;
An external lead rod connected to the other end of the metal foil and led out of the sealing tube portion;
A short arc type discharge lamp comprising:
The current collecting disc and internal lead rod are mixed in the vicinity of the lead rod insertion hole on the inner end face of the current collecting disc by the laser beam welding method or the electron beam welding method. It is joined by being formed in
In the section through the tube axis of the valve,
An imaginary half-line n starting from the intersection (A) of the inner end face of the current collecting disk and the boundary (L) of the mixed layer and the current collecting disk constituting material, and passing on the tangent line of the boundary (L);
The angle α formed with the virtual half-line m drawn in the direction perpendicular to the tube axis of the bulb from the intersection (A) toward the internal lead rod is 90 ° or less,
A short formed by an angle β formed by a tangent line h drawn from the intersection (A) toward the inner surface of the current collecting disk in the mixed layer and the virtual half-line m is greater than 0 °. Arc type discharge lamp.

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