JP5303923B2 - Discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp capable of preventing temperature rise of the tip parts of electrodes at lamp lighting, and yet, having an arc tube without fear of rocking in a vertical direction. <P>SOLUTION: For the discharge lamp with a pair of electrodes arranged in opposition inside an arc tube, with a heat-transfer element made of metal having a melting point lower than that of metal constituting the electrodes sealed in an enclosed space formed inside at least either of the pair of electrodes, a sintered body of metal particles as another body different from the heat-transfer element is sealed in the enclosed space. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a discharge lamp, and in particular, is used as an exposure light source such as a semiconductor wafer, a liquid crystal substrate, a printed circuit board, or a color filter, or an image projection light source for projecting an image on a screen of a movie theater or the like. It relates to a discharge lamp.

  In the manufacturing process of a semiconductor wafer or the like, a short arc type discharge lamp that emits ultraviolet light having a center wavelength of 365 nm is used. In such a discharge lamp, in order to improve the throughput in the manufacturing process, it is necessary to rapidly expose the object to be processed such as a semiconductor wafer, so that the output of ultraviolet light having a wavelength of 365 nm is increased. Is required to do.

  When the output of ultraviolet rays emitted from the discharge lamp is increased, the temperature of the tip of the electrode on the side of the discharge lamp subjected to electron collision becomes extremely high, and the tip of the electrode melts and deforms, thereby causing a discharge arc. It is predicted that there will be a problem that the output of the ultraviolet rays irradiated to the outside of the arc tube will decrease due to the instability of the electrode and the substances constituting the electrode evaporate and adhere to the inner wall surface of the arc tube Is done. Conventionally, in order to prevent the occurrence of such a problem, a cooling water channel is provided inside the electrode, and the cooling water is provided separately from the discharge lamp to circulate the cooling water inside the electrode, thereby leading the tip of the electrode. A so-called water-cooled discharge lamp that suppresses the temperature rise is disclosed in Patent Document 1.

  On the other hand, Patent Document 2 discloses a discharge lamp that can suppress the temperature rise at the tip of the electrode without providing a water cooling mechanism. The discharge lamp disclosed in Patent Document 2 is configured such that a pair of electrodes are arranged to face each other inside an arc tube, and at least one of the electrodes forms an electrode body inside an electrode body in which a sealed space is formed. And a heat transfer body made of a metal having a melting point lower than the melting point of the metal to be sealed. According to the discharge lamp disclosed in this document, the heat transfer material melted at the time of lighting is convected in a sealed space formed inside the electrode body, thereby melting the heat generated at the tip of the electrode. Since it can be efficiently transported in the direction of the rear end portion of the electrode through the body, the temperature rise at the front end portion of the electrode can be suppressed.

Japanese Patent No. 3075094 JP 2004-6246 A

However, in the discharge lamp disclosed in Patent Document 2, the rated lighting power is higher than that in the past in order to meet the demand for further improvement in throughput, and lighting driving is performed by supplying a large current to the electrodes. It was found that the arc tube sways in the vertical direction. When such a shake occurs, when the discharge lamp is installed and lit in the exposure apparatus or the like, the bright spot of the discharge lamp does not coincide with the first focal position of the optical system in the exposure apparatus or the like, and the light irradiation surface There was a problem that the fluctuation of irradiance was large. Furthermore, in the manufacture of semiconductor wafers and the like, there has been a problem that defective products are generated due to uneven exposure of the object to be processed.
The cause of such a problem is not clear, but is considered as follows, for example.

  That is, the arc tube shakes because the load on the electrode increases and the tip of the electrode that receives electron collision becomes extremely hot, so that it melts and becomes liquid when the discharge lamp is turned on. It is thought that this is caused by sudden boiling. The bumping of the heat transfer member occurs because the heat transfer member melts in the sealed space in the electrode when the discharge lamp is turned on, and large bubbles are formed in the melt of the heat transfer member. Then, if the heat transfer body in the liquid state changes into a large bubble in an instant and the volume rapidly expands, the heat transfer body in the liquid state is pushed by the bubble and hits the lid of the electrode body violently. It is considered that the arc tube of the discharge lamp holding the electrode swings up and down as the electrode swings up and down in the vertical direction due to the impact at that time.

  In view of the above, an object of the present invention is to provide a discharge lamp that can suppress the temperature rise at the tip of the electrode during lighting and that does not cause the arc tube to swing in the vertical direction.

  In the discharge lamp according to the present invention, a pair of electrodes are arranged to face each other inside the arc tube, and at least one of the pair of electrodes constitutes an electrode in a sealed space formed therein. In the case where a heat transfer body made of a metal having a melting point lower than the melting point of the metal is sealed, a sintered body of metal particles separate from the heat transfer body is sealed in the sealed space. And

  Furthermore, in 293K (Kelvin), the density of the metal which comprises the said sintered compact is larger than the density of the said heat exchanger.

Furthermore, the sintered body is obtained by firing metal particles excluding a metal that forms an alloy by reacting with the metal constituting the heat transfer body.
Furthermore, the melting point of the sintered body is higher than the boiling point of the heat transfer body at 0.1 MPa (megapascal).

Furthermore, the combination of the heat transfer body and the sintered body corresponds to any one of the following combinations 1 to 4.
(Combination 1)
The heat transfer body is a metal containing one or more of Cu (copper), Zn (zinc) and In (indium), and the sintered body is W (tungsten), Ta (tantalum), Re (Rhenium) and Mo (molybdenum) are fired particles containing one or more of them.
(Combination 2)
The heat transfer body is a metal containing one or more of Cu (copper), Zn (zinc), Sn (tin) and In (indium), and the sintered body is W (tungsten), Re (Rhenium) and Mo (molybdenum) are fired particles containing one or more of them.
(Combination 3)
The heat transfer body is a metal containing one or more of Ag (silver), Pb (lead), Cu (copper), Zn (zinc), and In (indium), and the sintered body is W Particles containing any one or more of (tungsten), Ta (tantalum), and Re (rhenium) are fired.
(Combination 4)
The heat transfer body is a metal containing one or more of Ag (silver), Pb (lead), Cu (copper), Zn (zinc), Sn (tin) and In (indium), The sintered body is obtained by firing particles containing one or more of W (tungsten) and Re (rhenium).

  Furthermore, the discharge lamp of the present invention has a bottomed cylindrical shape in which a pair of electrodes are disposed opposite to each other inside the arc tube, and at least one of the pair of electrodes has an opening on the base end side. A heat transfer body made of a metal having a melting point lower than that of the metal constituting the base portion is enclosed in a sealed space formed by the base portion and a lid portion fitted into the internal space of the base portion. The metal particles are attached to the surface of the base portion on the inner space side by firing.

  Furthermore, the discharge lamp of the present invention is lit with its tube axis arranged in the vertical direction, and the one electrode is arranged on the upper side in the vertical direction.

Furthermore, in the method for manufacturing a discharge lamp according to the present invention, a pair of electrodes are disposed to face each other inside the arc tube, and at least one of the electrodes includes a bottomed cylindrical base portion having an opening on the base end side, A discharge lamp in which a heat transfer body made of a metal having a melting point lower than the melting point of a metal constituting the base portion is enclosed in a sealed space formed by a lid portion fitted into the internal space of the base portion. The manufacturing method includes at least the following steps.
(Process 1)
Step of introducing the heat transfer body into the base portion (Step 2)
Step of introducing a sintered body of metal particles separate from the heat transfer body to the base portion (step 3)
After the step 1 and step 2, the step of inserting the lid portion into the internal space of the base portion (step 4)
After the step 3, the step of welding the base portion and the lid portion

Furthermore, in the method for manufacturing a discharge lamp according to the present invention, a pair of electrodes are disposed to face each other inside the arc tube, and at least one of the electrodes includes a bottomed cylindrical base portion having an opening on the base end side, A discharge lamp in which a heat transfer body made of a metal having a melting point lower than the melting point of a metal constituting the base portion is enclosed in a sealed space formed by a lid portion fitted into the internal space of the base portion. The manufacturing method includes at least the following steps.
(Process 1)
A step of applying paste-like metal particles to the inner surface of the base portion (step 2)
Step of firing the paste-like metal particles (Step 3)
After the step 2, the step of introducing the heat transfer body into the base portion (step 4)
After the step 3, the step of fitting the lid into the internal space of the base portion (step 5)
After the step 4, the step of welding the base portion and the lid portion

  In the discharge lamp of the present invention, since the heat transfer body made of a metal having a melting point lower than that of the metal constituting the electrode is enclosed in the electrode having the sealed space, the heat transfer body melted when the discharge lamp is turned on. Convection allows the heat at the tip of the electrode to be transported in the direction of the rear end of the electrode, thereby suppressing an increase in temperature at the tip of the electrode.

In addition, since a sintered body of metal particles separate from the heat transfer body is enclosed in the sealed space, porous sintering is performed in the melt of the heat transfer body melted when the discharge lamp is turned on. Bubbles are preferentially formed around the body, and the bubbles formed around the sintered body are maintained without being crushed in the melt of the heat transfer body. There is no possibility that large bubbles are formed.
As described above, the discharge lamp shakes because a large bubble is formed in the melt of the heat transfer body melted when the discharge lamp is turned on and the heat transfer body bumps, so that the volume of the heat transfer body is reduced. This is thought to be caused by rapid expansion. Therefore, as in the present invention, by encapsulating a sintered body of metal particles separate from the heat transfer body in the sealed space in the electrode, it is submerged in the melt of the heat transfer body when the discharge lamp is turned on. By preferentially forming small bubbles around the sintered body and maintaining them as small bubbles, the heat transfer body can be boiled before the heat transfer body bumps, so the discharge lamp emits light. It is possible to reliably prevent the tube from shaking.

Furthermore, if the density of the metal constituting the sintered body of the metal particles is larger than the density of the heat transfer body, the discharge lamp can be more reliably prevented from shaking for the following reason.
That is, the electrode on the side subjected to the electron collision has a temperature gradient such that when the discharge lamp is turned on, the temperature of the tip portion facing the other electrode is higher than that on the base end side. Accordingly, when the discharge lamp is turned on, the melt of the heat transfer body melted in the sealed space formed in the electrode gradually becomes hot as it approaches the tip end side of the electrode, and bubbles are generated at the position on the electrode tip side. Is likely to occur. Therefore, the sintered body is preferably located near the tip of the electrode in order to form bubbles. From the above, in the discharge lamp in which the electrode on the side subjected to the electron collision is arranged on the upper side in the vertical direction, if the density of the metal constituting the sintered body of the metal particles is larger than the density of the heat transfer body, the sintered body Will sink in the melt of the heat transfer body melted when the discharge lamp is turned on and will be located in the vicinity of the tip of the electrode, so that bumping of the heat transfer body can be reliably prevented.

[First Embodiment]
FIG. 1 is a front view showing the overall configuration of the discharge lamp of the present invention.
The arc tube 10 is made of quartz glass, and rod-shaped sealing portions 12 are continuously formed on both ends of a substantially spherical light emitting portion 11. In the light emitting section 11, a pair of electrodes each made of a metal anode 14 and cathode 16 are arranged so as to face each other. An electrode core rod 17 extending from each of the anode 14 and the cathode 16 is held in the sealing portion 12 and is connected to an external lead rod or metal via a metal foil (not shown) provided in an airtight manner in the sealing portion 12. It is connected to an external terminal, and an external power source is connected to this. A predetermined amount of a light-emitting substance such as mercury, xenon, or argon or a starting gas is sealed in the light-emitting unit 11.

  Such a discharge lamp emits light by arc discharge between the anode 14 and the cathode 16 when electric power is supplied from an external power source. In the discharge lamp shown in the example of FIG. 1, the anode 14 is arranged in the vertical direction upper side and the cathode 16 is arranged in the vertical direction lower side, that is, the tube axis of the light emitting unit 11 is perpendicular to the ground. A vertical lighting type that is supported and lit.

  FIG. 2 is an enlarged cross-sectional view of the anode 14 according to the first embodiment of the present invention. The anode 14 is shown in a state in which a tip portion 14A facing the cathode 16 is positioned downward in the vertical direction. The anode 14 is configured such that a heat transfer body D is enclosed in a sealed space C formed by fitting and welding the base portion 20 and the lid portion 40. It is more effective to enclose the heat transfer body D with some air gaps rather than being fully enclosed in the sealed space C.

The base portion 20 has a bottomed cylindrical shape in which an inner space 22 having an opening 21 is formed on an end face of a base end portion (an end portion opposite to the tip end portion 14A of the anode 14), and the base end portion has a radial direction at the base end portion. A base portion side flange portion 24 protruding outward is formed. The base portion side flange portion 24 is continuous with the base portion side flat surface 23 extending in the radial direction and the outer peripheral edge of the base portion side flat surface 23, and the base portion side inclined surface extending radially inward toward the distal end direction. 26. The bottom portion 22A on the inner space 22 side of the base portion 20 is rounded so that the heat transfer body D melted when the discharge lamp is turned on smoothly convects.
The base portion side flange portion 24 is formed with an annular groove 25 extending in the circumferential direction at a position close to the base end portion of the base portion 20, and the annular groove 25 is formed by the base portion side inclined surface 26. . The outer diameter of the base portion side flange portion 24 is smaller than the outer diameter of the base portion 20. As a result, even after the base portion 20 and the lid portion 40 are welded, a portion having a diameter larger than the outer diameter of the base portion 20 is not formed, and the outer diameter of the base portion 20 is increased when the discharge lamp is assembled. However, it is not necessary to use a glass tube having a large inner diameter. Therefore, there is an advantage that a conventional envelope can be used without requiring a design change.

  The lid portion 40 includes a lid body 41 having a truncated cone shape as a whole, and a cylindrical fitting portion 42 that is integrally formed so as to protrude from the center of the bottom surface of the lid body 41. The lid main body 41 has a lid portion side flange portion 44 having the same outer diameter as the base portion side flange portion 24. The lid-side flange portion 44 is continuous with the lid-side flat surface 43 extending radially outward and the outer peripheral edge of the lid-side flat surface 43, and is a circle extending radially inward toward the proximal direction. It has a truncated cone shape having an annular lid-side slope 46. The fitting portion 42 is formed so as to protrude from the lid portion-side flat surface 43 in the distal direction, and has an outer diameter that matches the inner diameter of the inner space 22 of the base portion 20.

  Then, the fitting portion 42 of the lid portion 40 is fitted into the internal space 22 of the base portion 20, and the lid portion side flat surface 43 of the lid portion side flange portion 44 is formed on the base portion side flat surface 23 of the base portion side flange portion 24. The outer peripheral edge portion of the base portion side flange portion 24 and the outer peripheral edge portion of the lid portion side flange portion 44 which are brought into contact with and in close contact with each other are welded to form an annular welded portion Y.

  A rare gas is sealed in the sealed space C so as to have a predetermined pressure. Specifically, when 50% or more of the heat transfer body D is enclosed with respect to the internal volume of the sealed space C, the rare gas is 1 atm or more, and thereby the heat transfer body D and the sealed space C Bubbles are prevented from being generated at the interface with the inner surface. On the other hand, when the amount of the heat transfer body D enclosed is small relative to the inner volume of the sealed space C, the boiling of the heat transfer body D is promoted by setting the inside of the sealed space C to a pressure state lower than the atmospheric pressure. The heat transport effect due to boiling transfer can be expected.

  The anode 14 is made of a metal having a high melting point. Specifically, the anode 14 is made of a metal having a melting point of about 3000 ° C. or higher, such as tungsten, rhenium, or tantalum. Among these, tungsten is particularly preferable. Similarly, the material constituting the cathode 16 is also preferably tungsten. On the other hand, the heat transfer body D is made of a metal having a lower melting point at the time of lighting compared to the metal constituting the electrode. Specifically, when the electrode is made of tungsten, Ag (silver), Cu ( Copper), Zn (zinc), Sn (tin), In (indium), Pb (lead), or the like is used.

In addition to the heat transfer body D, a sintered body M of metal particles that is a separate body from the heat transfer body D is enclosed in the anode 14 according to the present invention. The metal constituting the sintered body M preferably has a density higher than that of the heat transfer body. For example, W (tungsten), Ta (tantalum), Re (rhenium), and Mo (molybdenum) are used. it can. The density of the metal composing the sintered body M is made larger than the density of the heat transfer body D because it is sintered in the melt of the heat transfer body D melted in the sealed space C of the anode 14 when the discharge lamp is turned on. This is because the body M sinks and the sintered body M is positioned in the vicinity of the bottom portion 22A of the base body portion 20. In addition, said density is based on the numerical value in 293K (Kelvin), and it is based on the said reason for the said temperature.
As the temperature increases, the metal expands in volume and decreases in density. The inclination is expressed by a linear expansion coefficient, and the ratio between the heat transfer body and the sintered body does not change so much. Furthermore, as the temperature rises, the phase changes from solid to liquid, with which the volume expands and the density decreases rapidly. In 293K (Kelvin), when the density of the metal constituting the sintered body is higher than the density of the heat transfer body D, the sintered body is in a solid state when the lamp is turned on, whereas the heat transfer body is in a liquid state. For this reason, the density of the metal constituting the sintered body remains larger than the density of the heat transfer body even during lamp operation. Therefore, the numerical value at 293K (Kelvin) was used as a reference.

  The sintered body M is preferably formed of metal particles that do not react with the heat transfer body D to form an alloy when the discharge lamp is turned on. If the sintered body M and the heat transfer body D react when the discharge lamp is turned on, the effect of the present invention of forming small bubbles around the pores of the sintered body M as described above is lost. It is. The melting point of the sintered body M is preferably higher than the boiling point of the heat transfer body D at the internal pressure of the sealed space C of the anode 14 at the time of lighting. This is because the shape cannot be maintained if the sintered body M melts when the discharge lamp is turned on, and the effect of the present invention of forming small bubbles around the pores of the sintered body M as described above is reduced. . For example, when Zn is used as the heat transfer body, the melting point of the sintered body M is preferably 1200K or higher.

As described above, the relationship between the density of the heat transfer body D and the density of the metal constituting the sintered body, the reactivity of the sintered body M with respect to the heat transfer body D, and the boiling point of the heat transfer body D and the sintered body M Considering the relationship with the melting point of the material, the combination of substances constituting the heat transfer body D and the sintered body M is as follows.
(Combination 1)
The heat transfer body is a metal containing one or more of Cu, Zn, and In, and the sintered body is made of W (tungsten), Ta (tantalum), Re (rhenium), or Mo (molybdenum). Among them, particles containing any one kind or two or more kinds are fired.
(Combination 2)
The heat transfer body is a metal containing one or more of Cu, Zn, Sn, and In, and the sintered body is any one of W (tungsten), Re (rhenium), and Mo (molybdenum). Particles containing one kind or two or more kinds are fired.
(Combination 3)
The heat transfer body is a metal containing one or more of Ag, Pb, Cu, Zn, and In, and the sintered body is made of W (tungsten), Ta (tantalum), and Re (rhenium). Particles containing any one kind or two or more kinds are fired.
(Combination 4)
The heat transfer body is a metal including one or more of Ag, Pb, Cu, Zn, Sn, and In, and the sintered body is any one of W (tungsten) and Re (rhenium). Or the particle | grains containing 2 or more types are baked.

The sintered body M is manufactured through the following steps, for example. The following is an example.
(Process 1)
Step of mixing W and Ta powder after weighing a predetermined amount of W and Ta powder to a weight ratio of 1: 1 (step 2)
A step of forming pellets by compression molding the powder obtained in step 1 at a pressure of 12 MPa (step 3)
The step of firing the pellets obtained in step 2 at 2000 ° C. for 4 hours.

The sintered body M thus manufactured has the following specifications.
The outer diameter is 5 mm and the thickness is 8 mm. The particle size is in the range of 0.01 to 3.0 mm, for example, 1.0 mm. However, it is not always necessary to make the particle size uniform in all the metal particles.

  Furthermore, the ratio of the total volume of the sintered body M to the volume of the heat transfer body D is preferably in the range of 0.1 to 10.0%. The reason for this is that if the ratio of the sintered body M is extremely small, there is a risk that bubbles formed in the melt of the heat transfer body will increase, and conversely, if the ratio of the sintered body M is extremely large, the anode 14 This is because the heat of the tip portion 14A is not easily transported by the heat transfer body D, and thus the temperature rise of the tip portion 14A of the anode 14 cannot be suppressed.

Such an anode 14 according to the present invention is manufactured through the following steps, for example.
(Process 1)
Step of introducing the heat transfer body D into the internal space 22 of the base portion 20 (step 2)
Step of introducing the sintered body M into the internal space 22 of the base portion 20 (step 3)
After Step 2, the fitting portion 42 of the lid portion 40 is fitted into the internal space 22 of the base portion 20 from the opening 21 so that the lid portion side flat surface 43 is in contact with the base portion side flat surface 23. Process (Process 4)
The process of forming the welding part Y by welding the outer peripheral part of the base | substrate part side flange part 24 and the cover part side flange part 44 which adjoin each other after the process 3 over the perimeter.

According to the first embodiment of the discharge lamp of the present invention as described above, the heat transfer body D made of a metal having a melting point lower than that of the metal constituting the anode 14 is enclosed in the anode 14 having the sealed space C. Therefore, the heat of the tip 14A of the anode 14 can be transported toward the rear end of the anode 14 by the convection of the heat transfer element D melted when the discharge lamp is turned on. Temperature rise can be suppressed.
Moreover, since the sintered body M of metal particles separate from the heat transfer body D is sealed inside the anode 14 in addition to the heat transfer body D, the following effects can be expected.

That is, as shown in FIG. 3, the sintered body M is a porous body in which many openings Q having a small surface area are formed in the gaps between the particles P. Therefore, in the melt of the heat transfer body D, small bubbles are easily formed around the sintered body M that is a porous body. Since the force acting on the bubbles in an attempt to crush the bubbles increases in proportion to the outer surface area of the bubbles in contact with the melt at the location where the bubbles are formed, a porous body having a large number of openings with small surface areas The presence of the sintered body M in the melt of the heat transfer body makes it difficult for the bubbles formed around the openings having a small surface area present on the surface of the sintered body M to be crushed, It is thought that it is maintained in a state of small bubbles.
Accordingly, since no large bubbles are formed in the melt of the heat transfer body D when the discharge lamp is turned on, the melt of the heat transfer body D can be boiled before the heat transfer body D bumps, and the volume rapidly increases. Since the expanded heat transfer body is not struck against the lid portion 40 of the anode 14, the problem that the arc tube 10 swings up and down in the vertical direction can be solved.

Further, when the density of the metal constituting the sintered body is higher than the density of the heat transfer body D, when the discharge lamp is turned on with the anode 14 positioned on the upper side in the vertical direction, the sintered body M Sunk in the melt of the heat transfer body D melted in the sealed space C of the anode 14 and is positioned in the vicinity of the tip end portion 14A of the anode 14, and therefore has the following advantages.
That is, when the discharge lamp is turned on, the anode 14 facing the cathode 16 has a temperature gradient such that the temperature of the distal end portion 14A is higher than the temperature on the proximal end side. Accordingly, when the discharge lamp is turned on, the melt of the heat transfer body D melted in the sealed space C formed in the anode 14 gradually increases in temperature as it approaches the bottom portion 22A side of the base portion 20. Air bubbles are likely to be generated in the vicinity of 22A. Therefore, the sintered body M is preferably located near the bottom portion 22A of the base portion 20 in order to form bubbles. From the above, in the discharge lamp in which the anode 14 that receives electron collision is arranged on the upper side in the vertical direction, the sintered body M sinks into the melt of the heat transfer body D that is melted when the discharge lamp is turned on, and the bottom of the base portion 20. Thus, the heat transfer body D can be reliably prevented from bumping.

[Second Embodiment]
FIG. 4 is a cross-sectional view showing the configuration of the anode according to the second embodiment of the discharge lamp of the present invention. In the figure, the same reference numerals as those in FIG. 2 are assigned to portions common to the anode 14 shown in FIG. In the anode 14 shown in FIG. 4, the inner surface 20 </ b> A of the base portion 20 is coated with metal particles N. The substances constituting the metal particles N and the heat transfer body D are selected from any one of the above combinations 1 to 4. The metal particles N preferably have a particle size in the range of 0.01 to 3.0 mm, for example, 1.0 mm.

The metal particles N are attached to the inner surface 20 </ b> A of the base portion 20 through, for example, the following steps.
(Process 1)
Step of mixing W powder having an average particle diameter of 1 mm with an organic solvent to form a paste (Step 2)
After introducing the paste-like W obtained in the step 1 into the upright internal space 22 of the base portion 20, the base portion 20 is rotated in an inclined state to paste the paste on the inner surface 20A of the base portion 20. Step of applying W (step 3)
A step of drying pasty W after step 2 (step 4)
After step 3, the base portion 20 is baked under a temperature condition of 2000 ° C. for 4 hours to attach W particles to the inner surface 20A of the base portion 20

The anode 14 shown in FIG. 4 is manufactured through the following steps.
(Process 5)
A step of introducing the heat transfer body D into the internal space 22 of the base body 20 after the step 4 (step 6).
After Step 5, the fitting portion 42 of the lid portion 40 is fitted into the internal space 22 of the base portion 20 from the opening 21 so that the lid portion side flat surface 43 is in contact with the base portion side flat surface 23. Process (process 7)
The process of forming the welding part Y by welding the outer peripheral part of the base | substrate part side flange part 24 and the cover part side flange part 44 which adjoin mutually after the process 6 over the perimeter.

  According to the second embodiment of the discharge lamp of the present invention, since the heat transfer body D made of a metal having a melting point lower than that of the metal constituting the anode 14 is enclosed in the sealed space C of the anode 14, the discharge is performed. Since the heat of the tip 14A of the anode 14 can be transported toward the rear end of the anode 14 by the convection of the heat transfer material D melted when the lamp is turned on, the temperature rise of the tip 14A of the anode 14 is suppressed. be able to.

  Moreover, the metal particles N are attached to the inner surface 20A of the base portion 20 by firing, and a large number of openings having a small surface area are formed on the surface of the metal particles N. Small bubbles are formed and the bubbles are not crushed. Therefore, when the discharge lamp is turned on, similarly to the anode 14 according to the first embodiment, the melt of the heat transfer body is boiled by boiling the melt of the heat transfer body before large bubbles are formed. Therefore, it is possible to solve the problem that the arc tube 10 sways in the vertical direction because the heat transfer body whose volume has expanded rapidly is not struck against the lid 40 of the anode 14. it can.

[Experiment 1]
Hereinafter, Experiment 1 performed to confirm the effect of the present invention will be described. In Experiment 1, three types of experimental lamps were manufactured by the following design according to the configuration shown in FIGS.
<Discharge lamp>
Total length of arc tube 1: 400mm
Encapsulated mercury: 130 μl
Rated current: 200A
Total length of anode 14: 72 mm
Anode 14 outer diameter: 30 mm
The thickness of the tip of the anode 14 (base part 20): 4 mm
Heat transfer body D: Zn (zinc)
Weight of heat transfer body D: 48.9 g

In Table 1, the lamp 1 has only the heat transfer body D enclosed in the sealed space C of the anode 14, and the lamp 2 has the heat transfer body D and the sintered body M in the sealed space C of the anode 14. In the sealed lamp 3, the metal particles N are attached to the inner surface 20A of the base portion 20 of the anode 14, and the heat transfer body D is sealed in the sealed space C. In the lamps 2 and 3, the sintered body M and the metal particles N have the following specifications, respectively.
Sintered body M: outer diameter 5 mm, total length 8 mm, average particle diameter 1 mm
Metal particle N: average particle diameter 1 mm

In Experiment 1, each of the lamps 1 to 3 was lit at a rated power of 7000 W, and the illuminance fluctuation rate was measured as follows. FIG. 5 is a schematic diagram showing the configuration of an optical system for measuring the illuminance fluctuation rate. As shown in the figure, the light emitted from the lamp passes through a spheroid mirror and a plane reflecting mirror, reaches a collimate lens, a band pass filter having a center wavelength of 365 nm and a bandwidth of 10 nm, passes through an integrator lens, and passes through the plane reflecting mirror. And pass through the condensation lens and reach the irradiation surface. And the illuminance meter whose opening diameter is 3 mm was fixed on the irradiation surface, and the irradiance of i line | wire emitted from a lamp | ramp was measured over 1 hour for every second.
The illuminance fluctuation rate S (%) is expressed by the following formula 1 when the maximum illuminance is X, the minimum illuminance is Y, and the average illuminance is A among 3600 illuminance data measured over 1 hour. . Table 1 shows the results of Experiment 1 (Formula 1) S (%) = 100 × (XY) / A

  As shown in Table 1, the illuminance fluctuation rate of the lamp 1 having the same anode configuration as the conventional one is 2.12%, whereas the illuminance fluctuation rates of the lamp 2 and the lamp 3 having the configuration of the present invention are each 0. .77% and 0.81%. Therefore, it was confirmed that the illuminance fluctuation rate on the light irradiation surface can be reduced by adopting the configuration of the anode of the present invention.

  Next, Experiment 2 will be described. In Experiment 2, each of the experimental lamps 1 to 3 manufactured in the same manner as in Experiment 1 was turned on at a rated power of 7000 W, and it was confirmed by visual observation whether the anode 14 was shaken up and down in the vertical direction. Table 2 shows the results of Experiment 2.

  As shown in Table 2, the lamp 1 having the same anode configuration as the conventional one has the anode 14 swaying vertically, whereas the lamp 2 and the lamp 3 having the configuration of the present invention have the anode 14 in the vertical direction. It was confirmed that it did not shake up and down.

  The electrode structure of the present invention can also be applied to a discharge lamp other than a discharge lamp in which the anode is disposed on the upper side in the vertical direction and the cathode is disposed on the lower side in the vertical direction. For example, when the cathode is arranged on the upper side in the vertical direction, both the heat transfer body and the sintered body are enclosed in a sealed space formed inside the cathode, or the inner surface of the cathode is metalized by firing. Particles can also be deposited.

  Further, as shown in FIG. 6, in addition to the heat transfer body D, the metal particle sintered body M is enclosed in the sealed space C of the anode 14, and the metal particles N are baked on the inner surface 20 </ b> A of the base portion 20. It can also be attached. By doing this, the number of locations for forming small bubbles increases, so that it is possible to more reliably prevent bumping of the heat transfer body, thus preventing the problem of the arc tube shaking when the discharge lamp is turned on. be able to.

It is a front view which shows the whole structure of the discharge lamp of this invention. It is an expanded sectional view of anode 14 of a 1st embodiment concerning the present invention. The expanded sectional view of the sintered compact M is shown. It is an expanded sectional view of anode 14 of a 2nd embodiment concerning the present invention. It is the schematic which shows the structure of the optical system for measuring an illumination intensity fluctuation rate. It is an expanded sectional view of anode 14 of other embodiments concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light emission tube 11 Light emission part 12 Sealing part 14 Anode 16 Cathode 17 Electrode rod 20 Base part 21 Opening 22 Internal space 23 Base part side flat surface 24 Base part side flange part 25 Annular groove 26 Base part side slope 40 Lid part 41 Lid body 42 Insertion part 43 Lid side flat surface 44 Lid side flange 46 Lid side slope C Sealed space D Heat transfer body M Sintered body N Metal particle Y Welded part

Claims (1)

A pair of electrodes are arranged opposite to each other inside the arc tube,
In at least one of the pair of electrodes, a discharge lamp in which a heat transfer body made of a metal having a melting point lower than the melting point of the metal constituting the electrode is sealed in a sealed space formed therein,
In the sealed space, a sintered body of metal particles separate from the heat transfer body is enclosed,
The heat transfer body is a metal containing one or more of Ag (silver), Pb (lead), Cu (copper), Zn (zinc), Sn (tin) and In (indium),
Be those the sintered body is fired particles containing either one or two of W (tungsten) and Mo (molybdenum),
In 293K (Kelvin), the density of the metal constituting the sintered body is larger than the density of the heat transfer body,
The sintered body is obtained by firing metal particles excluding a metal that reacts with a metal constituting the heat transfer body to form an alloy,
A discharge lamp, wherein a melting point of the sintered body is higher than a boiling point of the heat transfer body at 0.1 MPa (megapascal).

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