JP4442124B2 - Short arc discharge lamp - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a short arc discharge lamp used for a light source for projectors, semiconductor exposure, ultraviolet curing and the like.
[0002]
[Prior art]
For example, as a light source for a projector, a short arc discharge lamp in which xenon gas is sealed is often used. Recently, there has been a strong demand for a brighter projected image from the projector. For this reason, there exists a tendency for the gas amount of the xenon gas enclosed to increase. Therefore, recent short arc discharge lamps have extremely high gas pressure in the arc tube during lighting.
[0003]
In such a short arc discharge lamp, a xenon gas is sealed in a spherical or elliptical arc tube made of quartz glass, and a cathode and an anode are arranged to face each other. And the electrode core rod of a cathode and an anode is sealed by the edge part of the side tube which follows the both sides of an arc_tube | light_emitting_tube. And in order to hold | maintain the electrode core rod of a cathode and an anode, the edge part by the side of the arc_tube | light_emitting_tube side of a side tube is heated and squeezed, and it reduces in diameter and forms the squeezed part. However, in order to directly hold the cathode and anode electrode core rods at the narrowing portion of the side tube, it is necessary to increase the narrowing amount.
[0004]
Therefore, the cathode and anode electrode core rods are conventionally inserted by inserting the electrode core rods of the cathode and anode into the electrode core rod holding cylinder made of quartz glass and welding the narrowed portion of the side tube to the holding cylinder. The technology that holds is used.
[0005]
When the narrowed portion of the side tube is welded to the holding cylinder, a small wedge-shaped gap is formed at the weld end. And it can be a cause of cracking during lighting. As a technique in which the narrowed portion of the side tube is not welded to the holding cylinder, Japanese Patent Application Laid-Open No. 51-148274 discloses a high melting point metal foil such as molybdenum, tantalum, tungsten, titanium on the outer periphery of the holding cylinder. It is described that a thin layer of 30 μm is provided.
[0006]
FIG. 1 shows a schematic diagram of a side tube on the anode side of a conventional short arc discharge lamp using the technique of the publication as a conventional technique. Shown in partial cross-sectional view. The electrode core rod 23 is inserted and held in a holding cylinder 30 made of quartz glass for holding the electrode core rod. A covering material 40 is interposed on the outer periphery of the holding cylinder 30. It is described that an inner recess 70 is provided in the side tube 11 so that the holding cylinder 30 does not move in the axial direction. 14 is a base.
[0007]
However, in the technique disclosed in Japanese Patent Laid-Open No. 51-148274, there is a possibility that the holding cylinder 30 may move in the axial direction toward the arc tube 10, so that the vibration resistance of the lamp is lowered and the lamp is damaged. It is easy to cause. In order to prevent the holding cylinder 30 from moving to the arc tube 10 side, the tungsten winding 60 is provided. However, the number of parts increases, and tungsten windings having different dimensions for lamps having different dimensions. There is a problem that 60 must be additionally provided.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 51-148274
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a short arc discharge lamp that can prevent axial movement of a quartz glass holding cylinder for holding an electrode core bar, can improve vibration resistance, and can prevent lamp burst. It is in.
[0010]
In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that the cathode and the anode are disposed opposite to each other in the arc tube, and the cathode electrode core and the anode electrode core are inserted into the holding cylinder. In the short arc discharge lamp, the holding cylinder is supported by a narrowing portion of a side tube following the arc tube, and the outer periphery of the holding cylinder is covered with a coating material made of metal. The cylinder for the tube has a small-diameter portion at the center in the tube axis direction , the narrowed portion of the side tube is provided so as to press the small-diameter portion of the tube for holding, and the covering material is a tube of the tube for holding A short having a plurality of ridges extending continuously in the axial direction, and the cross-sectional shape of the covering cylinder in the circumferential direction is a wave shape and / or a sawtooth shape This is an arc discharge lamp.
[0014]
[Action]
In the present invention, the holding cylinder has a small-diameter portion in the tube axis direction, so that the inside of the side tube is depressurized and heated from the outer periphery of the side tube where the holding cylinder is located. In particular, the side tube is burned at a position corresponding to the portion, and is fixed so as to be pressed by the small-diameter portion of the holding cylinder, thereby preventing the holding cylinder from moving in the axial direction. There is no need for parts other than the holding cylinder as shown in Japanese Patent Publication No. 51-148274.
[0015]
However, in order to prevent welding between the holding cylinder and the side tube, it is necessary to provide a coating material made of a refractory metal on the outer periphery of the holding cylinder. Therefore, when the covering material is a flat foil shape or thin plate shape when heated and reduced in diameter from the outer periphery of the side tube where the holding cylinder with the small diameter portion is located, the covering material is wound around the holding cylinder. When the coating material is coated and burned from the outer periphery of the side tube, the coating material is pushed against the inner wall of the side tube, and the surface of the coating material may be locally bent and have wrinkles with sharp corners. The generation of the wrinkles not only deteriorates the appearance of the lamp but also deteriorates the appearance of the lamp, thereby reducing the commercial value of the lamp. In addition, stress concentration may occur at the end of the bent portion of the wrinkle, which may cause lamp explosion.
[0016]
Therefore, even if the holding cylinder has a small diameter portion and a coating material made of a refractory metal is provided on the outer periphery of the holding cylinder, the coating material continues in the tube axis direction of the holding cylinder. The outer periphery of the side tube has a plurality of extending ridges, and the cross-sectional shape in the circumferential direction of the holding cylinder of the covering material is a wave shape or a sawtooth shape, or a mixed shape of a wave shape and a sawtooth shape. The coating material expands and contracts when heated and reduced in diameter, and the wrinkles that are locally bent of the coating material can be prevented.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 2 shows a schematic view of the side tube on the anode side of the short arc discharge lamp of the present invention. Shown in partial cross-sectional view. An example of the short arc discharge lamp of the present invention is a xenon short arc discharge lamp. In the arc tube 10 made of quartz glass, an anode 22 and a cathode (not shown) are arranged to face each other when fixed to the tips of a pair of electrode core rods 23 made of a tungsten rod. In addition, the arc tube 10 is filled with xenon gas. The side tube 11 extends from both sides of the arc tube 10, and the electrode core bar 23 is sealed at the end of the side tube 11. Reference numeral 14 denotes a base 14 that covers the seal portion.
[0018]
The electrode core rods 23 are respectively inserted into holding cylinders 30 made of quartz glass and having a small diameter portion at the central portion in the longitudinal direction on the outer peripheral surface, and the electrode core rods 23 are held by the holding cylinders 30. The holding cylinder 30 has a small-diameter portion 31 in the longitudinal direction thereof, and the side tube 11 is particularly baked in a portion corresponding to the small-diameter portion 31 by heating from the outer periphery of the side tube, and the holding cylinder 30 is It is fixed to hold down. The holding cylinder 30 may have the shapes shown in FIGS. 3A, 3B, and 3C if examples other than the shapes shown in FIG. 2 are illustrated, but are limited to these shapes. It is not a thing. FIG. 3B shows the holding cylinder 30 having protrusions 32 at both ends in the longitudinal direction. The protrusion 32 is not limited to both ends, and may be on the outer peripheral surface of the holding cylinder. FIG. 3C shows a substantially drum-like appearance, which is particularly preferable from the viewpoint of ease of glass molding (manufacturability). 33 is a through hole through which the electrode core rod is inserted.
[0019]
As shown in FIGS. 3A, 3B and 3C, a half of the maximum difference in diameter between the small diameter portion 31 of the holding cylinder 30 and the portion other than the small diameter portion is a (mm). When a is 0.1 mm, the hollow as the small-diameter portion 31 is too small, and the holding cylinder 30 cannot be sufficiently fixed even when heated and contracted from the outer periphery of the side tube 11. Further, if it exceeds 2 mm, the diameter is excessively reduced when heated and reduced from the outer periphery of the side tube 11, so that distortion may occur in the glass. Therefore, 0.2 ≦ a ≦ 2 is preferable.
[0020]
4A, 4B, and 4C, the holding cylinders 30 shown in FIGS. 3A, 3B, and 3C are placed in the side tube 11 and heated from the outside of the side tube 11. FIG. To show the narrowed state. And the inside of the arc tube 10 is made into a pressure-reduced state, the side tube 11 is diameter-reduced by heating the edge part by the side of the arc tube 10 of the side tube 11, and the narrowing part 12 is formed. As shown in FIG. 2, the holding cylinder 30 and the narrowed portion 12 are covered with a covering material 50 made of a refractory metal. By this covering, the holding cylinder 30 and the narrowing portion 12 are fixed without being integrated by welding.
FIG. 4D shows a cross-sectional view taken along the line AA ′ of FIG. In the figure, the covering material 50 has a cross-sectional shape that extends over the entire circumference of the holding cylinder, and shows a wave-like shape or a sawtooth shape, or a mixed shape of a wave shape and a sawtooth shape.
[0021]
Specifically, as the covering material 50, as shown in FIG. 5, a corrugated molybdenum foil or thin plate is preferably used. The protrusions 50a and 50b are made so as to be alternately bent and folded in a certain direction on a molybdenum foil or thin plate, and so-called jagged processing is performed.
[0022]
As an example of the dimensions, in FIG. 5, the height c of the peak of the covering material 50 is 0.2 mm, the pitch b of the peak of the covering material 50 is 1.0 mm, and the thickness t is 15 μm. In the jagged processing, the bending height corresponds to the crest height c of the covering material 50, but the foil expansion / contraction effect is difficult to obtain unless the height is 2 mm or less. Further, if the pitch is not 2 mm or less, the expansion / contraction effect of the foil is hardly obtained.
[0023]
As the covering material 50, a molybdenum foil can be used as described above. Molybdenum foil is suitable because of its good spreadability. In addition to molybdenum, refractory metals such as tungsten, tantalum, zirconium and titanium can also be used. The thickness of the covering material 50 is preferably 30 μm or less.
[0024]
A method of welding the holding cylindrical portion when using a molybdenum foil as the covering material will be described. First, a molybdenum foil, which is a knurled coating material 50, is wound around the outer peripheral surface of the holding cylinder 30 so that a plurality of protrusions continuously extend in the axial direction, and then the axial direction of the holding cylinder 30 Molybdenum foil is bent on both side faces. FIG. 6 is a perspective view showing a state in which the covering material 50 is wound around the holding cylinder 30. In FIG. 6, the holding cylinder 30 corresponds to an example having a small-diameter portion 31 at a substantially central portion in the axial direction, and a molybdenum foil as the covering material 50 is continuously extended in the axial direction with a plurality of protrusions. The appearance of wrapping is shown.
[0025]
Then, a holding cylindrical body 30 through which an electrode core rod 23 having an electrode at the tip is inserted is inserted into the side tube 11, the inside of the arc tube following the side tube 11 is in a reduced pressure state, and the side tube 11 is moved to the tube axis. When heated along the direction, the diameter of the side tube 11 is reduced and the narrowed portion 12 is formed. However, since the covering material 50 made of molybdenum foil is interposed, the holding cylinder 30 and the narrowed portion 12 are integrated by welding. It is fixed without. At that time, the plurality of protrusions continuously extending in the axial direction of the covering material 50 are deformed while changing the shape in the process of heating and reducing the diameter of the side tube 11, thereby suppressing the occurrence of local bending wrinkles. The holding cylinder 30 may be not only a perfect cylinder but also a polygonal cylinder of pentagon or more.
[0026]
【The invention's effect】
As described above, in the short arc discharge lamp of the present invention, the holding tube made of quartz glass has a small-diameter portion, and the refractory metal coating material which has been subjected to the knurling process is wound around the outer periphery of the holding tube. Therefore, even if the diameter of the side tube is reduced by heating from the outer surface of the side tube where the holding cylinder is located, no locally bent wrinkles are generated on the coating material surface, and stress is applied to the foil and glass contact portion. Will not break without concentrating.
[0027]
According to the present invention, the glass tube of the holding cylinder does not move even when vibration is applied to the lamp during transportation, etc., and the force is not concentrated on the seal portion, so that a short arc discharge lamp can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view of a side tube on the anode side of a conventional short arc discharge lamp.
FIG. 2 is a schematic view of a side tube on the anode side of a short arc discharge lamp of the present invention.
FIG. 3 shows an embodiment of a holding cylinder used in the short arc discharge lamp of the present invention.
FIGS. 4A and 4B are an enlarged view and a sectional view of the vicinity of a holding cylinder portion of the short arc discharge lamp of the present invention. FIGS.
FIG. 5 is an enlarged view of a coating material of a refractory metal.
FIG. 6 is a perspective view showing a state in which a knurled molybdenum foil is wound around a holding cylinder.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Light emission tube 11 Side tube 12 Restriction part 13 Seal part 14 Base 22 Anode 23 Electrode core rod 30 Holding cylinder 31 Small diameter part 32 Projection part 33 Through hole 40 Coating material 50 Coating material 50a Projection part 50b Projection part 60 Tungsten Winding 70 Inner recess

Claims (1)

A cathode and an anode are disposed opposite to each other in the arc tube, the cathode electrode core rod and the electrode core rod of the anode are inserted and held in a holding cylinder, and the holding cylinder is connected to the arc tube. In a short arc discharge lamp that is supported by a narrowing portion and the outer periphery of the holding cylinder is covered with a coating material made of a refractory metal,
The holding cylinder has a small-diameter portion at a central portion in the tube axis direction , the narrowing portion of the side tube is provided so as to press the small-diameter portion of the holding cylinder, and the covering material is the holding cylinder. A plurality of protrusions extending continuously in the tube axis direction, and the circumferential cross-sectional shape of the holding cylinder of the covering material is a wave shape and / or a sawtooth shape. Short arc discharge lamp.

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