JP2004259644A - Discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a large-output discharge lamp capable of feeding a large amount of current thereto without the need of a cooling facility. <P>SOLUTION: In a discharge lamp 10 in which a pair of electrodes 3, 4 are oppositely disposed inside a light-emitting tube 1, at least one electrode 3 out of the electrodes 3, 4 is characterized in that a heat transfer body M is sealed into a sealed space S formed inside an electrode body 30 made of a main member 31 and a lid member 32, and the lid member 32 has a projection 33 extending into the space S in contact with the heat transfer body M. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp. In particular, the present invention relates to a short arc type discharge lamp used as a light source for a projection device, a photochemical reaction device, and an inspection device.
[0002]
[Prior art]
Discharge lamps can be classified into several lamps from the viewpoints of luminescent materials, distance between electrodes, and pressure in the arc tube. Among these, xenon lamps that use xenon gas as the luminescent material, and mercury that use mercury as the luminescent material. There are lamps and metal halide lamps that use rare earth metals other than mercury as luminescent materials. Further, there are short arc type discharge lamps and long arc type discharge lamps in terms of the distance between the electrodes, and there are low pressure discharge lamps, high pressure discharge lamps, ultra high pressure discharge lamps, etc. in terms of the vapor pressure in the arc tube. .
Among them, the short arc type high-pressure mercury lamp, for example, emits light with a wavelength of 365 nm efficiently, and an electrode made of tungsten is arranged with a gap of about 2 to 12 mm inside an arc tube made of quartz glass. Furthermore, a starting gas such as mercury or argon with a vapor pressure of 10 ⁵ to 10 ⁷ Pa at the time of lighting is enclosed as a luminescent substance in the arc tube.
Such a short arc type high-pressure mercury lamp has been conventionally used as a light source for exposure of a semiconductor wafer.
On the other hand, in recent years, it has been attracting attention as a light source for exposure of liquid crystal substrates, particularly liquid crystal substrates used in large area liquid crystal displays. From the viewpoint of shortening the processing time associated with the increase in the size of products, Larger output is required.
[0003]
When the rated power consumption is increased by increasing the output of the discharge lamp, the value of the current flowing through the discharge lamp is usually increased.
For this reason, the tip of the electrode (especially the anode in direct current lighting) receives a large amount of electron collision, and easily rises in temperature and melts, resulting in a problem that the arc becomes unstable. In addition, not only the anode but also the discharge lamp arranged in the vertical direction, the upper electrode is easily affected by the heat convection in the arc tube, and easily receives heat from the arc. Resulting in.
Further, when the tip of the electrode is melted, the substance constituting the electrode evaporates and adheres to the inner wall of the arc tube, thereby reducing the transmittance of the arc tube, thereby reducing the radiation output.
[0004]
Such a problem is not limited to a short arc type high-pressure mercury lamp, but generally occurs when the discharge lamp has a large output. Conventionally, an air cooling mechanism has been provided outside the discharge lamp. A forced air cooling structure has been proposed. As a high-power discharge lamp, a so-called water-cooled discharge lamp (for example, Japanese Patent No. 3075094) has been proposed in which a water channel is provided inside an electrode to flow cooling water.
[0005]
[Patent Document 1]
Japanese Patent No. 3075094 [0006]
[Problems to be solved by the invention]
However, if a method of forcibly cooling the air by providing an air cooling mechanism outside the discharge lamp in order to increase the output of the discharge lamp, a sufficient cooling effect cannot be obtained and the discharge lamp can be thrown into the discharge lamp. Since the current value is limited, it was difficult to increase the output. This limit value varies depending on the type of discharge lamp and the environment in which the discharge lamp is disposed, but is approximately 200 A.
Further, in the case of a water-cooled discharge lamp, a water channel is formed in the electrode and the cooling water is allowed to flow, so that the discharge lamp is increased in size as the electrode is increased in size. Furthermore, a cooling water supply and discharge device and a circulation pump have to be provided, and a cooling facility several times larger than that of the discharge lamp is required, and the versatility of the discharge lamp is poor.
[0007]
Further, in such a discharge lamp, an encapsulated substance such as mercury may accumulate in an unevaporated state at the coldest spot formed inside the arc tube. In this case, since a predetermined mercury vapor pressure cannot be obtained, a desired amount of radiated light and luminance cannot be obtained. Further, when the temperature is excessively reduced inside the arc tube, the arc becomes unstable and the discharge lamp flickers to emit light.
[0008]
Therefore, in view of the above problems, the problem to be solved by the present invention is to provide a high-power discharge lamp that does not require a cooling facility and can flow a large current through the discharge lamp.
[0009]
[Means for Solving the Problems]
In a discharge lamp in which a pair of electrodes are arranged opposite to each other inside an arc tube, at least one of the electrodes has a heat transfer member sealed in a sealed space formed inside an electrode body composed of a main member and a lid member. The member has a protrusion that extends into a sealed space in contact with the heat transfer body.
Further, the projection is provided on the electrode shaft.
[0010]
[Action]
According to the discharge lamp of the present invention, the heat transfer body is enclosed in a sealed space formed inside the electrode body including the main member and the lid member, and the protrusion provided on the lid member is provided with the protrusion provided on the lid member. It is a structure that comes into contact with a heat transfer body that has melted into a liquid state when lit.
According to such a structure, even when the tip of the electrode reaches a high temperature when the lamp is turned on, heat is effectively transferred in the axial direction through the main member in contact with the heat transfer body due to the high transport effect of the heat transfer body. Can be transported. In addition to this, the protrusion provided on the lid member contacts the heat transfer body that has melted and turned into a liquid state when the lamp is lit, thereby transporting heat in the axial direction also through the protrusion. Can do. That is, the heat of the electrode tip can be effectively transported by utilizing the conductive action of the heat transfer body.
Further, by utilizing the convection action of the heat transfer member that has melted into a liquid state when the lamp is lit, the heat at the electrode tip can be more effectively transported.
[0011]
Further, the protrusion is provided on the lid member so as to overlap the electrode shaft. Here, the heat transfer body that has been melted into a liquid state when the lamp is lit has a temperature distribution in the electrode radial direction, and the vicinity of the electrode axis is the highest temperature. Therefore, when the protrusion is provided on the lid member so as to overlap the electrode shaft, the heat at the electrode tip can be efficiently transported.
[0012]
For the reasons described above, the problem that the tip of the electrode melts when a large current is input to increase the output of the discharge lamp can be solved without using a large cooling facility as described in the prior art. .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic configuration of a discharge lamp according to the present invention. In the discharge lamp 10, the sealing portions 2 extend at both ends of the substantially spherical light emitting portion 1. An anode 3 and a cathode 4 held by the sealing portion 2 are disposed in the light emitting portion 1 so as to face each other, and an external lead rod 5 electrically connected to the anode 3 and the cathode 4 has an external power source (not shown). Is connected. A predetermined amount of mercury, xenon, argon, or the like is sealed in the light emitting unit 1, and power is supplied from an external power source, and light is emitted by arc discharge between the anode 3 and the cathode 4. The discharge lamp is lit with the anode 3 facing up and the cathode 4 facing down, with the tube axis of the light emitting section 1 supported in the vertical direction.
[0014]
FIG. 2 shows a cross-sectional view of the anode 3 in the electrode axis direction. The electrode axis coincides with the tube axis of FIG. Hereinafter, the anode 3 is also referred to as an electrode 3.
The electrode 3 has a heat transfer body M in a sealed space S formed inside an electrode main body 30 composed of a main member 31 and a lid member 32, and a protrusion 33 provided on the lid member 32 has a projection 33 when the lamp is lit. It is a structure which contacts with the heat transfer body M which has been melted to become a liquid state. The electrode body 30 forms a sealed space S by welding the opening edge 31 a of the main member 31 and the opening edge 32 a of the lid member 32. The main member 31 includes an opening edge portion 31a, a body portion 31b, and a tip portion 31c, and the lid member 32 is an approximate circle provided so as to overlap the opening edge portion 32a, the insertion hole 32b of the internal lead bar 34, and the electrode shaft. It consists of a columnar projection 33.
[0015]
The main member 31 and the lid member 32 constituting the electrode body 30 are made of a refractory metal or an alloy containing a refractory metal as a main component.
As the refractory metal, for example, a metal having a melting point of 3000 K or more, such as tungsten, rhenium, and tantalum, is employed. In particular, tungsten is preferable in that it hardly reacts with the internal heat transfer body M, and so-called pure tungsten having a purity of 99.9% or more is more preferable.
As an alloy mainly composed of a refractory metal, for example, a tungsten-rhenium alloy mainly composed of tungsten can be adopted. In this case, resistance to repetitive stress at high temperature is high, and the life of the electrode can be extended.
[0016]
The heat transfer body M is a metal that has a lower melting point than the metal constituting the electrode body 30 and melts when the lamp is lit. When the electrode body 30 is made of tungsten, gold, silver, copper, indium, tin, zinc, and Lead can be used. In addition, these metals may be monoatomic metals or alloys, and may be composed of any one of them, or may be composed of a combination of two or more metals. Good.
When any one of gold, silver, and copper is used as the heat transfer body M, these metals have higher thermal conductivity than tungsten constituting the electrode body 30, so that the heat transport effect using the above-described conduction action is used. Is obtained. Furthermore, the heat transport effect using the above-mentioned convection action is also obtained.
When any one of indium, tin, zinc, and lead is used as the heat transfer body M, these metals have lower thermal conductivity than tungsten that constitutes the electrode body 30, and therefore heat using the above-described conduction action. The transportation effect cannot be expected. Therefore, only the heat transport effect utilizing the above-described convection action can be obtained.
Here, although it depends on the type of discharge lamp and the environment in which the discharge lamp is arranged, generally, when the current value to be supplied to the discharge lamp is 150 A or more, only the convection action of the heat transfer body M is used. Since the heat transport effect is not sufficient, it is desirable to employ any one of gold, silver and copper as the heat transfer body M.
[0017]
FIG. 3 shows a method for arranging the protrusion 33 and the heat transfer body M during the production of the electrode. The same reference numerals as those shown in FIG.
FIG. 4A shows a method in which a massive heat transfer body M ′ having an insertion hole for the protrusion 33 on the upper surface is arranged in the internal space S, and the protrusion 33 is inserted into the insertion hole. In the same figure, it seems that a gap exists between the protrusion 33 and the massive heat transfer body M ′, but no gap exists by fitting the projection 33 and the massive heat transfer body M ′. You may arrange as follows.
FIG. 2B shows a method in which the protrusion 33 is arranged so as to be buried in a plurality of small piece-like heat transfer piece M ′ arranged in the internal space S. In the drawing, the shape of the small piece of heat transfer body piece M ′ is substantially spherical, but is not limited to this, and other shapes such as a tetrahedron and a hexahedron may be used.
Note that the electrode structure shown in FIGS. 1A and 1B is in a state where the lamp has not been turned on once after the discharge lamp is manufactured. As shown in FIG. The protrusion 33 and the heat transfer body M are in contact with each other.
[0018]
Here, a method for producing the protrusion 33 will be described. The protrusion 33 may be provided by projecting a part of the lid member 32 by cutting one bar, or a member to be the projection 33 is welded to the lid member 32 prepared in advance. The part 33 may be used.
2 and 3 has a cylindrical shape, but is not limited thereto, and may be, for example, a prismatic shape.
[0019]
FIG. 4 is a cross-sectional view in the axial direction of the electrode 3 using the protrusion 33 of another embodiment with respect to the protrusion 33 shown in FIGS. The same reference numerals as those shown in FIG. 2 and FIG.
The protrusion 33 shown in FIG. 1 (a) includes a rear end 33a, a body 33b, and a front end 33c. The rear end 33a and the body 33b are cylindrical, and the front end 33c is formed in a spherical shape. ing. The rear end portion 33a and the body portion 33b are not limited to a cylindrical shape, and may be, for example, a prismatic shape.
The protrusion 33 shown in FIG. (B) includes a rear end portion 33a, a body portion 33b, and a front end portion 33c, and the outer diameter gradually decreases from the rear end portion 33a toward the front end portion 33c. Although not shown in the figure, the middle part 33b may have a columnar shape, and the outer diameter of the tip portion may gradually decrease.
The protrusion 33 shown in FIG. (C) includes a rear end 33a, a body 33b, and a front end 33c, and the front end 33c is formed in an uneven shape. Thereby, the contact area with respect to the heat exchanger M can be increased. Moreover, you may form not only the front-end | tip part 33c but all the parts which are contacting the heat-transfer body M in uneven | corrugated shape.
The protrusion 33 shown in FIG. (D) includes a rear end portion 33a, a body portion 33b, and a front end portion 33c, and the middle portion of the body portion 33b is formed of a single member, and a plurality of portions from there are formed. It is formed with the member of.
2, 3, and 4, only one protrusion 33 is shown. However, a plurality of protrusions 33 may be provided. ), (B), (c) and (d) can be adopted.
[0020]
It is preferable that 5 volume%-70 volume% of the projection part 33 is contacting the heat transfer body M with respect to the whole volume.
If the volume exceeds 70% by volume, the convection of the heat transfer element M melted when the lamp is lit is obstructed by the protrusion 33, so that a sufficient heat transport effect by convection cannot be obtained. It is because the heat transport effect by the projection part 33 cannot fully be exhibited as it is less than 5 volume%.
[0021]
The heat transfer body M is preferably sealed at a ratio of 50% by volume or more with respect to the internal volume of the electrode body 30, and is preferably sealed in a range of 80% by volume to 95% by volume.
If the amount of the heat transfer body M is small, the effect of conducting the heat generated at the tip portion of the electrode body 30 (tip portion 31c of the main member 31) to the lid member 32 is not sufficient. Because it invites.
It is more effective to enclose the heat transfer body M in the presence of a gap than to fully enclose the internal space S of the electrode body 30. The reason for this is that the current distribution flowing in the heat transfer body melted in the vicinity of the air gap changes due to the presence of the air gap, and the convection flow rate of the heat transfer body melted by the Lorentz force generated by the change in the current distribution becomes faster. This is to increase heat transport. Even if the gap is small, it is effective, but it is desirable that the gap is at least 5% by volume with respect to the inner volume of the internal space S.
[0022]
Referring to FIG. 2, a numerical example of the protrusion 33 is 6 mm in the axial length l1 and 5 mm in the outer diameter d3.
The outer diameter d3 of the protrusion 33 is preferably 10 to 50% (d2 / 10 to d2 / 2) with respect to the inner diameter d2 of the electrode body 30. If it exceeds 50%, the voids existing in the internal space S are excessively narrowed, so that the vapor pressure of the heat transfer body M may increase and the electrode body 30 may be damaged. This is because if the contact area with the heat transfer body M is small, the heat transport effect by the protrusion 33 cannot be sufficiently exhibited.
[0023]
With reference to FIG. 2, the numerical example of the electrode which concerns on this invention is demonstrated. The length of the case where the electrode main body 30 (main member 31), the internal space S of the inner volume 6700Mm ^3, the heat conductor M added amount 6000 mm ^3, and there is no axial length l2 (heat conductor M inside the space S ) 30 mm, the outer diameter d1 is 25 mm, the inner diameter d2 is 17 mm, the side wall thickness t1 is 4 mm (average value), and the opposing electrode side wall thickness t2 is 4 mm.
[0024]
As described above, the heat transfer body is disposed in the sealed space formed inside the electrode body composed of the main member and the lid member, and the protrusion provided on the lid member melts into a liquid state when the lamp is turned on. An excellent heat transport effect can be exhibited by constituting an electrode having a novel structure of contacting the heat transfer body. As a result, problems such as melting and evaporation due to the high temperature of the electrode tip when the lamp is turned on can be solved.
Therefore, a large output discharge lamp can be produced by supplying a large current without using a large cooling facility like a conventional water-cooled discharge lamp.
[0025]
Note that the electrode structure of the present invention is used for an electrode arranged on the upper side in a vertically lit discharge lamp in which the tube axis of the discharge lamp is arranged in the vertical direction because the heat transfer material melts when the lamp is lit. preferable. Since the electrode disposed on the upper side is likely to be heated to a high temperature, an anode having a larger volume than that of the cathode is usually used. However, this does not exclude the arrangement of the cathode employing the electrode structure of the present invention on the upper side. Absent.
Further, in an AC lighting type discharge lamp, the electrode structure of the present invention can be adopted for both electrodes.
[0026]
The discharge lamp of the present invention is not limited to a short arc type high-pressure mercury lamp, but a xenon lamp using xenon gas as a luminescent material, a metal halide lamp using a rare earth metal other than mercury as a luminescent material, and a discharge enclosing halogen. It can employ | adopt without being limited to luminescent substances, such as a lamp | ramp. Further, the present invention is not limited to short arc type discharge lamps, but can be used for middle arc type discharge lamps and long arc type discharge lamps, and can be applied to various discharge lamps such as low pressure discharge lamps, high pressure discharge lamps, and ultra high pressure discharge lamps.
[0027]
【The invention's effect】
As described above, the heat transfer body is disposed in the sealed space formed inside the electrode main body composed of the main member and the lid member, and the protrusion provided on the lid member melts and is in a liquid state when the lamp is turned on. An excellent heat transport effect can be exhibited by configuring an electrode having a novel structure of contacting the heat transfer body. As a result, problems such as melting and evaporation due to the high temperature of the electrode tip when the lamp is lit can be solved, so that a large current can be generated without using a large cooling facility like a conventional water-cooled discharge lamp. It is possible to produce a discharge lamp with high output.
[Brief description of the drawings]
FIG. 1 is a view showing an entire discharge lamp according to the present invention.
FIG. 2 is a sectional view in the electrode axis direction when the anode lamp is lit according to the present invention.
FIG. 3 is a view showing a method of arranging a protrusion and a heat transfer body during the production of an electrode.
FIG. 4 is a cross-sectional view in the electrode axis direction of another embodiment of the protrusion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light emission part 2 Sealing part 3 Anode (electrode)
4 Cathode (electrode)
5 External Lead Bar 10 Discharge Lamp 30 Electrode Body 31 Main Member 31a Opening Edge 31b Body 31c Tip 32 Cover Member 32a Opening Edge 32b Internal Lead Bar Insertion Hole 33 Projection 34 Internal Lead Bar M Heat Transfer Body S Sealed Space

Claims (2)

In a discharge lamp in which a pair of electrodes are arranged opposite to each other inside the arc tube,
At least one of the electrodes has a heat transfer member sealed in a sealed space formed inside an electrode body composed of a main member and a lid member,
The discharge lamp according to claim 1, wherein the lid member has a protrusion that extends into a sealed space in contact with the heat transfer body. The discharge lamp according to claim 1, wherein the protrusion is provided on an electrode shaft.

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