JP2003123688A - Short-arc high pressure discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to efficiently lower temperature of an electrode by heat radiation from the electrode in a short-arc high pressure discharge lamp with input power to the lamp raised in order to increase intensity of light emitted. SOLUTION: With the short-arc high pressure discharge lamp equipped with a pair of electrodes (20, 30) inside its luminous tube (11), at least either of the pair of the electrodes has hole parts of honeycomb shape formed at least at a part of its sides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short arc type high pressure discharge lamp, and more particularly to a side surface shape of an electrode of a short arc type high pressure discharge lamp.

[0002]

2. Description of the Related Art In recent years, a short arc type high pressure discharge lamp has been used as a light source in a photolithography process, which is a manufacturing process of a liquid crystal color filter, and the emitted light at this time has a wavelength of 365 nm or a wavelength of 436.
Those having a strong line spectrum in nm are used. On the other hand, the market demands that the color filter be upsized and the exposure time be shortened, and that the amount of light emitted from the short arc type high pressure discharge lamp be also increased.
It is strongly desired to increase the amount of emitted light in the vicinity of 65 nm.

It is conventionally known that the amount of light emitted from a short arc type high pressure discharge lamp is proportional to the electrical input to the discharge lamp. In other words, the amount of emitted light can be increased by increasing the electric input to the discharge lamp. Here, the following methods exist to increase the electric input to the discharge lamp. First, increase the distance between the electrodes to increase the light emission length of the short arc type high pressure discharge lamp. Second, increase the amount of mercury enclosed in the discharge lamp to light the lamp at a higher pressure. Third, increasing the input current to the discharge lamp.

However, each of the above-mentioned various methods has its own problems. The first method is to extend the emission length,
Compared to the point light source lamp used, the light emitting part becomes large. When used as a light source in an exposure apparatus for photolithography, since a point light source is desired in relation to the irradiation optical system, it is unsuitable for the light source of the exposure apparatus to extend the emission length in this way. Next to
Even if the amount of emitted light is improved, it becomes unusable in practice.

The second method has a problem in mechanical strength of the arc tube because the internal pressure of the short arc type high pressure discharge lamp becomes large. Conventional short arc type high pressure discharge lamps are often designed so that the vapor pressure of mercury enclosed inside is designed to be close to the upper limit of the internal pressure strength of the lamp. The high pressure discharge lamp is destroyed. In other words, the method of increasing the amount of mercury enclosed and igniting at an ultrahigh pressure as compared with the conventional short arc type high pressure discharge lamp cannot be used for improving the radiation amount.

In the third method, when the lamp current increases, the tip of the anode is heated by the increase in electron flow, and the temperature of the anode rises. Usually, the heat generated in the anode is radiated to the outside by heat conduction of the anode and radiated from the surface of the anode to the outside. But,
In the method of increasing the lamp current, the heat released to the outside is insufficient as compared with the heating by increasing the electron flow, and as a result, the thermal evaporation of the anode member due to the temperature rise of the anode is promoted and the inner wall of the arc tube is increased. Was blackened and the lamp life was shortened.

In order to solve this problem, a method of improving the efficiency of heat radiation from the anode and lowering the temperature of the anode has been proposed. For example, Japanese Patent Publication No. 39-11128 discloses that a groove having a V-shaped structure is provided on the side surface of the anode.
Specifically, a cooling groove having a depth of about 1 mm to 3 mm and an opening angle of 90 ° is provided, and the surface of the cooling groove is sintered with tantalum carbide to obtain the anode surface. It is described that the heat radiation from the is further enhanced. However, this method has a problem that carbon is liberated depending on the temperature of the anode and the arc tube of the short arc type high pressure discharge lamp is blackened, or carbon moves to the tip of the electrode to melt the electrode.

Further, in Japanese Patent Laid-Open No. 9-231946,
It is disclosed that tungsten powder is sintered on the side surface of the anode to improve the thermal emissivity of the electrode surface. However, even in this structure, although the heat radiation from the electrode can be increased as compared with the case where the tungsten powder is not applied, when the electric input to the discharge lamp is made higher, the cooling of the electrode becomes insufficient. As a result, there is a problem that the heat radiation from the electrode becomes insufficient. That is, the structure was not sufficient as a light source lamp in the photolithography process, which is a manufacturing process of the liquid crystal color filter described above.

[0009]

The problem to be solved by the present invention is to improve the heat radiation characteristics from the electrodes in a short arc type high pressure discharge lamp in which the input power to the lamp is increased in order to increase the amount of radiated light. Then, the temperature of the electrode is lowered efficiently. Then, by efficiently lowering the electrode temperature, it is possible to suppress or mitigate the evaporation of the electrode constituent substances from the anode tip portion, and it is also possible to mitigate the wear and thermal deformation of the electrode tip, and as a result ,
The purpose is to maintain stable light emission of the discharge lamp for a long time.

[0010]

In order to solve the above problems, a short arc type high pressure discharge lamp according to the present invention is a short arc type high pressure discharge lamp having a set of electrodes in an arc tube. At least one of the electrodes has a honeycomb-shaped hole formed on at least a part of its side surface.

The invention according to claim 2 is characterized in that the honeycomb-shaped hole is formed by irradiation of laser light. The invention according to claim 3 is characterized in that a curved surface is provided at the bottom and / or the top of the hole. Further, in the invention according to claim 4, in the hole, the depth D of the hole is within 12% of the diameter of the electrode, and the relationship between the depth D of the hole and the opening diameter W of the hole is D / W ≧. It is characterized by being 2.

[0012]

1 is a general view of a short arc type high pressure discharge lamp. The discharge lamp 10 includes an arc tube unit 1.
1 and a sealing tube portion 12, and in the arc tube portion 11, an anode 20 and a cathode 30 made of tungsten are provided at a tip distance of 1
They are arranged to face each other at about 0 mm. Anode 20, cathode 30
Are embedded in the sealing tube portion 12, and the external terminals 13
Electrically connected to. The arc tube portion 11 is filled with a filling gas made of a rare gas such as xenon, argon, or krypton or a mixture thereof, and a light emitting substance such as mercury. The pressure of the filling gas is, for example, 0.1 to 10 atm at the time of filling, and the filling amount of mercury is the arc tube portion 11.
It is 10 to 60 mg / cc in terms of weight per internal volume.
This discharge lamp is lit at a rated voltage of 50 V and a rated voltage of 5 KW, for example. In FIG. 1, a hole portion described later is omitted in the anode 20.

FIG. 2 shows an enlarged view of the anode 20. In the figure, the anode 20 includes a tip portion 21, a cone portion 22, a body portion 2
It is composed of 3. The tip portion 21 is planar and faces the cathode. The cone portion 22 is provided with a taper that connects the tip portion 21 and the body portion 23. The body portion 23 is provided with a honeycomb-shaped hole portion 24 on its side surface. An electrode shaft 25 continues to the body portion 23. The electrode shaft 25 may also be referred to as an electrode.
With respect to the anode, to give a numerical example, the body portion 23 has a diameter φ.
The cone portion 22 has an opening angle of 120 °, and the tip portion 21 has a diameter of φ8 mm.

The hole portion 24 is formed, for example, by irradiating a laser beam from a YAG laser in a spot manner, and by irradiating the hole portion in order for each hole, a honeycomb-like shape can be formed.

FIG. 3 is an enlarged view of some of the holes 24, and FIG. 2 shows three holes in the cross section along the line AA. The apex 31 and the bottom 32 are formed in the hole 24. (a) shows the bottom and the top of the hole formed at an acute angle, and (b) shows the bottom and the top of the hole rounded. Showing things. The distance between the tops 31 of the adjacent hole portions 24 is the opening diameter W of the hole, and forms the depth D in the vertical direction of the hole. To give a numerical example, the hole 24
The opening diameter W is, for example, 0.5 mm, and the depth D of the holes is, for example, 1.5 mm, and 6000 holes of 150 × 40 are formed in a range of 40 mm on the side surface of the anode 20. Further, as shown in (b), the top portion 31 and the bottom portion 32 are not sharp, but are formed to have a rounded shape and a curved surface, so that the electric field concentration at the time of starting the lighting can be prevented as described later.

FIG. 4 shows another embodiment of the honeycomb-shaped hole. In (a), the holes 24 are not formed adjacent to each other, but are formed with a space on the side surface of the anode. In (b), the hole portion 24 is formed not only in the body portion 23 but also in the tip cone portion 22. In (c), the holes 24 are not formed in a uniform number in the body portion 23, but are formed unevenly. (D) is
The holes 24 are formed at random on the side surface of the body portion 23. The anode structure of the present invention is only required to have a hole formed by laser irradiation and to have a good cooling effect, and the embodiment thereof is not limited to the above, and a combination of these and other It goes without saying that the form can be considered. Also, depending on the form,
Although there are some that are not suitable for the "honeycomb shape" according to a general interpretation, the "honeycomb shape" in the present invention means that a hole is formed in the above meaning.

The short arc type discharge lamp of the present invention comprises:
The structure of the hole as described above is provided to the electrode to improve the thermal emissivity from the electrode, and further, it is possible to define the relationship between the opening diameter and the depth of the hole. , This effect is further improved. In particular,
The relationship between the opening diameter D of the hole and the depth W is D / W ≧ 2,
It has been confirmed that the heat dissipation effect is high when the depth W of the hole is within 12% of the diameter of the electrode shaft.

[0018]

As described above, the short arc type discharge lamp of the present invention is a short arc type high pressure discharge lamp having a set of electrodes in an arc tube, and at least one electrode of the set of electrodes is used. Has a honeycomb-shaped hole on at least a part of its side,
The heat emissivity from the electrode can be increased, and even if the input power of the discharge lamp is increased, the heat can be efficiently radiated, so that the emitted light amount can be increased.

[Brief description of drawings]

FIG. 1 shows an overall view of a short arc type high pressure discharge lamp.

FIG. 2 shows an enlarged view of the anode of the short arc type high pressure discharge lamp of the present invention.

FIG. 3 shows an embodiment of an anode of a short arc type high pressure discharge lamp of the present invention.

FIG. 4 shows another embodiment of the anode of the short arc type high pressure discharge lamp of the present invention.

[Explanation of symbols]

10 Short arc type high pressure discharge lamp 11 arc tube 12 Sealed tube 20 Anode 21 Tip 22 Cone part 23 Body 24 holes W groove opening diameter D groove depth

Continued front page    (72) Inventor Mitsuru Ikeuchi             1194 Sado, Bessho Town, Himeji City, Hyogo Prefecture Usio             Electric Co., Ltd. F-term (reference) 5C015 JJ06                 5C039 HH04

Claims (4)

[Claims] 1. A short arc type high pressure discharge lamp having a set of electrodes inside an arc tube, wherein at least one electrode of the set of electrodes is provided with a honeycomb-shaped hole on at least a part of its side surface. Short arc type high pressure discharge lamp characterized by being. 2. The short arc type high pressure discharge lamp according to claim 1, wherein the honeycomb-shaped hole is formed by irradiating a laser beam. 3. The short arc type high pressure discharge lamp according to claim 2, wherein the bottom and / or the top of the hole is provided with a curved surface. 4. The depth D of the hole in the hole is within 12% of the diameter of the electrode, and the relationship between the depth D of the hole and the opening diameter W of the hole is D / W ≧ 2. The short arc type ultra high pressure discharge lamp according to claim 1.