KR102602644B1 - Discharge lamp and method for producing electrode for discharge lamp - Google Patents

Abstract

In a discharge lamp, heat is effectively dissipated to suppress electrode temperature. In the electrode 30, a cylindrical concave portion 40 is formed on the front end side member 34, facing opposite to the front end side, and the rear end side. A columnar portion 50 is formed coaxially on the member 32. The cylindrical recessed portion 40 accommodates the columnar portion 50, and a gap 60 is formed therebetween along the axial direction (X) and the axial direction. The surface area of the gap 60 is larger than the surface area of the electrode side portion T along the axial length L1 of the gap 60.

Description

Discharge lamp and method for manufacturing electrodes for discharge lamp {DISCHARGE LAMP AND METHOD FOR PRODUCING ELECTRODE FOR DISCHARGE LAMP}

The present invention relates to a discharge lamp with electrodes and, in particular, to the internal structure of the electrodes.

When a discharge lamp is turned on, the tip of the electrode becomes hot, the electrode material such as tungsten melts and evaporates, and the discharge tube turns black, resulting in a decrease in lamp illumination. In order to prevent overheating of the electrode tip, the electrode tip made of a durable metal and the body part made of a metal with higher thermal conductivity are molded separately and joined by solid phase bonding or the like. For example, an electrode can be formed by solid-state bonding of SPS or the like (see Patent Document 1). By joining a plurality of members to form an electrode, it is possible to make the electrode durable even when it is enlarged, and at the same time, it is possible to form an electrode with excellent thermal conductivity.

Japanese Patent No. 5472915 Publication

In order to increase the size of exposure objects and improve throughput, higher output (larger power) of lamps is required. Accordingly, the electrode temperature during lamp lighting also increases, making it difficult to effectively suppress electrode overheating simply by solid-phase joining the tip side member and the fuselage side member.

Therefore, an electrode structure that can effectively suppress the temperature rise of the electrode during lighting of the discharge lamp is required.

The discharge lamp of the present invention has a discharge tube and a pair of electrodes disposed oppositely in the discharge tube, wherein at least one electrode has an internal space, and the surface area of the internal space is the axis of the internal space. It is larger than the surface area of the side part of the electrode along the length of the direction. For example, the surface area of the internal space can be made larger than the surface area of the side portion of the electrode along the electrode axis direction.

The electrode has a recessed portion along the electrode axis direction and a columnar portion located in the recessed portion, and an internal space can be formed between the recessed portion and the columnar portion. Here, “columnar part” and “recessed part” are defined parts including the contact surface or joining surface when the electrode formed by joining a plurality of members is viewed in cross section, and the cross section of the columnar part and the recessed part are defined. It does not matter whether there is contact or non-contact with the bottom surface. For example, it has a first solid member forming a recessed portion, and a second solid member joined to the first solid member or an intermediate member joined to the first solid member to form a columnar portion, and the internal space is formed by the first solid member. It is formed between the member and the second solid member or intermediate member.

The internal space may include a space formed along the electrode axis. Additionally, the internal space can be formed in the shape of a bottom pipe. A heat dissipation portion can be provided on the surface portion of the internal space.

A discharge lamp, which is another aspect of the present invention, is provided with a discharge tube and a pair of electrodes opposed to each other in the discharge tube, wherein at least one electrode includes a recessed portion along the electrode axis direction, a columnar portion located in the recessed portion, and the recessed portion and the columnar portion. It has an internal space formed between the upper and lower parts, and the volume of the lumbar part is larger than the volume of the internal space.

A method of manufacturing an electrode for a discharge lamp, which is another aspect of the present invention, includes forming a cylindrical recess around a central axis with respect to a pillar-shaped tip-side solid member having an electrode tip surface. A columnar portion smaller in size than the cylindrical recess is formed around the central axis with respect to the pillar-shaped rear end solid member, and the columnar portion is disposed coaxially with the cylindrical recess on the distal end side. A manufacturing method comprising combining a solid member and a rear-end solid member and forming an electrode including the front-end solid member and the rear-end solid member by solid phase bonding, wherein the cylindrical recessed portion and the columnar portion are formed. A cylindrical recessed portion and a columnar portion are formed so that the surface area of the internal space formed between the and is larger than the surface area of the side portion of the electrode along the axial length of the internal space.

According to the present invention, in a discharge lamp, heat can be effectively dissipated and the electrode temperature can be suppressed.

(Figure 1) It is a top view of the discharge lamp which is 1st Embodiment.
(FIG. 2) A schematic cross-sectional view of the electrode of the first embodiment.
(FIG. 3) A schematic cross-sectional view of the electrode of the second embodiment.
(FIG. 4) is a graph showing the temperature change from the joint surface of the Example and Comparative Example.

The short arc type discharge lamp 10 is a large discharge lamp capable of outputting light of high brightness, and is equipped with a substantially spherical discharge tube (light emitting tube) 12 made of transparent quartz glass, and the discharge tube ( Inside 12), a pair of electrodes 20 and 30 made of tungsten are arranged to face each other (coaxially). On both sides of the discharge tube 12, sealing tubes 13A, 13B made of quartz glass are connected to the discharge tube 12 and are formed as one piece. The discharge space DS within the discharge tube 12 is filled with rare gases such as mercury, halogen, and argon gas.

The electrode 20, which is a cathode, is supported by an electrode support rod 17A. The sealing tube 13A includes a glass tube (not shown) into which the electrode support rod 17A is inserted, a lead rod 15A connected to an external power source, an electrode support rod 17A, and a lead rod ( The metal foil 16A connecting 15A) is sealed. Similarly, for the anode electrode 30, mount parts such as a glass tube (not shown) into which the electrode support rod 17B is inserted, metal foil 16B, and lead rod 15B are sealed. Additionally, clasps 19A and 19B are attached to the ends of the sealing pipes 13A and 13B, respectively.

When voltage is applied to a pair of electrodes 20 and 30, an arc discharge occurs between the electrodes 20 and 30, and light is emitted toward the outside of the discharge tube 12. Here, power of 1 kW or more is input. The light emitted from the discharge tube 12 is guided in a predetermined direction by a reflector (not shown). For example, when the discharge lamp 10 is incorporated into the exposure apparatus, the radiated light becomes patterned light and is irradiated to the substrate or the like.

Figure 2 is a schematic cross-sectional view of the electrode (anode) 30. Additionally, it is possible to have a similar structure for the electrode (cathode) 20.

The electrode 30 is comprised of a rear end side member 32 (second solid member) connected to the electrode support rod 17B and a front end side member 34 (first solid member) having an electrode front end surface 34D. The electrode 30 is formed by joining the rear end side member 32 and the front end side member 34. Here, the rear end side member 32 and the front end side member 34 are joined by solid bonding such as SPS.

The rear end side member 32 is a cylindrical member with the electrode axis 50 (here, cylindrical shape) is formed. In the distal end member 34, a cylindrical recess 40 surrounding the columnar portion 50 is formed coaxially along the axial direction X. The cylindrical recess 40 faces in the opposite direction to the electrode tip surface 34D, that is, it is recessed in the opposite direction. The rear end member 32 is solidly joined to the end 34E of the front end member 34 at its end 32E. Additionally, a columnar portion may be formed on the front end member and a recessed portion may be formed on the rear end member.

Between the columnar portion 50 extending from the solid joint surface toward the electrode tip side and the cylindrical recessed portion 40, a gap (internal space) 60 is formed along the axial direction ) is formed throughout the circumference of the columnar portion 50. Here, the gap portion along the axis vertical direction is set to 60D, and the gap portion along the axial direction (X) is set to 60V. The gap portions 60D and 60V are spatially connected.

The central axes of the columnar portion 50 and the cylindrical recessed portion 40 both coincide with the electrode axis X and are symmetrical with respect to the electrode axis X. In addition, the bottom surface 40B of the cylindrical recessed portion 40 is also symmetrical with respect to the electrode axis X, and the gap 60 also has a spatial shape symmetrical with respect to the electrode axis X.

The radial width D4 of the gap portion 60V, that is, the radial distance between the side surface 50S of the columnar portion 50 and the side surface 40S of the cylindrical recessed portion 40, is the diameter of the columnar portion 50. It is shorter than (D3) (D4<D3). The axial width L4 of the gap portion 60D is equal to the radial width D4 of the gap portion 60V here, and is shorter than the height L3 of the columnar portion 50 (L4 < L3). The gap 60 is formed within the electrode 30 and is a space region in the shape of a bottom cylinder.

Here, the radial width D4 and the axial width L4 are sufficiently short compared to the diameter D3 and the height L3 of the columnar portion 50, respectively, and the side surfaces 50S of the columnar portion 50, The cross section 50E is close to the side surface 40S and the bottom surface 40B of the cylindrical recessed portion 40, respectively, and the volume of the space formed by the gap 60 is smaller than the volume of the columnar portion 50. Additionally, no member such as a heat transfer body is provided in the gap 60.

While the lamp is turned on, the temperature of the tip member 34 of the electrode rises, and the heat of the electrode tip member 34 is transmitted to the columnar portion 50. The heat of the columnar portion 50 is transmitted to the electrode support rod 17B side and is radiated to the gap 60. The heat that has moved not only in the axial direction (X) but also in the vertical direction is transmitted from the outer surface of the electrode (30M) to the discharge space (DS).

In this embodiment, in order to effectively suppress the temperature rise of the electrode 30, the surface area of the gap 60 is made larger than the surface area of the electrode side portion T along the axial length of the gap 60. 60) is formed.

As described above, the volume of the columnar portion 50 is larger than the volume of the gap 60. Accordingly, the columnar portion 50 has a large heat absorption capacity, and can absorb heat from the cylindrical recessed portion 40 and effectively transport it to the electrode support rod side.

On the other hand, since the radial width D4 and the axial width L4 of the gap 60 are relatively small, the heat of the columnar portion 50 is transmitted to the electrode outer surface 30M and is dissipated into the discharge space DS. . In this way, the heat dissipation effect for the electrode side portion (T) along the axial length (L1) of the gap (60) can be increased.

This heat dissipation effect is realized by forming a gap 60 along the axis as far away from the axis center as possible. In that case, the surface area of the gap 60 becomes larger than the surface area of the electrode side portion T corresponding to the axial length L1.

Additionally, the surface area of the gap 60 in this embodiment is larger than the surface area of the entire electrode side surface T1 along the electrode axis X. That is, the electrode side surface excluding the electrode tip side tapered portion 34T, the electrode support rod side tapered portion 32T, the electrode tip surface 34D, and the electrode rear end surface 32L, which have a small heat dissipating area from the electrode surface (small surface area). The surface area of the gap 60 is larger than the surface area.

By forming a gap 60 having a relatively large surface area in relation to the side portion of the electrode, an increase in electrode temperature can be effectively suppressed.

However, in the case of an electrode structure in which a gap 60 is formed between the columnar portion 50 and the cylindrical recessed portion 40, the fact that the surface area of the gap 60 described above is relatively large is due to the volume of the columnar portion 50. It can also be said that it represents something larger than the volume of the gap 60. Since the volume of the columnar portion 50 is relatively larger than the volume of the gap 60, an increase in electrode temperature can be effectively suppressed.

An electrode that realizes such electrode temperature suppression can be manufactured as follows. That is, with respect to the pillar-shaped solid member on the front end having an electrode end surface, a cylindrical recess is formed around the central axis, and with respect to the pillar-shaped rear end solid member, a columnar part smaller in size than the cylindrical recess is formed. Formed around a central axis. At this time, the cylindrical recess and the columnar portion are formed so that the surface area of the internal space formed between the cylindrical recess and the columnar portion is larger than the surface area of the electrode side portion along the axial length of the internal space. The front end solid member and the rear end solid member are combined so that the columnar portion is arranged coaxially with the cylindrical recess, and an electrode including the front end solid member and the rear end solid member is formed by solid phase bonding using SPS or the like.

The spatial shape of the gap 60 is not limited to a bottomed tubular shape. For example, a bottomless tubular space may be formed without forming the axis-vertical gap 60D. In addition, an internal space other than a tubular space may be formed, and a space connected to the outside may be formed in a sealed state or through a hole. In this case, by forming a space around the electrode axis, it is possible to make the surface area larger than the surface area of the side portion of the electrode along the length of the space axis. In addition, the surface area of the gap (internal space) is the surface area of the space formed closer to the center of the electrode than the outer surface of the electrode. In addition, it is possible to form a closed space in which a heat transfer element that melts at a high temperature is provided. In this case, the surface area of the space (gap) represents the surface area of the exposed portion, and the surface covered with the heat transfer element is not included.

A heat dissipation portion may be provided in the columnar portion 50. For example, it is possible to construct a structure that increases the existing surface area, a structure that increases the emissivity (absorption rate), a heat dissipation material (a heat dissipation layer of a carbon film or an oxide film), or materials such as carbon nanotubes. Additionally, a heat dissipation portion may be provided in a location other than the columnar portion 50 (such as the cylindrical recessed portion 40 or the side of the electrode).

Next, the second embodiment will be described using FIG. 3. In the second embodiment, a through hole is formed on the side of the electrode.

Fig. 3 is a schematic cross-sectional view of the electrode (anode) 130 in the second embodiment. As shown in FIG. 3, a plurality of through holes J1 to J4 are formed. The through holes J1 to J4 are within the range of the axial length L3 of the columnar portion 50 here. By forming these through holes J1 to J4, heat from the gap 60 can escape and an increase in the temperature of the electrode can be suppressed. Accordingly, the surface area of the gap 60, including the surface area of the through holes J1 to J4, is determined to be larger than the electrode side portion T or T1. Additionally, the angle of the through hole is not limited to the vertical direction (horizontal direction) of the electrode axis, and may be defined as a predetermined angle. In addition, the number, hole diameter, and position are appropriately determined depending on the lamp size, electrode size, etc. For example, a through hole may be formed in the electrode tip surface 34D. Additionally, a heat dissipation portion may be provided in the second embodiment.

The present invention is not limited to the above-described embodiments, and various modifications are possible based on the technical idea of the present invention. The electrodes shown in the first and second embodiments can also be applied to discharge lamps other than a short arc type discharge lamp. Since the temperature rise of the electrode can be suppressed, it is very suitable for discharge lamps with relatively large power of 1 kW or more. The shape of the electrode can be any desired shape and size, for example, a shape without a tapered portion on the electrode support rod side. Additionally, the bonding method is preferably solid-state bonding (SPS, HP, etc.), but other bonding methods (for example, melt bonding) can also be applied. When joining, an intermediate member may be placed between the front end side member and the rear end side member to bring the joint surfaces into close contact. Examples of the intermediate member include rhenium, tantalum, molybdenum, tungsten, or alloys thereof.

The shape and size of the column and recess are arbitrary, for example, a column whose diameter changes along the axial direction ( And, an internal space with a large surface area can be formed arbitrarily. Additionally, it is possible to construct the columnar portion and the cylindrical recessed portion from different members. For example, it is possible to form the columnar portion (rear end member) from a lightweight member with excellent heat radiation properties, and to form the distal end member from a member with excellent heat resistance and thermal conductivity. In addition, it may be constructed by joining the columnar portion to the rear end member. Specifically, it may be tungsten, molybdenum, ceramic, etc., and may contain an emitter. Additionally, alloys thereof may be used, and may be selected appropriately.

(Example)

Below, an example according to the second embodiment will be described.

The discharge lamp of the embodiment is a discharge lamp equipped with an electrode provided with eight through holes on the side of the electrode and also provided with a through hole on the tip of the electrode, and has a total length of 60 mm, L1 = 28 mm, L3 = 25 mm, L4 = 3 mm, D1 = 38 mm, D2 = 26 mm, D3 = 22 mm, D4 = 2 mm, through hole diameter = 3 mm, and electrode tip hole diameter = 3 mm. The surface area of the gap is larger than the surface area of the electrode side portion along the axial length of the gap (5552.3 > 3286.1).

This discharge lamp was turned on by inputting a predetermined amount of power, and the temperature was measured for the electrode in a stable lighting state. The temperature was measured with a thermo tracer set to emissivity: ε0.68 and measurement wavelength range: 2.2 to 2.6 μm. On the other hand, as for the discharge lamp of the comparative example, the temperature was measured similarly to the discharge lamp incorporating the same electrodes as in the examples except for the configuration in which no gap or through hole was provided.

Figure 4 is a graph showing the temperature change at the tip of the electrode in Examples and Comparative Examples. This is obtained by measuring multiple locations from the joint surface to the tip of the electrode, that is, in the area corresponding to the electrode side portion T, and approximately straightening the plot. The same applies to comparative examples. As shown in Fig. 4, the temperature of the electrode of the example was lower than that of the comparative example, and it was confirmed that temperature suppression was maintained even toward the tip of the electrode.

10: Discharge lamp
30: Electrode (anode)
32: Rear end member
34: Tip side member
40: barrel-shaped waist
50: Scapular region
60: Gap (internal space)

Claims (10)

discharge tube,
Equipped with a pair of electrodes opposed to each other in the discharge tube,
At least one electrode has an internal space,
The internal space has a symmetrical spatial shape with respect to the electrode axis,
A discharge lamp, wherein the surface area of the internal space is larger than the surface area of the side portion of the electrode along the axial length of the internal space. According to paragraph 1,
A discharge lamp, wherein the surface area of the internal space is larger than the surface area of the side portion of the electrode along the electrode axis direction. discharge tube,
Equipped with a pair of electrodes opposed to each other in the discharge tube,
At least one electrode has an internal space,
The internal space has a space formed around the entire circumference of the electrode axis,
A discharge lamp, wherein the surface area of the internal space is larger than the surface area of the side portion of the electrode along the axial length of the internal space. discharge tube,
Equipped with a pair of electrodes opposed to each other in the discharge tube,
At least one electrode has an internal space,
The electrode has a recessed portion along the electrode axis direction and a columnar portion located in the recessed portion,
The internal space is formed to be widened between the recessed portion and the columnar portion,
A discharge lamp, wherein the surface area of the internal space is larger than the surface area of the side portion of the electrode along the axial length of the internal space. According to any one of claims 1 to 4,
A discharge lamp characterized in that the internal space is formed in the shape of a bottom tube. According to any one of claims 1 to 4,
A discharge lamp, characterized in that the internal space has a through hole along the vertical direction of the electrode axis. According to any one of claims 1 to 4,
A discharge lamp characterized in that a heat dissipation portion is provided on a surface portion of the interior space. According to paragraph 4,
The at least one electrode is
It has a first solid member forming the recessed portion, and a second solid member joining the first solid member or an intermediate member joined to the first solid member to form the columnar portion,
A discharge lamp characterized in that the internal space is formed between the first solid member and the second solid member or the intermediate member. discharge tube,
Equipped with a pair of electrodes opposed to each other in the discharge tube,
At least one electrode,
A lumbar portion along the electrode axis direction, a columnar portion located in the lumbar portion, and
Equipped with an internal space formed between the recessed portion and the columnar portion,
The internal space has a space formed around the entire circumference of the electrode axis,
A discharge lamp characterized in that the volume of the columnar portion is larger than the volume of the interior space. A cylindrical recess is formed around the central axis on a column-shaped tip-side solid member having an electrode tip end surface,
For the pillar-shaped rear end side solid member, a columnar portion smaller in size than the cylindrical recess is formed around the central axis,
The columnar portion is arranged coaxially with the cylindrical recess, so that an internal space spanning the entire circumference around the electrode axis is formed between the columnar portion and the cylindrical recess, and the front end solid member and the rear end solid member Combine,
A method for manufacturing an electrode for a discharge lamp, comprising forming an electrode including the front-end solid member and the rear-end solid member by solid-phase bonding,
The cylindrical recess and the columnar portion are formed so that the surface area of the inner space formed between the cylindrical recess and the columnar portion is larger than the surface area of the electrode side portion along the axial length of the interior space. A method of manufacturing an electrode for a discharge lamp.

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