Discharge lamp and method for manufacturing electrode for discharge lamp

Abstract

The present invention provides a discharge lamp and a method for manufacturing an electrode for a discharge lamp. In the discharge lamp, heat is effectively dissipated to suppress the electrode temperature. An internal space (40) is formed to be sealed inside an electrode (30) of the discharge lamp (10), and heat dissipation parts (50A, 50B) facing each other are formed along an electrode axis (X).

Description

Technical Field

[0001] The present invention relates to a discharge lamp having a pair of electrodes, and more particularly to an internal structure of the electrodes. Background Art

[0002] When the discharge lamp is lit, the electrode tip reaches a high temperature, the electrode material such as tungsten melts and evaporates, the discharge tube blackens, and the lamp illumination decreases. In order to prevent the electrode tip from overheating, for example, the electrode tip made of a durable metal and the body made of a metal with higher thermal conductivity are separately molded and joined by solid phase bonding or the like (see Patent Document 1). In addition, a gap is formed inside the electrode along the electrode axis direction to function as a heat dissipation space (see Patent Document 2).

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] [Patent Document 1] Japanese Patent No. 5472915

[0006] [Patent Document 2] Japanese Patent Application Publication No. 2018-142482 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] In recent years, in order to increase the size of exposure objects and throughput, higher output (higher power) of lamps has been required. As a result, the temperature of the electrodes during lamp lighting has also increased, and an electrode structure that can more effectively suppress the temperature rise of the electrodes has been required.

[0009] [Methods used to solve the problem]

[0010] The discharge lamp of the present invention comprises a discharge tube and a pair of electrodes disposed opposite to each other in the discharge tube, and at least one of the electrodes has an internal space, for example, the internal space is configured as a closed vacuum space.

[0011] In the present invention, heat dissipation / heat absorption structures facing each other are provided on the surface of the internal space. Here, the so-called "heat dissipation / heat absorption structure" refers to a structure that can radiate heat and absorb heat when the lamp is lit. When one side functions as a heat radiation structure, the other side functions as a heat absorption structure. In addition, the heat dissipation / heat absorption structure includes surface shapes such as grooves or rough surfaces, and structures such as coating materials.

[0012] The heat dissipation / heat absorption structures of the present invention are opposite to each other. Here, the term "opposite to each other" includes not only that the heat dissipation structure and the heat absorption structure are opposite to each other with the same area size, but also that a part of the area of ​​the heat dissipation structure (or heat absorption structure) on one side is opposite to the area of ​​the heat absorption structure (or heat dissipation structure) on the other side. In addition, the heat dissipation / heat absorption structure may be provided on the entire surface of the internal space, or may be provided partially.

[0013] For example, when the discharge lamp is arranged in a vertical direction, a heat dissipation structure can be set on the surface on the electrode end side of the internal space, and a heat absorption structure can be set on the surface opposite to the surface on the electrode end side (the heat absorption structure is also a heat dissipation structure, and the heat absorption structure is also a heat dissipation structure).

[0014] By making the heat dissipation / absorption structures facing each other the same structure, the characteristics of the emissivity and absorptivity can be made the same. For example, they can all be made of groove shapes or coatings. In addition, the heat dissipation / absorption structures facing each other can be provided not only on the surface of the electrode end side of the internal space and the surface facing thereto, but also on the surface along the electrode axis of the internal space.

[0015] It is also possible to make the length along the electrode axis from the electrode end surface to the side surface of the electrode end where the heat dissipation structure is provided in the internal space smaller than the length along the electrode axis from the side surface of the electrode end to the side surface of the electrode support rod where the heat absorption structure is provided in the internal space, thereby accelerating the transition from heat conduction to heat radiation.

[0016] As another embodiment of the present invention, a method for manufacturing a discharge lamp electrode is provided, wherein a plurality of electrode components are solid-phase bonded, wherein the plurality of electrode components include: a first electrode component having a columnar shape with a heat dissipation / heat absorption structure at one end surface; a second electrode component having a columnar shape with a heat dissipation / heat absorption structure at one end surface; and a tubular component with both ends open, wherein the first electrode component and the second electrode component are solid-phase bonded between the tubular component and the end surface side having the heat dissipation / heat absorption structure. For example, an intermediate component may be provided between the plurality of components.

[0017] As another embodiment of the present invention, a method for manufacturing a discharge lamp electrode includes forming a columnar electrode end side component having a heat dissipation structure on one end face, a columnar electrode support rod side component having a heat absorption structure on one end face, and a cylindrical trunk component with both ends open, so that the electrode end side component and the electrode support rod side component are solidly bonded to the cylindrical trunk component at the end face side having the heat dissipation / heat absorption structure. For example, the heat dissipation / heat absorption structure of the same structure can be formed on the electrode end side component and the electrode support side component.

[0018] [Effects of the Invention]

[0019] According to the present invention, in the discharge lamp, heat can be efficiently dissipated to suppress the electrode temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a top view of the discharge lamp according to the first embodiment.

[0021] Figure 2 This is a schematic cross-sectional view of the electrode according to the first embodiment.

[0022] Figure 3 It is a diagram showing the heat dissipation / absorption structure.

[0023] Figure 4 It is a diagram showing a method for manufacturing an electrode.

[0024] Figure 5 It is a schematic cross-sectional view of an electrode according to the second embodiment.

[0025] Description of symbols

[0026] 10 Discharge lamp

[0027] 30 Electrode (anode)

[0028] 32 Rear side parts

[0029] 34 End side parts

[0030] 40 Interior Space

[0031] 50A, 50B heat dissipation unit (heat dissipation / heat absorption structure) DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0033] Figure 1 It is a top view of the discharge lamp according to the first embodiment.

[0034] The short arc type discharge lamp 10 is a large discharge lamp capable of outputting high brightness light, and includes a substantially spherical discharge tube (light emitting tube) 12 made of transparent quartz glass, and a pair of electrodes 20 and 30 made of tungsten are arranged opposite to each other in the discharge tube 12. On both sides of the discharge tube 12, sealing tubes 13A and 13B made of quartz glass are connected to the discharge tube 12 and formed integrally. Mercury and halogen or rare gas such as argon are sealed in the discharge space DS in the discharge tube 12.

[0035] The electrode 20 as the cathode is supported by the electrode support rod 17A. A glass tube (not shown) through which the electrode support rod 17A is inserted, a lead rod 15A connected to an external power source, and a metal foil 16A connecting the electrode support rod 17A and the lead rod 15A are sealed in the sealed tube 13A. Similarly, the electrode 30 as the anode is sealed with mounting components such as a glass tube (not shown) through which the electrode support rod 17B is inserted, a metal foil 16B, and a lead rod 15B. In addition, lamp caps 19A and 19B are respectively mounted at the ends of the sealed tubes 13A and 13B.

[0036] When a voltage is applied to a pair of electrodes 20 and 30, arc discharge is generated between the electrodes 20 and 30, and light is radiated to the outside of the discharge tube 12. Here, a power of 1 kW or more is connected. The light radiated from the discharge tube 12 is guided in a predetermined direction by a reflector (not shown). For example, when the discharge lamp 10 is assembled in an exposure device, the radiated light becomes pattern light and is irradiated onto a substrate or the like.

[0037] Figure 2 It is a schematic cross-sectional view of the electrode 30 according to the first embodiment. Figure 3 This is a top view of the heat dissipation unit as viewed from above. The electrode 20 may also have the same structure.

[0038] The electrode 30 has a sealed space 40 therein and is formed by joining a rear end member 32 connected to the electrode support rod 17B, a terminal member 34 having an electrode terminal surface 30S, and a trunk member 36 with both ends open. Here, the joining is performed by solid phase joining such as SPS.

[0039] The rear end side member 32 is a cylindrical member with a substantially constant thickness along the axial direction X (hereinafter also referred to as the electrode axis X), and the tip side member 34 is formed in a truncated cone shape. The internal space 40 surrounded by the rear end side member 32, the tip side member 34, and the trunk member 36 is configured as a cylindrical space here, and is formed coaxially with the electrode axis X. In addition, the internal space 40 is in a vacuum state.

[0040] A heat dissipation portion (heat dissipation structure) 50A is provided on the electrode tip side surface (hereinafter referred to as the bottom surface) 40S1 of the internal space 40, that is, a portion of the end surface of the tip side component 34. In addition, a heat dissipation portion (heat absorption structure) 50B is also provided on the electrode support rod side surface (hereinafter referred to as the top surface) 40S2, that is, a portion of the end surface of the rear end side component 32. The length L1 along the electrode axis X from the electrode tip surface 30S to the bottom surface 40S1 of the internal space 40 is shorter than the length L2 along the electrode axis X from the bottom surface 40S1 to the top surface 40S2 (L1 <L2)。

[0041] like Figure 3As shown, the heat dissipation portion 50A formed on the bottom surface 40S1 of the internal space 40 is composed of grooves G formed in a concentric circle at a predetermined radial interval, and the depth of the grooves is approximately constant. The heat dissipation portion 50A can be formed by a known method such as laser processing or cutting processing. The heat dissipation portion 50B formed on the top surface 40S2 on the opposite side is also composed of the same concentric circle grooves, and the shape, depth, and formation area of ​​the grooves are the same as those of the heat dissipation portion 50A. In addition, Figure 2 The depth of the groove G (the thickness of the heat dissipating portions 50A and 50B) is exaggerated in FIG.

[0042] The heat dissipating portions 50A and 50B facing each other along the electrode axis X can achieve effective heat dissipation during lamp lighting as described below, and can suppress the electrode temperature.

[0043] Generally, heat is transferred through three methods: heat conduction, convection (heat transfer), and thermal radiation (thermal emission). In heat conduction, heat is transferred through matter through intermolecular vibration or the movement of free electrons. Convection transfers heat from a solid surface to a fluid, and heat is transported through the movement of the fluid caused by the temperature difference. On the other hand, thermal radiation is a phenomenon in which heat is transported through electromagnetic waves, and heat is not transferred through matter.

[0044] The electrode temperature during lamp lighting is about 2000°C, and sometimes reaches nearly 3000°C. In such a high temperature state, heat radiation is more dominant than heat conduction. The heat of the electrode tip surface 30S is transferred to the electrode support rod 17B side by heat conduction, but by forming the internal space 40, the heat is radiated from the bottom surface 40S1 of the internal space 40 to the top surface 40S2.

[0045] At this time, the heat dissipation portion 50A functions as a heat dissipation structure that effectively releases heat to the internal space 40. Most of the heat radiated as electromagnetic waves travels along the electrode axis X and is transferred to the heat dissipation portion 50B formed on the top surface 40S2 disposed opposite to the bottom surface 40S1.

[0046] Here, according to Kirchhoff's law, an object that easily radiates heat also easily absorbs heat to the same extent, and the radiation rate and the absorption rate are equal. Since the heat dissipation portion 50B has the same structure as the heat dissipation portion 50A and is formed in the same area, it functions as a heat absorption structure that absorbs heat with an excellent absorption rate and transfers it to the rear end side member 32. Part of the transferred heat is transferred to the electrode support rod 17B by heat conduction, and part of the heat is radiated from the outer surface of the electrode.

[0047] Thus, according to the present embodiment, the internal space 40 is formed to be sealed inside the electrode 30 of the discharge lamp 10, and the heat sinks 50A and 50B are formed to be opposite to each other along the electrode axis X. By forming the internal space 40 and the heat sinks 50A and 50B that are effective for the transport of heat mainly by thermal radiation, the temperature of the lamp can be effectively suppressed.

[0048] Since the internal space 40 is in a vacuum state, heat can be effectively moved to the top surface 40S2 side, and since the structures of the heat dissipation parts 50A and 50B are grooves and the forming area (size) is also the same, the heat radiation and heat absorption are the same, and the balance between radiation and absorption is good, so heat can be transported in a way that does not cause heat retention.

[0049] Even in the lamp temperature state dominated by heat conduction or convection, heat is effectively transferred to the internal space 40 due to the presence of the heat dissipation portion 50A, and heat conduction from the top surface 40S2 to the rear end side member 32 is also effectively performed through the heat dissipation portion 50B.

[0050] Furthermore, since the length L1 from the electrode tip surface 30S to the bottom surface 40S1 of the internal space 40, that is, the length L1 to the heat dissipation portion 50A is shorter than the length L2 from the bottom surface 40S1 to the top surface 40S2 where the heat dissipation portion 50B is provided, the heat dissipation portion 50A is close to the arc and can quickly switch from heat conduction to heat radiation.

[0051] In addition, the heat dissipation parts 50A and 50B may be formed by structures other than the groove G. For example, the bottom surface 40S1 and the top surface 40S2 may be covered with heat dissipation materials (heat dissipation layers of carbonized films or oxide films), and components with high emissivity (absorption rate) such as carbon nanotubes may be used. It is sufficient to form an area with a shape or material for improving heat dissipation. In addition, the heat dissipation parts 50A and 50B may not have the same structure, and one of the heat dissipation parts 50A and 50B may be formed by a coating or the like. Furthermore, the sizes of the areas where the heat dissipation parts 50A and 50B are provided may be different.

[0052] Figure 4 It is a diagram showing the manufacturing process of the electrode 30 .

[0053] First, the columnar electrode tip side member 110 and the columnar electrode support rod side member 130 are formed, and the cylindrical trunk member 120 with both ends opened is formed. The heat dissipation parts 50A and 50B consisting of grooves are formed on the surface of one end of the electrode tip side member 110 and the electrode support rod side member 130 by laser processing or the like. At this time, the heat dissipation parts 50A and 50B are processed to have the same shape and area size.

[0054] Then, the electrode tip side member 110, the trunk member 120, and the electrode support rod side member 130 are joined to each other by solid phase bonding such as SPS. At this time, the end surface provided with the heat dissipation parts 50A and 50B is solid phase bonded to both ends of the trunk member 120 so that the heat dissipation parts 50A and 50B face each other. Then, the desired electrode shape is formed by cutting.

[0055] By adopting the step of performing cutting after solid phase bonding to form the internal space 40 , the heat dissipation portion can be formed before solid phase bonding, and a desired heat dissipation portion can be formed regardless of the shape of the electrodes after bonding.

[0056] exist Figure 4 In the embodiment, the heat dissipation parts 50A and 50B are provided in the same area size as the bottom surface 40S1 and the top surface 40S2 of the internal space 40, but they may be formed on the entire end surface of the electrode tip side component 110 and the electrode support rod side component 130 and solid-phase bonded. In addition, more components may be prepared and solid-phase bonded to each other.

[0057] Next, use Figure 5 A discharge lamp according to a second embodiment will be described. In the second embodiment, a heat dissipation portion is provided along the side surface of the internal space, and a columnar portion is formed on the bottom surface of the internal space.

[0058] The electrode 100 includes an internal space 140, and a columnar portion 160 is coaxially provided so as to extend from a bottom surface 140S1 of the internal space 140 along the electrode axis X. Different from the first embodiment, a heat dissipation portion 150A is formed of a coating material on a surface 160S of the columnar portion 160. In addition, a heat dissipation portion 150B is also formed of a coating material on a top surface 140S2 opposite to the bottom surface 140S1.

[0059] The area size of the heat dissipation portion 150A is smaller than the area size of the heat dissipation portion 150B. In addition, the length L1 from the electrode tip surface 130S to the heat dissipation portion 150A, that is, the length L1 to the surface 160S of the columnar portion 160, is shorter than the length L2 from the top surface 140S2 provided with the heat dissipation portion 150B to the surface 160S of the columnar portion 160. According to such a structure, for example, by making the columnar portion 160 other materials with high thermal conductivity, both heat conduction and heat radiation can be effectively performed. In addition, since the heat dissipation portion is provided on the entire top surface, heat absorption also becomes effective.

[0060] On the other hand, heat dissipation parts (side heat dissipation / heat absorption structures) 250A and 250B facing each other are provided on the side surface 140T of the internal space 140. The heat dissipation parts 250A and 250B are formed in an arc shape here, and are made of, for example, a coating material. By also providing the heat dissipation parts on the side surface 140T of the internal space 140, heat dissipation in a direction perpendicular to the electrode axis X also becomes effective. In addition, it is also possible to configure the internal space not to be a closed space, but to seal a rare gas or the like.

[0061] Although it can also be applied to discharge lamps other than short arc type discharge lamps, it is suitable for discharge lamps with a higher power of more than 1 kW because it can suppress the temperature rise of the electrode. In addition, the joining method is preferably solid phase joining (SPS, HP, etc.), but other joining methods (such as melting welding) can also be applied. When joining, an intermediate component can also be sandwiched between the end side component and the rear end side component (between the first electrode component and the second electrode component) to make the joint surfaces close. Furthermore, the end side component and the rear end side component can be tungsten or molybdenum, or their alloys, ceramics, etc., and can also contain an emitter, which can be appropriately selected.

Claims

1. A discharge lamp, characterized in that The discharge lamp has: discharge tube; and A pair of electrodes are arranged opposite to each other in the discharge tube, At least one of the electrodes comprises: a rear end side member connected to the electrode support rod, a terminal side member having an electrode terminal surface, and a trunk member with both ends opened, the trunk member being joined between the rear end side member and the terminal side member, On the surface of the inner space in the electrode surrounded by the rear end side member, the tip side member and the trunk member, heat dissipation and heat absorption structures facing each other and capable of radiating and absorbing heat are provided.

2. The discharge lamp according to claim 1, characterized in that A heat dissipation structure is provided on a surface of the inner space on the electrode end side, and a heat absorption structure is provided on a surface opposite to the surface on the electrode end side.

3. The discharge lamp according to claim 1 or 2, characterized in that The heat dissipating and heat absorbing structures opposite to each other are of the same structure.

4. The discharge lamp according to claim 1 or 2, characterized in that On the surface of the inner space along the electrode axis, side heat dissipation and heat absorption structures opposite to each other are also provided.

5. The discharge lamp according to claim 1 or 2, characterized in that The length along the electrode axis from the electrode tip surface to the electrode tip side surface with the heat dissipation structure in the internal space is smaller than the length along the electrode axis from the electrode tip side surface to the electrode support rod side surface with the heat absorption structure in the internal space.

6. The discharge lamp according to claim 1 or 2, characterized in that The internal space is a closed vacuum space.

7. The discharge lamp according to claim 1 or 2, characterized in that The discharge lamp lights up at the temperature of the heat dissipation and heat absorption structure mainly based on heat radiation.

8. A method for manufacturing an electrode for a discharge lamp, comprising solid-phase bonding a plurality of electrode components, characterized in that: The plurality of electrode components include: a first electrode component having a columnar shape and a heat dissipation and absorption structure capable of radiating and absorbing heat on one end surface; a second electrode component having a columnar shape and a heat dissipation and absorption structure capable of radiating and absorbing heat on one end surface; and a tubular component with openings at both ends. The first electrode member and the second electrode member are solid-phase bonded between the end surface side provided with the heat dissipating and heat absorbing structure and the cylindrical member.

9. A method for manufacturing an electrode for a discharge lamp, characterized in that: A columnar electrode end side component with a heat dissipation structure on one end surface, a columnar electrode support rod side component with a heat absorption structure on one end surface, and a cylindrical trunk component with openings at both ends are formed. The electrode tip side member and the electrode support rod side member are solidly bonded to the cylindrical body member at the end surface sides where the heat dissipation structure and the heat absorption structure are provided, respectively.

10. The method for manufacturing a discharge lamp electrode according to claim 9, characterized in that: The electrode tip side member and the electrode support rod side member have a heat dissipation structure and a heat absorption structure of the same structure.

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