Discharge lamp and electrode for use in the discharge lamp

Abstract

A discharge lamp and an electrode used for the discharge lamp, which realize high output and long life of the discharge lamp. At least one electrode of the discharge lamp has: a main body having a closed space; a heat transfer body disposed in the closed space; a restriction body that restricts convection of the heat transfer body. A distance between a reference position P0 of a bottom surface of the closed space and a lowest position P1 of a vane of the restriction body is set as a first distance B1 (mm). A distance between the lowest position P1 of the vane and a highest position P2 of the vane is set as a second distance L1 (mm). A distance between the highest position P2 of the vane and an interface position P3 of the heat transfer body is set as a third distance H1 (mm). An area of a filled region of the heat transfer body in a cross section through a center axis of the at least one electrode, which is sandwiched by the lowest position P1 and an upper surface of the heat transfer body, is set as an upper area S1 (mm 2 ) of the heat transfer body. At this time, the following (1) to (3) are satisfied, 3 ≤ B1 ≤ 15 … (1) 0.0 ≤ H1 / L1 ≤ 1.0 … (2) S1 ≥ 40 … (3).

Description

Technical Field

[0001] This invention relates to a discharge lamp and the electrodes used in the discharge lamp. Background Technology

[0002] Traditionally, the exposure equipment used in the manufacturing processes of semiconductor components, liquid crystal display components, etc., uses discharge lamps, especially short-arc discharge lamps, as the light source. In this discharge lamp, the anode and cathode are arranged axially opposite each other inside the light-emitting tube, and a luminescent material such as mercury is sealed inside the light-emitting tube.

[0003] In such discharge lamps, the heat load acting on the electrodes is high when lit, which sometimes leads to evaporation of the electrode material due to overheating of the anode. If this evaporation adheres to the inner wall of the light-emitting tube, the discharge lamp will experience a so-called blackening, resulting in a decrease in the light transmittance of the light-emitting tube.

[0004] To address this problem, a discharge lamp with a structure in which a heat transfer medium is sealed within a closed space inside the anode has been proposed. The heat transfer medium melts when the lamp is lit and convects within the closed space according to the overall temperature distribution of the anode. This convection transfers heat from the front end of the anode (the end closest to the cathode) to the rear end (the end furthest from the cathode), thereby lowering the temperature at the front end of the anode and suppressing the evaporation of the electrode material.

[0005] Patent documents 1 and 2 describe a limiting body installed within a sealed space to restrict circumferential convection of a heat transfer medium. By installing the limiting body within the sealed space, openings at the electrode tip caused by circumferential convection of the heat transfer medium are prevented.

[0006] Prior technology literature

[0007] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2012-028168

[0009] [Patent Document 2] Japanese Patent Application Publication No. 2017-016761 Summary of the Invention

[0010] [Summary of the Invention]

[0011] [The problem the invention aims to solve]

[0012] Recently, the market has demanded further increases in the output and lifespan of discharge lamps. When discharge lamps are made to have high output, the heat load on the electrodes increases, thus requiring electrodes designed to withstand this heat load for extended periods. The objective of this invention is to provide a discharge lamp that achieves both high output and long lifespan, and the electrodes used in this discharge lamp.

[0013] [Solutions for solving the problem]

[0014] To investigate the thermal load on the electrodes of a discharge lamp used at high output, the inventors measured the temperature distribution on the electrode surface during illumination using a radiation thermometer. The measurements revealed discharge lamps exhibiting high temperatures at the electrode tip and those with large localized temperature fluctuations on the electrode surface. Temperature fluctuations refer to changes in temperature over a short period (e.g., 1 minute). When the high temperature at the electrode tip or the large temperature fluctuations on the inner surface of the electrode persist for an extended period, high-temperature creep deformation occurs, resulting in protrusions from the inner surface of the electrode tip. This leads to openings at the electrode tip, causing leakage of the heat transfer medium. Consequently, the electrode loses its heat dissipation capacity, resulting in a short lifespan for the discharge lamp.

[0015] The inventors considered that the increase in temperature at the electrode tip or the widening of temperature fluctuation range could cause problems with the flow rate or turbulence of the heat transfer medium. Furthermore, to solve this problem, it was deemed important that not only a confinement body restricting the convection of the heat transfer medium be configured in a confined space, but also that the size design of the electrode, which includes both the confinement body and the heat transfer medium, is crucial. The following discharge lamp was proposed, details of which are described later.

[0016] The discharge lamp of the present invention has a pair of electrodes arranged axially opposite each other inside, wherein,

[0017] At least one of the electrodes in the pair of electrodes has:

[0018] The main body has a closed space;

[0019] The heat transfer element, within the enclosed space, has a lower melting point than the material constituting the main body;

[0020] A confinement body, within the enclosed space, is made of a material with a higher melting point than the heat transfer body, thereby restricting convection within the heat transfer body; and

[0021] A gas space, within the sealed space, is in contact with the heat transfer element.

[0022] The limiting body includes at least one blade extending along the axial direction and radially orthogonal to the axial direction.

[0023] When the at least one electrode is configured such that its front end is below and its rear end is above, and the lowest axial position of the bottom surface of the sealed space is set as the reference position P0, the end position of the blade closest to the bottom surface is set as the lowest position P1 of the blade, the end position of the blade furthest from the bottom surface is set as the highest position P2 of the blade, and the axial position of the interface between the heat transfer element and the gas space is set as the interface position P3,

[0024] The axial distance between the reference position P0 and the lowest position P1 is the first distance B1 (mm); the axial distance between the lowest position P1 and the highest position P2 is the second distance L1 (mm); the axial distance between the highest position P2 and the interface position P3 is the third distance H1 (mm); and the upper area S1 (mm²) of the heat transfer body filled by the lowest position P1 and the interface in the cross-section that is the axis of the axial direction is included. 2 It satisfies the following equations (1) to (3).

[0025] 3≤B1≤15…(1)

[0026] 0.0≤H1 / L1≤1.0…(2)

[0027] S1≥40…(3)

[0028] This dimensionally designed electrode allows for sufficient convection of the heat transfer medium. Therefore, it facilitates a decrease in the temperature at the electrode tip. Furthermore, by suppressing turbulence in the heat transfer medium, the localized temperature fluctuations on the electrode surface are reduced. Consequently, openings at the electrode tip caused by high-temperature creep deformation are suppressed. This enables high output and long lifespan of the discharge lamp.

[0029] The discharge lamp may have three or more blades. This can suppress the tilting of the confinement body and suppress turbulence in the heat transfer medium.

[0030] The bottom surface of the enclosed space may include a curved surface. This can suppress stagnation or turbulence in the convection of the heat transfer medium.

[0031] When the outer diameter of the main body is set to D1 and the outer diameter of the sealed space is set to D2, the following equation (4) can be satisfied. This can reduce the temperature at the electrode tip and decrease the temperature fluctuation range.

[0032] 0.45×D1+1.5≤D2≤0.55×D1+1.5…(4)

[0033] The electrode of the present invention for use in a discharge lamp comprises:

[0034] The main body has a closed space;

[0035] The heat transfer element, within the enclosed space, has a lower melting point than the material constituting the main body;

[0036] A confinement body, within the enclosed space, is made of a material with a higher melting point than the heat transfer body, thereby restricting convection within the heat transfer body; and

[0037] A gas space, within the sealed space, is in contact with the heat transfer element.

[0038] The limiting body includes at least one blade extending along the axial direction and radially orthogonal to the axial direction.

[0039] When the at least one electrode is configured such that its front end is below and its rear end is above, and the lowest axial position of the bottom surface of the sealed space is set as the reference position P0, the end position of the blade closest to the bottom surface is set as the lowest position P1 of the blade, the end position of the blade furthest from the bottom surface is set as the highest position P2 of the blade, and the axial position of the interface between the heat transfer element and the gas space is set as the interface position P3,

[0040] The axial distance between the reference position P0 and the lowest position P1 is the first distance B1 (mm); the axial distance between the lowest position P1 and the highest position P2 is the second distance L1 (mm); the axial distance between the highest position P2 and the interface position P3 is the third distance H1 (mm); and the upper area S1 (mm²) of the heat transfer body filled by the lowest position P1 and the interface in the cross-section that is the axis of the axial direction is included. 2 It satisfies the following equations (1) to (3).

[0041] 3≤B1≤15…(1)

[0042] 0.0≤H1 / L1≤1.0…(2)

[0043] S1≥40…(3)

[0044] [Invention Effects]

[0045] It can provide discharge lamps that achieve high output and long lifespan, and electrodes used in such discharge lamps. Attached Figure Description

[0046] Figure 1 This is a diagram showing the outline of a discharge lamp.

[0047] Figure 2 yes Figure 1 An enlarged cross-sectional view of the anode in a discharge lamp.

[0048] Figure 3 yes Figure 2 AA-direction sectional view.

[0049] Figure 4 This is a diagram illustrating an example of convection in a heat transfer medium.

[0050] Figure 5 This is a diagram illustrating an example of convection in a heat transfer medium.

[0051] Figure 6 This is a side view of the constrained body.

[0052] Figure 7 This is a top view of the constrained object.

[0053] Figure 8 A cross-sectional view showing the anode through which the central axis passes.

[0054] Figure 9 It is a coordinate graph showing the relationship between the third interval H1 and the temperature TE at the front end of the anode.

[0055] Figure 10 It is a coordinate graph showing the relationship between the first interval B1 and the maximum value of the temperature variation TX.

[0056] Figure 11 It is a coordinate graph showing the relationship between the third interval H1 / second interval L1 and the maximum value of the temperature variation TX.

[0057] Figure 12 It is a coordinate graph showing the relationship between the upper area S1 of the heat transfer body and the temperature TE at the front end of the anode.

[0058] Figure 13A This is a diagram representing the anode that satisfies equation (2) but not equation (3).

[0059] Figure 13B This is a diagram representing the anode that satisfies both equations (2) and (3).

[0060] Figure 14 This is a coordinate graph representing the simulation results for the six anodes A through F.

[0061] Figure 15 This is a diagram showing the anode, which is recessed near the central axis of the heat transfer body.

[0062] Figure 16 This is a diagram showing a variation of a restricted body.

[0063] Figure 17 This is a diagram showing a variation of a restricted body.

[0064] Figure 18 This is a diagram showing a variation of a restricted body.

[0065] Figure 19 It is a cross-sectional view of the anode in the YZ plane.

[0066] Figure 20 This is a cross-sectional view showing a modified example of the anode body.

[0067] [Label Explanation]

[0068] 1: LED

[0069] 2: Anode

[0070] 3: Cathode

[0071] 4: Guide rod

[0072] 5: Main Body

[0073] 5a: Container

[0074] 5b: Cover

[0075] 8: Gas Space

[0076] 8i: Interface

[0077] 9: Heat transfer element

[0078] 9s: Upper area

[0079] 10: Restricted Body

[0080] 10b: Blade

[0081] 10t: (upper surface of the blade)

[0082] 10t1: Plane

[0083] 10t2: Conical surface

[0084] 10u: (The lower surface of the blade)

[0085] 11: Sealing tube

[0086] 12: Lamp holder

[0087] 13: Front-end

[0088] 14: Backend

[0089] 15: Inner wall

[0090] 20, 30, 40: Restricted Body

[0091] 20b, 30b, 40b: Blades

[0092] 100: Discharge lamp

[0093] B1: First Interval

[0094] D1: Outer diameter

[0095] D2: Outer diameter

[0096] G1: Gap

[0097] H1: Third Interval

[0098] L1: Second Interval

[0099] P0: Reference position

[0100] P1: Lowest position

[0101] P2: Highest position

[0102] P3: Interface Location

[0103] S1: Upper area

[0104] T1: Thickness

[0105] Z1: Central axis Detailed Implementation

[0106] The implementation method of the discharge lamp will be described with reference to the accompanying drawings. It should be noted that, except for the coordinate diagrams, the following drawings are schematic illustrations, and the dimension ratios in the drawings may not be consistent with the actual dimension ratios, nor may the dimension ratios be consistent between different drawings.

[0107] The following figures, except for the coordinate graphs, will be explained with reference to the XYZ coordinate system. In this specification, when expressing direction, positive and negative directions are distinguished by using symbols such as "+X direction" and "-X direction". When expressing direction without distinguishing positive and negative directions, it is simply referred to as "X direction". That is, in this specification, the abbreviation "X direction" includes both "+X direction" and "-X direction". The same applies to the Y and Z directions. In the embodiments described below, the -Z direction represents the direction of gravity.

[0108] [Overview of Discharge Lamps]

[0109] Reference Figure 1 The following describes the general outline of a discharge lamp as an embodiment of the present invention. The discharge lamp 100 is a short-arc type discharge lamp comprising a light-emitting tube 1, an anode 2 and a cathode 3 arranged opposite to each other along the extension direction of the central axis Z1 inside the light-emitting tube 1, and a guide rod 4 supporting the anode 2 and the cathode 3 respectively. In this embodiment, the discharge lamp 100 is arranged such that the anode 2 is located above the cathode 3 (in the +Z direction) to illuminate the discharge lamp 100.

[0110] A short-arc discharge lamp refers to a structure in which the front end of the anode 2 and the front end of the cathode 3 are spaced apart by a gap of 40 mm or less (at room temperature without thermal expansion). Examples of such discharge lamps include those with a rated power of 2 kW to 35 kW used in exposure apparatuses used in the manufacturing processes of semiconductor devices, liquid crystal display devices, etc. It should be noted that the discharge lamp 100 of this embodiment is configured with a 6 mm gap between the front end of the anode 2 and the front end of the cathode 3.

[0111] The light-emitting tube 1, anode 2, cathode 3, and guide rod 4 are all arranged around the central axis Z1. The anode 2 is positioned above the cathode 3 (in the +Z direction). Sealing tubes 11 are provided at both ends of the light-emitting tube 1 along the extension direction of the central axis Z1. A lamp holder 12, which is electrically connected to the guide rod 4, is installed in the sealing tube 11.

[0112] The light-emitting tube 1 is formed of a glass tube. The light-emitting tube 1 has a region where the inner diameter of the glass tube increases from both ends toward the center along the central axis Z1. This region with the increased inner diameter can be spherical or ellipsoidal in shape. The glass tube can be, for example, quartz glass. The region with the increased inner diameter functions as a light-emitting space. A luminescent substance such as mercury is enclosed in this light-emitting space.

[0113] [Anode Overview]

[0114] Reference Figure 2 and Figure 3 This section provides an overview of anode 2. Figure 2 yes Figure 1 An enlarged cross-sectional view of anode 2 in the discharge lamp. Figure 2 In the diagram, the cross-section of the anode 2 in the plane through which the central axis Z1 passes is shown with the front end 13 of the anode 2, which is close to the opposite cathode 3, located on the lower side (-Z side), while the rear end 14 of the connecting guide rod 4 is located on the upper side (+Z side). It should be noted that in... Figure 2 In order to facilitate understanding of the shape of the constraint, the side surface of the constraint, which includes the surface, is used instead of the cross-section of the constraint. Figure 3 yes Figure 2 AA-direction sectional view.

[0115] like Figure 2 As shown, the anode 2 is a rotating body centered on the central axis Z1. The anode 2 has a main body 5, a heat transfer body 9, and a convection confinement body 10 that restricts the convection of the heat transfer body 9.

[0116] [main body]

[0117] The main body 5 includes a container 5a and a lid 5b. When the lid 5b is fitted onto the container 5a, a sealed space is formed inside the main body 5. This sealed space includes a heat transfer element 9, a confinement element 10, and a gas space 8 not filled by the heat transfer element 9 and the confinement element 10. An inert gas (e.g., argon) can be sealed into this gas space 8 instead of air. The main body 5 is made of a high-melting-point material to prevent it from melting when the discharge lamp 100 is lit. In this embodiment, the main body 5 (container 5a and lid 5b) is primarily made of a tungsten-containing material.

[0118] [Heat transfer medium]

[0119] The heat transfer element 9 is made of a material that is liquid at the high temperature required to ignite the discharge lamp 100 and solid at the low temperature required to extinguish the discharge lamp 100. The melting point of the heat transfer element 9 is lower than that of the material constituting the main body 5. The material constituting the heat transfer element 9 is made of a thermally conductive material. The heat transfer element 9 preferably has a higher thermal conductivity than the main body 5. In this embodiment, the heat transfer element 9 uses a material primarily containing silver. The heat transfer element 9 may also use a material primarily containing gold. The heat transfer element 9, which melts upon ignition of the discharge lamp 100, is convection primarily along the Z-direction (vertical direction) within the enclosed space due to the confinement body 10, as detailed later. This Z-direction convection transfers the heat generated near the front end 13 of the anode 2 to the rear end 14 of the anode 2. The heat transferred to the rear end 14 is guided by the guide rod 4 (in... Figure 2 (Not shown in the diagram). As a result, the temperature of the front end 13 of the anode 2 decreases.

[0120] [Restricted Body]

[0121] The limiting body 10 has at least one blade 10b. For example... Figure 3 As shown, the limiting body 10 of this embodiment has four blades 10b. The four blades 10b are in a cross shape extending radially around the central axis Z1. Two of the four blades 10b extend along the Z and X directions. The remaining two blades 10b extend along the Z and Y directions.

[0122] Regarding the manufacturing method of the limiting body 10, four blades 10b can be arranged and joined at 90-degree intervals with the Z1 axis as the center. The limiting body 10 can be made such that the plate extending in the X direction and the plate extending in the Y direction intersect and join at the Z1 axis. The limiting body 10 can also be manufactured by integral molding.

[0123] Figure 4 and Figure 5 These are diagrams illustrating examples of convection in the heat transfer medium 9. The confinement body 10 is covered by the heat transfer medium 9. When the discharge lamp is lit, the heat transfer medium 9 melts and convection begins. Figure 4 and Figure 5 Let f1 represent an example of the direction of convection. The confinement body 10 acts as an obstacle to convection in the direction about the central axis Z1, thereby promoting convection in the Z direction. Thus, the confinement body 10 promotes heat transfer from the front end 13 to the rear end 14 of the anode 2 and suppresses turbulence in the heat transfer body 9. Consequently, the temperature at the front end 13 of the anode 2 decreases, and the temperature fluctuation range is reduced.

[0124] A gap G1 (see reference) is typically present between the blade 10b constituting the confinement body 10 and the inner wall 15 constituting the anode 2. Figure 3Because of the presence of gap G1, when the heat transfer body 9 melts, the blade 10b is pressed by convection in the direction of the central axis Z1 of the heat transfer body 9, and the confinement body 10 can rotate around the central axis Z1.

[0125] Reference Figure 6 , 7 The limitation body 10 will be explained. Figure 6 This is a side view of the restrictor 10 obtained by observing the restrictor 10 in the +Y direction. Figure 7 This is a top view of the constraint body 10 obtained by observing the constraint body 10 in the -Z direction.

[0126] like Figure 6 and Figure 7 As shown, the upper surface 10t of the blade 10b in this embodiment includes a plane 10t1 and a conical surface 10t2 along the XY plane. Figure 6 As shown, the radial length B2 of plane 10t1 is smaller than the radial length B3 of the lower surface 10u of blade 10b. In conical surface 10t2, the height (length in the Z direction) of blade 10b decreases as it separates from the central axis Z1.

[0127] like Figure 7 As shown, the thickness T1 of the four blades 10b constituting the confinement body 10 is sufficient to withstand the impact of the convection heat transfer body 9. The thickness T1 can be, for example, 1 mm or more, and preferably 2 mm or more and 3 mm or less.

[0128] To prevent the confinement body 10 from melting when the discharge lamp 100 is lit, the melting point of the material constituting the confinement body 10 is higher than that of the material constituting the heat transfer body 9. Alternatively, the material of the confinement body 10 can be the same as the material constituting the main body 5. For example, the confinement body 10 is made of a material mainly containing tungsten.

[0129] [Anode Size Design]

[0130] Reference Figure 8 This explains the size design of anode 2. Figure 8 This is a cross-sectional view showing the anode 2 through which the central axis Z1 passes. Within the sealed space located closer to the interface 8i between the heat transfer body 9 and the gas space 8 in the -Z direction, the heat transfer body 9 is filled, except for the confinement body 10. It should be noted that... Figure 8 It should be noted that the shaded areas marked only by diagonal lines are not the areas where heat transfer element 9 exists. Figure 13A , Figure 13B , Figure 19 The same applies to China.

[0131] like Figure 8As shown, the lowest position in the Z-axis direction of the bottom surface 18 of the sealed space is set as the reference position P0. The end position of the blade 10b closest to the bottom surface 18 (in this embodiment, the position of the lower surface 10u) is set as the lowest position P1 of the blade 10b. The end position of the blade 10b furthest from the bottom surface 18 (in this embodiment, the position of the plane 10t1 in the upper surface 10t) is set as the highest position P2 of the blade 10b. The Z-axis position of the interface 8i between the heat transfer body 9 and the gas space 8 in the sealed space is set as the interface position P3 of the heat transfer body 9.

[0132] With positions P0 to P3 set in this way, the first interval B1, the second interval L1, and the third interval H1 are represented as follows.

[0133] First interval B1 = Lowest position P1 - Reference position P0

[0134] Second interval L1 = highest position P2 - lowest position P1

[0135] Third interval H1 = Interface position P3 - Highest position P2

[0136] The area where the heat transfer element 9 exists is divided into an upper region and a lower region. The upper region is the region 9s between the lowest position P1 of the blade 10b and the interface position P3 (in... Figure 8 The shaded area is marked with a diagonal line. The area of ​​the upper region 9s is set as the upper area S1 (mm) of the heat transfer body 9. 2 Set the outer diameter of the main body 5 as D1 (mm), and the outer diameter of the enclosed space as D2 (mm).

[0137] The first spacing B1, the second spacing L1, the third spacing H1, the upper area S1, the outer diameter D1 of the main body 5, and the outer diameter D2 of the enclosed space, which are related to the dimensions of the anode 2, are closely related to the convection rate and convection state of the heat transfer body 9, and thus affect the temperature of the anode 2. Therefore, the inventors determined the temperature of the anode 2 when these parameters changed by actually measuring the convection simulation of the heat transfer body 9 or the actual lit discharge lamp 100. The conditions for the convection simulation of the heat transfer body 9 and the actual lit discharge lamp 100 are shown below.

[0138] <Discharge lamp>

[0139] Present Figure 1 The shape shown.

[0140] Material of LED 1: Quartz glass

[0141] Spacing between anode 2 and cathode 3: 6mm

[0142] The encapsulated contents inside LED 1: Mercury 2.0 mg / cc, Argon 100 kPa

[0143] Rated current: 200A

[0144] Rated power: 12kW

[0145] <Anode 2>

[0146] Present Figure 2 The shape shown.

[0147] Volume of the enclosed space: 17cm³ 3

[0148] Material of heat transfer element 9: silver

[0149] Gas filling space 8: Argon 100kPa

[0150] <Restricted Body>

[0151] Present Figure 2 and Figure 3 The shape shown.

[0152] The radial length B2 of plane 10t1 is 8.15 mm.

[0153] The radial length B3 of the lower surface 10u of blade 10b is 10.75 mm.

[0154] Thickness T1: 3mm

[0155] Figure 9 The graph, generated by convection simulation of heat transfer element 9, shows the relationship between the third gap H1 (mm) and the temperature TE (K) of the bottom surface 18 of the sealed space of anode 2. Temperature TE is the average temperature across five points in the model at a steady state: the center point of the bottom surface 18 and four points within a 1mm radius on the XY plane. This average is the result of 2000 calculations. It should be noted that in the (X, Y, Z) coordinate system, when the center point is set to (0, 0, 0), the surrounding points are (1, 0, 0), (0, 1, 0), (-1, 0, 1), and (0, -1, 0).

[0156] The temperature TE of the bottom surface 18 of the sealed space of anode 2 is preferably below 1800K. (Refer to...) Figure 9 Therefore, it can be seen that the change in temperature TE is small relative to the change in the third interval H1. That is, the constraint of the third interval H1 on making the temperature TE below 1800K is small.

[0157] Regarding the first gap B1, it is known that in order to achieve a temperature TE below 1800K, the first gap B1 needs to be 3 (mm) or more. If the first gap B1 is 3 (mm) or more, the convection flow rate of the heat transfer medium 9 passing through the lower part of the confinement body 10 (the -Z side of the confinement body 10) increases, which can stably transfer the heat from the bottom surface 18 of the sealed space of the anode 2 to the rear end 14 side. As a result, it is speculated that the temperature TE can be reduced. When the temperature TE is reduced, the heat load acting on the anode 2 is decreased, and damage (openings, etc.) to the bottom surface 18 of the sealed space of the anode 2 caused by high-temperature creep deformation can be suppressed. Thus, high output and long life of the discharge lamp can be achieved.

[0158] Figure 10 This is a coordinate graph representing the relationship between the first interval B1 and the maximum temperature variation amplitude TX, calculated from the convection simulation of heat transfer body 9. The temperature variation amplitude is represented by the difference between the maximum and minimum temperatures at any location on the electrode surface during a specified time (e.g., 1 minute) when the discharge lamp is lit. If the large temperature variation amplitude persists for a long time, deformation such as protrusions from the inner surface of the electrode tip due to high-temperature creep deformation will occur, creating holes at the electrode tip and causing leakage from heat transfer body 9. In this case, the electrode loses its heat dissipation capacity, thus the electrode becomes overheated, and the discharge lamp deteriorates rapidly. The temperature variation amplitude varies depending on the location on the electrode surface. The maximum temperature variation amplitude TX (°C) also varies depending on the location on the electrode surface. If the maximum temperature variation amplitude TX is suppressed, the heat load acting on the anode 2 is reduced, and damage such as holes at the electrode tip caused by high-temperature creep deformation can be suppressed. As a result, high output and long lifespan of the discharge lamp can be achieved.

[0159] The maximum temperature variation TX is preferably below 13°C. Figure 10 It can be seen that when the first interval B1 is less than 15mm, the maximum value TX can be made to be less than 13℃.

[0160] according to Figure 9 , Figure 10 In order to achieve high output and long life of the discharge lamp, the first interval B1 preferably satisfies equation (1).

[0161] 3≤B1≤15…(1)

[0162] Furthermore, the first interval B1 is more preferably 4 or more.

[0163] As described above, the constraint of the third interval H1, which is used to lower the temperature TE of the bottom surface 18 of the enclosed space of the anode 2, is small. However, according to the results of the convection simulation of the heat transfer body 9, if the third interval H1 is too large compared to the second interval L1 (i.e., the height of the confinement body 10), the convection of the heat transfer body 9 in the upper part (+Z side) of the confinement body 10 cannot be sufficiently restricted, and turbulence will occur. When turbulence occurs, the temperature fluctuation range increases.

[0164] Therefore, by measuring the anode 2 of the actually lit discharge lamp 100, the relationship between the size of the third interval H1 (i.e., the ratio of the third interval H1 to the second interval L1) and the maximum value TX (°C) of the temperature variation amplitude is determined, and shown in the actual measurement. Figure 11 In the coordinate diagram. As mentioned above, the maximum value of the temperature variation TX is preferably below 13℃, so the value of H1 / L1 preferably satisfies equation (2).

[0165] 0.0≤H1 / L1≤1.0…(2)

[0166] This formula indicates that the third interval H1, which is also the distance between the upper surface 10t of the blade 10b and the interface 8i, is smaller than the second interval L1, which is also the height of the restrictor 10, and the third interval H1 is 0 or more.

[0167] Within the sealed space, in order for the heat transfer medium 9 to convect over the blades 10b, it needs to occupy the upper region 9s of the confinement body 10 (in Figure 8 The area marked in the middle is the majority of the area between the upper surface 10t of the blade 10b and the interface 8i. Figure 12 This is a coordinate graph showing the relationship between the upper area S1, which is the area of ​​the upper region 9s of the heat transfer body 9, and the temperature TE (K) of the bottom surface 18 of the sealed space of the anode 2, obtained by convection simulation of the heat transfer body 9. As mentioned above, the temperature TE is preferably below 1800K, so the upper area S1 preferably satisfies the following equation (3).

[0168] S1≥40…(3)

[0169] When equation (3) is satisfied, the convection of the heat transfer body 9 becomes sufficient, enabling it to stably transfer the heat from the front end 13 of the anode 2 to the rear end 14.

[0170] Reference Figure 13A and Figure 13B This demonstrates the necessity of determining the size of anode 2 not only through equation (2), but also through both equations (2) and (3). Figure 13A and Figure 13B Set the reference position P0, the lowest position P1, the highest position P2, and the interface position P3 to be the same value for each other. Therefore, Figure 13A and Figure 13B The first interval B1, the second interval L1, and the third interval H1 are also the same value. However, in Figure 13A In the anode 2 shown, the upper surface 10t of the blade 10b is flat, but in Figure 13B In the anode 2 shown, there are irregularities on the upper surface 10t of the blade 10b.

[0171] Figure 13A The anode 2 shown is a comparison method of the present invention where, although H1 / L1 satisfies equation (2), the area S1 of the upper region 9s does not satisfy equation (3). On the other hand, Figure 13B The anode 2 shown is an embodiment of the present invention in which H1 / L1 satisfies equation (2) and the upper area S1 satisfies equation (3). Therefore, the present invention cannot be determined by equation (2) alone, and requires determination by both equations (2) and (3).

[0172] The above simulation and temperature measurement were performed with the outer diameter D1 of anode 2 fixed at 40 mm and the outer diameter D2 of the sealed space of anode 2 fixed at 22 mm. However, it is shown that even if the outer diameter D1 or outer diameter D2 are different, as long as equations (1), (2), and (3) are satisfied, the temperature TE can be set to below 1800 K and the maximum temperature variation TX can be set to below 13 °C.

[0173] For six anodes A through F, whose D1 or D2 was changed based on anode G (D1: 40mm, D2: 22mm), convection simulation of heat transfer element 9 was performed. These six anodes A through F are identical to anode G except for the following points and the amount of heat transfer element 9. The rated current and rated power of the lamps using these anodes were selected based on the anode dimensions to ensure optimal performance. The amount of heat transfer element 9 for anodes A through F was adjusted so that the H1 / L1 value was identical to that of anode G. Figure 14 The diagram shows anodes A through F as a coordinate graph with outer diameter D1 as the horizontal axis and outer diameter D2 as the vertical axis.

[0174] Anode A, D1: 25mm, D2: 15.25mm, Rated Current: 150A, Rated Power: 5kW

[0175] Anode B, D1: 35mm, D2: 20.75mm, Rated Current: 175A, Rated Power: 10kW

[0176] Anode C D1: 45mm, D2: 26.25mm, Rated Current: 250A, Rated Power: 15kW

[0177] Anode D: D1: 25mm, D2: 12.75mm, Rated current: 150A, Rated power: 5kW

[0178] Anode E D1: 35mm, D2: 17.25mm, Rated Current: 175A, Rated Power: 10kW

[0179] Anode F D1: 45mm, D2: 21.75mm, Rated Current: 250A, Rated Power: 15kW

[0180] The convection simulation results for heat transfer element 9 show that if it satisfies equations (1), (2), and (3) in the same way as anode G, then the six anodes A through F can also keep the temperature TE below 1800 K and the maximum temperature variation TX below 13 °C. Therefore, in Figure 14 The relationship between the outer diameter D1 of the main body 5 and the outer diameter D2 of the sealed space in the coordinate diagram is within the range of the quadrilateral ADFC. It also makes the temperature TE below 1800K by satisfying equations (1), (2), and (3), and makes the maximum value of the temperature variation TX below 13℃.

[0181] The straight line f11 passing through anodes A to C is represented by D2 = 0.55 × D1 + 1.5. The straight line f12 passing through anodes D to F is represented by D2 = 0.45 × D1 + 1.5. Therefore, the outer diameter D1 of anode 2 and the outer diameter D2 of the sealed space satisfy the following equation (4).

[0182] 0.45×D1+1.5≤D2≤0.55×D1+1.5…(4)

[0183] In addition, the outer diameter D1 satisfies the following equation (5).

[0184] 25≤D1≤45…(5)

[0185] [A method for determining dimensional design values ​​based on the manufactured anode]

[0186] The method for determining the dimensional design value based on the manufactured anode 2 is described below. The method described below is particularly suitable for determining the interface position P3 of the heat transfer body 9 when determining the dimensional design value of the anode 2 in a discharge lamp to be lit for use or testing after the discharge lamp has been manufactured, in the case where the interface 8i is not flat.

[0187] The main reason for the unevenness of interface 8i is explained below. After the discharge lamp 100 is manufactured, the heat transfer element 9 inside the anode 2 of the discharge lamp 100, which is lit for use or testing, temporarily melts. As the anode 2 is cooled with the lamp being extinguished, the temperature drops from the surface of the anode 2 towards its interior. As a result, the time of thermal contraction accompanying solidification differs between the surface and interior of the anode 2, thus... Figure 15 As shown, the interface 8i between the heat transfer body 9 and the gas space 8 is sometimes concave near the central axis Z1.

[0188] To determine the dimensional design values ​​based on the manufactured anode 2, follow these steps.

[0189] (Step 1) Remove the anode 2 from the discharge lamp and measure the outer diameter D1 of the anode 2. In the upper gas space 8 of the sealed space (excluding the part containing the heat transfer body 9), cut the container 5a along the XY plane to divide it into a first electrode part containing the heat transfer body 9 and the confinement body 10 and a second electrode part containing the cover 5b.

[0190] (Step 2) Measure the weight a of the first electrode portion. Furthermore, select a small amount of heat transfer fluid 9 from the cross-section to estimate its composition and density ρ. Composition analysis can be performed using, for example, a fluorescence X-ray device.

[0191] (Step 3) Immerse the first electrode portion in a liquid in which the anode 2 does not dissolve but the heat transfer body 9 dissolves, and remove the confinement body 10 by dissolving the heat transfer body 9 from the first electrode portion. For example, nitric acid is used when the anode 2 is tungsten and the heat transfer body 9 is silver. Then, remove the heat transfer body 9 from the first electrode portion and measure the weight b including the confinement body 10. Thus, the volume VM of the heat transfer body 9 is calculated by equation (6).

[0192] VM=(ab) / ρ…(6)

[0193] (Step 4) Measure the second interval L1, which is the height of the blade 10b; the outer diameter D2 of the sealed space of the anode 2; the reference position P0; and the lowest position P1 of the blade 10b. Calculate the first interval B1 based on the reference position P0 and the lowest position P1. Calculate the highest position P2 of the blade based on the lowest position P1 and the second interval L1.

[0194] (Step 5) Place the confinement body 10 and a liquid (e.g., water) of the same volume as the heat transfer body 9 into the sealed space of the anode 2, keeping the liquid surface horizontal. Consider the position of the liquid surface at this point as the position P3 of the interface 8i between the heat transfer body 9 and the gas space 8. Calculate the third gap H1 based on the highest position P2 of the confinement body 10 and the interface position P3 of the heat transfer body 9. Calculate the upper area S1 based on the third gap H1, the outer diameter D2 of the sealed space, and the dimensional measurements of the shape of the confinement body 10.

[0195] It should be noted that the multiple blades 10b constituting the limiting body 10 can have different shapes, as detailed below. Such a limiting body 10 may have an upper area S1 that varies depending on the blade 10b. In this case, the blade 10b with the largest upper area S1 is selected, and the highest position P2 and the upper area S1 are set according to the selected blade 10b.

[0196] [Examples of variations of the restricted body]

[0197] Figure 16 , Figure 17 and Figure 18 These are diagrams showing variations of the confined body. These diagrams are obtained by observing the confined body in the -Z direction.

[0198] Figure 16 In the confinement body 20 shown, two blades 20b extend radially around the central axis Z1, and the two blades 20b are arranged in one direction. The confinement body 20 can also be constructed from a single plate. However, even when constructed from a single plate, the number of blades 20b shown in the figure is counted as two. The confinement body 20 may sometimes tilt due to convection from the heat transfer medium 9, but further tilting of the confinement body 20 is suppressed when the blades 20b contact the inner wall 15 of the enclosed space.

[0199] Figure 17 In the shown restrictor 30, three blades 30b extend radially around the central axis Z1, and two of the blades 30b are arranged in one direction. The number of blades 30b shown in the figure is counted as three. The restrictor 30 with three blades 30b is more likely to suppress tilting than the restrictor 20 with two blades.

[0200] Figure 18 In the shown confinement body 40, three blades 40b extend radially at equal angles to each other around the central axis Z1. The number of blades 40b shown in the figure is calculated to be 3. Because the blades 40b are at equal angles to each other, the tilting of the confinement body 40 can be suppressed compared to confinement bodies 20 and 30.

[0201] Furthermore, when the restrictor 10 is viewed from the Y direction (side), the upper surface 10t of the blade 10b may not have a conical surface. When the restrictor 10 is viewed from the Y direction, the blade 10b may be rectangular or... Figure 13B The upper surface 10t of the blade 10b has irregularities.

[0202] Within the confinement body 10, the blades 10b can have different shapes. For example, when observing a cross-section in the XZ plane through which the central axis Z1 passes, they can be as follows: Figure 8 The blade 10b shown has a conical shape and a second spacing L1 of 16 mm, but when observing the cross-section at the YZ plane through which the central axis Z1 passes, it appears as follows: Figure 19 The constraint body 10 shown is a rectangular blade 10b without a tapered shape and with a second spacing L1 of 14 mm.

[0203] [The shape of a confined space]

[0204] Figure 20This is a modified example of the main body 5 of anode 2. In Figure 20 Only the main body 5 is shown in the figure. As shown in the figure, in the cross-sectional view through which the central axis Z1 passes, the bottom surface 18 connecting the two opposing inner walls 15 is composed of a curved surface. If the surface with varying angles is composed of curved surfaces without corners, it can suppress stagnation or turbulence in the convection of the heat transfer body 9. Furthermore, it can also avoid stress concentration caused by the expansion of the heat transfer body 9 during illumination. The bottom surface 18 can be at least partially composed of curved surfaces (surfaces without corners).

[0205] The above describes the embodiments and variations. This invention is not limited to the embodiments described above; various improvements or modifications can be made to the embodiments and variations without departing from the spirit of the invention.

[0206] The above describes an example where the anode 2 has a heat transfer element 9 and a confinement element 10; however, similarly to the anode 2, the cathode 3 may also have a confinement element 10 and a heat transfer element 9. The discharge lamp 100 may be configured such that the cathode 3 is located above the anode 2. The discharge lamp 100 may be configured such that the anode 2 and the cathode 3 are arranged in a horizontal direction.

[0207] In the above, the main body 5 of the anode 2, the confinement body 10 in the sealed space of the anode 2, the guide rod 4, the cathode 3 and the light-emitting tube 1 have a common central axis Z1, but the central axes of each part do not necessarily have to have a common axis.

[0208]

Example

[0209] An anode 2 was fabricated having the following dimensions and, except under the following conditions, the same dimensions as those described in the simulation conditions. Furthermore, the anode 2 satisfies the above equations (1) to (5).

[0210] First gap B1: 6.2mm

[0211] Second interval L1: 16mm

[0212] Third interval H1: 14mm

[0213] Outer diameter D1 of anode 2: 40mm

[0214] The outer diameter D2 of the sealed space of anode 2 is 22mm.

[0215] Anode 2 wall thickness: 9.0 mm

[0216] The amount of heat transfer element 9 encapsulated within anode 2: 11.4 cm 3

[0217] When the discharge lamp 100 equipped with the anode 2 was lit for a reference time at the aforementioned rated power, it was confirmed that the illuminance maintained a value exceeding the standard. Then, 30 sets of lighting and extinguishing cycles were repeated, each consisting of 15 minutes of lighting followed by 12 minutes of extinguishing. During this period, the illuminance did not fall below the standard value. After the test, the anode 2 was disassembled, and no damage was found to the main body 5. Therefore, it is presumed that the lifespan of the discharge lamp 100 has been improved.

[0218] An anode 3 was fabricated with the following dimensions and, except for the following conditions, the same dimensions as those described in the simulation. Furthermore, although this anode 2 satisfies the above equations (1), (3) to (5), it has H1 / L1 = 1.3 and does not satisfy equation (2).

[0219] First gap B1: 6.2mm

[0220] Second interval L1: 13mm

[0221] Third interval H1: 17mm

[0222] Outer diameter D1 of anode 2: 40mm

[0223] The outer diameter D2 of the sealed space of anode 2 is 22mm.

[0224] Anode 2 wall thickness: 9.0 mm

[0225] The amount of heat transfer element 9 encapsulated within anode 2: 11.4 cm 3

[0226] When the discharge lamp 100 equipped with the anode 2 is lit at the aforementioned rated power, the maximum temperature fluctuation TX exceeds the reference value (13°C) by 16°C. Furthermore, during the reference time for lighting the discharge lamp 100, an opening is formed on the bottom surface. The cause is presumably that the bottom surface deforms due to creep deformation because the temperature fluctuation exceeds the reference value.

Claims

1. A discharge lamp having a pair of electrodes arranged axially opposite each other inside, characterized in that, At least one of the electrodes in the pair of electrodes has: The main body has a closed space; The heat transfer element, within the enclosed space, has a lower melting point than the material constituting the main body; A confinement body, within the enclosed space, is made of a material with a higher melting point than the heat transfer body, thereby restricting convection within the heat transfer body; and A gas space, within the sealed space, is in contact with the heat transfer element. The limiting body includes at least one blade extending along the axial direction and radially orthogonal to the axial direction. When the at least one electrode is configured such that its front end is below and its rear end is above, and the lowest axial position of the bottom surface of the sealed space is set as the reference position P0, the end position of the blade closest to the bottom surface is set as the lowest position P1 of the blade, the end position of the blade furthest from the bottom surface is set as the highest position P2 of the blade, and the axial position of the interface between the heat transfer element and the gas space is set as the interface position P3, The axial distance between the reference position P0 and the lowest position P1 is the first distance B1 (mm); the axial distance between the lowest position P1 and the highest position P2 is the second distance L1 (mm); the axial distance between the highest position P2 and the interface position P3 is the third distance H1 (mm); and the upper area S1 (mm²) of the heat transfer body is... 2 The upper area S1 (mm) satisfies the following equations (1) to (3). 2 The area represents the upper region of the heat transfer body sandwiched between the lowest position P1 and the interface, within a cross-section that includes the axis that forms the axis. 3≤B1≤15…(1) 0.0≤H1 / L1≤1.0…(2) S1≥40…(3)。 2. The discharge lamp according to claim 1, characterized in that, The discharge lamp has three or more of the aforementioned blades.

3. The discharge lamp according to claim 1, characterized in that, The bottom surface of the enclosed space comprises a curved surface.

4. The discharge lamp according to any one of claims 1 to 3, characterized in that, When the outer diameter of the main body is set as D1 and the outer diameter of the sealed space is set as D2, the following equation (4) is satisfied. 0.45×D1+1.5≤D2≤0.55×D1+1.5…(4).

5. An electrode for use in a discharge lamp, characterized in that, The electrode has the following features: The main body has a closed space; The heat transfer element, within the enclosed space, has a lower melting point than the material constituting the main body; A confinement body, within the enclosed space, is made of a material with a higher melting point than the heat transfer body, thereby restricting convection within the heat transfer body; and A gas space, within the sealed space, is in contact with the heat transfer element. The limiting body includes at least one blade extending along an axial direction and a radial direction orthogonal to the axial direction. When the at least one electrode is configured such that its front end is below and its rear end is above, and the lowest axial position of the bottom surface of the sealed space is set as the reference position P0, the end position of the blade closest to the bottom surface is set as the lowest position P1 of the blade, the end position of the blade furthest from the bottom surface is set as the highest position P2 of the blade, and the axial position of the interface between the heat transfer element and the gas space is set as the interface position P3, The axial distance between the reference position P0 and the lowest position P1 is the first distance B1 (mm); the axial distance between the lowest position P1 and the highest position P2 is the second distance L1 (mm); the axial distance between the highest position P2 and the interface position P3 is the third distance H1 (mm); and the upper area S1 (mm²) of the heat transfer body is... 2 The upper area S1 (mm) satisfies the following equations (1) to (3). 2 The area represents the upper region of the heat transfer body sandwiched between the lowest position P1 and the interface, within a cross-section that includes the axis that forms the axis. 3≤B1≤15…(1) 0.0≤H1 / L1≤1.0…(2) S1≥40…(3)。

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