JP2023000705A - Discharge lamp, and electrode used for the discharge lamp - Google Patents

Abstract

To plan high output and long life of a discharge lamp.SOLUTION: At least one electrode of a discharge lamp comprises a main body having a hermetically sealed space, a heat transfer body disposed in the hermetically sealed space, and a restriction body restricting convection flow of the heat transfer body. An interval between a reference position P0 of a bottom surface of the hermetically sealed space and the lowest position P1 of a blade of the restriction body is denoted as a first interval B1 (mm). An interval between the lowest position P1 of the blade and the highest position P2 of the blade is denoted as a second interval L1 (mm). An interval between the highest position P2 of the blade and an interface position P3 of the heat transfer body is denoted as a third interval H1 (mm). An area of a filling region of the heat transfer body sandwiched between the lowest position P1 and a top surface of the heat transfer body on a cross section passing the central axis of the at least one electrode is denoted as upper area S1 (mm2) of the heat transfer body. In this case, the electrode of the discharge lamp satisfies three expressions of (1) 3≤B1≤15, (2) 0.0≤H1/L1≤1.0, and (3) S1≥40.SELECTED DRAWING: Figure 8

Description

The present invention relates to discharge lamps and electrodes used in such discharge lamps.

2. Description of the Related Art Conventionally, a discharge lamp, particularly a short-arc discharge lamp, is used as a light source in an exposure apparatus used in the manufacturing process of semiconductor devices, liquid crystal display devices, and the like. In this discharge lamp, an anode and a cathode are arranged opposite to each other in an arc tube in the axial direction, and a luminous substance such as mercury is enclosed in the arc tube.

In such a discharge lamp, a high thermal load is applied to the electrodes during lighting, and the electrode material may evaporate due to overheating of the anode or the like. When this vapor adheres to the inner wall of the arc tube, the discharge lamp causes so-called blackening, resulting in a decrease in the light transmittance of the arc tube.

In order to solve this problem, there has been proposed a discharge lamp having a structure in which a heat conductor is enclosed in a sealed space inside the anode. The heat conductor is molten when the lamp is lit, and convection occurs in the closed space due to the temperature distribution of the entire anode. The convection of this heat transfer body transfers the heat from the tip of the anode (the end closest to the cathode) to the rear end (the end furthest from the cathode), lowering the temperature of the tip of the anode and suppressing the amount of evaporation of the electrode material. be done.

Patent Literature 1 and Patent Literature 2 describe that a regulating body for regulating convection in the circumferential direction of a heat transfer body is provided in a closed space. By providing the restrictor in the sealed space, it is possible to prevent the tip of the electrode from being perforated due to the convection in the circumferential direction of the heat transfer body.

JP 2012-028168 A JP 2017-016761 A

Recently, there is a demand from the market for a further increase in output and a longer life of discharge lamps. As the output of a discharge lamp increases, the thermal load applied to the electrodes increases, so it is necessary to design electrodes that can withstand the thermal load for a long period of time. SUMMARY OF THE INVENTION An object of the present invention is to provide a discharge lamp with high output and long life, and an electrode used in the discharge lamp.

In order to investigate the thermal load on the electrode when the discharge lamp is used at high output, the inventor measured the temperature distribution of the electrode surface during lighting using a radiation thermometer. As a result of the measurement, it was found that some discharge lamps have a large temperature at the tip of the electrode and a discharge lamp has a wide range of local temperature fluctuations on the surface of the electrode. Temperature fluctuations refer to temperature fluctuations within a short period of time (for example, 1 minute). If the temperature of the tip of the electrode is high, or the temperature fluctuation width on the inner surface of the electrode continues for a long period of time, high-temperature creep deformation causes deformation such that a projection protrudes from the inner surface of the tip of the electrode. As a result, a hole is formed at the tip of the electrode and the heat conductor leaks out. In this case, the discharge lamp loses its ability to dissipate heat, shortening the service life of the discharge lamp.

The inventor of the present invention considered that such an increase in the temperature of the tip of the electrode or an increase in the temperature fluctuation width causes problems in the convective flow rate of the heat transfer body or in the turbulence of the heat transfer body. Although the details will be described later, in order to solve this problem, it is necessary not only to place a restrictor for restricting the convection of the heat conductor in the closed space, but also to adjust the dimensions of the electrodes including the restrictor and the heat conductor. Considering the importance of design, the following discharge lamp was devised.

The discharge lamp of the present invention is a discharge lamp having therein a pair of electrodes disposed facing each other in the axial direction,
At least one of the pair of electrodes is
a main body having an enclosed space;
a heat transfer body having a melting point lower than that of the material forming the main body in the closed space;
a regulating body made of a material having a melting point higher than that of the heat transfer body and regulating convection of the heat transfer body in the closed space;
a gas space in contact with the heat transfer body in the sealed space,
the regulating body includes at least one blade extending in the axial direction and in a radial direction orthogonal to the axial direction;
The tip of the at least one electrode is arranged downward and the rear end is arranged upward, the lowest position in the axial direction on the bottom surface of the sealed space is defined as a reference position P0, and the edge of the blade closest to the bottom surface. The position of the blade is the lowest position P1 of the blade, the end position of the blade farthest from the bottom surface is the highest position P2 of the blade, and the position of the interface between the heat transfer body and the gas space in the axial direction is the interface When the position is P3,
A first interval B1 (mm), which is the interval in the axial direction between the reference position P0 and the lowest position P1, and a second interval L1 (mm), which is the interval in the axial direction between the lowest position P1 and the highest position P2. ), a third interval H1 (mm) that is the interval in the axial direction between the highest position P2 and the interface position P3, and the lowest position P1 and the interface in a cross section including the axis in the axial direction An upper area S1 (mm ² ) of the heat conductor, which is the filling region of the sandwiched heat conductor, satisfies the following equations (1) to (3).
3≤B1≤15 (1)
0.0≦H1/L1≦1.0 (2)
S1≧40 (3)

An electrode dimensioned in this way has sufficient flow resistance for the heat transfer medium. Therefore, it is easy to lower the temperature of the tip of the electrode. In addition, since turbulence of the heat transfer body is suppressed, the local temperature fluctuation width of the electrode surface is reduced. As a result, opening of the tip of the electrode due to high-temperature creep deformation is suppressed. Therefore, it is possible to increase the output and extend the life of the discharge lamp.

Three or more blades may be provided. Turbulence in the heat transfer body can be suppressed by suppressing the inclination of the regulation body.

The bottom surface of the closed space may include a curved surface. Convection stagnation or turbulence in the heat transfer body can be suppressed.

When the outer diameter of the main body is D1 and the outer diameter of the sealed space is D2, the following formula (4) may be satisfied. The temperature of the tip of the electrode can be lowered and the width of temperature fluctuation can be reduced.
0.45×D1+1.5≦D2≦0.55×D1+1.5 (4)

The electrodes used in the discharge lamp of the present invention are
a main body having an enclosed space;
a heat transfer body having a melting point lower than that of the material forming the main body in the closed space;
a regulating body made of a material having a melting point higher than that of the heat transfer body and regulating convection of the heat transfer body in the closed space;
a gas space in contact with the heat transfer body in the sealed space,
the regulating body includes at least one blade extending in the axial direction and in a radial direction orthogonal to the axial direction;
The tip of the at least one electrode is arranged downward and the rear end is arranged upward, the lowest position in the axial direction on the bottom surface of the sealed space is defined as a reference position P0, and the edge of the blade closest to the bottom surface. The position of the blade is the lowest position P1 of the blade, the end position of the blade farthest from the bottom surface is the highest position P2 of the blade, and the position of the interface between the heat transfer body and the gas space in the axial direction is the interface When the position is P3,
A first interval B1 (mm), which is the interval in the axial direction between the reference position P0 and the lowest position P1, and a second interval L1 (mm), which is the interval in the axial direction between the lowest position P1 and the highest position P2. ), a third interval H1 (mm) that is the interval in the axial direction between the highest position P2 and the interface position P3, and the lowest position P1 and the interface in a cross section including the axis in the axial direction An upper area S1 (mm ² ) of the heat conductor, which is the filling region of the sandwiched heat conductor, satisfies the following equations (1) to (3).
3≤B1≤15 (1)
0.0≦H1/L1≦1.0 (2)
S1≧40 (3)

INDUSTRIAL APPLICABILITY It is possible to provide a discharge lamp having a high output and a long life, and an electrode used for the discharge lamp.

It is a figure which shows the outline|summary of a discharge lamp. 2 is an enlarged sectional view of an anode in the discharge lamp of FIG. 1; FIG. FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2; It is a figure which shows the example of the convection of a heat-transfer body. It is a figure which shows the example of the convection of a heat-transfer body. It is a side view of a regulator. It is a top view of a regulator. Figure 2 represents a cross-sectional view through the central axis of the anode; 4 is a graph showing the relationship between the third distance H1 and the temperature TE of the tip of the anode. 4 is a graph showing the relationship between the first interval B1 and the maximum value TX of the width of temperature fluctuation. 7 is a graph showing the relationship between the third interval H1/second interval L1 and the maximum temperature fluctuation width TX. 4 is a graph showing the relationship between the upper area S1 of the heat transfer body and the temperature TE of the tip of the anode. It is a figure which shows the anode which satisfy|fills (2) Formula and does not satisfy|fill (3) Formula. FIG. 4 is a diagram showing an anode that satisfies both formulas (2) and (3). 4 is a graph showing simulation results for six anodes A to F; FIG. 4 is a diagram showing an anode recessed near the center axis where the surface of the heat transfer body is inside; It is a figure which shows the modification of a regulation body. It is a figure which shows the modification of a regulation body. It is a figure which shows the modification of a regulation body. It is sectional drawing in YZ plane of an anode. It is a sectional view showing a modification of an anode main part.

An embodiment of a discharge lamp will be described with reference to the drawings. The following drawings, except for graphs, are schematic representations, and the dimensional ratios on the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios do not necessarily match between the drawings. not

In the following, each drawing, except graphs, will be described with reference to the XYZ coordinate system. In this specification, to distinguish between positive and negative directions when expressing directions, positive and negative signs are added, such as “+X direction” and “−X direction”. When a direction is expressed without distinguishing between positive and negative directions, it is simply described as “X direction”. That is, in the present specification, the term “X direction” includes both “+X direction” and “−X direction”. The same applies to the Y direction and Z direction. In the embodiments described below, the -Z direction represents the direction of gravity.

[Outline of discharge lamp]
An outline of a discharge lamp that is an embodiment of the present invention will be described with reference to FIG. The discharge lamp 100 includes an arc tube 1, an anode 2 and a cathode 3 arranged inside the arc tube 1 so as to face each other in an extending direction of a central axis Z1, and a lead rod 4 supporting the anode 2 and the cathode 3, respectively. short arc discharge lamp. In this embodiment, the discharge lamp 100 is arranged such that the anode 2 is located above the cathode 3 (+Z direction), and the discharge lamp 100 is lit.

A short-arc discharge lamp is one in which the tip of the anode 2 and the tip of the cathode 3 are arranged with a gap of 40 mm or less (value at room temperature when there is no thermal expansion). Examples of such discharge lamps include discharge lamps with a rated power of 2 kW to 35 kW, which are used in exposure apparatuses used in manufacturing processes of semiconductor devices, liquid crystal display devices, and the like. In the discharge lamp 100 of this embodiment, the tip of the anode 2 and the tip of the cathode 3 are arranged with a gap of 6 mm.

The arc tube 1, the anode 2, the cathode 3, and the lead rod 4 are all arranged around the central axis Z1. An anode 2 is arranged above the cathode 3 (+Z direction). Sealing tubes 11 are provided at both ends of the arc tube 1 in the extending direction of the central axis Z1. A base 12 electrically connected to the lead rod 4 is attached to the sealing tube 11 .

The arc tube 1 is formed from a glass tube. The arc tube 1 has regions where the inner diameter of the glass tube increases toward the center from both ends of the central axis Z1. This region of increased inner diameter may have the shape of a sphere or an ellipsoid. Quartz glass, for example, can be used for the glass tube. A region with a larger inner diameter functions as a light emitting space. A light-emitting substance such as mercury is enclosed in the light-emitting space.

[Overview of Anode]
The outline of the anode 2 will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 is an enlarged sectional view of the anode 2 in the discharge lamp of FIG. In FIG. 2, the cross section of the anode 2 in the plane passing through the central axis Z1 is arranged so that the tip 13 of the anode 2 near the opposing cathode 3 is on the lower side (-Z side) and the rear end 14 to which the lead rod 4 is connected is on the upper side. (+Z side) is shown. In addition, in FIG. 2, in order to facilitate understanding of the shape of the regulating body, a side surface of the regulating body including surface irregularities is shown instead of a cross section of the regulating body. 3 is a cross-sectional view taken along line AA of FIG. 2. FIG.

As shown in FIG. 2, the anode 2 has a shape of a body of revolution centered on the central axis Z1. The anode 2 has a main body 5 , a heat conductor 9 , and a regulator 10 that regulates convection of the heat conductor 9 .

[Body]
The body 5 includes a container 5a and a lid 5b. A closed space is formed inside the body 5 when the lid 5b is attached to the container 5a. The closed space includes a heat transfer body 9 , a regulating body 10 , a gas space 8 which is not filled with the heat transfer body 9 and the regulating body 10 . This gas space 8 may be filled with an inert gas (for example, argon) instead of air. The main body 5 is made of a high-melting-point material so that the main body 5 is difficult to melt when the discharge lamp 100 is lit. In this embodiment, the main body 5 (container 5a and lid 5b) is mainly made of a material containing tungsten.

[Heat transfer body]
The heat transfer body 9 is made of a material that is liquid at a high temperature when the discharge lamp 100 is turned on and a solid at a low temperature when the discharge lamp 100 is turned off. The melting point of the heat conductor 9 is lower than the melting point of the material forming the main body 5 . The material forming the heat conductor 9 is made of a thermally conductive material. The heat transfer body 9 should exhibit a higher thermal conductivity than the main body 5 . In this embodiment, a material mainly containing silver is used for the heat conductor 9 . A material mainly containing gold may be used for the heat transfer body 9 . Although the details will be described later, the heat transfer body 9 melted by lighting of the discharge lamp 100 convects mainly in the Z direction (vertical direction) in the closed space due to the regulation body 10 . Such Z-direction convection transfers heat generated near the front end 13 of the anode 2 to the rear end 14 of the anode 2 . Heat transferred to trailing end 14 is transferred to lead rod 4 (not shown in FIG. 2). This lowers the temperature of the tip 13 of the anode 2 .

[Regulator]
The regulating body 10 has at least one blade 10b. The regulator 10 of this embodiment has four blades 10b, as shown in FIG. The four blades 10b have a cross shape extending radially about the central axis Z1. Two of the four blades 10b extend in the Z direction and the X direction. The remaining two blades 10b extend in the Z and Y directions.

Regarding the manufacturing method of the regulation body 10, the four blades 10b may be arranged at intervals of 90 degrees around the Z1 axis and joined together. The restricting body 10 may be joined by intersecting a flat plate extending in the X direction and a flat plate extending in the Y direction along the Z1 axis. The regulation body 10 may be manufactured by integral molding.

4 and 5 are diagrams showing examples of convection in the heat transfer body 9, respectively. The regulating body 10 is in a state of being covered with the heat transfer body 9 . When the discharge lamp is lit, the heat conductor 9 melts and begins convection. An example of the direction of convection is indicated by f1 in FIGS. The regulating body 10 acts as an obstacle to regulate the convection in the direction around the central axis Z1 and promotes the convection in the Z direction. Thereby, the regulating body 10 promotes heat transfer from the front end 13 to the rear end 14 of the anode 2 and suppresses turbulent flow of the heat transfer body 9 . Therefore, the temperature of the tip 13 of the anode 2 is lowered, and the width of temperature fluctuation is reduced.

Between the blade 10b that constitutes the regulator 10 and the inner wall 15 that constitutes the closed space of the anode 2, there is usually a gap G1 (see FIG. 3). Due to the presence of the gap G1, when the heat transfer body 9 is melted, the blade 10b is pushed by the convection in the direction around the central axis Z1 of the heat transfer body 9, so that the regulating body 10 can rotate about the central axis Z1.

The restrictor 10 will be described with reference to FIGS. FIG. 6 is a side view of the regulating body 10 when the regulating body 10 is viewed in the +Y direction. FIG. 7 is a top view of the regulating body 10 when the regulating body 10 is viewed in the -Z direction.

As shown in FIGS. 6 and 7, the upper surface 10t of the blade 10b in this embodiment includes a plane 10t1 along the XY plane and a tapered surface 10t2. As shown in FIG. 6, the radial length B2 of the plane 10t1 is smaller than the radial length B3 of the lower surface 10u of the blade 10b. On the tapered surface 10t2, the height (the length in the Z direction) of the blade 10b decreases with distance from the central axis Z1.

As shown in FIG. 7, the thickness T1 of the four blades 10b forming the regulator 10 has a thickness that withstands the collision of the convective heat transfer member 9. As shown in FIG. The thickness T1 is, for example, 1 mm or more, preferably 2 mm or more and 3 mm or less.

The melting point of the material forming the regulator 10 is higher than the melting point of the material forming the heat conductor 9 so that the regulator 10 does not melt when the discharge lamp 100 is lit. The material of the regulating body 10 may be the same as the material forming the main body 5 . The regulation body 10 is made of, for example, a material mainly containing tungsten.

[Dimensional design of the anode]
The dimensional design of the anode 2 will be described with reference to FIG. FIG. 8 represents a cross-sectional view through the central axis Z1 of the anode 2. FIG. The sealed space in the −Z direction from the interface 8i between the heat transfer body 9 and the gas space 8 provided in the sealed space is filled with the heat transfer body 9 except for the regulator 10. FIG. It should be noted that in FIG. 8, only the area hatched with oblique lines is not the area where the heat conductor 9 exists. The same applies to FIGS. 13A, 13B, and 19 as well.

As shown in FIG. 8, the lowest position in the Z-axis direction on the bottom surface 18 of the closed space is defined as a 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 the lowest position P1 of the blade 10b. The end position of the blade 10b farthest from the bottom surface 18 (in this embodiment, the position of the flat surface 10t1 of the upper surface 10t) is the highest position P2 of the blade 10b. The Z-axis direction position of the interface 8i between the heat transfer body 9 provided in the closed space and the gas space 8 is defined as the interface position P3 of the heat transfer body 9 .

When the positions P0 to P3 are set in this way, the first interval B1, the second interval L1, and the third interval H1 are expressed as follows.
First interval B1 = lowest position P1 - reference position P0
Second interval L1 = highest position P2 - lowest position P1
Third interval H1=interface position P3−highest position P2

The area in which the heat conductor 9 is present is divided into an upper area and a lower area. The upper region is a region 9s (a hatched region in FIG. 8) between the lowest position P1 of the blade 10b and the interface position P3. Let the area of the upper region 9s be the upper area S1 (mm ² ) of the heat transfer body 9 . Let D1 (mm) be the outer diameter of the main body 5, and D2 (mm) be the outer diameter of the sealed space.

Regarding the dimensions of the anode 2 described above, 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 sealed space are is closely related to the convection state and affects the temperature of the anode 2 . Therefore, the inventor obtained the temperature of the anode 2 when these parameters were changed by conducting a convection simulation of the heat transfer body 9 or by actually measuring the discharge lamp 100 that was actually lit. The convection simulation of the heat conductor 9 and the conditions of the actually lit discharge lamp 100 are shown below.

<Discharge lamp>
It has the shape shown in FIG.
Material of arc tube 1: quartz glass Distance between anode 2 and cathode 3: 6 mm
Filled material in arc tube 1: mercury 2.0 mg/cc, argon 100 kPa
Rated current: 200A
Rated power: 12kW
<Anode 2>
It has the shape shown in FIG.
Volume of closed space: ^17cm3
Material of heat transfer element 9: silver Sealed gas in gas space 8: argon 100 kPa
<Regulator>
It presents the shape shown in FIGS.
Radial length B2 of plane 10t1: 8.15 mm
Radial length B3 of lower surface 10u of blade 10b: 10.75 mm
Thickness T1: 3mm

FIG. 9 is a graph showing the relationship between the third gap H1 (mm) and the temperature TE (K) of the bottom surface 18 of the sealed space of the anode 2 from the convection simulation of the heat transfer body 9. As shown in FIG. The temperature TE is a temperature obtained by further averaging 2000 calculation results for a total of 5 spatial average temperatures of the center point of the bottom surface 18 and 4 points of 1 mm circumference on the XY plane in the model in a steady state. be. In the (X, Y, Z) coordinate system, if the center point is (0, 0, 0), the peripheral points are (1, 0, 0), (0, 1, 0), (-1, 0 , 1), and (0,-1,0).

The temperature TE of the bottom surface 18 of the closed space of the anode 2 is preferably 1800K or less. Referring to FIG. 9, it can be seen that the change in the temperature TE with respect to the change in the third interval H1 is small. In other words, the restriction on the third interval H1 for setting the temperature TE to 1800K or less is small.

Regarding the first interval B1, it was found that the first interval B1 must be 3 (mm) or more in order to make the temperature TE 1800K or less. When the first interval B1 is 3 (mm) or more, the convective flow rate of the heat transfer body 9 passing through the lower part of the regulation body 10 (the −Z side of the regulation body 10) increases, and the bottom surface 18 of the closed space of the anode 2 increases. It is presumed that heat can be stably sent to the rear end 14 side, and as a result, the temperature TE can be lowered. When the temperature TE is lowered, the thermal load applied to the anode 2 can be reduced, and damage (perforation, etc.) of the bottom surface 18 of the sealed space of the anode 2 due to high-temperature creep deformation can be suppressed. Therefore, it is possible to increase the output and extend the life of the discharge lamp.

FIG. 10 is a graph showing the relationship between the first interval B1 and the maximum value TX of the width of temperature fluctuation obtained from the convection simulation of the heat transfer body 9. As shown in FIG. The temperature fluctuation width is expressed by the difference between the maximum temperature and the minimum temperature for a predetermined time (for example, 1 minute) at any place on the electrode surface when the discharge lamp is lit. If the temperature fluctuation range continues for a long time, high-temperature creep deformation causes protrusions to protrude from the inner surface of the tip of the electrode. As a result, the electrode loses its ability to dissipate heat, resulting in overheating of the electrode and rapid deterioration of the discharge lamp. The width of temperature fluctuation shows different values depending on the location of the electrode surface. The maximum temperature fluctuation width TX (° C.) indicates the maximum temperature fluctuation width that varies depending on the location of the electrode surface. By suppressing the maximum value TX of the temperature fluctuation width, the thermal load applied to the anode 2 can be reduced, and damage such as hole opening at the tip of the electrode due to high-temperature creep deformation can be suppressed. Therefore, it is possible to increase the output and extend the life of the discharge lamp.

The maximum value TX of the temperature fluctuation width is preferably 13° C. or less. From FIG. 10, it was found that the maximum value TX can be set to 13° C. or less when the first interval B1 is 15 mm or less.

From FIGS. 9 and 10, it is preferable that the first interval B1 satisfies the formula (1) in order to increase the power output and extend the life of the discharge lamp.
3≤B1≤15 (1)
Moreover, it is more preferable that the first interval B1 is 4 or more.

As described above, the restriction on the third distance H1 for lowering the temperature TE of the bottom surface 18 of the closed space of the anode 2 is small. However, from the result of the convection simulation of the heat transfer body 9, if the third distance H1 is too large compared to the second distance L1 (that is, the height of the regulation body 10), the upper part of the regulation body 10 (+Z side) It was found that the convection of the heat transfer body 9 could not be sufficiently controlled, and turbulence occurred. When turbulence occurs, the width of temperature fluctuation increases.

Therefore, by actually measuring the anode 2 of the discharge lamp 100 that is actually lit, the size of the third gap H1 based on the second gap L1 (that is, the ratio of the third gap H1 to the second gap L1) and The relationship with the maximum value TX (° C.) of the temperature fluctuation range was obtained and shown in the graph of FIG. As described above, the maximum value TX of the temperature fluctuation width is preferably 13° C. or less, so the value of H1/L1 should satisfy the expression (2).
0.0≦H1/L1≦1.0 (2)
This formula indicates that the third distance H1, which is also the distance between the upper surface 10t of the blade 10b and the interface 8i, is smaller than the second distance L1, which is also the height of the regulating body 10, and that the third distance H1 is 0 or more. represent.

In the sealed space, the area sandwiched between the upper surface 10t of the blade 10b and the interface 8i, which occupies most of the upper area 9s (hatched area in FIG. 8) of the regulating body 10, transfers heat beyond the blade 10b. It is necessary to convect the body 9. FIG. 12 shows 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 by convection simulation of the heat transfer body 9. It is a graph showing. As described above, since the temperature TE is preferably 1800 K or less, the upper area S1 should preferably satisfy the following formula (3).
S1≧40 (3)
When the formula (3) is satisfied, the heat transfer element 9 has a sufficient flow rate, and the heat from the front end 13 of the anode 2 can be stably transferred to the rear end 14 .

13A and 13B, the necessity of specifying the dimensions of the anode 2 not only by the formula (2) but also by both the formulas (2) and (3) will be explained. 13A and 13B, the reference position P0, the lowest position P1, the highest position P2, and the interface position P3 are set to have the same value. Therefore, in FIGS. 13A and 13B, the first interval B1, the second interval L1 and the third interval H1 are also equivalent to each other. However, in the anode 2 shown in FIG. 13A, the upper surface 10t of the blade 10b is flat, but in the anode 2 shown in FIG. 13B, the upper surface 10t of the blade 10b is uneven.

Anode 2 shown in FIG. 13A is a comparative embodiment of the present invention in which H1/L1 satisfies formula (2), but area S1 of upper region 9s does not satisfy formula (3). On the other hand, anode 2 shown in FIG. 13B is an embodiment of the present invention in which H1/L1 satisfies formula (2) and top area S1 satisfies formula (3). Therefore, the present invention cannot be specified only by the formula (2), and is required to be specified by both the formulas (2) and (3).

The simulation and temperature measurement described above are the results obtained by fixing the outer diameter D1 of the anode 2 to 40 mm and the outer diameter D2 of the closed space of the anode 2 to 22 mm. However, even if the outer diameter D1 or the outer diameter D2 is different, if the formulas (1), (2), and (3) are satisfied, the temperature TE can be set to 1800 K or less, and the maximum value TX of the temperature fluctuation width can be set to 13° C. or less. Explain that you can set

Based on the anode G (D1: 40 mm, D2: 22 mm), the convection simulation of the heat transfer body 9 was performed for six anodes A to F in which D1 or D2 was changed. The six anodes, Anodes AF, are similar to Anode G, except for the following points and the amount of heat transfer material 9 . For the rated current and rated power of the lamp using the anode, optimal values were selected according to the size of the anode. The amounts of the heat conductors 9 of the anodes A to F were adjusted so that the value of H1/L1 was equivalent to that of the anode G. FIG. 14 shows the anodes A to F as a graph with the outer diameter D1 on the horizontal axis and the outer diameter D2 on the vertical axis.
Anode A D1: 25 mm, D2: 15.25 mm, rated current: 150 A, rated power: 5 kW
Anode B D1: 35 mm, D2: 20.75 mm, rated current: 175 A, rated power: 10 kW
Anode C D1: 45 mm, D2: 26.25 mm, rated current: 250 A, rated power: 15 kW
Anode D D1: 25 mm, D2: 12.75 mm, rated current: 150 A, rated power: 5 kW
Anode E D1: 35 mm, D2: 17.25 mm, rated current: 175 A, rated power: 10 kW
Anode F D1: 45 mm, D2: 21.75 mm, rated current: 250 A, rated power: 15 kW

As a result of the convection simulation of the heat transfer body 9, if the equations (1), (2), and (3) are satisfied in the same way as the anode G, the six anodes A to F also have a temperature TE of 1800 K or less, In addition, the maximum value TX of the temperature variation range was reduced to 13°C or less. Therefore, even in the range where the relationship between the outer diameter D1 of the main body 5 and the outer diameter D2 of the closed space in the graph of FIG. As a result, the temperature TE becomes 1800 K or less, and the maximum value TX of the temperature fluctuation range becomes 13° C. or less.

A straight line f11 passing through the anodes A to C is expressed by D2=0.55×D1+1.5. A straight line f12 passing through the anodes D to F is expressed by D2=0.45×D1+1.5. Therefore, the outer diameter D1 of the anode 2 and the outer diameter D2 of the sealed space preferably satisfy the following formula (4).
0.45×D1+1.5≦D2≦0.55×D1+1.5 (4)

In addition, the outer diameter D1 preferably satisfies the following formula (5).
25≦D1≦45 (5)

[Method for obtaining dimensional design values from manufactured anodes]
A method for obtaining dimensional design values from the manufactured anode 2 will be described. In the method described below, when determining the dimensional design values of the anode 2 in the discharge lamp that is lit for use or testing after manufacturing the discharge lamp, if the interface 8i is not flat, the interface position of the heat conductor 9 It is particularly suitable for determining P3.

The main reason why the interface 8i is not flat will be explained. After the discharge lamp 100 is manufactured, the anode 2 of the discharge lamp 100 that is lit for use or testing has the heat conductor 9 inside it melted once. When the anode 2 is cooled as the light is turned off, the temperature decreases from the surface of the anode 2 toward the inside of the anode 2 . As a result, the timing of thermal contraction due to solidification is different between the surface of the anode 2 and the inside of the anode 2. Therefore, as shown in FIG. There may be dents in the vicinity.

To obtain the dimensional design values from the manufactured anode 2, the following procedure is followed.
(Procedure 1) The anode 2 is removed from the discharge lamp, and the outer diameter D1 of the anode 2 is measured. In the gas space 8 (the portion not containing the heat transfer body 9) relatively above the sealed space, the container 5a is cut along the XY plane to form a first electrode portion including the heat transfer body 9 and the regulating body 10. , and the second electrode portion including the lid 5b.

(Procedure 2) Measure the weight a of the first electrode portion. Also, a minute amount of the heat transfer element 9 is sampled from the cut surface, and the components are analyzed and the density ρ is estimated. For analysis of the components, for example, a fluorescent X-ray device or the like may be used.

(Procedure 3) The first electrode portion is immersed in a liquid in which the anode 2 does not dissolve but the heat transfer member 9 dissolves, the heat transfer member 9 dissolves, and the regulator 10 is removed from the first electrode portion. As such a liquid, for example, nitric acid is used when the anode 2 is tungsten and the heat conductor 9 is silver. Then, from the first electrode portion, the heat transfer body 9 is removed and the weight b including the regulating body 10 is measured. As a result, the volume VM of the heat transfer body 9 is obtained by the formula (6).
VM=(ab)/ρ (6)

(Step 4) Measure the second distance L1, which is the height of the blade 10b, the outer diameter D2 of the closed space of the anode 2, the reference position P0, and the lowest position P1 of the blade 10b. A first interval B1 is obtained from the reference position P0 and the lowest position P1. A highest position P2 of the blade is obtained from the lowest position P1 and the second interval L1.

(Procedure 5) The closed space of the anode 2 is filled with the regulator 10 and a liquid (for example, water) having the same volume as the volume VM of the heat transfer body 9, and the liquid surface is kept horizontal. The position of the liquid surface at this time is regarded as the position P3 of the interface 8i between the heat transfer body 9 and the gas space 8. FIG. A third gap H1 is obtained from the highest position P2 of the regulating body 10 and the interface position P3 of the heat transfer body 9 . The upper area S1 is obtained from the third gap H1, the outer diameter D2 of the sealed space, and the dimensional measurement result of the shape of the restrictor 10. FIG.

Although the details will be described later, the plurality of blades 10b forming the regulating body 10 may have different shapes. Such a regulator 10 may have different top areas S1 depending on the blade 10b. In that case, the blade 10b with the largest upper area S1 is selected, and the highest position P2 and the upper area S1 are set from the selected blade 10b.

[Modified example of regulator]
16, 17 and 18 are diagrams showing modifications of the restrictor. These figures are views of the regulator viewed in the -Z direction.

The regulating body 20 shown in FIG. 16 has two blades 20b radially extending about the central axis Z1 and the two blades 20b are arranged in one direction. The regulation body 20 may be composed of a single plate. However, the number of blades 20b shown in this drawing is counted as two, even if it is composed of a single plate. Although the regulation body 20 may be tilted due to the convection of the heat transfer body 9, when the blade 20b comes into contact with the inner wall 15 of the closed space, further tilting of the regulation body 20 is suppressed.

The restricting body 30 shown in FIG. 17 has three blades 30b radially extending around the central axis Z1, and two of the blades 30b are arranged in one direction. The number of blades 30b shown in this drawing is counted as three. The regulation body 30 having three blades 30b is more likely to suppress tilting of the regulation body 30 than the regulation body 20 having two blades.

The restricting body 40 shown in FIG. 18 has three blades 40b extending radially about the central axis Z1 so as to form equal angles with each other. The number of blades 40b shown in this drawing is counted as three. Since the blades 40 b form an equal angle with each other, the inclination of the restricting body 40 can be suppressed more than the restricting bodies 20 and 30 .

Further, when the regulating body 10 is viewed from the Y direction (side), the upper surface 10t of the blade 10b may not have a tapered surface. When the regulator 10 is viewed from the Y direction, the blade 10b may be rectangular, or the upper surface 10t of the blade 10b may be uneven as shown in FIG. 13B.

The blades 10b in the regulating body 10 may have different shapes. For example, when looking at the cross section on the XZ plane passing through the central axis Z1, as shown in FIG. As shown in FIG. 19, the restricting body 10 may be a blade 10b having a rectangular shape with no taper and a second interval L1 of 14 mm when viewed in plan view.

[Shape of closed space]
FIG. 20 shows a modification of the main body 5 of the anode 2. FIG. FIG. 20 only shows the main body 5 . As shown in this drawing, in a cross-sectional view passing through the central axis Z1, the bottom surface 18 to which the two opposing inner walls 15 are connected is formed of a curved surface. The stagnation or turbulence of the convection of the heat transfer body 9 can be suppressed by forming the curved surface without corners. Also, stress concentration due to expansion of the heat transfer member 9 during lighting can be avoided. At least a portion of the bottom surface 18 may be configured with a curved surface (a surface without corners).

The embodiments and modifications have been described above. The present invention is by no means limited to the above-described embodiments, and various improvements and modifications can be made to the above-described embodiments and modifications without departing from the scope of the present invention.

Although an example in which the anode 2 has the heat transfer body 9 and the heat transfer body 10 has been described above, the cathode 3 may have the heat transfer body 10 and the heat transfer body 9 in the same manner as the anode 2 . The discharge lamp 100 may be arranged such that the cathode 3 is positioned above the anode 2 . The discharge lamp 100 may be arranged so that the anode 2 and the cathode 3 are arranged horizontally.

In the above, the main body 5 of the anode 2, the regulator 10 in the closed space of the anode 2, the lead rod 4, the cathode 3 and the arc tube 1 have a common central axis Z1, but the central axis of each part is not necessarily the same. may not have a common axis.

An anode 2 having the following dimensions and having the same dimensions as the simulation conditions described above except for the following conditions was fabricated. This anode 2 satisfies the above formulas (1) to (5).
First interval B1: 6.2 mm
Second interval L1: 16 mm
Third interval H1: 14 mm
Outer diameter D1 of anode 2: 40 mm
Outer diameter D2 of closed space of anode 2: 22 mm
Thickness of anode 2: 9.0 mm
Amount of heat transfer element 9 enclosed in anode 2: 11.4 cm ³

When the discharge lamp 100 provided with this anode 2 was lit for the reference time at the above rated power, it was confirmed that the illuminance exceeding the standard value was maintained. After that, 30 sets of lighting and extinguishing were repeated with 15 minutes of lighting and 12 minutes of extinguishing as one set, during which the illuminance did not fall below the standard value. After the test was completed, the anode 2 was dismantled and the main body 5 of the anode 2 was checked. From this, it is estimated that the life of the discharge lamp 100 is improved.

An anode 3 having the following dimensions and having the same dimensions as the simulation conditions described above except for the following conditions was fabricated. Although this anode 2 satisfies the above expressions (1) and (3) to (5), H1/L1=1.3 and does not satisfy the expression (2).
First interval B1: 6.2 mm
Second interval L1: 13 mm
Third interval H1: 17 mm
Outer diameter D1 of anode 2: 40 mm
Outer diameter D2 of closed space of anode 2: 22 mm
Thickness of anode 2: 9.0 mm
Amount of heat transfer element 9 enclosed in anode 2: 11.4 cm ³

When the discharge lamp 100 having this anode 2 was lit at the above-described rated power, the maximum value TX of the temperature fluctuation range was 16° C., exceeding the reference value (13° C.). Then, while the discharge lamp 100 was being lit for the reference time, a hole was formed in the bottom surface. It is presumed that this is because the bottom surface was deformed by creep deformation due to the temperature fluctuation width exceeding the reference value.

1: arc tube 2: anode 3: cathode 4: lead rod 5: main body 5a: container 5b: lid 8: gas space 8i: interface 9: heat transfer element 9s: upper region 10: regulator 10b: blade 10t: (blade of) upper surface 10t1: flat surface 10t2: tapered surface 10u: lower surface (of blade) 11: sealing tube 12: mouthpiece 13: tip 14: rear end 15: inner wall 20, 30, 40: regulator 20b, 30b, 40b: blade 100: Discharge lamp B1: First interval D1: Outer diameter D2: Outer diameter G1: Gap H1: Third interval L1: Second interval P0: Reference position P1: Lowest position P2: Highest position P3: Interface position S1: Upper area T1: thickness Z1: central axis

Claims (5)

In a discharge lamp having therein a pair of electrodes arranged opposite to each other in the axial direction,
At least one of the pair of electrodes is
a main body having an enclosed space;
a heat transfer body having a melting point lower than that of the material forming the main body in the closed space;
a regulating body made of a material having a melting point higher than that of the heat transfer body and regulating convection of the heat transfer body in the closed space;
a gas space in contact with the heat transfer body in the sealed space,
the regulating body includes at least one blade extending in the axial direction and in a radial direction orthogonal to the axial direction;
The tip of the at least one electrode is arranged downward and the rear end is arranged upward, the lowest position in the axial direction on the bottom surface of the sealed space is defined as a reference position P0, and the edge of the blade closest to the bottom surface. The position of the blade is the lowest position P1 of the blade, the end position of the blade farthest from the bottom surface is the highest position P2 of the blade, and the position of the interface between the heat transfer body and the gas space in the axial direction is the interface When the position is P3,
A first interval B1 (mm), which is the interval in the axial direction between the reference position P0 and the lowest position P1, and a second interval L1 (mm), which is the interval in the axial direction between the lowest position P1 and the highest position P2. ), a third interval H1 (mm) that is the interval in the axial direction between the highest position P2 and the interface position P3, and the lowest position P1 and the interface in a cross section including the axis in the axial direction The upper area S1 (mm ² ) of the heat conductor, which is the filling region of the sandwiched heat conductor, satisfies the following equations (1) to (3): 3≦B1≦15 (1)
0.0≦H1/L1≦1.0 (2)
S1≧40 (3)
A discharge lamp characterized by: 2. The discharge lamp according to claim 1, comprising three or more blades. 2. The discharge lamp of claim 1, wherein the bottom surface of the closed space includes a curved surface. When the outer diameter of the main body is D1 and the outer diameter of the closed space is D2, the following expression (4) is satisfied: 0.45×D1+1.5≦D2≦0.55×D1+1.5 (4)
The discharge lamp according to any one of claims 1 to 3, characterized in that: An electrode for use in a discharge lamp, said electrode comprising:
a main body having an enclosed space;
a heat transfer body having a melting point lower than that of the material forming the main body in the closed space;
a regulating body made of a material having a melting point higher than that of the heat transfer body and regulating convection of the heat transfer body in the closed space;
a gas space in contact with the heat transfer body in the sealed space,
the regulating body includes at least one blade extending in the axial direction and in a radial direction orthogonal to the axial direction;
The tip of the at least one electrode is arranged downward and the rear end is arranged upward, the lowest position in the axial direction on the bottom surface of the sealed space is defined as a reference position P0, and the edge of the blade closest to the bottom surface. The position of the blade is the lowest position P1 of the blade, the end position of the blade farthest from the bottom surface is the highest position P2 of the blade, and the position of the interface between the heat transfer body and the gas space in the axial direction is the interface When the position is P3,
A first interval B1 (mm), which is the interval in the axial direction between the reference position P0 and the lowest position P1, and a second interval L1 (mm), which is the interval in the axial direction between the lowest position P1 and the highest position P2. ), a third interval H1 (mm) that is the interval in the axial direction between the highest position P2 and the interface position P3, and the lowest position P1 and the interface in a cross section including the axis in the axial direction The upper area S1 (mm ² ) of the heat conductor, which is the filled region of the sandwiched heat conductor, satisfies the following equations (1) to (3): 3≦B1≦15 (1)
0.0≦H1/L1≦1.0 (2)
S1≧40 (3)
An electrode characterized by:

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