JPWO2014170734A1 - Discharge lamp - Google Patents

Abstract

Provided is a discharge lamp in which cracks are prevented from occurring in a sealing tube during lamp operation. The short arc type discharge lamp includes an electrode support bar that supports an electrode in the arc tube, and an electrical connection rod that is electrically connected to an external power source, provided in a sealed tube integrally formed with the arc tube. A glass member in which the electrode support rod and the electrical connecting rod are inserted and welded to the sealing tube, a plurality of strip metal foils extending along an outer surface of the glass member, the strip metal foil and the electrode support And a pair of annular members that electrically connect the rod and the electrical connecting rod. The thickness of the strip-shaped metal foil is determined so that the rated power is 3 kW or more, the current value during stable lighting is 130 A or more, the mercury content in the arc tube is 7 mg / cc or less, and the following formula is satisfied. . σ = 7.54 × 105T−6 × 107T = 1.92 (I / nwd) +98.9 σ ≦ 1.20 × 108

Description

  The present invention relates to a short arc type discharge lamp, and more particularly to a discharge lamp sealing structure.

In a short arc type discharge lamp, a glass sealing tube is integrally formed at both ends of an arc tube sealed with an electrode, and an electrode support rod for supporting the electrode is held by a cylindrical glass tube in the sealing tube. Is done. In the sealing structure with metal foil, the diameter of the sealing tube is reduced by heat, and the sealing tube is welded to the glass tube. Thereby, metal foil is sealed and the inside of an arc_tube | light_emitting_tube becomes an airtight state.
In the semiconductor and liquid crystal manufacturing fields, in order to improve production efficiency, the power of short arc type discharge lamps is increasing. Therefore, in a discharge lamp having a large rated power, a metal ring is fixed to the electrode support rod, and a plurality of metal foils are welded to the metal ring. Thereby, electric power is supplied through metal foil, a metal ring, and an electrode support rod (for example, refer patent document 1).
If a crack occurs near the metal ring due to the difference in thermal expansion coefficient between the metal ring and the sealing tube while the lamp is lit, the metal ring in a high temperature state is oxidized by touching the outside air and the metal foil is blown out. Alternatively, the arc tube may be ruptured by the progress of the crack. In order to prevent the occurrence of cracks, a structure in which the sealing tube has a double structure is known, and the thickness of the sealing tube is adjusted so that the current density of the current flowing through the metal link and the metal foil does not exceed the limit value. Determined (see Patent Document 2).

JP 2007-115414 A JP 2007-095328 A

In a discharge lamp, the amount of enclosed mercury may be extremely small in order to realize fine exposure. As a result, the peak half-value width is reduced, and a spectral distribution characteristic that stands out in the vicinity of the peak wavelength is obtained. Such a discharge lamp with a small amount of enclosed mercury emits light at a low voltage and is in a stable lighting state. As a result, the current that flows when the lamp is lit in a high-power (3 kW or more) discharge lamp has a high current value (for example, 130 A or more).
More heat is generated by increasing the value of the current flowing through the metal foil and metal ring, and a large thermal stress acts on the seal tube, especially at the contact surface between the metal ring and metal foil and the seal tube. To do. However, in the case of a short arc type discharge lamp having a small outer diameter of the sealing portion, it is difficult to adopt the sealing tube as a double structure, and the thickness of the metal foil is limited. Therefore, the generation of cracks in the vicinity of the metal ring cannot be sufficiently prevented.
Therefore, in a high output, high current short arc type discharge lamp (particularly in the case of a single sealed tube structure), it is required to suppress the occurrence of cracks in the sealed tube during lamp operation.

The discharge lamp of the present invention is provided in a sealed tube formed integrally with the arc tube, and an electrode support bar that supports the electrode in the arc tube, an electrical connection rod that is electrically connected to an external power source, A glass member into which the electrode support rod and the electrical connecting rod are inserted and welded to the sealing tube, a plurality of strip metal foils extending along an outer surface of the glass member, the strip metal foil, and the electrode support rod And a pair of annular members for electrically connecting the electrical connecting rods.
The annular member only needs to be a conductive member, and can be composed of, for example, a metal ring, and a plurality of metal foils are connected to the outer surface of the ring. The glass member can be configured as a cylindrical glass having shaft holes formed at both ends.
In the present invention, the thickness of the strip metal foil is such that the rated power is 3 kW or more, the current value during stable lighting is 130 A or more, the mercury content in the arc tube is 7 mg / cc (cm ³ ) or less, and the following formula is satisfied. Is determined.
σ = 7.54 × 10 ⁵ T-6 × 10 ⁷
T = 1.92 (I / nwd) +98.9
σ ≦ 1.20 × 10 ⁸
However, the thermal stress applied from the outer surface of the annular member to the inner surface of the sealing tube is σ (Pa), the outer surface temperature of the sealing tube is T (° C.), and the current value during stable lighting is I (A ), The number of the strip-shaped metal foil is n, the width of the strip-shaped metal foil is w (mm), and the thickness of the strip-shaped metal foil is d (mm).
In addition, it is good also as thermal stress (sigma) in both a pair of annular members, and outer surface temperature T, or you may prescribe | regulate about one annular member. What is necessary is just to determine in the connection part of the sealing pipe | tube and annular member which a crack by large current tends to generate | occur | produce.
In the present invention, in a discharge lamp having a large rated output, lighted at a low voltage, and having a small outer diameter of the sealed tube, the heat generated in the metal foil during lamp lighting is a conductive ring such as the inner surface of the sealed tube and the metal ring. It is found that the thermal stress applied to the contact surface with the outer surface of the member is affected, and the thickness of the metal foil is determined to be a specific thickness so that cracks do not occur even when a large current flows through the metal foil. By applying a metal foil having a thickness that has not been considered necessary until now, a discharge lamp having excellent durability can be realized.
It is possible to effectively suppress the occurrence of cracks in a short type discharge lamp having a relatively small outer diameter of the sealing tube, and the sealing tube can be applied to a discharge lamp that satisfies the following expression.
I / L ≧ 5
If the outer surface temperature of the sealing tube is too low, thermal distortion occurs due to a large temperature difference between the sealing tube and the arc tube. On the other hand, if the outer surface temperature is too high, the cap portion and the sealing tube Thermal distortion occurs due to the large temperature difference. Therefore, it is preferable that the outer surface temperature of the sealing tube during stable lamp lighting satisfies the following formula.
150 ≦ T ≦ 800
In another aspect of the present invention, a discharge lamp is provided in a sealing tube formed integrally with the arc tube, and is electrically connected to an electrode support bar for supporting the electrode in the arc tube and an external power source. A connecting rod, a glass member into which the electrode support rod and the electrical connecting rod are inserted and welded to the sealing tube, a plurality of strip-shaped metal foils extending along an outer surface of the glass member, and the strip-shaped metal foil And an annular member that electrically connects the electrical connecting rod, and the thickness of the strip-shaped metal foil is determined so as to satisfy the following expression.
σ ≦ 1.20 × 10 ⁸
However, the thermal stress applied from the outer surface of the annular member to the inner surface of the sealing tube is σ (Pa).

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that a crack generate | occur | produces in a sealing tube during lighting, and can obtain the discharge lamp with a highly reliable sealing structure.

It is a schematic sectional drawing of the short arc type discharge lamp which is this embodiment. It is a schematic sectional drawing of a cathode side sealing tube. It is the graph which showed the relationship between sealing pipe outer surface temperature and a thermal stress. It is the graph which showed the relationship between the current density of the electric current which flows through metal foil, and the sealing tube outer surface temperature.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a short arc type discharge lamp according to this embodiment.
The short arc type discharge lamp 10 is a lamp in which an anode 14 and a cathode 16 are opposed to each other in a spherical light emitting tube 12 made of quartz glass, and quartz glass sealing tubes 20 and 60 are provided at both ends of the light emitting tube 12. It is integrally formed so as to face each other. Both ends of the sealing tubes 20 and 60 are closed with caps 80A and 80B.
Inside the sealing tubes 20 and 60, parts (hereinafter referred to as mounting parts) 18A and 18B for supporting the anode 14 and the cathode 16 and sealing the discharge space 11 in the arc tube 12 are encapsulated, respectively. . Mercury and a rare gas are sealed in the discharge space 11.
The short arc type discharge lamp 10 is a high output discharge lamp having a rated power of 3 kW or more, while the outer diameter of the sealed tube is relatively small, and the illumination light has a spectral distribution characteristic that stands out in the vicinity of the peak wavelength. The amount of mercury enclosed in the issuance tube is set to 7 mg / cc or less. For this reason, the voltage value at the time of stable lighting is low, and conversely, the current value becomes large and the current value becomes 130 A or more.
FIG. 2 is a schematic cross-sectional view of the cathode side sealing tube. The anode side sealing tube is configured similarly.
As shown in FIG. 2, an electrode support bar 17B that supports the cathode 16 is provided inside the sealing tube 60 in which the mount component 18B is enclosed, and is disposed along the axial direction. The electrode support rod 17 </ b> B is inserted through a shaft hole formed in a cylindrical thick glass tube (hereinafter referred to as an electrode side glass tube) 22 and is held by the electrode side glass tube 22.
The electrode support rod 17B does not extend to the end portion of the sealing tube 60, and a metal lead rod (electrical connection rod) 19B is coaxially disposed opposite to the electrode support rod 17B at a predetermined interval. The electrode support bar 17B and the lead bar 19B are inserted into insertion holes provided at both ends of a thick cylindrical glass member (hereinafter referred to as an outer glass member) 26. The outer glass member 26 is inserted into the electrode support bar 17B and the lead bar 19B. Hold. The lead bar 19B is connected to an external lead wire (not shown) connected to a power supply unit (not shown).
Metal rings (annular members) 23 and 25 are arranged in close contact with both ends of the outer glass member 26, and the electrode support bar 17B and the lead bar 19B are inserted into the shaft holes of the metal rings 23 and 25 and welded. . A metal ring (hereinafter referred to as an inner metal ring) 23 close to the arc tube 12 is in contact with the electrode-side glass tube 22, and the other metal ring (hereinafter referred to as an outer metal ring) 25 is inserted through the lead bar 19B. It contacts with the fixed thickness glass tube 28 to be held.
Between the inner metal ring 23 and the outer metal ring 25, a plurality of strip-shaped metal foils 27 extend in the axial direction along the outer surface of the outer glass member 26, and are arranged at equal intervals along the circumferential direction. Yes. Further, both ends of each of the plurality of strip-shaped metal foils 27 are welded to the circumferential surfaces of the inner metal ring 23 and the outer metal ring 25. The outer metal ring 25 electrically connects the lead bar 19B and the band-shaped metal foil 27, and the inner metal ring 23 electrically connects the band-shaped metal foil 27 and the electrode support bar 22, whereby the power supply unit Power is supplied to the cathode 16 from the lead bar 19B that is electrically connected to the cathode 16.
The sealing tube 60 is reduced in diameter by being heated by a gas burner or the like during the sealing process, and is welded to the electrode side glass tube 22, the outer glass member 26, and the fixed glass tube 28. As a result, the inside of the sealing tube 60 is sealed, and the mounting component 18B including the electrode side glass tube 22, the inner metal ring 23, the outer metal ring 25, the outer glass member 26, and the fixed glass tube 28 moves in the axial direction. It is fixed so that there is no.
Hereinafter, the sealing structure of this embodiment will be described with reference to FIGS.
FIG. 3 is a graph showing the relationship between the outer surface temperature of the sealed tube and the thermal stress. FIG. 4 is a graph showing the relationship between the current density of the current flowing through the metal foil and the outer surface temperature of the sealed tube.
When the lamp is turned on, the thermal expansion coefficients of the metal and glass are different, and thermal stress is generated on the contact surface / welding surface between the metal foil 27 and the sealing tube 60 and the outer metal ring 25 and the sealing tube 60. Similarly, thermal stress is generated between the inner metal ring 23, the metal foil 27, and the sealing tube 60.
As described above, the discharge lamp 10 is a short arc type discharge lamp, a low voltage, large current type discharge lamp, and has a relatively small outer diameter of the sealed tube. Therefore, the heat generated in the entire metal foil 27 during lamp lighting affects the thermal stress applied from the vicinity of the outer peripheral surface of the inner and outer metal rings 25 toward the sealing tube 60. The influence of this heat is very large compared to a discharge lamp having a large outer diameter of the sealed tube. Furthermore, when the outer diameter of the sealing tube is reduced, it is difficult to increase the strength of the sealing portion by adopting a double sealing structure.
As the current density of the current flowing through the metal foil 27 increases, the temperature of the metal foil 27 increases and the amount of heat increases, but the current density varies depending on the thickness of the metal foil 27. Therefore, if the metal foil 27 is made too thin in order to prevent foil peeling due to insufficient welding, thermal stress may increase and cracks may occur. Therefore, in this embodiment, the thickness of the metal foil 27 related to the current density is determined to be equal to or greater than a predetermined thickness.
As shown in FIGS. 3 and 4, regarding the thermal stress σ (Pa) applied from the outer peripheral surface of the outer metal ring 25 to the inner surface of the sealing tube 60, the outer surface temperature of the sealing tube 60 is T (° C.), Assuming that the current value during stable lighting is I (A), the number of metal foils 27 is n, the width of the metal foil is w (mm), and the thickness of the metal foil is d (mm), the following equation holds: Further, the thickness d (mm) of the metal foil, the width w (mm) of the metal foil, and the number n of the metal foils 27 are determined.
σ = 7.54 × 10 ⁵ T-6 × 10 ⁷ (1)
T = 1.92 (I / nwd) +98.9 (2)
σ ≦ 1.20 × 10 ⁸ (3)
Equation (1) indicates that the outer surface temperature T of the sealed tube and the thermal stress σ are in a proportional relationship (see FIG. 3). However, the surface temperature at the sealing tube point PT shown in FIG. Moreover, (2) Formula has shown that the sealing tube outer surface temperature T and current density (I / nwd) have a proportional relationship (refer FIG. 4). Equations (1) and (2) are equations that are clarified by actually measuring the outer surface temperature of the sealed tube with a thermocouple and measuring the thermal stress by simulation.
Equation (3) is an empirical equation derived from experiments and the like. If the current value I is determined, the number n of metal foils 27, the width w, the thickness so as to satisfy the above equation (3). d can be determined. The same relationship applies to the inner metal ring 23.
By the way, the number and width of the metal foils 27 are generally the same as those of the conventional short arc type discharge lamp, and the degree of freedom is small due to restrictions and requirements in the manufacturing process. Therefore, in practice, the occurrence of cracks is prevented by adjusting the thickness of the metal foil 27. Specifically, the metal foil is thicker than the conventional one. However, if the thickness is too large, peeling of the foil occurs, so the thickness is set to 0.1 mm or less.
If the temperature difference between the sealing tube 60 and the arc tube 12 or the base 80B is too large, the thermal strain of the glass increases and cracks are likely to occur. Therefore, the rated power, the sealed tube diameter, and the like are determined so that the sealed tube outer surface temperature satisfies the following formula.
150 ≦ T ≦ 800 (4)
By making the outer surface temperature T of the sealing tube 150 ° or more, thermal distortion due to the temperature difference with the arc tube is suppressed, and by making the outer surface temperature T of the sealing tube 800 ° or less, it depends on the temperature difference with the base part. Reduce thermal distortion.
Further, it is desirable to adopt a sealing structure that satisfies the above formula for a short arc type discharge lamp having a relatively small outer diameter L of the sealed tube, and here, the outer diameter L of the sealed tube that satisfies the following formula is adopted. A discharge lamp is applied. For example, when the current value is 200 A, the outer shape L is set to 40 mm or less.
I / L ≧ 5 (5)
In a short arc type discharge lamp having a relatively small outer diameter L of the sealing tube, the number and width of the metal foils become very small if a double sealing structure is adopted in order to increase crack resistance. It must be extremely thick, increasing the risk of foil peeling. That is, in the discharge lamp satisfying the expression (5), it is required to determine the thickness of the sealing foil so as to satisfy the expressions (1), (2), and (3).
As described above, according to the present embodiment, in the short arc type discharge lamp in which the outer diameter of the sealed tube is small, the rated output is large (3 kW or more), and a large current (130 mmA or more) flows by lighting with a low voltage, the above (1 ) To (3) are satisfied so that the thickness of the metal foil is determined.
In addition, about a metal ring and a glass member, it is also possible to make it another structure and shape.

表１に示すように、３．５ｋＷ、４．５ｋＷいずれにおいても、熱応力はどれも１．２０×１０８Ｐａ以下となり、金属箔の厚さ０．０６ｍｍ、０．０５ｍｍ両方において、クラックが発生しなかった。
一方、比較例として、金属箔の厚さを０．０３３ｍｍとした放電ランプについて同様の実験を行い、熱応力を計算してクラック発生の有無を調べた。ただし、点灯条件を変えて行った。
その結果、熱応力が１．２０×１０^８Ｐａより大きくなると、クラックが発生した。このように、金属箔の厚さを従来と比べて適切な厚みにすることにより、二重封止構造を採用せず、封止管外径が小さく、低電圧で大電流を流すショートアーク型放電ランプにおいて、クラックが発生しないことが明らかになった。
本発明に関しては、添付されたクレームによって定義される本発明の意図および範囲から離れることなく、様々な変更、置換、代替が可能である。さらに、本発明では、明細書に記載された特定の実施形態のプロセス、装置、製造、構成物、手段、方法およびステップに限定されることを意図していない。当業者であれば、本発明の開示から、ここに記載された実施形態がもたらす機能と同様の機能を実質的に果たし、又は同等の作用、効果を実質的にもたらす装置、手段、方法が導かれることを認識するであろう。したがって、添付した請求の範囲は、そのような装置、手段、方法の範囲に含まれることが意図されている。
本願は、日本出願（特願２０１３−０８４９２９号、２０１３年４月１５日出願）を基礎出願として優先権主張する出願であり、基礎出願の明細書、図面およびクレームを含む開示内容は、参照することによって本願全体に組み入れられている。Hereinafter, the discharge lamp which is an Example is demonstrated. Here, the thickness of the metal foil was changed to examine the presence or absence of cracks.
In the short arc type discharge lamp of the embodiment, the outer diameter of the sealing tube is 27 mm, the thickness of the sealing tube is 3.5 mm, the outer diameter of the cylindrical outer glass member is 20 mm, the number of metal foils is 5, and the width is 10 mm. The rated power is 4.5 kW and the current value is 155 mA.
Then, the thickness of the metal foil is set to 0.06 mm and 0.05 mm, the lamp is continuously lit for 1000 hours, and the temperature is measured by a thermocouple, while the thermal stress is calculated by a computer simulation and whether or not cracks are generated. I investigated. The results are shown in Table 1 below.

As shown in Table 1, the thermal stress is 1.20 × 108 Pa or less for both 3.5 kW and 4.5 kW, and cracks occur in both the metal foil thicknesses 0.06 mm and 0.05 mm. There wasn't.
On the other hand, as a comparative example, a similar experiment was performed on a discharge lamp in which the thickness of the metal foil was 0.033 mm, and the presence or absence of cracks was examined by calculating the thermal stress. However, the lighting conditions were changed.
As a result, cracks occurred when the thermal stress was higher than 1.20 × 10 ⁸ Pa. In this way, by making the thickness of the metal foil appropriate, it does not adopt a double sealing structure, the outer diameter of the sealed tube is small, and the short arc type that flows a large current at a low voltage It became clear that no cracks occurred in the discharge lamp.
Various changes, substitutions and alternatives are possible with respect to the present invention without departing from the spirit and scope of the present invention as defined by the appended claims. Furthermore, the present invention is not intended to be limited to the specific embodiments of the processes, apparatus, manufacture, components, means, methods, and steps described in the specification. Those skilled in the art will appreciate from the disclosure of the present invention devices, means, and methods that perform substantially the same functions as those provided by the embodiments described herein, or that provide substantially the same operations and effects. You will recognize it. Accordingly, the appended claims are intended to be included within the scope of such devices, means, and methods.
This application is an application claiming priority from a Japanese application (Japanese Patent Application No. 2013-084929, filed on April 15, 2013) as a basic application, and the disclosure including the specification, drawings and claims of the basic application is referred to. Which is incorporated herein by reference in its entirety.

10 Discharge lamp 17B Electrode support rod 19B Lead rod (electrical connection rod)
23 Inner metal ring (annular member)
25 Outer metal ring (annular member)
26 Outer glass member (glass member)
27 Metal foil 60 Sealed tube

Claims (4)

An electrode support rod provided in a sealing tube integrally formed with the arc tube, and supporting an electrode in the arc tube;
An electrical connecting rod electrically connected to an external power source;
A glass member into which the electrode support rod and the electrical connecting rod are inserted and welded to the sealing tube;
A plurality of strip-shaped metal foils extending along the outer surface of the glass member;
A pair of annular members for electrically connecting the strip-shaped metal foil, the electrode support rod and the electrical connecting rod;
The rated power is 3 kW or more, the current value during stable lighting is 130 A or more, the amount of mercury enclosed in the arc tube is 7 mg / cc or less,
A short arc type discharge lamp characterized in that the thickness of the strip-shaped metal foil is determined so as to satisfy the following formula.
σ = 7.54 × 10 ⁵ T-6 × 10 ⁷
T = 1.92 (I / nwd) +98.9
σ ≦ 1.20 × 10 ⁸
However, the thermal stress applied from the outer surface of the annular member to the inner surface of the sealing tube is σ (Pa), the outer surface temperature of the sealing tube is T (° C.), and the current value during stable lighting is I (A ), The number of the strip-shaped metal foil is n, the width of the strip-shaped metal foil is w (mm), and the thickness of the strip-shaped metal foil is d (mm). The short arc type discharge lamp according to claim 1, wherein an outer surface temperature of the sealed tube during stable lamp lighting is determined so as to satisfy the following expression.
150 ≦ T ≦ 800 The short arc type discharge lamp according to any one of claims 1 to 2, wherein an outer diameter L (mm) of the sealing tube is determined so as to satisfy the following formula.
I / L ≧ 5 An electrode support rod provided in a sealing tube integrally formed with the arc tube, and supporting an electrode in the arc tube;
An electrical connecting rod electrically connected to an external power source;
A glass member into which the electrode support rod and the electrical connecting rod are inserted and welded to the sealing tube;
A plurality of strip-shaped metal foils extending along the outer surface of the glass member;
An annular member for electrically connecting the strip-shaped metal foil and the electrical connecting rod;
A short arc type discharge lamp characterized in that the thickness of the strip-shaped metal foil is determined so as to satisfy the following formula.
σ ≦ 1.20 × 10 ⁸
However, the thermal stress applied from the outer surface of at least one of the annular members to the inner surface of the sealing tube is σ (Pa).

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