JP5800190B2 - Short arc type discharge lamp - Google Patents

Description

  The present invention relates to a short arc type discharge lamp used for an exposure apparatus such as a semiconductor, a liquid crystal, and a printed circuit board.

  High-intensity discharge lamps (HID lamps) such as high-pressure mercury lamps, high-pressure sodium lamps, metal halide lamps, and ceramic metal halide lamps emit light using discharge between electrodes. For this reason, the high-intensity discharge lamp has various features such that it is suitable for lighting a large space with a large luminous flux and has high energy efficiency compared to an incandescent lamp.

  In particular, short arc discharge lamps with short arc length that emit high-intensity light are used as light sources in light application fields such as light sources for exposure in the manufacturing process of semiconductors, liquid crystals, printed circuit boards, etc. For example, an i-line lamp having an increased emission intensity of 365 nm and a g-line lamp having an increased emission intensity of 436 nm are known.

  In many of the short arc type discharge lamps, the center of the arc tube envelope made of quartz is spherical, and both ends are narrowed and formed into a tube shape. A cathode and an anode are opposed to each other inside the central spherical portion, and an electrode mount is fixed in a narrowed glass tube via a sealing portion. The electrode core rod of the cathode and the anode is connected to an external lead wire through it.

  In particular, a short arc type discharge lamp used in a semiconductor exposure apparatus is required to maintain high luminance and maintain stable light emission efficiency over a long period of time in an exposure process. For this reason, the short arc type discharge lamp has a large input power in the direct current lighting method, and the temperature and pressure in the lamp become considerably high at the time of lighting. Further, as one method for increasing the illuminance of the lamp, more mercury or rare gas is enclosed to increase the lamp luminous efficiency in the ultraviolet region. For this reason, in a sealed tube to which an electrode mount that supports an electrode core is welded, there is a possibility that a burst may occur at the time of lighting, particularly starting from a portion where the end of the electrode mount contacts and a portion where the current collecting disk contacts. high.

  Among them, in a short arc type discharge lamp used for a liquid crystal / print board exposure apparatus, it is necessary to enclose a large amount of mercury in the arc tube in order to satisfy various characteristics such as voltage and illuminance. Therefore, when the lamp is turned on, there are some lamps whose temperature in the lamp is 800K to 1200K and whose internal pressure is 2.0MPa to 3.5MPa. If the strength of the portion is insufficient, the lamp vessel may be ruptured from the portion where the strength is insufficient.

  Although it is conceivable to increase the thickness of the seal tube so that it can withstand the pressure (stress) at the time of lighting, the part that can be the starting point of the rupture, that is, the outer diameter part of the welded part and the current collector disk contact Only by increasing the thickness of only the part, the internal pressure (stress) of the mercury or sealed gas during lighting, thermal stress, structural deterioration of the glass due to ultraviolet rays, stress concentration due to the end face shape of the welded part (for example, two or more types) It is difficult to avoid rupture during lighting due to accumulation such as that the stress is concentrated at one point as the welding point between the glass becomes sharper.

  In addition, since the exposure mercury lamp is used by being incorporated in the expensive optical system of the exposure apparatus, the expensive optical system will be damaged when the lamp ruptures, and mercury is enclosed in the lamp. In this case, mercury is scattered to the outside due to the rupture of the lamp. Therefore, there is a strong demand for avoiding the rupture of the lamp.

Japanese Patent Application Laid-Open No. 2010-198947 discloses a short arc type discharge lamp configured to prevent the sealing tube from bursting by giving a predetermined relationship to the outer diameters of the disk member and the disk foil. . JP, 2006-286343, A JP, 2006-286343, A is constituted so that the burst at the time of lighting may be prevented by giving predetermined relation to the edge width of a crevice of a glass member for a seal, the depth of a groove, and the total length of an axial direction. A short arc discharge lamp is disclosed. Japanese Patent Laid-Open No. 2005-243484 discloses that the distance from the end of the tubular body holding the lead rod to the end of the sealing glass body on the discharge space side, the glass meat in the radial direction of the sealing glass body Short arc type discharge lamp constructed so that there is no problem such as breakage of the branch pipe part when the lamp is lit by giving a predetermined relationship between the thickness and the glass thickness in the radial direction of the glass pipe constituting the branch pipe part. Is disclosed.

  In Patent Document 1, the difference between the outer diameter of the inner metal ring and the outer diameter of the disc foil is taken into consideration, or the ratio between the inner metal ring and the thickness of the sealing tube and the pressure in the arc tube during lighting Considering the above, it is intended to prevent the bursting of the sealed tube, and the examination of the location where the lamp bursts is limited.

  In Patent Document 2, an attempt is made to prevent the lamp from rupturing from the relationship between the depth and the total length of the recess of the sealing glass member, and this document also restricts the examination of the location that is the starting point of the lamp rupture.

  Further, in Patent Document 3, in particular, an attempt is made to prevent breakage of the seal part and branch pipe part by considering the thickness of the glass body for sealing and the glass pipe of the branch pipe part, This document also limits the examination of the starting point of the lamp burst.

  From the above viewpoints, although the above-mentioned patent document has reduced the risk of lamp bursting, it is possible to more reliably grasp the location of the starting point of the lamp burst and improve them appropriately to ensure more reliable lamp ramping. There is a need to reduce the risk of explosion.

  Further, there is a demand for reducing the risk of lamp explosion by a mode different from the above-mentioned patent document.

  Furthermore, there is a demand for reliably reducing the risk of lamp explosion with a simpler structure.

  In any of the documents, a decrease in mechanical strength due to deterioration of the seal tube due to ultraviolet rays due to the OH group concentration contained in the quartz glass of the seal tube is not considered.

  Therefore, an object of the present invention is to provide a short arc type discharge lamp that reduces the risk of lamp burst more reliably and with a simple structure by using a different mode as compared with the prior art.

In view of the above problems, a short arc type discharge lamp according to the present invention includes a spherical portion and two seal tube portions disposed at opposite ends of the spherical portion along an axis passing through the center of the spherical portion. An arc tube sealing body, a cathode and an anode disposed facing each other at a predetermined distance inside the spherical portion, and an electrode core rod extending from the cathode and the anode to the two seal tube portions, respectively. A first sealing member, a first current collecting disk, a second sealing member, a second current collecting disk, and a third sealing member are provided on the inner side of each sealing tube part. The first current collecting disc and the second current collecting disc are arranged continuously in a direction away from the spherical portion along the central axis direction, a base is fixed to an outer end portion of each seal tube portion, and the first current collecting disc and the second current collecting disc Are electrically connected by an electrical connection foil disposed on the outer peripheral surface of the second seal member. It is,
Within each seal tube portion, one electrode core rod penetrates the first seal member along the direction of the central axis of the seal tube portion and is held therein, and is electrically connected to the first current collecting disk. Lead wires connected to an external power source through the base toward the spherical portion along the central axis direction of the seal tube portion and the second seal member. A short arc type discharge lamp having a lamp power of 2 kW to 30 kW, which is passed through and held by the current collecting discs and is electrically connected to the second current collecting disc, and the seal tube portion The thickness of the portion surrounding the first current collecting disk is a thickness t1, and the thickness of the portion surrounding the second current collecting disk of the seal tube is the thickness t2. Let L1 be the length of the pipe where the wall thickness gradually changes. In a short arc type discharge lamp having a structure of 3.0 (mm) ≦ t1 ≦ 8.0 (mm) and having a structure of t2 ≦ t1, 1.5 (mm) ≦ t2 ≦ 4.0 (mm), 0.5 (mm) ≦ t1−t2 ≦ 3.0 (mm), 0.5 ≦ t2 / t1 <1, and 2 ≦ L1.

  In the short arc type discharge lamp, the pressure in the spherical portion of the arc tube envelope is 1.0 MPa to 3.5 MPa when the lamp is turned on.

  In the short arc discharge lamp, the diameter of the second seal member is 16 mm to 35 mm.

  In the short arc type discharge lamp, the lamp power of the short arc type discharge lamp may be in the range of 2 kW to 36 kW.

  According to the present invention, it is possible to provide a short arc type discharge lamp that more reliably reduces the risk of lamp burst by more reliably grasping the starting point of the lamp burst and appropriately improving them. it can.

  In addition, according to the present invention, it is possible to provide a short arc type discharge lamp that reduces the risk of lamp rupture according to a new aspect.

  Furthermore, according to the present invention, it is possible to provide a short arc type discharge lamp that reliably reduces the risk of lamp explosion by a simpler method.

FIG. 1 is a simplified cross-sectional view for illustrating a schematic configuration of a short arc type discharge lamp according to an embodiment of the present invention. 2A is an enlarged cross-sectional view of a seal tube portion of the short arc type discharge lamp shown in FIG. FIG. 2B is an enlarged cross-sectional view of a seal tube portion of a short arc type discharge lamp according to another embodiment of the present invention. FIG. 3A is a conceptual diagram for explaining how stress is applied to the welded portion when the first sealing material 21-1 is welded to the seal tube portion. FIG. 3B illustrates how stress is applied to the welded portion due to the difference in the welding angle when the first sealing material 21-2 is welded to the seal tube portion 7 at a welding angle different from that in FIG. 3A. It is a conceptual diagram for doing. FIG. 3C is a cross-sectional view of an example in which the first sealing member 21-3 according to another embodiment of the present invention has a cylindrical concave shape, and is a conceptual diagram that supplements the welding angle position of FIG. 3A. FIG. 3D is a cross-sectional view of a double tube example in which the first sealing material 21-4 according to another embodiment of the present invention has a cylindrical concave shape and further has a multi-tube seal structure, and supplements the welding angle position of FIG. 3B. It is a conceptual diagram. FIG. 4 is a table showing the wall thickness at two predetermined positions of the seal tube portion, the wall thickness difference between them, and the wall thickness difference ratio. FIG. 5A is a graph 1 showing two kinds of wall thickness differences at two predetermined locations of the seal tube portion. FIG. 5B is a graph 2 showing two types of thickness ratios at two predetermined locations of the seal tube portion. FIG. 5C is a graph obtained by superimposing the graphs shown in FIGS. 5A and 5B.

  Hereinafter, a short arc type discharge lamp according to an embodiment of the present invention will be described with reference to the accompanying drawings. In all the drawings, the thickness, length, shape, spacing between members, gaps, and the like of each member are appropriately enlarged, reduced, deformed, simplified, etc. for easy understanding. In the description of the figure, the vertical and horizontal expressions represent directions along the plane of the drawing in a state where the figure is placed in the vertical plane.

[Schematic structure of short arc discharge lamp]
FIG. 1 is a simplified partial cross-sectional view for illustrating a schematic structure of a short arc type discharge lamp 10 according to an embodiment of the present invention. Here, for example, the short arc type discharge lamp 10 has a lamp power of 2 kW to 25 kW, or at least one kind of noble gas of argon, krypton, and xenon at room temperature (25 ° C.) from 0.05 MPa to 0.4 MPa. The lamp may be enclosed and have a mercury density of 5 mg / cc to 60 mg / cc with respect to the entire volume of the light emitting space, and an average gas temperature during lighting of 800 K to 1200 K and a lighting pressure exceeding 1 MPa. In the present embodiment, for example, the short arc type discharge lamp 10 has a lamp power of 12 kW and a lighting pressure exceeding 2 MPa. The pressure strength is desirably 3.5 MPa.

  The short arc type discharge lamp 10 is a lamp that strongly emits light having emission wavelengths of 313 nm, 365 nm, and 436 nm, and is an arc tube comprising a spherical portion and two seal tube portions 7 facing each other along an axis passing through the center thereof. An envelope 1 is provided. The anode 2 and the cathode 3 are disposed opposite to each other inside the spherical portion, and two opposing seal tube portions 7 are respectively provided with electrode mounts 9 for blocking the inside of the arc tube envelope 1 from the outside air. Is fixed. The distance between the front-end | tip parts of the anode 2 and the cathode 3 is 10 mm in the range of 3-30 mm, for example.

  As will be described in detail later, an electrode core rod 5 connected to the anode 2 and the cathode 3 is fixed to the end of the electrode mount 9 on the spherical portion side, and connected to an external power source on the opposite end. A lead bar 6 for connecting to the lead wire is connected. In this way, the electrode mount 9 holds the electrode core 5 and the lead rod 6 and hermetically seals so as to block between the outside air and the arc tube sealed body 1.

  A getter material 11 is attached to the electrode core 5 in order to remove impurities remaining in the arc tube envelope 1 after the arc tube 1 is sealed and impurities generated during lighting.

  In addition, when manufacturing the lamp, mercury is sealed into the arc tube envelope from the exhaust tube attached at the tip-off position 4 in FIG. 1, and at least inert gas such as argon, krypton, or xenon is used alone or Enclose in the form of their gas mixture.

    The outer diameter of the spherical portion of the arc tube envelope 1 varies depending on the light output and the input power, for example, 100 mm within the range of 50 mm to 300 mm, and the axial length of the spherical portion is within the range of 70 mm to 300 mm. For example, it is 140 mm. In the arc tube envelope 1, for example, 40 mg / cc mercury selected from the range of 3 mg / cc to 50 mg / cc, and at least one of xenon (Xe), argon (Ar) and krypton (Kr) Noble gas is enclosed. However, instead of one rare gas, a mixed gas, for example, two or more mixed gases such as Kr and Ar may be used. The enclosure pressure of the rare gas varies depending on the kind of the enclosed gas, but is, for example, 0.2 MPa within a range of about 0.05 MPa to 0.4 MPa. When this lamp is lit, the pressure in the arc tube envelope 1 is about 2.0 MPa to 3.5 MPa.

[Schematic structure of seal tube]
Since the cathode-side and anode-side seal tube portions 7 have the same structure, the following description will be made on, for example, the anode-side seal tube portion 7 on one side.

  2A is an enlarged cross-sectional view of the seal tube portion 7 of the short arc type discharge lamp 10 shown in FIG. As shown in FIG. 2A, an electrode mount 9 is welded to the inside of the seal tube portion 7 so that the airtightness of the arc tube sealed body 1 is maintained. The welding method will be described later.

  The electrode mount 9 includes a first sealing member 21, a second sealing member (or a sealing foil sealing cylindrical body) 22, and a third sealing member 23 that are quartz glass cylindrical bodies. The outer diameter of the first seal member is in the range of φ16 to φ35 mm, and the outer diameter may be different. In this embodiment, the diameter is 25 mm. The first seal member 21 is welded to the inner surface of the seal tube portion 7 from a position about 10 mm away from the connection position A between the spherical portion of the arc tube seal 1 and the seal tube portion 7 in a direction away from the spherical portion. Has been. The space of about 10 mm is provided because the seal tube portion 7 is heated by a flame burner or the like in order to weld the electrode mount 9 including the first seal member 21 and the like in the seal tube portion 7. This is because the heat is transmitted to the spherical portion and the spherical portion is prevented from being deformed. A through-hole is formed in the center of the first seal member 21, and the electrode core bar 5 is inserted into the through-hole. 1 sealing member 21 is fixed. In FIG. 2B, the first seal member has a concave shape obtained by cutting or laser processing the cylindrical light emitting portion side, and the seal tube 7 is illustrated as an example of a multi-tube as a reference for a double tube system. In FIG. 2A and FIG. 2B, the same reference numerals are assigned to the same members.

  A first current collecting disk 31 is interposed between the first seal member 21 and the second seal member 22, and the first current collecting disk 31 includes a first seal member. The ends of the electrode core bar 5 penetrating through 21 are connected. As a result, the electrode core 5 is electrically connected to the first current collecting disk 31. Note that the end portion of the electrode core 5 may be configured to further pass through the first current collecting disk 31 and be connected to the second seal member 22. The outer diameter of the current collecting disk 31 is smaller than that of the electrode mount 9, and a thickness of 0.5 mm to 15 mm is frequently used.

  Further, a second current collecting disk 32 is interposed between the second seal member 22 and the third seal member 23. A through hole is formed at the center of the third seal member 23, and a lead rod 6 is inserted into the through hole and fixed to the third seal member 23. In addition, the end portion of the lead rod 6 that penetrates is inserted into the end portion of the second seal member 22 through the second current collecting disk 32 and fixed. Thereby, the lead rod 6 is electrically connected to the second current collecting disk 32 and mechanically held by the second seal member 22. However, the end portion of the lead rod 6 may be electrically connected to the second current collecting disk 32 without penetrating it.

  The outer peripheral surface of the first current collecting disc 31 and the outer peripheral surfaces of the first seal member 21 and the second seal member 22 located on both sides of the first current collecting disc 31 are made of a metal buffer. Covered with foil 15. In this embodiment, a metal buffer foil 15 having a thickness of 0.015 mm is mounted among metal foils having a thickness of 0.01 mm to 0.1 mm, and the foil is further subjected to uneven processing. The buffer foil 15 is wound with a width equal to or greater than the thickness of the current collecting disk and is welded to the current collecting disk or the sealing foil. Further, on the outer peripheral surface of the second seal member 22, a plurality of strip-shaped molybdenum seal foils 25 (hatching obtained by alternately drawing solid lines and broken lines in FIGS. 1 and 2A) are provided in parallel with the axial direction. (Shown) are arranged at intervals. The first current collecting disk 31 and the second current collecting disk 32 are electrically connected by the buffer foil 15 and the sealing foil 25 which are these electrical connection foils, and as a result, the electrodes The core bar 5 and the lead bar 6 are electrically connected. The sealing foil of this example was equipped with five sealing foils having a thickness of 0.04 mm and a width of 12 mm among knife edge type molybdenum sealing foils having a thickness of 0.02 mm to 0.05 mm.

    As shown by a broken line in FIG. 2A, the base 28 is attached to the end of the seal tube portion 7. A lead wire is connected to the base 28, and power is supplied to the lead bar 6 from an external power source via the base 28.

  Also, as shown in FIG. 2A, the seal tube portion 7 in contact with the outer peripheral surface of the first current collecting disk 31 includes a relatively thick portion from position A to position B and a rear portion from position B. Comparing the thickness of the seal tube portion 7 in the portion surrounding the first current collecting disk 31 to the thickness t1 (mm), the thickness of the seal tube portion 7 is relatively thin. The thickness of the seal tube portion 7 in the portion surrounding the second current collecting disk 32 in the portion having a small thickness is defined as the thickness t2 (mm), and the thickness t1 is 3.0 ≦ t1 (mm) ≦ It is in the range of 8.0, and the wall thickness t2 is in the range of 1.5 ≦ t2 (mm) ≦ 4.0. Further, in the seal tube portion 7, the length L1 of the portion where the thickness of the seal tube portion 7 gradually changes is 2 ≦ L1 (mm). In the case of the double pipe system of FIG. 2B, the wall thicknesses t1 and t2 of the seal tube portion are the total size of the seal tube portion 7 and the seal tube inner tube 8 in each range.

  In FIG. 2A, the end portion of the base 28 is drawn so as to be in the position B where the thickness of the seal tube portion 7 is thinned, but the end portion is not specified at that position.

  Here, an outline method for fixing the electrode mount 9 in the seal tube portion 7 when the short arc type discharge lamp 10 is manufactured will be described. First, the electrode mount 9 is prepared, and the electrode mount 9 is inserted into the cylindrical portion of the arc tube sealing body 1 serving as a seal tube portion having an inner diameter larger than the outer diameter thereof. At this time, as described above, the electrode mount 9 is arranged so that the end surface of the first seal member 21 facing the spherical portion of the electrode mount 9 is separated from the position A by about 10 mm in the cap direction. Next, the end portion of the cylindrical portion that becomes the seal tube portion is heated with a flame burner, and the inside of the arc tube sealed body 1 is decompressed by the exhaust pipe described above. In the reduced pressure state, the outer periphery of the cylindrical portion that becomes the seal tube portion into which the electrode mount 9 is inserted is heated with a flame burner. By the heating, the cylindrical portion that becomes the seal tube portion 7 is melted and contracted, and is in close contact with the outer peripheral surface of the electrode mount 9. That is, the inner surface of the seal tube portion 7 is the outer periphery of the first seal member 21, the first current collecting disk 31, the second seal member 22, the second current collection disk 32, and the third seal member 23. Weld with the surface. As a result, the electrode mount 9 and the cylindrical portion thereof are in close contact with each other to form the seal tube portion 7. In particular, in order to improve the weldability of the seal member 22, the heating power is increased by a flame burner using a plurality of oxygen and hydrogen, compared to when the first seal member 21 is welded. In the case of a double tube structure as shown in FIG. 2B, the sealing tube 8 made of quartz glass and the electrode mount 9 are first sealed and then inserted into the arc tube sealing body 1 and sealed in the same manner as described above. To do.

[Concept of stress at the starting point of lamp burst]
As described above, the wall thickness t1 and t2 are made different in thickness, and the portion of the length L1 in which the wall thickness changes between them is the starting point of the burst when the lamp is lit. 2 are the end face on the spherical body sealing side of the electrode mount 9 at the position C shown in FIG. 2 and the portion where the seal tube portion 7 is welded to the outer peripheral surface of the current collecting disk 31. Therefore, it is necessary to increase the thickness of the seal tube portion 7 including those portions. On the other hand, since the size of the base 28 is defined, the thickness of the seal tube portion 7 accommodated in the base cannot be increased. Because.

  In the short arc type discharge lamp 10, on the seal tube portion 7, a position C where the inner surface is in contact with the end surface on the spherical portion side of the first seal member 21, and the outer peripheral surface of the first current collecting disk 31, There is a strong tendency that the contact position D becomes the starting point of the lamp explosion when the lamp is lit. For example, when the lamp power of the short arc type discharge lamp 10 according to the present embodiment is 12 kW, the temperature in the lamp becomes about 800K to 1200K after about 15 minutes have elapsed after lighting. At that time, the internal pressure of the lamp at the time of lighting increases, and the position tends to burst and the lamp tends to burst.

  3A to 3D show how the stress is applied to the welded portion due to the difference in the welded state when the first seal members 21-1 to 21-4 of the electrode mount 9 are welded to the seal tube portion 7, respectively. It is a conceptual diagram for demonstrating whether this is. The difference between FIG. 3A and FIG. 3B is that the directions of the welding angles of the first seal members 21-1 and 21-2 are different. 3C and 3D, both of the first seal members 21-3 and 21-4 have a concave shape, and FIG. 3D further shows that the seal tube portion has a double tube structure of the seal tube portion 7 and the seal tube inner tube 8. It has become. As will be described in detail later, in FIG. 3C, the welding angle is formed between the seal tube portion 7 and the first seal member 21-3, but in FIG. 3D, the welding angle is the same as that of the seal tube inner tube 8 and the first seal member 21-3. It is formed between the sealing member 21-4.

  When the lamp is turned on, the internal pressure becomes as high as about 1.0 MPa to 3.5 MPa, and a tensile stress is applied to the inner surface portion of the spherical body portion of the arc tube sealing body 1. Since the spherical body portion is used as a condensing optical system such as an elliptical mirror, it is molded so as to have a smooth curve in order to improve the condensing efficiency. In addition, in order to improve the light distribution characteristics and suppress the change in the refractive index of the silica glass of the enveloped spherical surface, the spherical body portion has little change in wall thickness and less temperature change. A relatively uniform stress is applied to the entire portion. On the other hand, in the seal pipe part 7, the outer diameter may be greatly different in the part where the first seal member 21-1 or 21-2 is welded to the seal pipe part 7 even if the inner diameter is the same. That is, the thickness t of the seal tube portion 7 varies greatly depending on the location, and the difference in cross-sectional area may be 10 times or more. Further, at the portion where the first seal member 21-1 or 21-2 is welded to the seal tube portion 7, there is an acute angle between the inner surface of the seal tube portion 7 and the corner surface where the quartz cylindrical body is welded. A gap is formed. The angle that forms the gap is called the welding angle. The magnitude and direction of the stress concentration on the welded portion vary depending on the size of the weld angle and the direction of the weld angle.

  FIG. 3A shows a state where the first seal member 21-1 (quartz cylindrical body) is welded to the inner surface of the seal tube portion 7. The first seal member 21-1 is arranged so that its axis is parallel to the inner surface of the seal tube portion 7. Although the roundness of the corners welded to the inner surface of the seal tube portion 7 of the first seal member 21-1 is relatively large, the weld angle is an angle measured from the inner surface of the seal tube portion 7.

  FIG. 3B shows a state in which the first seal member 21-2 of the quartz cylindrical body is welded to the inner surface of the seal tube portion 7 as in FIG. 3A. In this case, the first seal member 21-2 is arranged so that its axis is parallel to the inner surface of the seal tube portion 7. The roundness of the corner where the first seal member 21-2 is welded to the inner surface of the seal tube portion 7 is relatively small. Although not shown in FIG. 3B, the inner surface of the seal tube portion 7 to which the first seal member 21-2 is welded is slightly raised toward the inside. For this reason, the welding angle is an angle measured from the tangent of the raised inner surface.

  FIG. 3C shows a structure in which a concave first seal member 21-3 is welded to the inner surface of the seal tube portion 7. In this case, the welding angle is formed between the inner surface of the seal tube portion 7 and the corner surface of the first seal member 21-3, as in FIG. It becomes an angle.

  In FIG. 3D, the seal tube portion has a double structure in which the seal tube inner tube 8 is disposed inside the seal tube portion 7, and the concave first seal member 21-is formed on the inner surface of the inner seal tube inner tube 8. 4 is welded. The tip of the seal tube inner tube 8 is deformed by reducing the diameter inward. In this case, the welding angle is formed between the inner surface of the seal tube inner tube 8 and the corner surface of the first seal member 21-4, and is an angle as viewed from the inner surface of the seal tube inner tube 8.

  Generally, the stress is concentrated in a predetermined portion after spreading radially inside the quartz cylinder. In FIG. 3A, since the welding angle is relatively in the direction along the inner surface of the seal tube portion 7, the stress concentration direction is the axial direction of the lamp as shown by the white arrow in the figure. On the other hand, in FIG. 3B, the welding angle is relatively in the direction along the end face of the quartz cylinder, so the stress concentration direction is the thickness direction of the seal tube portion 7 as indicated by the white arrow in the figure. become.

  The welding angle changes in the direction of the center of the angle, which is the stress concentration direction, as indicated by the white arrow due to the roundness of the quartz cylinder. This direction is not caused only by the roundness of the quartz cylindrical body, but the angle direction may change due to the inner surface of the seal tube biting inward by the flame burner sealing operation.

  These concentrated stresses can be dealt with by increasing the thickness of the seal tube portion 7. That is, since the distance from the inner surface to the outer surface of the seal tube portion 7 can be maintained, the stress can be widely dispersed. Therefore, even if the stress is concentrated at the welding point or the acute angle portion, the stress is dispersed and consequently strength is increased. It is because it can improve.

  As described above, particularly in FIG. 3A, stress concentrated in the axial direction of the lamp is directed. In addition, the stress has an action force and a reaction force, and particularly, there is a compressive stress around a portion where the tensile stress is concentrated. Therefore, if there is no compression resistance, the portion of the seal tube portion 7 is ruptured by the tensile stress. Become. For this reason, it is necessary to increase the wall thickness over a predetermined length of the seal tube portion 7 along the axial direction to which the stress is directed. Thereby, stress relaxation in the axial direction is achieved, and as a result, the pressure strength can be further improved.

  Also, if the thickness difference is large, for example, if it exceeds 3 mm, the volume difference in the cross-sectional direction of the electrode mount including the seal tube portion in the portion with the thickness difference becomes large, and the melting operation with the flame burner is uneven or uneven. Will occur and the workability of sealing will deteriorate. Moreover, the partial hermetic performance is deteriorated. That is, welding on the back side of the seal foil is insufficient, and for example, when the seal foil width is 10 mm, a float of about 5 mm to 10 mm is generated. When the airtightness is poor, the external oxidation phenomenon is accelerated when the lamp is lit, causing problems such as cracking due to an increase in the volume of the oxide and fusing due to the oxidation phenomenon of the welded part of the seal foil and current collector disk. Probability is high. On the other hand, if the difference in thickness is small, for example, if it is less than 0.5 mm, the airtight sealing performance on the lead wire side may deteriorate. For this reason, it is necessary to consider the optimum thickness difference.

[Example 1]
As shown in FIG. 2, the thickness of the seal tube portion 7 that surrounds the first current collecting disk 31 is the thickness t1 (mm), and the seal tube portion that surrounds the second current collecting disk 32. When the thickness of 7 was combined with the thickness t2 (mm) changed, the difference in thickness, the ratio of t2 to t1, and the ratio of the thickness difference to t1 were examined. . The result is shown in FIG.

  In FIG. 4, t1 and t2 represent the thickness (mm), t3 represents the difference (thickness difference) between t1 and t2, and t2 / t1 represents the ratio (%) (thickness ratio) of t2 to t1. T3 / t1 represents the ratio (%) (thickness difference ratio) of t3 to t1. For example, when t1 is 4.0 mm and t2 is 3.0 mm, the thickness difference t3 is 1.0 mm, the thickness ratio t2 / t1 is 75%, and the thickness difference ratio t3 / t1 is It became 25%.

  In Example 1, when t1 is 4.0 mm and t2 is 3.5 mm, the thickness difference ratio t3 / t1 is 13%. In the case of 13% or more, the stress concentrates on the portion L1 where the thickness is displaced, and the pressure strength decreases from 0.8 MPa to about 1.5 MPa. Moreover, when the thickness of t1 is less than 3 mm, the strength decreases from about 2.0 MPa to about 3.5 MPa. On the other hand, when the thickness of t1 exceeds 8 mm, the strength is improved from 3.5 MPa to 5 MPa. However, if the wall thickness exceeds 8 mm, when the electrode mount 9 is welded in the seal tube portion 7 by the flame burner, it is necessary to increase the flame burner's heating power to increase the time for melting. In this case, the sealing body is deformed by the heat of the flame burner, the end portions cannot be sufficiently welded, and the strength may vary between 3.0 MPa and 5.0 MPa.

  From the viewpoint of Example 1, the difference t1-t2 and the ratio t2 / t1 between the thickness t1 (mm) of the thickness of the seal tube portion 7 and the thickness t2 (mm) of the thickness of the seal tube portion 7 are generalized. And examined. The results are shown in FIGS. 5A to 5C.

  FIG. 5A is a graph 1 showing two relations when the thickness difference t1-t2 is 0.5 mm and 3.0 mm. When t1-t2 is 0.5 mm, it is represented by the upper straight line connecting the diamonds, and when t1-t2 is 3.0 mm, it is represented by the lower straight line connecting the rectangles. Both straight lines are parallel, and there is a relationship between the two straight lines when the difference in thickness t1-t2 is different from 0.5 mm to 3.0 mm.

  FIG. 5B is a graph 2 showing two relations when the thickness ratio t2 / t1 is 0.5 (50%) and 1.0 (100%). The case where the ratio t2 / t1 is 0.5 (50%) is the lower straight line connecting the diamonds, and the case where the ratio t2 / t1 is 1.0 (100%) is the upper straight line connecting the rectangles. There is a relationship between these two straight lines when the ratio t2 / t1 is different from 0.5 (50%) to 1.0 (100%).

  FIG. 5C shows a graph in which the graph 1 in FIG. 5A and the graph 2 in FIG. 5B are superimposed. In this graph, a hatched area is put in a region sandwiched between all of the two straight lines shown in the graph 1 and the graph 2, respectively. In this region, an optimum thickness difference and thickness ratio can be obtained.

  The short arc type discharge lamp according to one embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and additions, deletions, modifications, etc. that can be easily made by those skilled in the art are as follows. It should be understood that the invention is included in the present invention, and that the technical scope of the present invention is defined by the description of the appended claims. For example, the seal member may be made of other suitable material such as ozone-less quartz instead of quartz glass. The materials of these sealing members may be different. The first seal member may be made of a material other than glass, for example, molybdenum. In this case, if the sealing metal foil is electrically welded to the first sealing member made of molybdenum, the same function as the current collecting disk is achieved. Further, the method according to the above embodiment can be applied to a short arc type xenon lamp in which only xenon gas is sealed without sealing mercury or a noble gas short arc type discharge lamp of flash lighting type.

DESCRIPTION OF SYMBOLS 1 ... Arc tube sealing body 2 ... Anode 3 ... Cathode 5 ... Electrode core bar 6 ... Lead bar 7 ... Seal pipe | tube part 8 ... Seal pipe | tube 9 ... Electrode Mount 10 ... Short arc type discharge lamp 11 ... Getter material 15 ... Metal buffer foil 25 ... Seal foil 21 ... First seal member 22 ... Second seal member 23 ..Third sealing member 31 ... first current collecting disk 32 ... second current collecting disk

Claims (4)

An arc tube enclosing body comprising a spherical portion and two seal tube portions disposed opposite to each other along an axis passing through the center of the spherical portion at both ends of the spherical portion;
A cathode and an anode disposed facing each other at a predetermined distance inside the spherical portion;
An electrode core rod extending from the cathode and the anode to the two seal tube portions,
A first seal member, a first current collecting disk, a second seal member, a second current collecting disk, and a third seal member are disposed on the inner side of each seal tube portion, with the central axis of the seal tube portion Are arranged continuously in a direction away from the spherical portion along the direction, a base is fixed to an outer end portion of each seal tube portion, and the first current collecting disk and the second current collecting disk are Electrically connected by an electrical connection foil disposed on the outer peripheral surface of the second seal member;
Within each seal tube portion, one electrode core rod penetrates the first seal member along the direction of the central axis of the seal tube portion and is held therein, and is electrically connected to the first current collecting disk. Lead wires connected to an external power source through the base toward the spherical portion along the central axis direction of the seal tube portion and the second seal member. A short arc discharge lamp having a lamp power of 2 kW to 25 kW, which is held through them and electrically connected to the second current collecting disk,
The seal tube portion has a relatively thick first portion including a portion surrounding the first current collecting disc and a relatively thick portion including a portion surrounding the second current collecting disc. A thin second portion and a third portion in which the thickness between the first portion and the second portion gradually changes, and the base is fixed to the outer end of the second portion. ,
The thickness of the first portion of the seal tube portion is the thickness t1, the thickness of the second portion of the seal tube portion is the thickness t2, and the size of the third portion of the seal tube portion. Is the length L1,
In a short arc type discharge lamp having a structure of 3.0 (mm) ≦ t1 ≦ 8.0 (mm) and t2 ≦ t1,
1.5 (mm) ≦ t2 ≦ 4.0 (mm),
0.5 (mm) ≦ t1-t2 ≦ 3.0 (mm),
A short arc type discharge lamp in which 0.5 ≦ t2 / t1 <1 and 2 ≦ L1.   2. The short arc type discharge lamp according to claim 1, wherein a pressure in the spherical portion of the arc tube sealing body is 1.0 MPa to 3.5 MPa when the lamp is turned on.   3. The short arc type discharge lamp according to claim 1, wherein the second seal member has a diameter of 16 mm to 35 mm.   4. The short arc type discharge lamp according to claim 1, wherein the lamp power of the short arc type discharge lamp is in the range of 2 kW to 36 kW.

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