JP5967562B2 - Electrode lead bar fixing structure - Google Patents

Description

  The present invention relates to a structure for fixing an electrode lead rod in a flash lamp or the like used as a light source for ultraviolet sterilization by a light pulse.

  2. Description of the Related Art Conventionally, xenon flash lamps (flash discharge lamps) that emit ultraviolet rays with high output and high illuminance are known as lamps used for sterilization treatment and the like. For example, as shown in FIG. 11 (b), this xenon flash lamp 40 is formed of a pair of glass arc tubes 41 having a cylindrical shape made of quartz glass having a high ultraviolet transmittance and sealed with a rare gas xenon gas. The electrode units 42 and 43 are arranged to face each other. Each of the electrode units 42 and 43 includes electrodes 48 and 49 that are opposed to each other at both ends of the arc tube 41, and metal electrode lead bars 44 and 45 having the electrodes 48 and 49 joined to the tips thereof, respectively. Prepare. The pair of electrodes 48 and 49 and the electrode lead bars 44 and 45 are each formed of tungsten, and a sintered body of an electron-emitting substance (not shown) is fixed to the tip of the electrode 49 serving as a cathode.

  In the conventional sealing procedure of the electrode lead bars 44 and 45 of the flash lamp 40 to the end of the arc tube 41, the electrode lead bars 44 and 45 made of tungsten are inactivated as shown in FIG. Heating is performed with a high frequency or a heating element in a gas atmosphere, and a glass material for sealing is first glass-rolled on the outer peripheral surface of the intermediate portion to form glass winding portions 46 and 47. On the other hand, the arc tube 41 is heated in a mixed combustion gas of propane and oxygen or hydrogen and oxygen while rotating in the atmosphere, and the thermal expansion coefficient changes in the axial direction at both ends of the arc tube 41. The joint glass tubes 51 and 52 are joined coaxially. Then, the electrode units 42 and 43 are inserted into the openings of the stepped glass tubes 51 and 52 at the end of the arc tube 41 from the electrodes 48 and 49 side. Thereafter, while the arc tube 41 is rotated in the atmosphere, it is heated with a mixed combustion gas of propane and oxygen or hydrogen and oxygen to reduce the diameters of the end portions of the stepped glass tubes 51 and 52, so that the electrode lead rods 44 and 45 It connects with the glass winding parts 46 and 47 formed in the circumference | surroundings (for example, refer patent document 1).

  However, since the coefficient of thermal expansion is different between the arc tube 41 made of quartz glass and the electrode lead rods 44 and 45 made of tungsten, the electrode lead rods 44 and 45 are tightly sealed to the end of the arc tube 41. Is applied to the arc tube 41 and the electrode lead bars 44, 45, and the mechanical strength of the arc tube 41 is lower than that of the arc tube 41 made of quartz glass alone. To do. Such a decrease in the strength of the joint portion occurs even when the joint glass tubes 51 and 52 are interposed at the joint portion. For this reason, when the worker who handles the flash lamp 40 grips the end of the arc tube 41 in the flash lamp 40, the force gripped by the worker is the jointed glass tube existing at the joint or the joint. It is directly applied to 51 and 52, and the applied force causes a problem that the joint is damaged.

  In order to solve such a problem, as shown in detail in FIG. 10, the stepped glass tube 52 is inserted into the end portion of the arc tube 41, and one end of the stepped glass tube 52 is reduced in diameter so as to lead the electrode lead. It welds to the glass winding part 47 formed in the stick | rod 45, and the other end of the joint glass tube 52 is welded to the edge part of the arc tube 41. FIG. With such a structure, the fusion fixing portion between the electrode lead rod 45 having a low mechanical strength and the joint glass tube 52 and the joint glass tube 52 itself are connected to the end of the arc tube 41 having a relatively high mechanical strength. Can be stored inside. Then, even if the worker holds the end portion of the arc tube 41, the fusion fixing portion between the electrode lead bar 45 and the step glass tube 52 existing inside the end portion of the arc tube 41 and the step glass tube 52 itself is not directly gripped by a worker's hand. For this reason, it is considered that the damage caused by the external force generated by the operator's gripping being directly applied to the joint portion between the arc tube 41 and the electrode lead bar 45 can be prevented.

Japanese Patent No. 2723573 (page 1-3, FIG. 3)

  However, the arc tube 41 shown in FIG. 10 conventionally used in the flash lamp 40 has an inner diameter D of about 8 mm, and the metal electrode lead rod 45 has a circular cross section and an outer diameter d of 2.4 mm. Degree. For this reason, the outer diameter E of the stepped glass tube 52 to be inserted into the arc tube 41 needs to be smaller than the inner diameter D of the arc tube 41, and about 7 mm is used. Further, the outer diameter e of the glass winding portion 47 formed on the outer periphery of the electrode lead bar 45 is larger than the outer diameter d of the electrode lead bar 45 and is about 3.5 mm. Therefore, when the metal electrode lead rod 45 is inserted into the stepped glass tube 52 having a small outer diameter E, the outer periphery of the glass winding portion 47 formed around the electrode lead rod 45 and the inner periphery of the stepped glass tube 52 are arranged. Will be significantly closer.

  In this way, with the outer periphery of the glass winding portion 47 and the inner periphery of the stepped glass tube 52 approaching each other, the end of the stepped glass tube 52 is heated to reduce the diameter and formed around the electrode lead rod 45. When the glass winding portion 47 and the end portion of the stepped glass tube 52 are connected, portions other than the end portion of the stepped glass tube 52 are joined to the glass winding portion 47 and separated from the end portion of the glass tube 52. There was a problem that a joint portion called a bridge 53 joined to the portion 47 was formed.

  That is, in order to weld one end of the spliced glass tube 52 to the glass winding portion 47, as shown in detail in FIG. 9, the glass winding portion 47 is formed on the outer peripheral surface of the intermediate portion of the electrode lead bar 45 (FIG. 9 ( a)) The electrode lead rod 45 is inserted into the stepped glass tube 52, and the end of the glass tube 52 is positioned at a substantially central portion of the glass winding portion 47 (FIG. 9B). Thereafter, the end of the glass tube 52 is heated while rotating in an inert gas atmosphere, and the end of the stepped glass tube 52 is reduced in diameter to be connected to the glass winding portion 47. However, when the end portion of the stepped glass tube 52 is heated, the portion of the stepped glass tube 52 other than the end portion inherently joined to the glass winding portion 47 is softened and reduced in diameter by the heating. For this reason, as shown in FIG.9 (c), when parts other than the edge part of the glass tube 52 contact with the glass winding part 47 by the core shift | offset | difference etc. at the time of the joining operation, other than the edge part of the joint glass tube 52 This part is also joined to the glass winding part 47. Therefore, as shown in FIG. 9 (d), even if the glass tube 52 and the electrode lead rod 45 are thereafter returned to the same axis, the portion away from the end joined to the glass winding portion 47 is the glass winding portion 47. In some cases, a bonding portion called a bridge 53 is formed.

  When the relatively small diameter stepped glass tube 52 is used, the probability that the outer periphery of the glass winding portion 47 and the inner periphery of the stepped glass tube 52 are close to each other and the portion other than the end portion of the glass tube 52 is in contact with the glass winding portion 47. The frequency with which the bridge 53 is formed increases. And since the site | part in which this bridge | bridging 53 was formed has left | separated from the edge part of the glass tube 52 joined to the glass winding part 47, the distortion | strain in what is called a thermal shock in which high temperature and low temperature are repeated tends to concentrate, and lamp 40 Each time the light is turned on and off repeatedly, distortion is accumulated in the bridge 53, and the bridge 53 serves as a base point to cause a crack, resulting in a lamp failure.

  An object of the present invention is to weld a glass winding portion formed around an electrode lead rod to the end portion of a relatively small-diameter glass tube so that a portion other than the end portion is joined to the glass winding portion. An object of the present invention is to provide an electrode lead bar fixing structure that can be prevented.

  The present invention is an improved electrode lead rod fixing structure in which a glass winding portion is formed around an electrode lead rod, and an end of a glass tube is welded to the glass winding portion.

  The characteristic configuration is that the longest distance in the axial direction between the edge of the glass winding portion surrounded by the glass tube and the inner edge of the glass tube welded to the glass winding portion is 2 mm or less.

  In this case, it is preferable that the shortest distance in the radial direction between the inner periphery of the glass tube and the outer periphery of the glass winding portion surrounded by the glass tube is 2 mm or less.

  When the end portion of the glass tube is heated and joined to the glass winding portion, the heating causes the glass tube to soften and reduce the diameter other than the end portion that is originally joined to the glass winding portion. However, in the electrode lead rod fixing structure of the present invention, the maximum distance in the axial direction between the edge of the glass winding portion surrounded by the glass tube and the inner edge of the glass tube welded to the glass winding portion is 2 mm or less. Therefore, the glass winding portion does not exist at a position exceeding 2 mm from the edge of the glass tube welded to the glass winding portion. For this reason, parts other than the end of the glass tube are softened and reduced in diameter, and even if a misalignment or the like occurs during the joining operation, the part other than the end of the glass tube is in contact with the glass winding part. The part other than the end of the glass tube exceeding the position of 2 mm from the edge on the inner side of the glass tube is joined to the glass winding part, and a joining part is formed at a place other than the end. Absent.

  If the glass tube is a stepped glass tube inserted into the end of the arc tube in the flash lamp, the electrode lead bar is hermetically sealed to the end of the arc tube through the stepped glass tube. Can do. Then, the fusion fixing part between the electrode lead bar and the stepped glass tube having a low mechanical strength and the stepped glass tube itself can be accommodated inside the end portion of the arc tube having a relatively high mechanical strength. For this reason, even if the worker holds the end of the arc tube in the flash lamp, the fusion fixing portion between the electrode lead bar and the step glass tube existing inside the end of the arc tube and the step glass tube Is not directly gripped by the operator's hand. For this reason, it is possible to prevent the damage caused by the external force generated by the gripping by the operator being directly applied to the joined portion between the arc tube and the electrode lead bar.

It is sectional drawing of the flash lamp which has the fixation structure of the electrode lead rod of this invention embodiment. It is a perspective view which shows the longest distance in the axial direction of the edge in the case where the edge of the glass winding part is deform | transforming to the axial direction, and the edge in the inside of a glass tube. It is a figure corresponding to FIG. 2 which shows the case where the longest distance in the axial direction is zero. It is a figure which shows the shortest distance in the radial direction of the inner periphery of a glass tube and the outer periphery of a glass winding part in case the outer periphery of the glass winding part is deform | transforming to radial direction. It is a figure corresponding to Drawing 4 showing the case where the shortest distance in the diameter direction is zero. It is a figure which shows the fixing procedure of the electrode lead rod. It is the EE sectional view taken on the line of FIG. 8 which shows another flash lamp which has the fixed structure of the electrode lead rod of this invention. It is a perspective view which shows the another flash lamp. It is a figure which shows the fixing procedure of the conventional electrode lead rod. It is sectional drawing which shows the fixation structure of the conventional electrode lead rod. It is sectional drawing which shows the fixation procedure of another conventional electrode lead rod.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows a flash lamp 10 having an electrode lead bar fixing structure of the present invention. The flash lamp 10 includes a straight tube-type arc tube 11 made of quartz glass in which xenon gas is sealed, and a pair of electrode units 12 and 16 disposed opposite to both ends of the straight arc tube 11. Prepare. The arc tube 11 is formed into a cylindrical shape by quartz glass having a high ultraviolet transmittance, and the pair of electrode units 12 and 16 disposed at both ends thereof are made of tungsten disposed to face the inner sides of both ends of the arc tube 11. Electrodes 13 and 17 and metal electrode lead bars 14 and 18 each having a distal end side coaxially joined to the base end surfaces of the electrodes 13 and 17 are provided.

  The electrode 13 serving as the anode has a circular cross section and is composed of only a bulky cylindrical trunk having an outer diameter slightly smaller than the inner diameter of the arc tube. The anode electrode lead rod 14 is joined to the base of the electrode 13. It is formed by a tungsten rod. The electrode 17 serving as a cathode has a circular cylindrical trunk portion 17a having a circular cross section and an outer diameter slightly smaller than the inner diameter of the arc tube 11, and faces the anode side electrode 13 of the trunk portion 17a. A sintered body 17b made of an electron-emitting material containing tungsten as a main component and containing barium oxide, calcium oxide or the like is fixed to the tip portion. The cathode electrode lead rod 18 is formed of a tungsten rod in which a trunk portion 17a of the electrode 17 is joined to the tip. The electrode lead rods 14 and 18 having the electrodes 13 and 17 joined to the distal ends of the electrode lead rods 14 and 18 are hermetically sealed at the ends of the arc tube 11, and the base ends are outside the arc tube 11. Each is derived. Xenon gas is sealed in the arc tube 11 sealed at both ends in this way.

  The electrode lead rods 14 and 18 are hermetically sealed at the end of the arc tube 11 through the stepped glass tubes 21 and 26 inserted at the end of the arc tube 11. It is assumed that the stepped glass tubes 21 and 26 at both ends of the lamp 11 are inserted into the ends of the arc tube 11, respectively. These stepped glass tubes 21 and 26 are provided with glass tubes 21a and 26a made of quartz glass and rings 21b and 26b made of tungsten glass at their ends, respectively, and a plurality of glass rings 21c, 21d and 21e between them. , 26c, 26d, and 26e are connected so that the coefficient of thermal expansion sequentially changes in the axial direction.

  The outer diameters of the stepped glass tubes 21 and 26 are large enough to be inserted into the arc tube 11, and are formed to have an inner diameter into which the electrode lead rods 14 and 18 can be inserted. Specifically, the arc tube 11 used in the flash lamp 10 generally has an inner diameter of about 8 mm, and the metal electrode lead bars 14 and 18 have a circular cross section and generally have an outer diameter. Is about 2.4 mm. For this reason, at least the rings 21b and 26b made of tungsten glass of the stepped glass tubes 21 and 26 have an outer diameter of about 7 mm and an inner diameter of about 3.5 mm.

  In the fixing structure of the present invention, the electrode lead bars 14 and 18 are fixed to the end portions of the stepped glass tubes 21 and 26 inserted into the arc tube 11. That is, the fixing structure of the present invention is a structure in which the glass winding portions 22 and 27 are formed around the electrode lead rods 14 and 18 and the ends of the glass tubes 21 and 26 are welded to the glass winding portions 22 and 27. . And the characteristic structure is the edge of the glass winding parts 22 and 27 enclosed by the glass tubes 21 and 26, and the edge inside the glass tubes 21 and 26 welded to the glass winding parts 22 and 27. The longest distance A in the axial direction is set to 2 mm or less. The reason why the longest distance A in the axial direction is 2 mm or less is that when the end portions of the glass tubes 21 and 26 are heated and joined to the glass winding portions 22 and 27, the portions other than the end portions of the glass tubes 21 and 26. This is to prevent bonding with the glass winding portions 22 and 27.

  Here, the structure of fixing the electrode lead rods 14 and 18 to the joint glass tubes 21 and 26 in each of the anode electrode unit 12 and the cathode electrode unit 16 is the same, and the electrode lead rods 18 in the cathode electrode unit 16 are jointed. The procedure for fixing to the glass tube 26 is shown in FIG. It will be described below that the electrode lead rod 18 can be prevented from being joined to the glass winding portion 27 by the procedure for fixing the electrode lead rod 18 except for the end portion of the glass tube 26.

  That is, as shown in FIG. 6A, first, the electrode lead bar 18 is heated with a high frequency or a heating element (not shown) in an inert gas atmosphere, and a tungsten glass having a thermal expansion coefficient close to that of tungsten is accustomed to the surface. A glass winding part 27 is formed. The glass winding part 27 can be formed around the electrode lead bar 18 by a conventional method.

  Next, as shown in FIG. 6B, the electrode lead rod 18 is inserted into the end of the glass tube 26, and the end of the ring 26b made of tungsten glass, which is the end of the glass tube 26, is glass-wound. It is made to overlap with part 27. Then, the overlap length C in the axial direction is adjusted to be equal to or larger than the thickness t of the glass tube 26 and smaller than a value obtained by adding 2 mm to the thickness t. If this adjustment is a manual operation by an operator, it is preferable to perform the adjustment by visual inspection of the operator. This is because if the worker is engaged in welding in normal work, whether or not it is in the range of 2 mm or less can be adjusted relatively accurately by visual observation.

  Next, as shown in FIG. 6 (c), the end portion of the stepped glass tube 26 overlapping the glass winding portion 27 is softened by being burned with a burner 30, and the diameter of the end portion is reduced to form the glass winding portion 27. Connecting. Then, generally the thickness of the axial direction in the edge part of the glass tube 26 joined to the glass winding part 27 becomes more than the thickness t of the glass tube 26. FIG. Here, when the end portion of the stepped glass tube 26 is heated, the portion of the stepped glass tube 26 is softened and reduced in diameter other than the end portion that is originally joined to the glass winding portion 27 by the heating. . However, the overlap length C in the axial direction of the end portion of the glass tube 26 and the glass winding portion 27 is adjusted to be not less than the thickness t of the glass tube 26 and smaller than the value obtained by adding 2 mm to the thickness t. ing. For this reason, the longest distance A in the axial direction between the edge of the glass winding part 27 surrounded by the glass tube 26 and the edge of the glass tube 26 welded to the glass winding part 27 is 2 mm or less. The glass winding portion 27 does not exist at a position exceeding 2 mm in the axial direction inward from the edge.

  Then, for example, as shown in FIG. 6C, even if a misalignment or the like in which the axis of the glass tube 26 is deviated from the axis of the glass winding portion 27 occurs during the joining operation, If it exceeds 2 mm in the axial direction inward from the end edge, the glass winding portion 27 does not exist at a position where a portion other than the end portion of the softened and reduced diameter glass tube 26 comes into contact. Therefore, even if a misalignment or the like occurs during the joining operation, a portion other than the end portion of the glass tube 26 does not come into contact with the glass winding portion 27, and a portion other than the end portion of the glass tube 26 It is joined to the glass winding part 27, and a joining part is not formed in places other than the edge part.

  In this way, by setting the longest distance A in the axial direction between the edge of the glass winding part 27 surrounded by the glass tube 26 and the inner edge of the glass tube 26 welded to the glass winding part 27 to 2 mm or less. In addition, while preventing the formation of a joint part called a bridge 53 (FIG. 10) joined to the glass winding part 27 at a part away from the end part joined to the glass winding part 27, The end of the glass tube 26 can be welded. As shown in FIG. 6 (d), even if the end of the stepped glass tube 26 is heated and the glass tube 52 and the electrode lead bar 45 are returned to the same axis, the bridge 53 shown in FIG. 10 is generated. It means that it can be prevented.

  The effect that can prevent the occurrence of the bridge 53 shown in FIG. 10 is established by the absence of the glass winding portion 27 at a position exceeding 2 mm in the axial direction inward from the edge of the glass tube 26. For this reason, in the present invention which requires that the longest distance A in the axial direction between the edge of the glass winding portion 22 and the inner edge of the glass tube 21 welded to the glass winding portion 22 is 2 mm or less, The same effect can be achieved regardless of the outer diameter of the glass winding portion 27 and the inner diameter of the glass tube 26.

  Here, the reason why the longest distance A in the axial direction is set to 2 mm or less is that the worker can visually confirm and adjust the distance as described above. Since confirmation and adjustment are possible, the longest distance A in the axial direction may be 1 mm or less.

  Further, the longest distance A in the axial direction takes into consideration that the edge of the glass winding portion 27 may be deformed in the axial direction as shown in FIG. That is, when the edge of the glass winding part 27 is deformed in the axial direction as described above, the axis between the edge of the glass winding part 27 and the edge inside the glass tube 26 welded to the glass winding part 27 is used. It is a requirement that the longest distance A in the direction is 2 mm or less.

  Further, as shown in FIG. 3, since it is required to be 2 mm or less, the longest distance A in the axial direction includes zero. That is, the longest distance A in the axial direction is required to be 0 mm or more and 2 mm or less. For this reason, the edge of the glass winding part 27 may become flush with the edge of the glass winding part 27, and the distance A in the axial direction of these edges may be zero. If the shortest distance A is zero as described above, it is possible to reliably avoid a portion other than the end of the softened and reduced diameter glass tube 26 coming into contact with the glass winding portion 27. Then, even if a misalignment or the like occurs during the joining operation, a portion other than the end portion of the glass tube 26 is joined to the glass winding portion 27 so that a joined portion is formed at a place other than the end portion. This is surely prevented.

  Returning to FIG. 1, the shortest distance B in the radial direction between the inner periphery of the glass tube 26 and the outer periphery of the glass winding portion 27 surrounded by the glass tube 26 is preferably 2 mm or less. This is because the inner periphery of the glass tube 26 comes into contact with the outer periphery of the glass winding portion 27 when a misalignment or the like occurs in which the axis of the glass tube 26 is deviated from the axial core of the glass winding portion 27. It is because it is easy to produce. In other words, if the shortest distance B in the radial direction between the inner periphery of the glass tube 26 and the outer periphery of the glass winding portion 27 exceeds 2 mm, the end portion of the glass tube 26 even if misalignment or the like occurs during the joining operation. This is because the portion other than is less likely to come into contact with the glass winding portion 27 and the occurrence of the bridge 53 shown in FIG. 10 due to the contact is suppressed.

  Here, the reason why the shortest distance B in the radial direction is set to 2 mm or less is that the center of the glass tube 26 is displaced with respect to the axis of the glass winding portion 27 in the normal operation, that is, in the normal operation by the worker. This is because the amount of bias is considered to be about 2 mm at the maximum. However, since it is possible for a skilled worker to perform a joining operation without causing a significant misalignment, the shortest distance B in the radial direction may be 1 mm or less.

  In addition, the shortest distance B in the radial direction is defined in consideration of the fact that the outer periphery of the glass winding portion 27 may be deformed in the radial direction as shown in FIG. That is, when the outer periphery of the glass winding portion 27 is deformed in the radial direction in this way, the radial direction from the maximum outer diameter surface of the glass winding portion 27 to the inner surface of the glass tube 26 facing the outer diameter surface. It is a requirement that the distance B in is 2 mm or less.

  Further, as shown in FIG. 5, since it is required to be 2 mm or less, this shortest distance B includes zero. That is, the shortest distance B in the radial direction is required to be 0 mm or more and 2 mm or less. For this reason, the inner peripheral surface of the glass tube 26 and the outer peripheral surface of the glass winding part 27 may be flush with each other, and the distance B in the radial direction may be zero. Thus, if the shortest distance B is zero, the inner peripheral surface at the end of the softened and reduced diameter glass tube 26 is continuous with the outer peripheral surface of the glass winding portion 27, and the portion other than the end of the glass tube 26. Can be reliably prevented from being bonded to the glass winding portion 27.

  As shown in FIG. 1, the other ends of the stepped glass tubes 21, 26 having the electrode lead bars 14, 18 fixed to one end of the stepped glass tubes 21, 26 in this way are connected to the end of the arc tube 11. After being inserted from the 13th and 17th sides, the ends are hermetically sealed. Then, the anode and cathode electrode lead rods 14 and 18 in which the anode and cathode electrodes 13 and 17 disposed inside the arc tube 11 are joined to the tip ends of the arc tube through intermediate glass tubes 21 and 26 in the middle. 11 is hermetically sealed at the end portion, and the base end thereof is led out of the arc tube 11. In this way, the anode and cathode electrode units 12 and 16 are hermetically sealed at the end of the arc tube 11.

  Then, the rings 21b and 26b of the stepped glass tubes 21 and 26 having a thermal expansion coefficient close to that of the tungsten are fused to the electrode lead rods 14 and 18 and are separated from the rings, Glass bottles 21 a and 26 a having the same thermal expansion coefficient as quartz glass are fused to the arc tube 11. Thereby, the damage by the thermal change at the time of a preservation | save and the use resulting from the difference in the thermal expansion coefficient of the arc_tube | light_emitting_tube 11 and the electrode lead rod 18 can be prevented.

  Further, the bridge 53 as shown in FIG. 10 is not formed at the portion where the rings 21b and 26b of the stepped glass tubes 21 and 26 are fused to the electrode lead rods 14 and 18. For this reason, even in a so-called thermal shock in which high and low temperatures are repeated, there is no occurrence of a defect such as a crack in the joint portion, and the lifetime is not shortened.

  Here, since each of the electrodes 13 and 17 in each of the electrode units 12 and 16 has at least the columnar trunk portions 13 and 17a, the outer sides of the columnar trunk portions 13 and 17a extend over the entire length of the arc tube 11. It is fixed to the arc tube 11 by a shrink seal so as to be in close contact with the wall surface. That is, in the xenon flash lamp 10 shown in FIG. 1, the electrode units 12 and 16 are provided at both ends of the arc tube 11, and the electrodes 13 and 17 are formed after the arc tube 11 is hermetically sealed. Each of the cylindrical trunk portions 13 and 17a to be heated is heated. Then, the arc tube 11 around each cylindrical stem 13, 17a is melted and softened, and since the inside is in a decompressed state, the diameter of the portion is reduced, so that each cylindrical stem 13, 17a Weld. By doing so, it is possible to obtain the flash lamp 10 in which the emission energy of one flash is 15 J / cm or more per unit emission length.

  In the flash lamp 10 thus configured, the anode and cathode electrode lead rods 14 and 18 are hermetically sealed at the end of the arc tube 11 via the stepped glass tubes 21 and 26 inserted at the end of the arc tube 11. Since the mechanical strength of the anode and cathode electrode lead rods 14 and 18 having low mechanical strength and the joint portions of the stepped glass tubes 21 and 26 and the joint portions of the stepped glass tubes 21 and 26 are compared, the mechanical strength is compared. The inner end of the strong arc tube 11 is housed inside. For this reason, even if the worker holds the end of the arc tube 11 in the flash lamp 10, the anode and cathode electrode lead rods 14 and 18 existing inside the end of the arc tube 11 and the stepped glass tubes 21 and 26 are provided. Thus, the fusion fixing part and the stepped glass tubes 21 and 26 themselves are not directly gripped by the hand of the operator. Therefore, the external force generated by the operator can be received by the arc tube 11 having relatively high mechanical strength, and the external force is directly applied to the joint portion between the arc tube 11 and the electrode lead bars 18 and 18. It is possible to prevent breakage caused by being damaged.

  Further, since the respective cylindrical trunk portions 13 and 17a of the electrodes 13 and 17 are fixed to the arc tube 11 by the shrink seal, the outer surfaces of the electrodes 13 and 17 are in close contact with the inner wall of the arc tube 11 by the shrink seal. . When the light emission energy of one flash under the use conditions is 15 J / cm or more per unit light emission length, the flash lamp 10 is used while being cooled by circulating cooling water. Then, the cooling water that circulates outside the arc tube 11 during the operation of the lamp 10 also cools the electrodes 13 and 17 that are in close contact with the arc tube 11, so that the oxidation of the electrodes 13 and 17 and the substances of the electrodes 13 and 17 are performed. Can be prevented from evaporating.

  In the above-described embodiment, although the flash lamp 10 using the straight tube-type arc tube 11 has been described, the arc tube is not limited to a straight tube. For example, as shown in FIG. 8, the arc tube 70 may have a substantially double annular shape as a whole. The arc tube 70 shown in FIG. 8 includes an inner tube portion 71 and an outer tube portion 72, a connecting portion 73 that connects one end of them to each other, and end portions 74 that are erected vertically upward in the vicinity of the other ends. 75. Although the inner tube portion 71 and the outer tube portion 72 are slightly dimensionally distorted, the centers of the tubes are located substantially on the same plane and are formed in a substantially precise double ring. Then, the electrode units 12 and 16 are provided at the end portions 74 and 75, respectively, and the flash lamp 80 is formed.

  FIG. 8 shows a case where the anode electrode unit 12 is provided at the end 74 continuous to the inner tube portion 71 and the cathode electrode unit 16 is provided at the end 75 continuous to the outer tube portion 72. The electrode units 12 and 16 are hermetically sealed to the end portions 74 and 75 of the electrode lead rods 14 and 18 through the stepped glass tubes 21 and 26 inserted into the end portions 74 and 75, respectively. It has the same structure. A cross section in which the cathode electrode unit 16 is provided at the end portion 75 continuing to the outer tube portion 72 is representatively shown in FIG.

  As shown in FIG. 7, the stepped glass tube 26 is inserted into the edge of the end portion 75, and a glass winding portion 27 is formed around the electrode lead rod 18. Although the end portion of the glass tube 26 is welded to the glass winding portion 27, the edge of the glass winding portion 27 surrounded by the glass tube 26 and the edge inside the glass tube 26 welded to the glass winding portion 27. The longest distance A in the axial direction is 2 mm or less. Thus, when the end portion of the glass tube 26 is heated and joined to the glass winding portion 27 by setting the longest distance A in the axial direction to 2 mm or less, portions other than the end portion of the glass tube 26 are made of glass. Bonding with the winding part 27 is prevented. The other end of the stepped glass tube 26 in which the electrode lead rod 18 is fixed to one end of the stepped glass tube 26 is inserted into the end portion 75 of the arc tube 70 from the electrode 17 side and then the end of the end portion 75. Hermetically sealed to the edge.

  As described above, even if the arc tube 70 has a substantially double annular shape as a whole, the edge of the glass winding portion 27 surrounded by the glass tube 26 and the glass welded to the glass winding portion 27. The longest distance A in the axial direction from the inner edge of the tube 26 is set to 2 mm or less, so that a portion away from the end portion joined to the glass winding portion 27 is joined to the glass winding portion 27 in FIG. The end portion of the glass tube 26 can be welded to the glass winding portion 27 while preventing the formation of a joining portion called a bridge 53 shown in the figure.

14, 18 Electrode lead rod 21, 26 Stepped glass tube (glass tube)
22, 27 Glass winding part A Longest distance in the axial direction B Shortest distance in the radial direction

Claims (1)

A glass winding portion (22, 27) is formed around the electrode lead rod (14, 18), and an end portion of the glass tube (21, 26) is welded to the glass winding portion (22, 27). In the fixed structure,
The edge of the glass winding part (22, 27) surrounded by the glass tube (21, 26) and the end inside the glass tube (21, 26) welded to the glass winding part (22, 27) Ri maximum distance (a) is der below 2mm in the axial direction of the edge,
The shortest distance (B) in the radial direction between the inner periphery of the glass tube (21, 26) and the outer periphery of the glass winding portion (22, 27) surrounded by the glass tube (21, 26) is 2 mm or less. A structure for fixing an electrode lead bar.

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