JP2004220883A - Method for manufacturing discharge tube and discharge tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a discharge tube where electrodes can be sealed without generating cracks in a bulb made of quartz glass where protrusions are not formed, and to provide the discharge tube manufactured by the method. <P>SOLUTION: End bulbs 15 made of hard glass are coaxially integrated with both edges of a main bulb 13 made of quartz glass, via an intermediate bulb 14 where the melting point becomes low gradually and the coefficient of thermal expansion becomes high gradually to manufacture a glass bulb 16. Then, a cathode electrode 17 is sealed in one end bulb 15. Then, a bead glass 22 made of hard glass where an anode electrode 20 penetrates is temporarily fastened so that a gap 23 is formed in the other end bulb 15. Then, after having exhausted air in the glass bulb 16 from the gap 23, a discharge gas is sealed in the glass bulb 16. Subsequently, the bead glass 22 is welded to the end bulb 15, and the gap 23 is closed, and the anode electrode 20 is sealed in the other end bulb 15. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a discharge tube in which rod-shaped electrodes are sealed at both ends of a glass bulb made of quartz glass, and more particularly to a method for manufacturing a discharge tube in which a projection is not formed on a glass bulb.
[0002]
[Prior art]
A discharge tube provided with a glass bulb made of hard quartz glass is used for a rod-shaped light source of a strobe or the like. As shown in FIG. 2, the discharge tube has rod-shaped electrodes 3 and 4 sealed at both ends of a glass bulb 1 made of quartz glass via bead glasses 2 and 2, and the inside of the glass bulb 1 is sealed. Discharge gas is sealed. Quartz glass is a glass mainly composed of silicon dioxide, exhibits high transmittance in a light wavelength region from ultraviolet to infrared, is strong against thermal shock, and is excellent in heat resistance.
[0003]
The electrodes 3 and 4 are constituted by a cathode electrode 3 for emitting electrons and an anode electrode 4 for receiving electrons. The cathode electrode 3 includes a rod-shaped terminal portion 5 penetrating the bead glass 2 and an electrode portion 6 attached to an inner end of the terminal portion 5 and emitting electrons. The anode electrode 4 includes a rod-shaped terminal portion 7 penetrating the bead glass 2 and a getter 8 attached near the inner end of the terminal portion 7.
[0004]
The electrodes 3 and 4 are formed of tungsten so as not to melt even when heated when sealing both ends of the glass bulb 1. That is, since quartz glass, which is the material of the glass bulb 1, has a high melting point of about 2,000 ° C., the electrodes 3 and 4 are formed of tungsten having a melting point of about 3,400 ° C. However, since the thermal expansion coefficient of quartz glass is about 0.55 × 10 ⁻⁶ / ° C. and the thermal expansion coefficient of tungsten is about 4.5 × 10 ⁻⁶ / ° C., the glass bulb 1 is heated and melted. If the electrodes 3 and 4 are directly welded, cracks occur in the glass bulb 1. Therefore, the electrodes 3 and 4 are sealed at both ends of the glass bulb 1 via the bead glass 2.
[0005]
The bead glass 2 has a structure in which through-holes are formed in the center of the electrodes 3 and 4, the outer diameter is slightly smaller than the inner diameter of the glass bulb 1, and glasses having different thermal expansion coefficients in the radial direction are laminated in multiple layers. It has become. That is, the coefficient of thermal expansion of the multi-layer glass is about 4.5 × 10 ⁻⁶ / ° C. on the center side, about 0.55 × 10 ⁻⁶ / ° C. on the outside, and gradually increases from the center to the outside at the middle. ing. The melting point of the outer layer of the bead glass 2 is almost the same as the melting point of the quartz glass, and when the electrodes 3 and 4 are sealed at both ends of the glass bulb 1, the bead glass 2 The difference between the coefficients of thermal expansion of the bulb 1 is absorbed, and the bead glass 2 and the glass bulb 1 are welded together without cracks occurring in the two 2 and 1.
[0006]
Here, a method for manufacturing such a discharge tube will be described with reference to FIG. The discharge tube is manufactured from a quartz glass T-tube consisting of a straight main tube 9 and a branch tube 10 connected to the middle of the main tube 9.
[0007]
First, as shown in FIG. 3A, multilayer bead glasses 2, 2 penetrating the electrodes 3, 4 are inserted into both ends of a straight main body tube 9. Then, as shown in FIG. 3B, both ends of the main tube 9 are heated and the both ends 9 and 2 are welded by melting the both ends and the bead glass 2. Since the melting point of the quartz glass and the melting point of the glass of the bead glass 2 are almost the same, they can be reliably welded, and the coefficient of thermal expansion of the bead glass 2 forms the electrodes 3 and 4 on the center side. Since it is formed so as to be the same as tungsten, cracks do not occur in the main body tube 9 and the bead glass 2 due to the difference in the thermal expansion coefficient between quartz glass and tungsten.
[0008]
Thereafter, as shown in FIG. 3C, the air in the main pipe 9 is exhausted by using the branch pipe 10, and subsequently, a discharge gas such as xenon gas is sealed in the main pipe 9. Thereafter, as shown in FIG. 3D, the connecting portion between the branch pipe 10 and the main pipe 9 is heated by the burner 11 to cut the branch pipe 10 from the main pipe 9 and cut and formed. The discharge tube in which the projection 12 is formed is completed by closing the glass of the branch tube 10 where the small hole is cut.
[0009]
Note that a paste-like sealing material is applied to both ends of the quartz glass tube portion, and each of the tube members is placed in a tubular protrusion projecting from a pair of soft glass sealing portions penetrating the electrodes. Patent Literature 1 discloses a discharge tube in which ends are inserted and both ends of a tube body portion and a tubular projection of a sealing portion are heated and melted to connect the two. The thermal expansion coefficient of the soft glass is about 5.6 × 10 ⁻⁶ / ° C., which is about 10 times as large as that of quartz glass. By being interposed between the both ends and the tubular projection of the sealing portion, the two can be connected without cracks.
[0010]
[Patent Document 1]
JP-A-2002-190275
[Problems to be solved by the invention]
By the way, the discharge tube has a shape in which the protruding portion 12 is formed although the branch tube 10 of the T-tube made of quartz glass is cut and the small hole formed by this cut is closed by the glass of the branch tube 10. Has become. However, the small holes may not be completely closed, so that the discharge gas in the glass bulb 1 leaks from the projections 12, and the discharge tube does not emit light from the beginning or gradually stops emitting light.
[0012]
Further, even when the small holes are completely closed, the projections 12 are susceptible to vibration, impact, and the like when transporting the discharge tube, and cause the glass bulb 1 to be damaged. Further, in the light emission durability test of the discharge tube, breakage or destruction may occur from the protrusion 12. When mounting the discharge tube at a predetermined position, the orientation of the projection 12 must be taken into consideration. Not only is the work efficiency inferior, but the mounted discharge tube differs from the other portions at the projection 12. Since the light is emitted in the state, so-called light distribution unevenness (unevenness) occurs.
[0013]
On the other hand, the discharge tube disclosed in Patent Document 1 absorbs a difference in thermal expansion coefficient between the soft glass forming the sealing portion and the quartz glass forming the tube portion by a sealing material interposed therebetween. , So that the two are joined without generating cracks. Therefore, in order to reliably absorb the difference in thermal expansion coefficient between the soft glass and the quartz glass, the sealing material must be thick. However, when the sealing material becomes thicker, the outer diameter of the sealing portion becomes larger, and it is not possible to meet the demand for downsizing the discharge tube.
[0014]
Therefore, the present invention provides a method for manufacturing a discharge tube that can seal an electrode without causing cracks in a glass bulb made of quartz glass on which a projection is not formed, and can further reduce the diameter. And to provide a discharge tube using the same.
[0015]
[Means for Solving the Problems]
The method for manufacturing a discharge tube according to the present invention is a method for manufacturing a discharge tube that seals rod-shaped electrodes at both ends of a glass bulb made of quartz glass. A step of manufacturing a glass bulb by welding to both end edges or one end edge of a quartz glass main valve through a, and a rod-shaped at one end valve or an end of the main valve not welding the end valve. A step of temporarily fixing a hard or soft glass bead glass having a rod-shaped electrode penetrated in an end valve not sealing the electrode, and temporarily fixing the bead glass. Discharging the air in the glass bulb from the stopped end bulb side, filling a discharge gas into the glass bulb from the end bulb side, welding the bead glass to the end bulb, The rod-shaped electrode through the glass, is characterized in that it contains a step of sealing the end portion the valve.
[0016]
According to this method of manufacturing a discharge tube, first, the relay valve has a small thermal expansion coefficient and a large thermal expansion coefficient at both ends or one end of a quartz glass main bulb having a high melting point and a high melting point. Weld the end valve made of hard or soft glass with low coaxial.
[0017]
Then, when welding the end valves to both edges of the main valve, for example, by melting one end valve into a bowl shape, or inserting a bead glass that has previously penetrated the electrode into one end valve. Then, by melting the end bulb and the bead glass, the rod-shaped electrode is sealed in the one end bulb.
[0018]
On the other hand, when the end valve is welded only to one edge of the main valve, for example, a glass having a different thermal expansion coefficient in the radial direction as in the related art is attached to the end of the main valve where the end valve is not welded. Are laminated in layers, and a bead glass penetrating the electrode at the center is welded to seal the electrode.
[0019]
Then, bead glass penetrating the electrode is inserted into the end bulb side where the electrode is not sealed, and thereafter, the bead glass is left while leaving a gap between the inner surface of the end bulb and the outer surface of the bead glass. Temporarily stop. Then, next, after the air in the glass bulb is discharged from the gap and the discharge gas is sealed, the end bulb and the bead glass are fused to fuse them together. In this case, since the melting point and the coefficient of thermal expansion of the end bulb and the bead glass are the same, the electrode can be sealed without cracking between the end bulb and the bead glass.
[0020]
In the method of manufacturing each of the discharge tubes, it is preferable that the electrode portion of the cathode electrode from which electrons are emitted is disposed in the main bulb. This is because the quartz glass that forms the main bulb has excellent impact resistance, so that even if electrons emitted from the electrode portion of the cathode electrode collide with the inside of the main bulb, the glass bulb will not be damaged. The discharge tube manufactured by this method can continue to emit light with initial characteristics.
[0021]
Further, in the method for manufacturing a discharge tube, the relay bulb has a melting point lower than that of quartz glass and a higher thermal expansion coefficient at one end, and a melting point higher than that of hard or soft glass at the other end, and It is preferable that a joint glass made of glass having a low expansion coefficient and having a melting point and a thermal expansion coefficient slightly different from each other in order is formed by welding a plurality of layers.
[0022]
According to this method for manufacturing a discharge tube, the relay valve fuses glass having a slightly lower melting point than quartz glass and a slightly higher thermal expansion coefficient to the edge of the main bulb, and has a melting point higher than that of the glass. Deposits glass with slightly lower and slightly higher coefficient of thermal expansion one after another, and finally welds glass with slightly higher melting point and slightly lower coefficient of thermal expansion to hard or soft glass than hard or soft glass. With this configuration, it is possible to manufacture a glass bulb in which a quartz glass main bulb and a hard or soft glass end glass having different melting points and thermal expansion coefficients are coaxially integrated.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of a method for manufacturing a discharge tube according to the present invention will be described with reference to FIG. In the method for manufacturing a discharge tube according to the first embodiment, as shown in FIG. 1A, a relay valve 14 is provided at both ends of a quartz glass main bulb 13 without using a conventional T-tube. It is manufactured from a glass bulb 16 in which a hard glass end bulb 15 is coaxially integrated.
[0024]
Quartz glass has a melting point of about 2,000 ° C., the thermal expansion coefficient is about 0.55 × ^{10 -6} / ℃, hard glass has a melting point of about 600 ° C., a coefficient of thermal expansion of about 5.6 × 10 ^{- Since the} temperature is ⁶ / ° C., the relay valve 14 for absorbing the difference between the melting point and the coefficient of thermal expansion is welded between the edge of the main valve 13 and the edge of the end valve 15. The relay valve 14 is composed of a plurality of layers of a spliced glass which are sequentially and differently fused in a melting point and a coefficient of thermal expansion between quartz glass and hard or soft glass.
[0025]
For example, joint glass having a melting point of 1,800 ° C. and a thermal expansion coefficient of about 1 × 10 ⁻⁶ / ° C. is welded to both end edges of the main valve 13. Then, a joining glass having, for example, a melting point of 1,600 ° C. and a thermal expansion coefficient of about 1.5 × 10 ⁻⁶ / ° C. is welded to the other end of the joining glass. In this manner, the spliced glass having different properties is sequentially welded, and finally, the spliced glass having a melting point of 800 ° C. and a thermal expansion coefficient of about 5 × 10 ⁻⁶ / ° C. is welded. Weld.
[0026]
Thus, the main valve 13 and the end valve 15 having greatly different melting points and coefficients of thermal expansion are integrated without cracking by the intermediate valve 14 in which a plurality of joint glasses are welded. Further, the inner and outer diameters of the main valve 13, the relay valve 14, and the end valve 15 are the same, and the main valve 13 and the end valve 15 are coaxially integrated by welding. 16 are manufactured.
[0027]
It is preferable that one end valve 15 be shorter than the other end valve 15 so that the one end valve 15 does not need to be cut off in a later step.
[0028]
Next, as shown in FIG. 1B, the terminal portion 18 of the cathode electrode 17 is sealed in one end valve 15. For example, by heating and melting one end valve 15, the end valve 15 is deformed into a bowl shape, and the terminal portion 18 can be sealed. By making the one end valve 15 long enough to seal the terminal portion 18 of the cathode electrode 17, an operation of cutting off an unnecessary portion is not required.
[0029]
However, by inserting a hard glass bead glass 22 penetrating the terminal portion 18 of the cathode electrode 17 into the end bulb 15 and heating and melting the end bulb 15 and the bead glass 22, the terminal of the cathode electrode 17 is heated. The part 18 can be sealed to one end valve 15.
[0030]
However, in any case, it is preferable that the electrode portion 19 of the cathode electrode 17 is disposed in the main bulb 13 so that the inside of the glass bulb 16 is hardly damaged by electrons emitted from the electrode portion 19.
[0031]
Next, a bead glass 22 penetrating the terminal portion 21 of the anode electrode 20 is arranged in the other end valve 15 as shown in FIG. The bead glass 22 is formed only of hard glass like the end bulb 15 and has an outer diameter slightly smaller than the inner diameter of the end bulb 15.
[0032]
By heating the outer periphery of the end bulb 15 on which the bead glass 22 is disposed by a plurality of burners 24, the end bulb 15 of the portion is partially constricted and the gap 23 remains, and the bead glass is heated. 22 is temporarily fixed at the position. The inner end of the terminal portion 21 of the anode electrode 20 penetrating the bead glass 22 is located in the main valve 13, and the getter 25 provided on the inner end side of the terminal portion 21 is located in the relay valve 14. It has been like that.
[0033]
Next, as shown in FIG. 1C, the air in the glass bulb 16 is exhausted from the gap 23, and then a discharge gas such as xenon gas is sealed in the glass bulb 16 from the gap 23. After that, as shown in FIG. 1D, the end bulb 15 around the bead glass 22 is heated again by a burner (not shown), thereby melting the end bulb 15 and the bead glass 22 and forming the gap 23. Close up. Since the end bulb 15 and the bead glass 22 are formed of the same hard glass, the gap 23 is closed without cracking between them, and the terminal 21 of the anode electrode 20 is sealed to the end bulb 15. It is done.
[0034]
Finally, when the end bulb 15 protruding from the position where the bead glass 22 is welded is cut off by the cutter 26, a discharge tube as shown in FIG. 1E is completed.
[0035]
Next, a second embodiment of the method for manufacturing a discharge tube according to the present invention will be described. The method of manufacturing the discharge tube according to the second embodiment is such that the relay valve 14 is welded to one end of the main bulb 13 instead of the both ends, and the end bulb 15 is welded only to the one end. is there. On the other end of the quartz glass main valve 13 to which the end valve 15 is not welded, a cathode electrode is formed by a bead glass 2 (see FIG. 3) in which glasses having different thermal expansion coefficients are laminated in multiple layers in the same manner as in the related art. The 17 terminal portions 18 are sealed.
[0036]
However, the subsequent steps such as disposing the bead glass 22 penetrating the terminal portion 21 of the anode electrode 20 on the end valve 15 welded to one end of the main valve 13 are the same as those in the first embodiment. Therefore, the description is omitted.
[0037]
It should be noted that the present invention is not limited to the above embodiment, but can be variously modified within the scope of the technical matters described in the claims. For example, the end bulb 15 can use soft glass instead of hard glass. Further, the melting point and the coefficient of thermal expansion of the relay valve 14 described in the embodiment are merely examples, and it goes without saying that they can be arbitrarily changed.
[0038]
Further, the relay valve 14 can be manufactured by welding the end valve 15 and welding it to the main valve 13. Further, the cathode electrode 17 and the anode electrode 20 may be sealed at the other end of the end valve 15 or the main valve 13 opposite to the above.
[0039]
【The invention's effect】
According to the present invention, a glass bulb is manufactured by welding a main valve made of quartz glass and an end valve made of hard or soft glass by a relay valve so that a gap is formed in the end valve. Since the bead glass can be temporarily fixed, the air in the main bulb can be exhausted, and the discharge gas can be sealed in the main bulb, the discharge tube can be manufactured without using a conventional T-tube. it can.
[0040]
Therefore, in the discharge tube manufactured according to the present invention, a small hole is not formed in the glass bulb, and the discharge gas does not leak from the small hole. Can be eliminated. In addition, since the projection is not formed on the glass bulb, the glass bulb is less susceptible to vibration and impact when transporting the discharge tube, and the glass bulb can be hardly damaged. Further, in the light emission durability test of the discharge tube, breakage or destruction can be prevented from occurring from the projection, so that the yield can be improved. Furthermore, when the discharge tube is mounted at a predetermined position, it is not necessary to consider the direction of the projection, and the efficiency of the assembling operation can be improved. Since the discharge tube emits light uniformly over the entire length, the quality can be improved.
[0041]
In addition, the glass bulb is formed by welding a main bulb made of quartz glass and an end bulb made of hard or soft glass by a relay bulb whose melting point and thermal expansion coefficient gradually change, so that a discharge tube having a small outer diameter can be formed. It can be provided and mounted on various miniaturized devices.
[Brief description of the drawings]
FIG. 1 is an embodiment of a method for manufacturing a discharge tube according to the present invention, in which (a) to (e) are cross-sectional views showing respective steps. FIG. 2 is a cross-sectional view of a conventional discharge tube. (A) to (d) are cross-sectional views showing respective steps.
13 Main Valve 14 Relay Valve 15 End Valve 16 Glass Valve 17 Cathode Electrode 19 Electrode 20 Anode Electrode 22 Bead Glass

Claims (3)

A method for manufacturing a discharge tube for sealing rod-shaped electrodes at both ends of a glass bulb made of quartz glass,
A step of manufacturing a glass bulb by welding a hard or soft glass end bulb to both end edges or one end edge of a quartz glass main valve via a relay valve;
A step of sealing a rod-shaped electrode at one end valve or at an end of the main valve not having the end valve welded thereto,
A step of temporarily fixing a hard or soft glass bead glass having a rod-shaped electrode penetrated thereinto in the end valve not sealing the electrode,
After exhausting the air in the glass bulb from the end bulb side where the bead glass is temporarily fixed, sealing the discharge gas into the glass bulb from the end bulb side,
Welding the bead glass to an end bulb and sealing a rod-shaped electrode penetrating the bead glass to the end bulb. In the relay valve, the quartz glass side has a lower melting point than quartz glass and a glass having a higher thermal expansion coefficient, and the other end side has a higher melting point than hard or soft glass and a glass having a lower thermal expansion coefficient. The method for manufacturing a discharge tube according to claim 1, wherein the discharge tube is formed by welding a plurality of glasses having a melting point and a thermal expansion coefficient in order. A discharge tube manufactured by the manufacturing method according to claim 1.

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