JP2008034239A - Manufacturing method of ceramic arc tube for high pressure discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent breakage of a ceramic narrow tube in a laser sealing process for performing frit sealing on a feed conductor carrying a W electrode, at a pair of opening ends of ceramic narrow tubes joined to both end of a main tube of a discharge tube made of ceramic materials. <P>SOLUTION: The frit sealing is carried out by means of laser sealing process on the ceramic light emitting tube mounted on a high-pressure discharge lamp, of which tube vessel is composed of the main tube of the discharge tube made of ceramic materials and a pair of ceramic narrow tubes 4 joined to both ends of the main tube, in order to form a pair of ceramic light emitting tube in which a pair of feed conductors 12 carrying W electrodes are frit-sealed at the opening ends 4a of the ceramic narrow tubes. The opening ends and the feed conductors are heated respectively by different laser devices irradiating lights of wavelength having high absorption for respective parts. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a ceramic arc tube made of a polycrystalline alumina ceramic material or the like for constituting a high-pressure discharge lamp such as a metal halide lamp.

  As an example of a high pressure discharge lamp, an arc tube made of a polycrystalline alumina ceramic (PCA) material is first used as a high pressure sodium lamp, which has been widely used as a main light source for outdoor lighting such as roads. In recent years, metal halide lamps using PCA arc tubes instead of conventional quartz have been actively developed and deployed.

  The PCA arc tube is characterized by high heat resistance up to about 1200 ° C compared to about 1000 ° C heat resistance of conventional quartz, and the tube wall load of the arc tube can be set higher accordingly, so it is basically highly efficient.・ Lamp characteristics with high color rendering properties can be obtained. For example, a 150 W metal halide lamp has an efficiency of about 97 lm / W and a general color rendering index of Ra92 or higher. Such a lamp is mainly applied to an indoor interior lighting field in a commercial space such as a store, and is widely used as an energy-saving light source replacing a conventional metal halide lamp of a quartz arc tube.

A PCA arc tube of a typical metal halide lamp according to the prior art is composed of a cylindrical discharge main body portion made of a PCA material and a pair of narrow tube portions joined to both ends thereof. A pair of tungsten (W) electrodes are installed at both ends of the discharge main tube portion of the arc tube, and both are joined and held to a power feeder made of, for example, an Al ₂ O ₃ —Mo based conductive cermet. The power supply body is hermetically sealed with a frit at the opening end portion of the thin tube portion of the arc tube, and an external lead bar made of niobium Nb is joined to the outer end portion of the tube. Note that some of the power feeders are composed of a series of niobium Nb rods including external lead rods. In the arc tube, a light-emitting substance composed of a metal halide such as DyI ₃ -TmI ₃ -HoI ₃ -TlI-NaI and a start-up rare gas such as mercury and argon as a buffer gas are sealed (for example, Patent Document 1).

  The completed lamp has a configuration in which the arc tube is installed inside an outer bulb made of quartz or hard glass, and a base is attached to the outer bulb. The lamp is lit by an electronic ballast with a built-in starter or a copper-iron inductance ballast.

  The main process in the manufacture of the PCA arc tube is a sealing process when the power feeder holding the W electrodes on the narrow tube portions at both ends of the PCA is hermetically sealed with frit.

  The current sealing process according to the prior art is basically based on an electrothermal sealing system using a carbon or tantalum heater in accordance with the conventional sealing process with high-pressure sodium orchid. Specifically, a power supply body with a W electrode and a ring-shaped frit member are first placed on a narrow tube portion of a PCA arc tube to be sealed, and a plurality of these are installed inside a long and narrow plate-like heater. To do. Finally, the frit member is melted by heating with a heater, and then the gap between the power feeding body and the thin tube portion is filled, whereby the power feeding body is hermetically sealed to the thin tube portion (see, for example, Patent Document 2).

  However, the conventional electrothermal sealing method has various problems. That is, the above-mentioned electric heater basically has thermal inertia, so precise temperature control is difficult, and because of the slender shape, the positional temperature fluctuation range is relatively large, so that each PCA arc tube is filled with frit. The state will fluctuate. As a result, the occurrence of defects such as breakage and leakage of the PCA thin tube portion in the sealing step is relatively large, and it is extremely difficult to achieve a good product yield of, for example, 95% or more. In addition, quality problems such as disappearance of luminescent materials through the sealing portion of the finished lamp and cracks in the sealing portion also occurred. In addition, problems such as poor starting of the lamp and lowering of luminous flux also occurred due to contamination of the arc tube by impure gas and substances released from the heater.

In the above situation, a new laser sealing method using a CO ₂ gas laser or a YAG laser is used in place of the electric heat sealing method which has been applied to the conventional high pressure sodium lamp and PCA tube metal halide lamp. Has been studied. The feature of this method is basically that precise temperature control for each arc tube is possible and a so-called clean sealing process can be realized. The prior art discloses the following technologies related to the laser sealing device, the sealing process, and the like.

First, a sealing device used for manufacturing a PCA tube metal halide to which the present invention relates is provided with a holder for holding a PCA tube in a large-sized so-called vacuum glow box, and a single unit disposed outside the box. It has a configuration equipped with three irradiation units branched from a laser oscillator. In the sealing step, a power supply body (electrode bar) with a W electrode and a ring-shaped solid frit member are placed on the PCA thin tube portion held by the holder. While rotating the PCA tube, laser light is irradiated to two places, the solid frit member and the PCA thin tube portion, in order to suppress the bias of the frit to the power supply body that becomes overheated in the sealing process. However, the PCA tubule is covered with a Mo tubule having a high absorption rate of laser light and irradiated with laser light from the two irradiation units. (See Patent Document 2)
Also, instead of directly sealing the power supply body to the PCA thin tube portion as described above, the Mo thin tube is first hermetically joined to the PCA thin tube portion, and then the Mo brazing member is the same quality as the Mo power supply body with the W electrode. There is also disclosed a technique of hermetically bonding a sealing portion in which is installed by irradiation with YAG laser light (see Patent Document 3).

In addition, for conventional high-pressure sodium lamps, a sealing part in which a so-called closed niobium cap and frit member is installed at the end of the PCA tube is used for CO ₂ gas laser radiation (wavelength 10.6 μm) with high absorption into the ceramic tube. Has been disclosed (see Patent Document 4).
Japanese Patent Laid-Open No. 11-273626 JP 2000-340118 A Japanese Patent Laid-Open No. 2004-6135 JP-A-53-72387

  The present inventors also made use of a laser sealing method that can be used for mass production in order to improve the yield of non-defective products and improve the lamp quality in the main sealing process for the manufacturing method of a metal halide lamp comprising a PCA arc tube. Worked on the development of the sealing device and the sealing process.

At the beginning of development, the sealing device was designed and manufactured based on the prior art disclosed in Patent Document 2 and the like, and the sealing process was defined in accordance with the prior art. Specifically, first, the sealing device has 20 holders for holding PCA tubes in a large vacuum glow box, and two CO ₂ gas laser devices (wavelength 10.6 μm) are attached to each. Consists of those equipped with an irradiation unit. In the sealing step, a power supply body with a W electrode and a solid frit member are installed in the thin tube portion of the PCA tube held by the holder, and the PCA tube is rotated, and the frit member and the thin tube portion are respectively disposed at two locations. By irradiating with laser radiation, hermetic sealing was performed on the thin tube portion of the power feeder. Since a CO ₂ gas laser was used, the Mo tubule that covers the PCA tubule portion was not used.

  The mass production trial of the PCA tube metal halide lamp was performed by the above-mentioned initial laser sealing device and process. As the most important problem, damage occurred relatively frequently especially in the narrow tube portion of the PCA arc tube with the power feeder sealed. I found out that For example, in the frit sealing process, about 6% of the defective rate of 8% was occupied by breakage of the thin tube portion.

  The present invention has been made in view of the above situation, and a power feeding body holding a W electrode is fritted at the opening end of a pair of ceramic thin tube portions joined to both ends of a discharge main tube portion made of a ceramic material. We provide a ceramic arc tube manufacturing method that can suppress the damage of the ceramic capillary tube in the laser sealing process for sealing, thereby improving the overall good product yield in the main sealing process at a low cost. The object is to enable the production of high-pressure discharge lamps such as high-quality metal halide lamps.

  A method of manufacturing a ceramic arc tube according to the present invention is a ceramic arc tube equipped in a high-pressure discharge lamp, wherein a tube envelope includes a discharge main body portion made of a ceramic material and a pair of ceramic thin tubes joined to both ends thereof. In order to form a ceramic arc tube in which a pair of feeders holding a W electrode is frit-sealed at the opening end of the ceramic thin tube portion, the frit sealing is performed by a laser sealing step. Do.

  In order to solve the above-described problem, the open end of the ceramic thin tube portion to be sealed with the frit and the power feeding body are heated by individual laser devices that emit radiation in a wavelength region having a high absorption rate. .

  According to the present invention, the temperature of the open end portion of the PCA thin tube portion to be frit-sealed and the power supply body can be controlled with high accuracy individually, and the temperature difference between the two can be relatively easily ensured. It becomes possible to reduce. Therefore, the occurrence of breakage of the PCA thin tube portion can be remarkably suppressed, and the overall good product yield in the main sealing process can be finally improved.

  In the method for manufacturing a ceramic arc tube of the present invention, in the laser sealing step, the opening end and the frit of the ceramic capillary tube are heated by a laser device that emits far-infrared radiation, and the power feeder is visible to near red. It can be heated by a laser device that emits external radiation. As a result, the temperature of the open end of the PCA narrow tube part and the power feeding body that are actually frit-sealed can be controlled with high accuracy individually, and the occurrence of breakage of the PCA thin tube part in the frit sealing process is remarkably suppressed. can do.

  In any one of the above manufacturing methods, a polycrystalline alumina ceramic (PCA) material can be used as the ceramic material.

  At the time of frit melting and filling in the laser sealing step, the temperature difference of the temperature Tb of the power supply body with respect to the temperature Ta of the opening end portion of the ceramic thin tube portion is set to a relative ratio | Ta−Tb | / Ta to 4.5. It is preferable to prescribe | regulate in the range below%. As a result, the occurrence rate of PCA narrow tube breakage in the laser sealing process can be remarkably suppressed to a level of 0.8% or less, for example, and the total good product yield can be improved to a high level of 97% or more, for example.

  Further, the slow cooling treatment of the ceramic thin tube portion and the power feeding body immediately after the frit filling in the laser sealing step is performed in parallel with the laser sealing step by a slow cooling furnace provided adjacent to the laser device. Is preferred. Thereby, the slow cooling process of the plurality of PCA tubes immediately after the frit filling can be performed promptly and the production efficiency in the laser sealing process can be greatly increased.

  By constructing a high-pressure discharge lamp including a ceramic arc tube manufactured by any one of the above manufacturing methods, a high-pressure discharge lamp such as a high-quality metal halide lamp can be obtained at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1A is a cross-sectional view showing a configuration of an arc tube of a PCA tube metal halide lamp with a lamp input of 150 W according to an embodiment of the present invention. FIG. 1B is an enlarged cross-sectional view showing a part of the arc tube. FIG. 2 is a cross-sectional view showing the assembly configuration of the metal halide lamp. The configuration of the arc tube in the present embodiment basically conforms to the configuration according to the above-described conventional technology.

  A PCA tube 2 made of PCA material which is a tube envelope of the arc tube 1 is composed of a discharge main tube portion 3 surrounding a discharge region and PCA thin tube portions 4 and 5 bonded to both ends thereof. Yes. The dimensions of the discharge main tube portion 3 are the tube inner diameter φi = 11.0 mm, the tube outer diameter φo = 12.3 mm, and the total length Lo = 16.2 mm of the central cylindrical portion. The PCA thin tube portions 4 and 5 have a tube outer diameter of 3.2 mm, a hole diameter of 1.03 mm, and a total length of 16.4 mm.

At both ends of the arc tube 1, a pair of W electrodes 6 comprising tungsten (W) coils 8 and 9 (single wire diameter 0.2 mm and 5 coil turns) and W electrode rods 10 and 11 (wire diameter 0.5 mm), respectively. , 7 (interelectrode distance Le10 mm). Further, at the ends of the W electrode rods 10 and 11 extended outward, the power feeders 12 and 13 made of Al ₂ O ₃ —Mo based conductive cermet (outer diameter 0.9 mm, total length 6.0 mm) Are joined by laser welding. The power feeders 12 and 13 are Dy ₂ O ₃ —Al ₂ O ₃ —SiO ₂ type sealing frit 14 (weight composition ratio 61%) as sealing members at the opening ends 4 a and 5 a of the PCA thin tube portions 4 and 5. -17% -22%, melting point 1350 ° C.). External lead rods 15 and 16 made of niobium Nb are joined to the outer ends of the feeders 12 and 13 by laser welding via so-called joining tubes 17 and 18 made of homogeneous Nb.

In the arc tube 1, for example, composition varieties of color temperature _{4300K (DyI 3 19.3% + TmI} 3 9.9% + HoI 3 8.7% + TlI8.4% + NaI22.6%) ( where the composition ratio wt %) Of a light-emitting substance 19 made of a metal halide, about 10 mg of mercury Hg20 as a buffer gas, and about 20 kPa of argon Ar21 as a start-up rare gas. In the gaps 22 and 23 between the PCA thin tube portions 4 and 5 and the W electrode rods 10 and 11, molybdenum coils (Mo) 24 and 25 are provided so as to be wound around the W electrode rods 10 and 11.

  In the configuration of the arc tube 1, three main points are incorporated regarding the hermetic attachment of the power feeding bodies 12 and 13 to the PCA thin tube portions 4 and 5. This will be described with reference to the enlarged view of FIG.

  (1) The power feeders 12 and 13 are basically frit-sealed to the open end portions 4a and 5a of the PCA thin tube portions 4 and 5 which are separated from the discharge main tube portion 3 by about 14 mm. As a result, the temperature of the sealing frit 14 when the lamp is lit is maintained at a low level of about 750 ° C. or less, and the erosion of the sealing frit 14 by the luminescent material 19 is suppressed.

  (2) The filling of the sealing frit 14 is defined so as to cover a distance range of Dmin = 0.2 mm or more from the joint portion between the power feeders 12 and 13 and the W electrode rods 10 and 11. The erosion of the power feeding bodies 12 and 13 by the substance 19 is also suppressed.

  (3) On the other hand, the filling of the sealing frit 14 is defined so as to cover a distance range of Dmax = 2.0 mm or less from the joint portion between the power feeders 12 and 13 and the W electrode rods 10 and 11. The PCA thin tube portions 4 and 5 are prevented from being damaged due to a difference in thermal expansion with the sealing frit 14. When the frit filling is out of the above distance range in the sealing step, the arc tube 1 is discarded as a frit filling defect.

  As shown in FIG. 2, the complete lamp 26 has a configuration in which the arc tube 1 is held inside an outer bulb 27 made of hard glass filled with nitrogen 60 to 80 kPa, and a base 28 is attached to the bulb 1. A quartz shield tube 29 is provided around the arc tube 1 to prevent damage to the outer tube bulb. The lamp 26 has an excellent lamp characteristic of an initial luminous flux of 14,500 lm, an efficiency of 97 lm / W, and an average color rendering index Ra of 92 or more at an input power of 150 W, and a lamp life of a rated life time of 12,000 hrs.

  As described above, when the PCA tube metal halide lamp 26 is mass-produced by the laser sealing device and the sealing process according to the prior art (see Patent Document 2) at the beginning of development, Damage to the PCA thin tube portions 4 and 5 in the sealing process occurred at a maximum rate of about 6%. As a result of analyzing the cause of the occurrence, it was found that the breakage was caused by a relatively large temperature difference between the power supply bodies 12 and 13 to be frit-sealed and the PCA thin tube portions 4 and 5. That is, in the sealing process in the mass production trial, the laser irradiation is converged on the PCA thin tube portions 4 and 5, and the temperature of the PCA thin tube portions 4 and 5 becomes higher than that of the power feeders 12 and 13. It can be said that the cooled PCA thin tube portions 4 and 5 are finally subjected to a tensile stress in a radial outward direction due to a difference in thermal expansion with the power feeders 12 and 13, and finally have been damaged. The breakage mainly occurred in the vertical axis direction of the PCA thin tube portion 4 as schematically shown in FIG. Eventually, in order to suppress the breakage of the PCA thin tube portions 4 and 5 in the frit sealing process by laser irradiation, the temperature difference between the PCA thin tube portions 4 and 5 and the power feeding bodies 12 and 13 to be frit sealed is reduced. This proved to be a basic requirement.

  Based on the above results, in the manufacturing method of the PCA arc tube by the laser sealing method, in order to surely suppress the occurrence of breakage of the PCA thin tube portion in the frit sealing step, the thin tube portion to be frit sealed and the power supply A specific laser sealing device and a sealing process capable of remarkably reducing the temperature difference between the two bodies were studied. Hereinafter, the laser sealing device and the sealing process according to the embodiment of the present invention will be described in detail.

FIG. 4 schematically shows the configuration of the laser sealing device 30 according to the embodiment of the present invention. The laser sealing device 30 is provided with 20 holders 32 made of oxygen-free copper for holding the PCA tube 2 inside a large vacuum glow box 31. Further, CO ₂ gas laser apparatus 33 of the heating sealing and a semiconductor (LD) laser device 34 (both output 200 W), the irradiation unit 33a and 34a incidental to each of which is equipped. Further, a small electric heating tunnel type slow cooling furnace 35 is provided for gradually cooling the PCA thin tube portion 4 or 5 and the power feeding body 12 or 13 immediately before frit fusion sealing.

  The vacuum glow box 31 is designed so that the inside can be evacuated to a high vacuum and the inside can be filled with high-purity argon Ar. Argon Ar is supplied from an accompanying high-purity argon circulation device (not shown). Further, the 20 holders 32 are held by an elongated rail-shaped base body 36 made of a single stainless steel, and the base body 36 is extended and disposed so as to pass through the slow cooling furnace 35. Each holder 32 can be (a) arbitrarily moved individually on the base body 36, and (b) can be stopped at a specific position when the frit is sealed, and is held around the vertical axis Z together with the held PCA pipe 2. Designed to rotate.

  FIG. 5 shows an installation configuration of the PCA tube 2 (in a range indicated by a one-dot chain line X in FIG. 4) in the sealing process by the laser sealing device 30 having the above configuration. For ease of understanding, only a part is shown in cross section. The sealing process includes (1) a first sealing process in which the power supply body 12 is frit-sealed to one narrow tube portion 4 of the PCA pipe 2; (2) the power supply body 12 is then frit-sealed; 2 includes a second sealing step in which the power supply body 13 is frit-sealed to the other thin tube portion 5 of the PCA tube 2 in a state where the luminescent material 19, mercury Hg20 and argon Ar are sealed. The first and second sealing steps themselves are basically the same, and in the following description, the first sealing step will be described.

  The sealing step in the present embodiment includes the following elementary steps performed in a vacuum glow box 31 in which high-purity argon Ar is sealed at about 20 kPa.

  (1) The power supply body 12 in which the W electrode 6 is joined to one end and the Nb external lead rod 15 and the joint Nb pipe 17 are joined to the other end together with the ring-shaped solid sealing frit 14 and the PCA pipe 2 The PCA tube 2 is sequentially installed in the 20 holders 32 after being inserted and installed in the open end 4 a of the thin tube 4.

  (2) Each holder 32 is sequentially moved to a specific position of the base body 36 and stopped.

(3) While rotating the holder 32, the laser radiation from the irradiation unit 33a of the CO ₂ gas laser device 33 and the irradiation unit 34a of the LD laser device 34 is supplied to the open end 4a of the PCA thin tube portion 4 and the power supply, respectively. Irradiation is applied to the open end 4a portion of the body 12, whereby the open end 4a of the PCA thin tube portion 4 and the power feeding body 12 are heated and heated together with the sealing frit 14.

  (4) By continuing the laser irradiation, the sealing frit 14 is finally melted, and the sealing frit 14 is filled in the gap between the opening end 4a of the thin tube portion 4 and the above-mentioned prescribed range of the power feeder 12.

  (5) Next, the holder 32 holding the PCA tube 2 is quickly moved into the slow cooling furnace 35, and the open end 4a of the narrow tube portion 4 and the power feeding body 12 immediately after the frit filling are slowly cooled.

  Of these, the quality of the main sealing process is determined by the elementary processes (3) to (5) from the heating by laser irradiation to the slow cooling treatment by the slow cooling furnace 35.

The characteristics of the laser sealing device 30 and the sealing process using the laser sealing device 30 in the present embodiment are as follows. The PCA thin tube section 4 and the power feeding body 12 to be frit-sealed emit radiation in a wavelength region having a high absorption rate. It is heating by the individual laser device to irradiate. Specifically, the laser sealing device 30 is equipped with a CO ₂ gas laser device 33 (radiation wavelength 10.6 μm) and an LD laser device 34 (radiation wavelength 0.8 μm). In the sealing step, the CO ₂ gas laser device 33 is used for heating the opening end 4a of the PCA thin tube portion 4 and the sealing frit 14, and the LD laser device 34 is used for heating the opening end 4a portion of the power feeder 12. In this case, the PCA member such as the narrow tube portion 4 has a high absorption rate of 90% or more for the laser radiation 10.6 μm from the CO ₂ gas laser device 33, while the metal such as the power feeder 12 is a laser from the LD laser device 34. It is well known that the absorption rate for radiation of 0.8 μm is as high as about 40%. Thereby, the temperature of the opening end part 4a of the PCA thin tube part 4 to be frit-sealed and the power feeding body 12 can be individually controlled with high accuracy. As a result, the temperature difference between the two can be reliably reduced relatively easily, and the occurrence of breakage of the PCA thin tube portion 4 in the actual frit sealing process can be remarkably suppressed.

Note that the sealing frit 14 in the elementary steps (3) to (5) in this embodiment has a very small heat capacity, so that the PCA thin tube portion 4 is irradiated with laser from the CO ₂ gas laser device 33 and the LD laser device 34. The opening end 4a and the power supply body 12 can be heated substantially in conjunction with the temperature rise. Therefore, unlike the sealing process according to the prior art described in Patent Document 2, it is not always necessary to heat the sealing frit by individual laser irradiation.

  Next, with respect to the main elementary steps (3) to (5) of the sealing step in the present embodiment, the specific sealing that can remarkably suppress the occurrence of breakage of the PCA thin tube portion 3 and thus improve the yield of good products. The results of examining the wearing conditions by repeating actual mass production trials will be described.

  At the time of examination, in accordance with the sealing conditions in the current electrothermal sealing process according to the conventional technique in advance, in the open end 4a of one PCA thin tube part 4 to be frit-sealed in the elementary processes (3) to (5) A reasonable temperature curve was set for the heat treatment time t. That is, as shown in FIG. 6, first, in the elementary step (3), the laser radiation output is increased to a maximum temperature of 1450 ° C. in about 60 seconds, and in the next elementary step (4), the highest temperature is increased. It is maintained for a predetermined time t (5 to 10 seconds) for melting and filling the sealing frit 14, and in the final elementary step (5), the maximum temperature 1450 ° C. to about 300 in about 5 minutes in the slow cooling furnace 35. A typical temperature curve was set to decrease to ° C.

  From the above examination results, in order to remarkably suppress the occurrence of breakage of the target PCA thin tube portion 4, at least the opening end portion of the PCA thin tube portion 4 to be frit-sealed in frit melting / filling in the elementary step (4). It is a basic sealing condition that the temperature difference of the temperature Tb of the power feeding body 12 with respect to the temperature Ta of 4a is defined as a relative ratio | Ta−Tb | / Ta within a range of 4.5% or less. I found it. Thereby, the failure occurrence rate of the PCA thin tube portions 4 and 5 combined with the first and second sealing steps in the present embodiment can be remarkably suppressed to a level of 0.8% or less, and the overall good product yield is also improved. It was proved that it can be improved to a high level of 97% or more.

  In addition, in the elementary step (4), as shown in an enlarged view in FIG. 1 (b), the sealing frit 14 is removed from the joint between the opening end 4a of the PCA thin tube portion 4 and the power feeder 12 by Dmin = It is desirable to fill a distance range of 0.2 mm to Dmax = 2.0 mm. From the examination results of the present inventors, the distance D from the joint where the sealing frit 14 is filled mainly depends on the time t for maintaining the maximum temperature in the elementary step (4). It has been found that in order to make the filling of the landing frit 14 within the distance range, the time t should be specified in the range of 5 to 10 seconds. As a result, the filling defect rate of the sealing frit 14 combined with the first and second sealing steps in the present embodiment can be remarkably suppressed to 0.4% or less, thereby contributing to the improvement of the total good product yield. did it. The defective filling rate of the sealing frit 14 is greatly reduced compared to, for example, a level of about 3% in the current electrothermal adhesion process according to the prior art.

Another feature of the sealing process in the present embodiment is that the PCA thin tube section 4 and the power feeding body 12 immediately after the frit filling in the final elementary process (5) are subjected to a slow cooling process, a CO ₂ gas laser device 33 and an LD laser device. 34 to switch to a tunnel-type slow cooling furnace 35. Thereby, the slow cooling process of the several PCA pipe | tube 2 immediately after frit filling can be performed rapidly rapidly, and the production efficiency of a laser sealing process can be improved significantly. As a result, it has become possible for the first time to cope with mass production by the laser sealing device 30 and the sealing process in the present embodiment. If the slow cooling process that requires about 5 minutes for each PCA tube 2 in the elementary step (5) is continued with the CO ₂ gas laser device 33 and the LD laser device 34, the production efficiency is too low and laser sealing is performed. Mass production by this method is impossible.

Note that the CO ₂ gas laser device 33 and the LD laser device 34 used in the sealing step in the present embodiment are not necessarily specified, and the former basically has a high absorption rate by a PCA tube, for example, a wavelength of 3 μm or more. Other laser devices that irradiate far-infrared radiation, and the latter may similarly be replaced with other laser devices that have a high absorption rate by metal, for example, irradiate visible radiation from near infrared with a wavelength of 1 μm or less. .

  As described above, a high pressure discharge lamp such as a metal halide lamp is provided, and the tube envelope is composed of a discharge main tube portion made of PCA material and a pair of narrow tube portions joined to both ends thereof, and the open end of the narrow tube portion PCA light emission in the sealing step by using the laser sealing device and the sealing step in the present embodiment in the manufacturing method of the PCA arc tube for frit-sealing the power feeder holding the W electrode in the part by the laser sealing step The tube breakage of the tube can be remarkably suppressed, thereby improving the overall good product yield in the main sealing process, and a high-quality metal halide lamp can be obtained at a low cost.

  The method for manufacturing a ceramic arc tube according to the present invention is basically applicable to the manufacture of a ceramic arc tube made of, for example, an yttria material in addition to the PCA material.

  The method for manufacturing a ceramic arc tube according to the present invention can suppress breakage of the ceramic thin tube portion in the laser sealing step, and is useful for manufacturing a high-pressure discharge lamp such as a metal halide lamp.

(A) is sectional drawing which shows the structure of the PCA arc tube which comprises the metal halide lamp which is the object of the manufacturing method in embodiment of this invention, (b) is sectional drawing which expanded and showed a part of the arc tube Sectional view showing the assembly configuration of the metal halide lamp The figure which shows the breakage occurrence condition in the thin tube part of the PCA arc tube of FIG. Configuration diagram of laser sealing apparatus according to an embodiment of the present invention The figure which shows the installation state of the PCA pipe | tube in which the sealing process by the laser sealing apparatus is given The figure which shows the temperature curve of the PCA thin tube part with the heat processing set about the sealing process

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emission tube 2 PCA tube 3 PCA discharge main tube part 4, 5 PCA thin tube part 6, 7 Tungsten electrode 8, 9 Tungsten (W) coil 10, 11 W electrode rod 12, 13 Feed body 14 Sealing frit 15, 16 External Lead rod 17, 18 Joint tube 19 Luminescent material 20 Mercury Hg
21 Argon Ar
22, 23 Clearance 24, 25 Molybdenum coil (Mo)
26 Lamp 27 Outer tube valve 28 Base 29 Quartz shield tube 30 Laser sealing device 31 Vacuum glow box 32 Holder 33 CO ₂ gas laser device 34 Semiconductor laser device 33a, 34a Irradiation unit 35 Slow cooling furnace 36 Base body

Claims (6)

A ceramic arc tube provided in a high-pressure discharge lamp, wherein a tube envelope is composed of a discharge main tube portion made of a ceramic material and a pair of ceramic thin tube portions joined to both ends thereof, In the method of manufacturing a ceramic arc tube, the frit sealing is performed by a laser sealing process in order to configure a ceramic arc tube in which a pair of power feeding members holding a W electrode is frit-sealed at an opening end.
The ceramic arc tube characterized in that the open end of the ceramic tube portion to be sealed with the frit and the power supply body are heated by individual laser devices that irradiate radiation in a wavelength region with high absorptance, respectively. Manufacturing method.   In the laser sealing step, the opening end and the frit of the ceramic thin tube portion are heated by a laser device that emits far-infrared radiation, and the power feeder is heated by a laser device that emits visible to near-infrared radiation. Item 2. A method for manufacturing a ceramic arc tube according to Item 1.   The method for manufacturing a ceramic arc tube according to claim 1, wherein a polycrystalline alumina ceramic (PCA) material is used as the ceramic material.   At the time of frit melting and filling in the laser sealing step, the temperature difference of the temperature Tb of the power supply body with respect to the temperature Ta of the opening end portion of the ceramic thin tube portion is set to a relative ratio | Ta−Tb | / Ta to 4.5. The manufacturing method of the ceramic arc tube of Claim 3 prescribed | regulated to the range below%.   The slow cooling process of the ceramic thin tube portion and the power feeding body immediately after frit filling in the laser sealing step is performed in parallel with the laser sealing step by a slow cooling furnace provided adjacent to the laser device. The manufacturing method of the ceramic arc tube in any one of -4.   A high-pressure discharge lamp comprising a ceramic arc tube manufactured by the manufacturing method according to claim 1.

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