JPH10125284A - Structure of sealing portion of light emitting tube, and manufacture of cap for sealing portion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oxidization in a metal rich portion in the case where a sealing cap for a discharge lamp is made of a functionally gradient material. SOLUTION: The sealing cap 3 is constituted of a core 5 and a coating layer 6 made of SiO2 . The core 5 is made of a functionally gradient material, the composition rate of which is gradually changed from a molybdenum rich portion 5a to a silica rich portion 5b. Electrode inserting holes 7, 8 are formed from both ends of the core 5 to the molybdenum rich portion 5a, wherein an outside electrode 9 is inserted into the electrode inserting hole 7, and an inside electrode 10 is inserted into the electrode inserting hole 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed structure of a discharge lamp using a cap made of a functionally graded material and a method of manufacturing a sealed cap.

[0002]

2. Description of the Related Art A high-intensity discharge lamp such as a metal halide lamp used as a light source for a projector television (PTV) or the like is configured such that one end of an arc tube made of a translucent ceramic or the like is closed with a cap with electrodes, and then the other end is opened. Then, a light emitting substance such as amalgam, metal halide, xenon, etc. is put in, and then the other end is closed with a cap with an electrode.

The cap has a structure in which a through hole is formed in the axial direction, an electrode rod is inserted into the through hole, and a portion protruding into the arc tube is an internal electrode, and a portion protruding outside the arc tube is an external electrode. However, with this structure, since the temperature of the sealing portion in the light emitting state is as high as 900 to 1500 ° C., a gap is formed between the electrode rod and the cap due to a difference in thermal expansion coefficient between the electrode rod and the cap. This causes a leak from the gap.

Therefore, a sealing structure using a functionally graded material in which the composition ratio of non-metal particles such as silicon oxide and metal particles such as molybdenum is continuously changed is considered.
Specifically, the above-described functionally graded material is processed into a columnar shape and the outer end side is a portion where metal particles are rich, the inner end side is a portion where non-metal particles are rich, and the metal particles are rich from both ends. The electrode insertion holes are formed separately so that they do not intersect.Internal electrodes are inserted into one electrode insertion hole, and external electrodes are inserted into the other electrode insertion hole. A structure in which the particles are rich is considered.

[0005] According to the above configuration, since no through hole for inserting the electrode is formed, there is no leakage through the through hole. The inner end of the cap (the side facing the discharge)
Is extremely high in temperature, but since this portion is substantially made of the material constituting the arc tube, there is no occurrence of cracks or the like due to a difference in the coefficient of thermal expansion and leakage.

[0006]

As described above, when the cap is made of a functionally graded material, leakage of the encapsulated luminescent substance can be effectively prevented, but a problem occurs in a portion where the metal particles are rich. That is, as described above, the arc tube becomes extremely hot during lighting. If a portion rich in metal particles is exposed in this state, oxidation of the metal starts at about 300 ° C. in air, which may cause conduction failure.

Therefore, the entire arc tube is housed in an outer tube filled with an inert gas, but it is difficult to completely prevent oxidation even with such a structure.

[0008]

In order to solve the above problems, a sealed structure of an arc tube according to the present invention comprises a cap for closing an opening of the arc tube, which comprises a core portion and a coating layer.
The core is made of a functionally graded material in which the composition ratio of the metal particles and the material forming the arc tube or the material forming the arc tube has a coefficient of thermal expansion that is continuously changed, and the coating layer is made of a luminescent material. It is made of a material having a thermal expansion coefficient similar to that of the material forming the tube or the material forming the arc tube, and covers at least the metal particle-rich portion of the core portion, and further extends to the metal particle-rich portion of the core portion. One end of the internal electrode was inserted.

Examples of the material constituting the arc tube or a material having a thermal expansion coefficient close to the material include silicon oxide, alumina, zirconia, magnesia, silica, silicon carbide, titanium carbide, silicon nitride, and AlON. The particles include molybdenum, nickel, tungsten, tantalum, chromium, and the like.

As a method of manufacturing a cap constituting the above-mentioned sealing portion structure, the following methods (1) to (5) can be mentioned. (1) In a porous mold such as a gypsum mold, a slurry of a material constituting the arc tube or a material having a thermal expansion coefficient similar to that of the material constituting the arc tube is supplied and allowed to deposit, and then excess slurry is removed. After that, a slurry containing a metal particle and a material constituting the arc tube or a material having a similar thermal expansion coefficient to the material constituting the arc tube is poured and molded.
A method of baking after necessary steps such as drying. (2) In a porous mold such as a gypsum mold, a slurry of a material having a thermal expansion coefficient similar to that of the material forming the arc tube or the material forming the arc tube is supplied and allowed to fill, and then, in the slurry, A method in which a metal particle or a slurry containing the metal particle is added, molded, and then fired after performing necessary steps such as demolding and drying. (3) A gradient function in which the composition ratio of metal particles and a material constituting the arc tube or a material having a thermal expansion coefficient similar to the material constituting the arc tube is continuously changed on a porous mold such as a gypsum mold. A core portion made of a material is set, the periphery of the core portion is surrounded by a tube, and a slurry of a material having a thermal expansion coefficient similar to that of the material forming the arc tube or the material forming the arc tube is supplied inside the tube. Then, a coating layer made of a material having a thermal expansion coefficient close to that of the material forming the arc tube or the material forming the arc tube is formed around the core portion, and then subjected to necessary steps such as demolding and drying. Then, firing method. (4) The metal particles and the arc tube are formed in an unfired sleeve-shaped coating layer formed by molding a material having a thermal expansion coefficient similar to that of the metal particles and the material constituting the arc tube or the material forming the arc tube. Inserted an unfired core made of functionally graded material in which the composition ratio of the material or the material constituting the arc tube and the material with a similar thermal expansion coefficient was continuously changed, and then passed through necessary steps such as drying. Then, a method of simultaneously firing the coating layer and the core. (5) a core portion made of a functionally graded material in which the composition ratio between the metal particles and the material forming the arc tube or the material forming the arc tube has a coefficient of thermal expansion that is continuously changed,
After forming a coating layer by immersing in a slurry of a material forming the arc tube or a material having a thermal expansion coefficient similar to that of the material forming the arc tube, and then performing necessary steps such as drying, the coating layer and the core portion are formed. And firing method.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view of a discharge lamp to which the sealing portion structure according to the present invention is applied. In the discharge lamp, openings 2, 2 are formed at both ends of a translucent light emitting tube 1 made of quartz glass or the like, sealing caps 3, 3 are fitted into these openings 2, 2, and high-frequency, infrared, or burner is used. Airtight sealing is achieved by heating.

The sealing cap 3 is composed of a core portion 5 and a coating layer 6, and the core portion 5 is made of a functionally graded material whose composition ratio changes from a molybdenum-rich portion 5a to a silica-rich portion 5b. The electrode insertion holes 7, 8 are formed from both ends of the core portion 5 to the molybdenum-rich portion 5a, and the external electrode 9 is inserted into the electrode insertion hole 7, and the internal electrode 10 is inserted into the electrode insertion hole 8, respectively.

The electrodes 9 and 10 are fixed to the insertion holes 7 and 8 by inserting the electrodes 9 and 10 before firing and fixing them by shrinkage force during firing, or by inserting the electrodes 9 and 10 after firing. An electrode fixing coil may be inserted into 8 and fixed by the tightening force of the coil.

As described above, by inserting the tips of the internal electrodes 10 and 10 into the molybdenum-rich portions 5a, they can be electrically connected to the external electrodes 9 and 9 and become electrically conductive.
Is connected to a power source, so that the molybdenum-rich portion 5a
Power can be supplied to the internal electrodes 10 and 10 via the.

The coating layer 6 made of the same material as that of the arc tube 1 or a material having a thermal expansion coefficient similar to that of the arc tube 1 is provided with a hole 6a through which the external electrode 9 penetrates. It is preferable to melt or fill with a heat-resistant paint to prevent the molybdenum-rich portion 5a from being exposed to prevent oxidation.

FIG. 2 is a cross-sectional view showing another embodiment of the cap. As in this embodiment, one end of the cap 3 opens in the axial direction of the inner end surface of the cap 3 and the other end 5a is molybdenum-rich. A concave portion 11 extending to the concave portion 1 is formed.
1 A gap is formed between the inner peripheral surface and the internal electrode 10, and a large difference in the coefficient of thermal expansion between tungsten, which is the material of the internal electrode 10, and quartz, which is the material of the cap 3, even at a high temperature during lighting. Even if there is, cracks are not generated, and excess luminescent substance can be stored in the concave portion 11 in a liquid state.

As a structure of the cap 3, it is conceivable that the entire core is made of molybdenum or molybdenum-rich. However, in such a configuration, the core 3 becomes extremely hot during discharge. Cracks occur due to the difference in the coefficient of thermal expansion between the part and the coating layer, and this easily becomes a leak path. On the other hand, as in the present invention, at the inner end of the cap 3, the core portion is a silica-rich portion 5b.
In this case, the difference in the coefficient of thermal expansion between the core and the coating layer can be considered to be almost zero, so that no crack occurs. In the outer end portion, there is a difference in thermal expansion coefficient between the core portion and the coating layer even in the cap of the present invention,
Since the temperature of this portion is lower than that of the inner end portion, cracks hardly occur, and even if it does occur, it does not easily become a leak path.

Next, a method for manufacturing the sealing cap will be described with reference to FIGS. (Manufacturing Method 1) First, as shown in FIG. 3 (a), a slurry of SiO ₂ alone is cast into a gypsum mold, and the coating is performed to form a coating layer. Next, as shown in FIG. 3B, an acrylic tube is set on a gypsum mold, a mixed slurry of SiO ₂ and Mo is poured into the acrylic tube, and a core made of a functionally graded material is placed on the coating layer. Form. Here, the mixing ratio of the mixed slurry was as follows: SiO ₂ : 10 to 30 g, Mo: 10 to 30 g.
g, pure water: 15 to 45 g. However, SiO ₂ is based on quartz, and when amorphous is used, the above amount is increased to 2.2 / 2.6 times. Then, as shown in FIG. 3 (c), when the body is deposited to a predetermined thickness, the mold is removed, and
After drying at ~ 50 ° C for 2 days and raw processing, 1100-1
After calcining at 250 ° C. for 1 hour, an electrode insertion hole or the like is formed in the calcined body, and then calcined at 1740 ° C. for 10 minutes to obtain a cap shown in FIG.

(Manufacturing Method 2) First, as shown in FIG. 4A, an acrylic tube is set up on a gypsum mold, and a single slurry of SiO ₂ is cast through the inside of the acrylic tube. When the coating layer is formed, Mo powder or Mo slurry is added to the SiO ₂ single slurry as shown in FIG. Thereafter, as shown in FIG. 3 (c), when the meat is deposited to a predetermined thickness, it is removed from the mold, dried at 40 to 50 ° C. for 2 days, processed green, and temporarily processed at 1100 to 1250 ° C. for 1 hour. After firing, the calcined body is provided with an electrode insertion hole and the like, and then fired at 1740 ° C. for 10 minutes to obtain a cap shown in FIG.

(Production Method 3) First, after the mixed slurry described in the above Production Method 1 is kneaded in a ball mill for 2 hours or more, the mixture is subjected to normal pressure or pressure (for example, 0.25 kg / cm ² at 1 kg / cm ²⁾ .
Casting is performed for 0 minute to obtain a columnar unfired core. Next, as shown in FIG. 5A, the core portion was set on the gypsum mold so that the SiO ₂ -rich portion was below, and
Further, an acrylic tube is erected so that the erected core becomes the center, and a single slurry of SiO ₂ is poured into the acryl tube as shown in FIG. Then, as shown in FIG. 3 (c), by gradually increasing the pressure after a certain time, as shown in FIG. 3 (c), when the SiO ₂ is more than 2 mm thicker than the core portion, the sludge is discharged, and after demolding, the mold is removed at 40 ° C. Dry for 2 days and calcine at 1100 ° C. For the electrode insertion hole, a hole is formed after calcination.
Thereafter, the cap is fired in a vacuum at a peak temperature of 1500 to 1760 ° C. for 1 to 10 minutes to obtain a cap shown in FIG.

(Manufacturing Method 4) First, as shown in FIG. 6A, an unsintered SiO ₂ coating layer having one end closed is formed by casting or press molding. Next, FIG.
As shown in (2), the calcined body of the core obtained by the same method as described in the manufacturing method 3 is inserted. The clearance at the time of inserting the calcined body of the core portion into the coating layer can be absorbed by making the shrinkage ratio of the coating layer at the time of firing larger than that of the calcined body of the core portion. Thereafter, a peak temperature of 1500
By firing in vacuum at １７1760 ° C. for 1 to 10 minutes,
The cap shown in FIG.

(Manufacturing Method 5) First, a calcined body of the core portion is obtained by the same method as described in the manufacturing method 3. As shown in FIGS. 7 (a) and 7 (b),
The SiO ₂ layer was coated on the surface of the calcined body of the core by pulling was immersed in the iO ₂ slurry and dried. This step is repeated several times to form a coating layer. Thereafter, the cap is fired in a vacuum at a peak temperature of 1500 to 1760 ° C. for 1 to 10 minutes to obtain a cap shown in FIG.

[0023]

As described above, according to the arc tube sealing structure of the present invention, the core of the cap for closing the opening of the arc tube is made of a functionally graded material, and this core is Since the cap is covered with a coating layer of silica or the like, cracks and the like hardly occur on the inner end side of the cap, and oxidation of the metal particles can be prevented on the outer end side where the metal particles are rich, so that a good conduction state can be maintained.

Further, according to the method of manufacturing a cap for a sealing portion according to the present invention, it is possible to easily manufacture a cap in which the inner core is made of a functionally graded material and the outer is covered with a coating layer of silica or the like. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view of a discharge lamp to which a sealing structure according to the present invention is applied.

FIG. 2 is a sectional view showing another embodiment of the cap.

FIGS. 3A to 3D are diagrams illustrating a method of manufacturing a sealing portion cap according to the present invention in the order of steps.

FIGS. 4A to 4D are diagrams illustrating another manufacturing method of the sealing portion cap according to the present invention in the order of steps.

FIGS. 5A to 5D are diagrams illustrating another manufacturing method of the sealing portion cap according to the present invention in the order of steps.

FIGS. 6A to 6C are diagrams illustrating another manufacturing method of the sealing portion cap according to the present invention in the order of steps.

FIGS. 7A to 7C are diagrams illustrating another manufacturing method of the sealing portion cap according to the present invention in the order of steps.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Arc tube, 2 ... Opening, 3 ... Cap, 5 ... Core part, 5
a: molybdenum-rich portion, 5b: silica-rich portion, 6: coating layer, 7, 8: electrode insertion hole, 9: external electrode,
10 internal electrodes.

Claims (6)

[Claims] In a sealed structure of an arc tube in which a cap having an electrode attached to an opening of a translucent arc tube is inserted, the cap includes a core portion and a coating layer, and the core portion includes metal particles and light emission. The material constituting the arc tube or the material constituting the arc tube is made of a functionally graded material in which the composition ratio is continuously changed with the material having a thermal expansion coefficient similar to that of the material constituting the arc tube, and the coating layer is made of the material constituting the arc tube or the arc tube A material having a coefficient of thermal expansion close to that of the material constituting the above, covers at least the metal particle-rich portion of the core portion, and one end of the internal electrode is further inserted to the metal particle-rich portion of the core portion. A sealed structure of an arc tube. 2. A slurry of a material constituting the arc tube or a material having a thermal expansion coefficient similar to that of the material constituting the arc tube is supplied into a porous mold such as a gypsum mold and the like, and then the excess slurry is added. After removing, the slurry containing the metal particles and the material constituting the arc tube or the material having a similar thermal expansion coefficient to the material constituting the arc tube is poured and molded, and thereafter, necessary mold removal, drying, etc. are performed. A method for producing a cap for a sealing portion, comprising firing after passing through a process. 3. A slurry of a material constituting the arc tube or a material having a coefficient of thermal expansion similar to that of the material constituting the arc tube is supplied into a porous mold such as a gypsum mold and the like, and the slurry is then filled. And a metal particle or a slurry containing the metal particles is added thereto, followed by molding, followed by performing necessary steps such as demolding and drying, and then firing. 4. The composition ratio between a metal particle and a material forming an arc tube or a material having a thermal expansion coefficient similar to that of a material forming an arc tube is continuously changed on a porous mold such as a gypsum mold. A core made of a functionally graded material is set, the core is surrounded by a tube, and a slurry of a material constituting the arc tube or a material having a thermal expansion coefficient similar to that of the arc tube is provided inside the tube. To form a coating layer of a material having a thermal expansion coefficient similar to the material forming the arc tube or the material forming the arc tube around the core portion, and thereafter,
A method for producing a cap for a sealing portion, comprising baking after necessary steps such as demolding and drying. 5. The metal particles and the arc tube are formed in an unfired sleeve-shaped coating layer formed by molding a metal particle and a material constituting the arc tube or a material having a thermal expansion coefficient close to that of the arc tube. Inserting an unfired core made of a functionally graded material in which the composition ratio of the material constituting the arc tube or the material constituting the arc tube is continuously changed with the material having a similar thermal expansion coefficient, followed by drying, etc. And then, simultaneously firing the coating layer and the core portion. 6. A core made of a functionally graded material in which the composition ratio of metal particles and a material constituting an arc tube or a material having a thermal expansion coefficient similar to that of a material constituting an arc tube is continuously changed to emit light. After forming a coating layer by immersing in a slurry of a material having a thermal expansion coefficient similar to that of the material forming the tube or the material forming the arc tube, and then performing necessary steps such as drying, the coating layer and the core And a method for producing a cap for a sealing portion.