JPH09115484A - Sealing part structure of discharge lamp and manufacture of sealing cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a crack in sealing caps by thermal expansion of electrodes at discharge lamp lighting time. SOLUTION: Sealing caps 20 and 30 are constituted by using a functionally gradient material whose composition rate is slantly changed to a layer abundantly containing quartz from a layer abundantly containing molybdenum, and holes 21 and 31 are cut up to a midway part of the layer abundantly containing molybdenum from end parts 20a and 30a of the layer abundantly containing quartz, and bar-shaped electrodes 22 and 32 are inserted through these holes 21 and 31, and the respective tips are inserted into the layer abundantly containing molybdenum. A clearance S is formed between the electrodes 22 and 32 and the holes 21 and 31, and this clearance S is set not less than a difference in thermal expansion between the electrodes 22 and 32 and the sealing caps 20 and 30 at lighting time, that is, an inside diameter of the holes 21 and 31 is set in the size by which the electrodes and a hole inside surface do not contact with each other by expansion of the electrodes 22 and 32 at discharge lighting time, and generation of a crack of the sealing caps 20 and 30 is prevented.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A functionally graded material has been conventionally known as a heat-resistant material for locations where the temperature difference between the inside and the outside is extremely large. International Publication No. WO94 / 06947 "functionally graded material and manufacturing method thereof" is known as a structure of a sealing portion of a discharge lamp using such a functionally graded material.

In this prior art, a functionally graded functional material molded body in which a sealing cap constituting a sealing portion is molded into a columnar shape is 900 ° C.
After calcination for 1 hour, or without calcination, raw processing is performed in consideration of shrinkage associated with calcination, then the molded body is calcined at 1350 ° C. for 6 hours, and then subjected to HIP treatment in an argon atmosphere. Further, cylindrical processing is performed so as to have an appropriate shape as a cap, and electrode holes are formed by displacing the axis lines from both ends of the layer containing many non-metal particles and the layer containing many metal particles, and containing many non-metal particles. The structure is such that the internal electrode is formed in the electrode hole formed from the layer and the external electrode is formed in the electrode hole formed from the layer containing many metal particles.

[0004]

In the above-mentioned prior art, the inner electrode extends from the layer containing a large amount of non-metal particles to the vicinity of the end face of the layer containing a large amount of metal particles, and the outer electrode forms the metal particles. The tips are arranged in a layer containing a large amount of so as to achieve conduction between both electrodes.

By the way, when comparing the thermal expansion coefficients of metal particles and non-metal particles, metal particles such as Mo (molybdenum) are 5 × 10 −6, and non-metal particles such as SiO 2 (quartz) are 5 × 10 −7. There is a big difference in the coefficient of thermal expansion.

Therefore, when the internal electrode is in a layer containing a lot of non-metal particles, cracks are generated due to the difference in thermal expansion between the metal particles and the non-metal particles when the discharge lamp is turned on. Resulting in.

Further, in the conventional method, there is a problem that the sintered body is warped due to processing, particularly when a functionally gradient material whose main raw material is quartz is used.

[0008]

[Means for Solving the Problems] Among the above problems, in the structure of the sealing portion of the discharge lamp according to the present invention, in order to prevent the occurrence of cracks, the composition ratio of non-metal particles and metal particles is continuously changed. An axial hole is formed in a cap made of functionally graded material, and this hole shall have one end open to the end face of the layer containing many non-metal particles and the other end extending halfway through the layer containing many metal particles. , Furthermore, a rod-shaped electrode is inserted into the hole with a gap, and the tip of this electrode is pressed into a layer containing a large amount of metal particles, and the inner diameter of the hole contacts the electrode and the inner surface of the hole due to expansion of the electrode during discharge lighting. I decided not to make it.

Among the above problems, in order to prevent warpage during firing, the method for producing a sealing cap according to the present invention is a cylindrical molded body in which the composition ratio of non-metal particles and metal particles is continuously changed. And then calcining this columnar molded body at a temperature lower than the firing temperature, and one end of the calcined body obtained by this calcining is opened at the end face of the layer containing many non-metal particles and the other end is formed. Forms a hole that extends partway through the layer containing many metal particles,
Insert the rod-shaped electrode from the opening through this hole and insert the tip into the layer containing many metal particles, and then support the calcined body with the electrode so that the layer containing many metal particles is on top. It was baked.

Here, the non-metal particles include one or more selected from alumina, zirconia, magnesia, silica, silicon carbide, titanium carbide, silicon nitride and AlON, and the metal particles include molybdenum, nickel and the like. One or more selected from tungsten, tantalum and chromium.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a discharge lamp to which a sealing structure for a discharge lamp using a functionally graded material according to the present invention is applied. The discharge lamp has openings 11 and 12 formed at both ends of a translucent arc tube 10 made of polycrystalline alumina or the like, and sealing caps 20 and 30 are fitted into the openings 11 and 12, and a sealing material such as a glass solder. 13 and 14 are hermetically sealed by heating with high frequency and infrared rays.

The sealing caps 20 and 30 are made of a functionally graded material in which the composition ratio is gradually changed from a layer containing a large amount of molybdenum to a layer containing a large amount of quartz. Holes 21 and 31 are cut from the end portions 20a and 30a to the middle of the molybdenum-rich layer, the rod-shaped electrodes 22 and 32 are inserted through the holes 21 and 31, and the respective tips are inserted into the molybdenum-rich layer. I'm out.

By inserting the tips of the electrodes 22, 32 into a layer containing a large amount of molybdenum, electrical conduction can be established with the outside. By connecting the ends 20b, 30b of the layer containing a large amount of molybdenum to a power source, molybdenum is removed. Electric power can be supplied to the electrodes 22 and 32 through a portion that occupies most of them.

A gap S is formed between the electrodes 22 and 32 and the holes 21 and 31. This gap S is equal to or larger than the difference in thermal expansion between the electrodes 22 and 32 and the sealing caps 20 and 30 during lighting, that is, the inner diameter of the holes 21 and 31 is increased by the expansion of the electrodes 22 and 32 during discharge lighting. The inner surface of the hole does not come into contact with the inner surface of the hole to prevent cracking of the sealing caps 20 and 30.

When the sealing caps 20 and 30 are fixed to the arc tube 10, the sealing caps 20 and 30 are fixed.
The part where 30 contacts the openings 11 and 12 of the arc tube 10 is
The ends 20a and 30a are occupied by the quartz particles so that the thermal expansion coefficient thereof is substantially the same as the thermal expansion coefficient of the quartz constituting the arc tube 10. This prevents leakage of the luminescent material from the connecting portion between the sealing caps 20 and 30 and the quartz arc tube 10 due to the difference in thermal expansion.

Next, a method of manufacturing the sealing cap will be described with reference to FIG. First, a molded body made of a functionally graded material formed in a columnar shape
It is calcined at ˜1350 ° C. for 1 hour to obtain a calcined body shown in FIG. In the figure, the upper portion is a layer containing a large amount of molybdenum and the lower portion is a layer containing a large amount of quartz.

Next, in consideration of shrinkage during firing of the calcined body, one end portion 20 (on the side containing a large amount of quartz) 20.
a (30a) is machined in the central part to form the electrode insertion hole 21
1) is formed. This cutting is performed until the layer containing a large amount of molybdenum is reached, and the press-fitting hole 23 (3
3) is formed, and as shown in FIG. 2B, the electrode insertion hole 2 is formed.
The tip of the electrode 22 (32) is inserted through 1 (31).

After obtaining a large number of calcined bodies as described above,
Insert the rod-shaped electrode into the electrode insertion hole 21 (31), and
As shown in (c), the calcined body is fired at 1700 to 1750 [deg.] C. for several hours in a state where the rod-shaped electrodes are maintained in the vertical direction to prevent warpage. Here, since the firing is performed with the electrode supported by the supporting portion 41 of the firing container 40, it is not necessary to provide a special supporting member. The firing container 40 and the support portion 41 of the calcined body are made of alumina.

Further, the support of the calcined body by the electrodes does not affect the ratio (gradient) in the composition direction during firing because the functionally graded material forming the calcined body is supported in the direction of gravity.

[0020]

As described above, the structure of the sealing portion of the discharge lamp according to the present invention includes a cap made of a functionally-graded material in which the composition ratio of non-metal particles and metal particles is continuously changed, and a shaft. Direction holes are formed, one end of which is opened at the end face of the layer containing a large amount of non-metallic particles and the other end extends to the middle of the layer containing a large amount of metallic particles. The tip of this electrode was pressed into a layer containing many metal particles, and the inner diameter of the hole was set so that the electrode did not contact the inner surface of the hole due to the expansion of the electrode during discharge lighting. At this time, the force due to the thermal expansion of the electrode is not applied to the layer containing many non-metal particles. Therefore, a crack does not occur in the sealing portion, especially in the layer containing a lot of non-metal particles, and a long-life discharge lamp can be provided.

Further, according to the method for producing a sealing cap of the present invention, a cylindrical molded body in which the composition ratio of non-metal particles and metal particles is continuously changed is molded, and then this cylindrical molding is carried out. The body is calcined at a temperature lower than the firing temperature, and one end of the calcined body obtained by this calcination is open to the end face of the layer containing many non-metal particles in the axial direction and the other end is in the middle of the layer containing many metal particles. A hole extending to the hole is formed, a rod-shaped electrode is inserted from the opening through this hole, the tip is inserted into a layer containing a large amount of metal particles, and then calcination is performed so that the layer containing a large amount of metal particles is on top. Since the body is supported by the electrodes and fired, the warp of the sintered body can be prevented, the composition ratio (gradient) is not affected, and a supporting member is not required during firing. Therefore,
A sealing cap of uniform quality can be provided easily and at low cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a discharge lamp to which a sealing structure for a discharge lamp using a functionally graded material according to the present invention is applied.

2A to 2C are explanatory views of a method for manufacturing a sealing cap according to the present invention.

[Explanation of symbols]

10 ... Arc tube, 11, 12 ... Opening, 13, 14 ... Sealing material, 20, 30 ... Sealing cap, 20a, 20b, 3
0a, 30b ... Ends, 21, 31 ... Holes, 22, 32 ... Electrodes, 40 ... Firing container, 41 ... Supporting portions, S ... Gap.

Claims (4)

[Claims] 1. A sealing structure of a discharge lamp using a cap made of a functionally gradient material in which the composition ratio of non-metal particles and metal particles is continuously changed, wherein an axial hole is formed in the cap. This hole has one end open to the end face of the layer containing a lot of non-metal particles and the other end extending halfway through the layer containing a lot of metal particles, and a rod-shaped electrode is inserted into this hole with a gap between the ends of this electrode. Is press-fitted into a layer containing a large amount of metal particles, and the inner diameter of the hole has a size such that the electrode does not come into contact with the inner surface of the hole due to expansion of the electrode during discharge lighting. 2. The discharge lamp sealing structure according to claim 1, wherein the non-metal particles are alumina, zirconia, magnesia, silica, silicon carbide, titanium carbide, silicon nitride and A.
A sealing structure for a discharge lamp, comprising at least one selected from lON, and metal particles comprising at least one selected from molybdenum, nickel, tungsten, tantalum, and chromium. 3. A cylindrical molded body in which the composition ratio of non-metal particles and metal particles is continuously changed is molded, and then this cylindrical molded body is calcined at a temperature lower than the firing temperature, and this calcination is performed. An axial end of the calcined body obtained by forming an opening in the end face of the layer containing many non-metal particles and the other end extending into the middle of the layer containing many metal particles, and from the opening through the hole A rod-shaped electrode is inserted and its tip is inserted into a layer containing a large amount of metal particles, and thereafter, a calcined body is supported by an electrode so that the layer containing a large amount of metal particles is on top, and the sealing is performed. Method for manufacturing stop cap. 4. The method of manufacturing a sealing cap according to claim 3, wherein the non-metal particle is one selected from alumina, zirconia, magnesia, silica, silicon carbide, titanium carbide, silicon nitride and AlON. Comprised of the above, the metal particles are molybdenum, nickel, tungsten,
A method of manufacturing a sealing cap, comprising one or more selected from tantalum and chromium.