JPH06168704A - Electrode material and high-pressure discharge lamp using thereof - Google Patents

Abstract

PURPOSE:To provide an electrode material having conductivity, high heat resistance and corrosion resistance, and a stable characteristic over a long period by forming the electrode material with a mixed sintered body of YAG grains and a metal constituent. CONSTITUTION:Sealing bodies 1 are jointed with a glass seal 5 at both ends of a cylindrical arc generating tube 2 made of a YAG multi-crystal body. An electrode 3 is jointed into a hole 1b inside each sealing body 1, and a lead rod 4 is jointed into a hole 1c on the outside respectively. The sealing bodies 1 have conductivity. When voltage is applied across the lead rods 4, 4 at both ends, an electric discharge is generated between the electrodes 3, 3, and luminescence can be obtained. The lead rods 4, 4 and the electrodes 3, 3 are not penetrated, the sealing bodies 1 and the arc generating tube 2 are jointed with the seal 5, and the arc generating tube 2 can be completely airtightly sealed. The sealing body 1 is mainly made of YAG, its thermal expansion coefficient is approximate to that of the arc generating tube 2 made of the YAG multi-crystal body, and good airtightness can be maintained even at a high temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high pressure metal vapor discharge lamp and a sealing body used for the same.

[0002]

2. Description of the Related Art High-pressure metal vapor discharge lamps such as high-pressure mercury lamps and high-pressure sodium lamps have been used as illumination for a wider area than before. Recently, metal halide lamps having high luminous efficiency and excellent color rendering properties have been used.

In this metal halide lamp, as shown in FIG. 3, an appropriate several kinds of light emitting metal halides are enclosed in an arc tube 12 together with mercury and a rare gas, and the arc tube 12
Both ends of which are sealed with a conductive sealing body 11,
A discharge electrode 13 is attached to the inside of the sealing body 11, and a lead rod 14 is attached to the outside thereof.
By discharging between 3 and 13, light is emitted.

Further, as the material of the arc tube 12, quartz glass, translucent polycrystalline alumina, single crystal sapphire or the like is used, and the sealing body 11 is made of alumina (Al ₂ O 3).
_A cermet composed of a composite of ₃ ) and tungsten (W) is used (for example, JP-A-57-151148).
No. 52-71695, etc.).

[0005]

However, in the conventional high pressure discharge lamp, when the arc tube 12 is made of quartz glass, it reacts with a halide, so that only a limited amount of a luminescent metal halide can be enclosed. However, the color rendering property was limited, and the life was short.

When the arc tube 12 is made of polycrystalline translucent alumina, it has a low linear transmittance of 30% or less, which makes it difficult to use as a discharge lamp.

Further, when the arc tube 12 is made of single crystal sapphire, the transmittance and the life can be improved, but it is extremely difficult to seal the end portion, and the center is bulged and complicated. There was a problem that it was not possible to manufacture arc tubes of various shapes.

As described above, the arc tube 12 having excellent characteristics has not been obtained conventionally. Therefore, in recent years, it has been proposed to use a yttrium-alumina-garnet (hereinafter referred to as YAG) polycrystalline material as the material of the arc tube 12 (see Japanese Patent Laid-Open No. 4-233154).
However, since an appropriate sealed body 11 has not been obtained, it has not been put to practical use.

[0009]

In view of the above, according to the present invention, an electrode material is formed by a mixed sintered body of YAG particles and a metal component such as tungsten and molybdenum.

Further, according to the present invention, an end portion of an arc tube made of a transparent material such as polycrystalline YAG is sealed by using the above electrode material,
This is a high pressure discharge lamp.

[0011]

EXAMPLES Examples of the present invention will be described below.

FIG. 1A shows an example in which the electrode material of the present invention is used in a sealing body for a high pressure discharge lamp. This sealing body 1 has a step portion 1a.
Cylindrical body with a hole that does not penetrate each other on both end faces 1
b, 1c are formed. And this sealing body 1 is Y
It is composed of a mixed sintered body of AG particles and metal components such as tungsten and molybdenum. The crystal structure of the sintered body is shown in FIG.
A metal phase 22 such as tungsten (W) or molybdenum (Mo) is present so as to cover the particles 21, and the metal phases 22 are connected to each other to be electrically conductive as a whole.

Next, a high pressure discharge lamp using this sealing body 1 is shown in FIG. The sealing body 1 is joined to both ends of a cylindrical arc tube 2 made of a YAG polycrystal with glass seals 5, and an electrode 3 is provided in an inside hole 1b of the sealing body 1 and an outside hole. Lead rods 4 are joined to 1c. When manufacturing this high-pressure discharge lamp, the sealing body 1 is bonded to only one end of the arc tube 2 in advance, a metal halide or the like is sealed inside the arc tube 2, and then the other end is sealed. The stopper 1 is joined.

In such a discharge lamp, since the sealing body 1 has conductivity, when electricity is applied between the lead rods 4 and 4 at both ends, it is possible to discharge between the electrodes 3 and 3 to emit light. At this time, the lead rod 4 and the electrode 3 do not penetrate, and the sealing body 1
Since the arc tube 2 and the arc tube 2 are joined by the glass seal 5,
The inside of the arc tube 2 can be completely hermetically sealed.
Further, since the main component of the sealing body 1 is YAG, the thermal expansion coefficient thereof is close to that of the arc tube 2 made of a YAG polycrystalline body, and excellent airtightness can be maintained even at high temperature. Furthermore Y
The arc tube 2 made of an AG polycrystal has excellent translucency,
Even complicated shapes can be easily manufactured.

Although the arc tube 2 is made of a YAG polycrystal in the above embodiment, the sealing body 1 of the present invention is also applicable to the arc tube 2 made of a transparent material such as sapphire or glass. Can be used.

Further, in the above-mentioned embodiments, the example used as the sealing body for the high pressure discharge lamp was shown, but the electrode material of the present invention has conductivity, and is excellent in corrosion resistance, abrasion resistance and the like. Since it is a material, it can be used for various other purposes.

Experimental Example Al ₂ O ₃ and Y ₂ O ₃ having a purity of 99% or more were mixed with Y ₃ A.
It was weighed so as to have a YAG composition of ₁₅ O ₁₂ and mixed and pulverized in a resin pot mill using high-purity alumina balls.
Then, it was calcined to obtain YAG powder, which was then crushed using the above-mentioned mill and balls, added with a binder, and then granulated with a spray dryer to obtain a secondary granulation raw material. The obtained secondary granulation raw material was sized, and as shown in Table 1, tungsten (W) or molybdenum (Mo) powder having an average particle diameter of 1 μm or less was added as a metal component, and the mixture was dry-mixed in a polypot. It was molded into the shape of.

An electrode 3 made of tungsten and a lead rod 4 are inserted into the holes 1b and 1c of this molded body, and 1700
After sintering and integrating at ~ 1800 ° C, the electrode 3 and the lead rod 4
The electrical resistance between them and the thermal expansion coefficient of the sealed body 1 were measured. Further, after bonding this sealing body 1 to the arc tube 2 made of a YAG polycrystal with the glass seal 5, the bonding surface was observed. The results are shown in Table 1.

[0019]

[Table 1]

No. 1 in Table 1 No. 12 is a comparative example made of a mixed sintered body of Al ₂ O ₃ and W, which has a low thermal expansion coefficient, and thus cracks are generated during sealing.

On the other hand, No. 1 to 4 and 6 to 10 contain YAG particles as a main component and contain a metal component such as W or Mo in an amount of 30% by weight or less, and thus have a thermal expansion coefficient of 80 × 10 ^-7 / ° C. or more. Then, since the thermal expansion coefficient (86 × 10 ⁻⁷ / ° C.) of the YAG polycrystal forming the arc tube was close, no crack was generated during sealing. Further, it can be seen that when the content of the metal component is 10% by weight or more, the resistance value of the sealing body can be 1000 mΩ or less, and good conductivity can be provided. Therefore, it is desirable that the metal components such as W and Mo be contained in the range of 10 to 30% by weight.

[0022]

As described above, according to the present invention, since the electrode material is formed of the mixed sintered body of YAG particles and the metal component such as tungsten and molybdenum, it has conductivity, heat resistance and corrosion resistance. It is possible to obtain an excellent electrode material.

Further, according to the present invention, an end portion of an arc tube made of a transparent material such as polycrystalline YAG is sealed by using the above electrode material,
Since the high-pressure discharge lamp has the same thermal expansion coefficient as the arc tube and the sealing body, a good sealing structure can be achieved even at high temperatures, and the high-pressure discharge lamp has stable characteristics over a long period of time. Can be obtained.

Furthermore, by forming the arc tube from polycrystalline YAG, it exhibits excellent translucency and can be easily manufactured even in a complicated shape.

[Brief description of drawings]

FIG. 1A is a vertical sectional view showing a high pressure discharge lamp sealing body using an electrode material of the present invention, and FIG. 1B is a partial sectional view showing a high pressure discharge lamp using this sealing body. .

FIG. 2 is a schematic diagram showing a crystal structure of an electrode material of the present invention.

FIG. 3 is a vertical sectional view showing a conventional high pressure discharge lamp.

[Explanation of symbols]

 1: Sealing body 2: Arc tube 3: Electrode 4: Lead rod 5: Glass seal

Claims (2)

[Claims] 1. An electrode material comprising a mixed sintered body of YAG (yttrium / alumina / garnet) particles and a metal component such as tungsten or molybdenum. 2. An end portion of an arc tube made of a transparent body is sealed with an electrode material made of a mixed sintered body of YAG (yttrium / alumina / garnet) particles and a metal component such as tungsten or molybdenum. High-pressure discharge lamp.