JPH01255151A - Metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To prevent leakage and prolong the lifetime of a lamp by using Al2O3- SiO2-rare earth metal oxide as a lamp sealing material with dysprosium halide encapsulated. CONSTITUTION:A sealing material 2 for joint of an end part choking member 3 shall be in a composition containing 11-35wt.% SiO2, 10-40wt.% Al2O3 and 25-70wt.% one or more of the Gd2O3, Tb2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3. In case the main encapsulated metal halide is dysprosium halide, no other than Gd2O3, Tb2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3 shall be used. Any other rare earth metal oxide will react with the dysprosium halide, and light characteristic and electric characteristic will drop during a long time of service, and leakage be generated. This yields a sealing material with chemical and physical stability even though it is a one using dysprosium halide, wherein leakage is prevented and the lifetime of the lamp prolonged.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention relates to a metal vapor discharge lamp, such as a metal halide lamp, whose end portion is closed with a sealing material by a closing member, This invention relates to improvements in the sealing adhesive.

(Prior art) For example, in a conventional metal halide lamp, a metal halide, mercury, and a rare gas are sealed in an arc tube made of quartz glass, and this arc tube is housed in an outer bulb filled with nitrogen gas, for example, to double-layer the lamp. It had a tubular structure.

However, in recent years, attempts have been made to use translucent alumina tubes, which have better heat resistance than quartz glass, as arc tube bulbs.

When a translucent alumina tube is used for the arc tube bulb, the temperature at the coldest part of the arc tube, which contributes to determining the vapor pressure of the enclosed metal halide, is around 700°C in the case of quartz glass. In the case of translucent alumina, which has excellent heat resistance, the temperature can be raised to 800° C. or higher, and the vapor pressure of the metal halide can be increased, so lamp characteristics such as luminous efficiency can be improved.

For example, when disbrosium halide is the main component of the metal halide, and a combination of sodium decogenide and thallium halide is used as a luminescent material,
It has been confirmed that at 150 W, characteristics such as a luminous efficiency of 95 Ωm/W or more and an average color rendering index (Ra) of 90 or more can be obtained.

Incidentally, FIG. 1 shows a conventional arc tube structure in which translucent alumina is used as the arc tube bulb.

In the figure, 1 is an arc tube bulb made of translucent alumina, and both ends of the arc tube bulb 1 are covered with a molten sealing material 2.
, 2, and are hermetically sealed by end closing members 3, 3 made of cermet, which is a mixture of tungsten and alumina. This end closure member 3.3 has an electrode 4 inside.
, 4, and has external conductive wires 5, 5 protruding from the outside. And inside the arc tube bulb 1,
Metal halide, mercury, and rare gas are sealed as luminescent substances.

Incidentally, although metal halides generally have excellent light efficiency, they also have extremely strong chemical reactivity at high temperatures, and this has a great influence on the selection of each member constituting the arc tube.

That is, the arc tube bulb 1 is made of translucent alumina, which is a material that is resistant to reactions with metal halides, and the end closing member 3゜3 is also made of cermet, which is resistant to reactions with metal halides. It is being

(Problems to be Solved by the Invention) However, the problem is the sealing material 2.2 that airtightly joins the end closing members 3, 3 as described above to both ends of the arc tube bulb 1.

That is, conventionally, it was thought that the sealing material 2.2 should satisfy the following characteristics.

(1) Good wettability with respect to the arc tube bulb 1 made of translucent alumina and the end closing member 3.3 made of cermet.

(2) High temperature when lighting the lamp (sealed part has a special lighting rating of 100
To withstand high temperatures (reaching temperatures as high as 0°C).

(3) The coefficient of thermal expansion is similar to that of alumina and cermet (the coefficient of thermal expansion of alumina is 7.2X10=/
'C level).

(4) It must be possible to melt at a temperature of 1600°C or less during sealing.

Al303, a sealing material used in high-pressure sodium lamps, etc., satisfies these characteristics.
-CaO-MgO-BaO was used.

However, the above Aj72O3-CaO-MgO-B
aO has the disadvantage of reacting with encapsulated metal halides.

In particular, when dysprosium Dy is used as the metal halide, dysprosium strongly reacts with CaO, the luminescence of dysprosium becomes weaker, and the optical properties are significantly deteriorated.

At the same time, the lamp voltage decreases and the electrical characteristics change significantly.

There is a drawback that the reaction progresses over time and the sealing material eventually leaks.

Therefore, in a lamp using an arc tube bulb made of translucent alumina, unless the reaction between the enclosed metal halide and the sealing material as described above is suppressed, the life of the lamp will be significantly adversely affected.

In other words, the sealing material 2.2 satisfies (5) as the fifth condition.
Must have chemical reactivity resistance to encapsulated metal halides.

is required.

Therefore, an object of the present invention is to provide a lamp containing dysprosium halide in which the sealing material does not undergo a chemical reaction.
The object of the present invention is to provide a metal vapor discharge lamp that prevents leakage and improves the life of the lamp.

[Structure of the Invention] (Means for Solving the Problems) As a result of various studies and experiments taken into consideration by the present inventors, the present inventors have found that a lamp containing dysprosium halide can be used as a sealing material. It was found that Al303-3102-rare earth metal oxide is good.

Therefore, as a result of further studies and experiments, SiO2 was used as the sealing material for joining the end closing member.
35% by weight, 10-40% by weight of Al2O3, G d2 03 , Tb2 03 , Ho2
03 , E r2O3 , Tm2O3 , Yb2O
It has been concluded that it is sufficient to use one or more of 25 to 70% by weight of one or more of the following.

(effect) According to the present invention, the following effects are achieved.

Aluminum oxide AΩ2O3 has good wettability with alumina and cermet, which are part materials for arc tubes, and has the effect of improving bonding properties, increasing chemical stability, and has a coefficient of thermal expansion similar to that of alumina and cermet. There is.

Note that if the amount of aluminum oxide added exceeds 40% by weight, the melting point will be 1600° C. or higher, making sealing work difficult. Conversely, if the amount of aluminum oxide added is less than 10% by weight, the above-mentioned effects of aluminum oxide cannot be expected.

Silicon dioxide, SiO2, lowers the melting point and has the effect of making river stone work easier.

It should be noted that if the amount of silicon dioxide added exceeds 35% by weight, the coefficient of thermal expansion decreases significantly, resulting in a large difference between the coefficients of thermal expansion of alumina and cermet, making it easy to leak. Conversely, if the amount of silicon dioxide added is less than 11% by weight, the melting point will be 1.
The temperature will exceed 600°C, making sealing work difficult.

The rare earth metal oxide has the effect of increasing the coefficient of thermal expansion by kV, and the coefficient of thermal expansion of the composition is about the same as that of alumina (7,2
x 10-6/°C) and further forms a compound with alumina to increase chemical stability. Moreover, even if the temperature is lowered relatively quickly after melting during sealing, the sealed product can have a crystalline phase, which leads to an improvement in the sealing strength.

Note that if the amount of rare earth metal oxide added exceeds 70 m96, the coefficient of thermal expansion will be significantly greater than that of alumina, causing leakage. Furthermore, if the amount of rare earth metal oxide added is less than 25% by weight, the effects of the rare earth metal oxide cannot be expected.

By the way, the selection of the rare earth metal oxide is related to the metal halide to be encapsulated, and when the main encapsulated metal halide is dysprosium halide, G d2O3 ,
T b2O3 , H02O3, E r2 o3, Tm2
It was found that neither O3 nor Yb2O3 L could be used.

Other rare earth metal oxides react with the dysprosium halide, leading to deterioration of optical characteristics and electrical characteristics during long-term lighting, and causing leakage.

Therefore, according to the present invention, although it uses dysprosium halide, a chemically and physically stable sealing material can be obtained, preventing the occurrence of leakage, and improving the lamp life. Become. Further, good results can also be obtained with a lamp containing dysprosium halide at a high molar ratio of 80% or more.

(Example) Examples of the present invention will be described below.

The structure of the arc tube is as shown in FIG. 1, and a description thereof will be omitted.

Various samples were made of the sealing materials 2, 2 for airtightly joining the end closing members 3.3 to both ends of the arc tube bulb 1, and a 150 W metal halide lamp was prototyped.

The sealing material is A fl 2O3, S t O2, T m
The mixing ratio of 2O3 was changed.

To explain how to make the sealing material, AN2O3, Si
02, Tm2O3 special grade reagent was weighed, acetone was added thereto, and the mixture was mixed in a ball mill for 122 hours. Furthermore, vinyl acetate polymer was added to make it 5% by weight.
After mixing for a period of time, drying, granulation, and molding were performed to produce a ring-shaped molded product.

The above-mentioned 150W metal halide lamp was prototyped using such a solid sealing material. In this case, the inclusion is Dy
13, NaI, Tj)I.

The airtightness and lifespan of the prototype lamp were investigated, as well as the temperature limit and coefficient of thermal expansion of the adhesive.

The results are shown in Table 1 below.

Table 1 From Table 1 above, the sealing materials of samples NO3, 4 and 5 are good, with Al2O3 being 14-25% by weight and SiO
2 is 2O to 40% by weight, Tm2O3 is 47 to 66% by weight
It is confirmed that SiO2 is in the range of 11 to 35% by weight, Al2O3 is in the range of 10 to 40% by weight, and Tm2O3 is in the range of 20 to 70% by weight.

In addition, instead of Tm2O3, Gd2O3, Tb2O3
, Ho2o3, Er2O3, and Yb2O3, similar results were obtained.

Next, we investigated the types of rare earth metal oxides that can be used using the above-mentioned preferred blending ratio.

The weight ratio relationship of g2O3 to SiO2 to rare earth metal oxide is 14:2O:66 and 25:28.
: For the case of No. 47, the reaction of various rare earth metal oxides with the encapsulated metal halide was investigated, and the results are shown in Table 2 below.

Note that the metal halides to be encapsulated include DyI3, Nal
It is STgI, and the evaluation was based on the optical characteristics and electrical characteristics after lighting for 2000 hours.

Table 2 From the results in Table 2 above, usable rare earth metal oxides include Gd2 as shown in samples Nos.
O3, Tb2O3, Ho2o3, E r2O3
, Tm2O3 and Yb2O3.

[Effects of the Invention] As explained above, according to the present invention, when dysprosium halide is used as a luminescent substance sealed in an arc tube bulb, SiO2 is used as a sealing material in an amount of 11 to 35
% by weight, 10-40% by weight of Al2O3, Gd2O3・Tb2O3・Ho2O3・Er2O3
, Tm2O3, and Yb2O3 in an amount of 25 to 70% by weight.
) to (5) are satisfied, and therefore, there is an advantage that no chemical reaction occurs between the dysprosium halide and the sealing material, and the occurrence of leakage is prevented and the life of the lamp is improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an arc tube of a metal halide lamp, showing a conventional example and an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Arc tube bulb, 2... Sealing material, 3... End closing member, 4... Electrode, 5... External conductor. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (1)

[Scope of Claims] In a metal vapor discharge lamp having an arc tube whose end portion is sealed by a closing member via a sealing material and in which dysprosium halide is sealed, the sealing material has a content of 11 to 35%. % by weight of SiO_2; 10-40% by weight of Al_2O_3; and 25-70% by weight of at least Gd_2O_3, Tb_
2O_3, Ho_2O_3, Er_2O_3, Tm_2
A metal vapor discharge lamp characterized by containing one or more materials selected from O_3, Yb_2O_3.