JPH09204902A - High pressure steam discharge lamp - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a long-life ceramic high-pressure vapor discharge lamp. In the high-pressure vapor discharge lamp of the present invention, the arc tube comprises an alumina arc tube main body and an electric conductor having an electrode for sealing the arc tube main body, and the inside of the arc tube main body Is filled with a metal or a metal halide, mercury, and an inert gas, and the arc tube body and the electric conductor are hermetically sealed by a glass frit, and the peripheral wall portion of the electric conductor is sealed. Is provided with a groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high pressure vapor discharge lamp using a translucent alumina tube as an arc tube.

[0002]

2. Description of the Related Art A translucent alumina tube is used for an arc tube of a high-pressure sodium lamp by taking advantage of its stability against alkali metals. In recent years, many attempts have been made to use this translucent alumina tube as an arc tube of a metal halide lamp in which a metal halide is enclosed.

The advantage of using an alumina tube for a metal halide lamp is that it is more chemically and thermally stable against a metal halide that is an enclosure than quartz glass which has been generally used as an arc tube in a conventional metal halide lamp. Therefore, unlike the conventional quartz metal halide lamp, the life is not shortened due to the chemical reaction between the enclosure and the quartz glass, and the life characteristics can be expected to be improved.

In addition, it has been possible to realize a highly efficient design of a lamp by taking advantage of the feature that the limit temperature of use is higher than that of quartz glass.
Since a quartz glass arc tube is highly reactive, there is an advantage that it is possible to encapsulate an alkali metal that cannot be practically encapsulated.

As a method for sealing the arc tube of a ceramic metal halide lamp, a structure in which an end disk coated with a metal as an electric conductor 2 is sealed with a glass frit 6 as shown in FIG. 1 or a conductor as shown in FIG. Body 7
A structure using a conductive cermet end disk is known as the above. As the glass frit 6, alumina,
Those containing calcium oxide as the main component, or those containing alumina or silicon oxide as the main component are used.

[0006]

A life test is conducted on a lamp having scandium iodide, sodium iodide, mercury and argon gas, which is a typical filling material of a high-efficiency metal halide lamp, having the structure shown in FIG. 1 or 2. When carried out, the emission intensity of scandium decreases with the passage of lighting time, and the emission mainly of sodium and mercury becomes Ra,
It was found that the color temperature decreased. Further, at the same time, free iodine was produced, and it was reacted with mercury to produce mercury iodide, and as a result, a lamp was generated in which the starting voltage increased and the lamp went out.

Such a phenomenon occurs early in the life of the lamp, and the reason why the emission intensity of scandium decreases is that it remains in the liquid state near the coldest part of the arc tube without being involved in the discharge during the lighting of the lamp. Scandium iodide reacts with the glass sealing the translucent alumina tube and the electrical conductor,
It is presumed that this is because scandium oxide is produced.

Since scandium oxide is a thermodynamically very stable compound, once produced, it does not participate in light emission. On the other hand, the glass component reacts with iodine to form iodide, and dissociates into metal and iodine in the arc to participate in light emission. For example, in glass containing alumina and calcium oxide as main components, scandium iodide and calcium oxide react with each other to produce scandium oxide and calcium iodide. When the glass component, that is, the generated calcium iodide, participates in light emission, the lamp characteristics are deteriorated in most cases.

The free iodine is generated by the disappearance of the metal due to some cause such as excess iodine depending on the form of the compound of the glass component and iodine, or reaction with an impure gas.
Presumed to happen. Such a phenomenon is particularly remarkable in a lamp in which scandium iodide or sodium iodide is enclosed as a metal iodide, but dysprosium iodide,
A similar phenomenon occurs to some extent in a lamp containing thallium iodide, neodymium iodide, thulium iodide, holmium iodide, etc., although to a different degree.

In order to prevent such a phenomenon, glass which does not react with the encapsulated metal iodide may be used, or the metal iodide and the glass may not come into contact with each other. Not yet developed in research.

On the other hand, the latter method, that is, the sealing of the alumina tube and the electric conductor with glass is performed by heating the glass with a heater of tungsten or carbon set outside the sealing portion in an enclosed inert gas atmosphere to melt the glass. A common method is to flow molten glass into the gap between the translucent alumina tube and the electrical conductor by gravity.

If the sealing is performed by such a method, the glass may be poured more than necessary due to variations in heating conditions, glass composition, and subtle differences in the amount of glass. The excessively flowing glass comes into contact with the liquid metal iodide and causes the above reaction.

Therefore, the object of the present invention is to provide a long-life ceramic high-pressure vapor in which the chemical reaction between the metal iodide and the sealing glass does not easily occur even if the latter method is used and the lamp characteristics are not deteriorated. It is to provide a discharge lamp.

[0014]

In the high-pressure vapor discharge lamp according to the first aspect of the present invention, the arc tube has an alumina arc tube body and an electrical conductor having an electrode for sealing the arc tube body. And a metal or metal halide, mercury, and an inert gas are sealed inside the arc tube body, and the arc tube body and the electrical conductor are hermetically sealed by a glass frit. A groove is provided in the peripheral wall portion of the electric conductor.

In the second invention according to the first invention, the groove is provided in the peripheral wall portion facing the internal space of the arc tube and separated from the end portion of the electric conductor by at least 0.5 mm or more. Is characterized by.

In the third invention according to the first or second invention, the electric conductor comprises an insulator for preventing back arc.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the high-pressure vapor discharge lamp of the first invention according to the present invention, the arc tube is an alumina arc tube body,
An electric conductor having an electrode for sealing the arc tube main body, wherein a metal or a metal halide, mercury, and an inert gas are enclosed in the arc tube main body and the light emission is performed. The tube body and the electric conductor are hermetically sealed by a glass frit, and a groove is provided in a peripheral wall portion of the electric conductor.

A groove is provided along the peripheral wall surface and the end portion of the electric conductor on the arc tube inner space side so that the sealing glass does not flow into the arc tube internal space. Can be suppressed to be small, and the reduction of light emission of the enclosed metal can also be suppressed.

Further, by providing the groove on the peripheral wall surface at least 0.5 mm or more from the end of the electric conductor on the inner space side of the arc tube, and by specifying the position of the groove, the metal iodide and the glass are separated. The contact can be minimized, and the reduction of the light emission of the encapsulating metal can be greatly suppressed.

Therefore, it is possible to provide a ceramic high-pressure vapor discharge lamp which can suppress the chemical reaction between the metal iodide and the glass and prevent the characteristics from deteriorating during the operation of the lamp and which has excellent life characteristics.

The cross-sectional shape of the groove may be a U shape (see FIG. 5), a square shape (see FIG. 6), a V shape (see FIG. 7), etc., and the groove may be a single layer. It may be double or multiple. Further, the cross-sectional shape may be W-shaped.

In addition, the end portion of the electric conductor on the inner space side of the arc tube means a flat portion facing the inner space of the arc tube. However, when the portion of the electric conductor facing the inner space of the arc tube is not a flat surface, for example, if there is a flat surface even in part, the flat surface means the end portion, and there is no flat surface in a W shape. In such a case, the tip of the electric conductor means the end portion.

In FIGS. 5 to 7, the end surface of the electric conductor on the inner space side of the arc tube corresponds to the end portion.

[0024]

The present invention will be described below with reference to the preferred embodiments.

FIG. 3 is an explanatory view showing a conventional arc tube structure.

As shown in the figure, 10 is a light emitting tube, 1 is a light emitting tube body, and is a translucent alumina tube.

Reference numeral 4 is an insulator for preventing back arc, which is an insulator made of alumina. Reference numeral 2 denotes an electric conductor (electrically conductive disc) having a back arc preventing insulator 4, which is a metal-coated disc here, and may be a cermet disc.

Although the electric conductor 2 is provided with the back arc preventing insulator 4 in this embodiment, it may not be provided.

Reference numeral 3 is an electrode held by the electric conductor 2, 5 is a metal coating layer, 6 is a glass frit, 8 is an encapsulant, and 11 is an arc tube body hermetically sealed by the electric conductor 2 and the glass frit 6. Sealing parts at both ends of 1. The relationship between the volume of the sealing portion and the volume of the glass frit is 1.2 to
2.0 to 16 m when frit melts against 4.0 mm ³ .
It is designed to be m ³ . Further, the shape of the conductor 2 is a cylindrical shape having a diameter of 2.5 mm and a length of 15 mm here. This is because the shape is matched with the shape of the sealing portion 11, and the shape is not limited to the cylindrical shape.

Next, the sealing portion 11 of the alumina arc tube body is sealed with the electric conductor 2 and the glass frit 6. The distance between the electrodes is 30 mm, and the inner diameter of the arc tube is 15 mm.

The glass frit 6 is made of aluminum oxide,
It is composed of dysprosium oxide and silicon oxide as components. In the arc tube, the filling material 8, namely, scandium iodide 5 mg, sodium iodide 30 mg, mercury 20 mg, and argon gas at room temperature were 4 × 10 ³ Pa.
It is enclosed.

The electric conductor 2 is formed by coating the surface of a ceramic base with platinum 5, and has an electrode 3 held at one end. Then, the back-arc preventing ceramic insulator 4 having a thickness of 1.0 mm is attached on the platinum-coated surface of the conductor 2 on the electrode side end. (See FIG. 4) Ten lamps designed in this way were prototyped and subjected to a life test.

The lighting conditions are as follows: all the lights are 250 watts, and the cycle is 5.5 hours on and 0.5 hours off.
Run for 00 hours.

As a result, the initial efficiency is 90 lm / W, Ra
68, color temperature was 4300K, but after 1000 hours efficiency 62lm / W, Ra28, color temperature 2800K
Had fallen. (The characteristic value is represented as an average value of 10 lamps.) Then, when the spectral distribution after 1000 hours was measured, the spectrum intensity of scandium was reduced to ¼ or less of the initial value. (Characteristic value is expressed as an average value of 10 lamps.) Next, a lamp is provided with 10 lamps by using an electric conductor 2 (see FIG. 5) having a groove at a position in contact with the back arc preventing insulator 4 in a sectional view. I made a prototype lamp. Then, perform the life test 1 as above.
It was carried out for 000 hours. The specifications are the same as the above except that the groove of the electric conductor 2 is provided.

As a result, the lamp characteristics after 1000 hours were as good as the initial ones with an efficiency of 85 m / W, Ra 68 and a color temperature of 4300K. (The characteristic value is expressed as an average value of 10 lights) Next, the thickness of the back arc preventing insulator 4 is set to 0.25,
A life test was performed by changing the length to 0.5 and 0.75 mm.

As a result, the specifications of the thicknesses of 0.5 and 0.75 mm showed good lamp characteristics after 1000 hours, like the thickness of 1.0 mm, but the specifications of the thickness of 0.25 mm showed the groove. Similar to the lamp using the electric conductor 2 not provided, the deterioration of the lamp characteristics after 1000 hours was large.

This is because the sealing glass that has not completely stopped in the groove has a thin back arc preventing insulator 4,
It is considered that it happened because it flowed into the electrode side.

From the above test results, in a high-pressure vapor discharge lamp in which an alumina tube is used as an arc tube and an electric conductor is sealed with a glass frit, a distance of 0.5 mm or more is placed from the end of the electric conductor on the electrode side. It was found that by providing a groove on the peripheral wall surface, a lamp having extremely excellent life characteristics can be obtained.

Since the electrical conductor of this embodiment has a back arc prevention insulator, the thickness of the back arc prevention insulator is changed, but the back arc prevention insulator is used. If not, a groove may be provided on the peripheral wall surface at a distance of 0.5 mm or more from the electrode-side end surface of the electric conductor in a sectional view.

[0040]

In the high-pressure vapor discharge lamp of the first invention according to the present invention, the arc tube comprises an alumina arc tube main body and an electric conductor having an electrode for sealing the arc tube main body. In the interior of the arc tube body, a metal or a metal halide, mercury, and an inert gas are sealed, and the arc tube body and the electrical conductor are hermetically sealed by a glass frit. A groove is provided in a peripheral wall portion of the electric conductor.

In the second invention according to the first invention, the groove is provided in the peripheral wall portion facing the inner space of the arc tube and separated from the end portion of the electric conductor by at least 0.5 mm or more. Characterize.

In the third invention according to the first or second invention, the electric conductor is provided with a back arc preventing insulator.

As described above, according to the present invention, the contact between the metal iodide and the sealing glass can be suppressed to a small level,
It is also possible to suppress a decrease in light emission of the enclosed metal.

Further, by specifying the position of the groove, it is possible to minimize the contact between the metal iodide and the sealing glass, and it is possible to greatly suppress the reduction of the light emission of the enclosed metal.

Therefore, according to the present invention, the chemical reaction between the metal iodide and the sealing glass can be made difficult to occur,
Since it is possible to provide a high-pressure vapor discharge lamp that has excellent life characteristics while preventing deterioration of characteristics during lamp travel, it is of great industrial value.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a ceramic high-pressure vapor discharge lamp using a metal-coated disk.

FIG. 2 is a schematic sectional view of a ceramic high-pressure vapor discharge lamp using a cermet disk.

FIG. 3 is an explanatory view showing a conventional arc tube structure.

FIG. 4 is a diagram showing an electrical conductor having a conventional electrode.

FIG. 5 is a diagram showing an electrical conductor having an electrode according to an embodiment of the present invention.

FIG. 6 is a diagram showing an electrical conductor having electrodes according to another embodiment of the present invention.

FIG. 7 is a view showing an electric conductor having electrodes according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc tube body 2, 7 Electrical conductor 3 Electrode 4 Insulator for back arc prevention 5 Metal coating layer 6 Glass frit 8 Encapsulation 9 Groove 10 Arc tube 11 Sealing part

Claims (3)

[Claims] 1. The arc tube comprises an alumina arc tube main body and an electrical conductor having an electrode for sealing the arc tube main body, and a metal or a metal halide is provided inside the arc tube main body. And mercury and an inert gas are enclosed, and the arc tube body and the electric conductor are hermetically sealed by a glass frit, and a groove is provided in a peripheral wall portion of the electric conductor. High-pressure vapor discharge lamp characterized by being 2. The high pressure according to claim 1, wherein the groove is provided in a peripheral wall portion facing the inner space of the arc tube and separated from the end portion of the electric conductor by at least 0.5 mm or more. Steam discharge lamp. 3. The high-pressure vapor discharge lamp according to claim 1, wherein the electric conductor comprises an insulator for preventing back arc.