JPH03108249A - One-side sealing type metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To extend the time until the sealed gas generates a leak and extend the lamp life by connecting electrode shaft sections and external lead wires on the opposite side faces of metal foil conductors respectively. CONSTITUTION:Electrodes 3a and 3b are constituted of electrode shaft sections 4a and 4b and coil sections 5a and 5b, and shaft sections 4a and 4b are connected to metal foil conductors 6a and 6b sealed in a crush seal section 2 respectively. External lead wires 7a and 7b are connected to conductors 6a and 6b respectively, and lead wires 7a and 7b are connected to conductors 6a and 6b on the opposite side faces to shaft sections 4a and 4b. Even if coil sections 5a and 5b are laterally displaced from a bulb axis by the inclination of shaft sections 4a and 4b, they are displaced in the direction of symmetrical positions to the bulb center, the arc center nearly coincides with the bulb center, and the luminous characteristic is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a single-sealed metal vapor discharge lamp such as a small metal halide lamp.

(Prior technology) High-intensity discharge lamps, that is, high-pressure metal vapor discharge lamps (HID), which were traditionally used for outdoor lighting and factory lighting, are now often used for indoor lighting with low ceilings such as stores. It has become.

The reason why lamps came to be used in stores, etc. was that arc tubes were made smaller, and along with this, the outer tube of the lamp was changed from hard glass to quartz, which has higher heat resistance, and the external shape was also made smaller and more compact. In addition to this, they can take advantage of the conventional characteristics of high efficiency, high color rendering, high output, and long life, so they can be used in place of incandescent or halogen light bulbs, making it possible to save energy. Can be mentioned.

In particular, metal halide lamps are superior to other discharge lamps in terms of high efficiency and high color rendering, and are extremely suitable for illuminating displayed products, so they are becoming increasingly popular.

By the way, in order to miniaturize the arc tube, if we use a conventional valve structure with both ends sealed, not only will molding be labor-intensive, but the sealing portion will become large, resulting in a large hole shape. There are disadvantages such as increased heat loss from the light tube through the stop.

For this reason, in this type of small lamp, the arc tube shape is a so-called single-sealed type, in which a crushed seal is formed at only one end of the bulb, and a pair of electrodes are sealed to the crushed seal end. structure is adopted.

In this way, since there is only one sealing part, the heat loss is smaller than that of a bulb with both ends sealed, which makes it possible to improve the luminous efficiency, and also eliminates the need for molding.
Moreover, since there is only one sealing portion, which tends to be relatively large in shape compared to the size of the discharge space, there is an advantage that the entire structure can be made smaller.

By the way, in such a single-sealed arc tube, a pair of metal foil conductors are sealed on the collapsed pair I, an electrode shaft portion and an external lead wire are connected to these metal foil conductors, respectively, and these electrode shaft portions are connected to an external lead wire. are introduced into the discharge space, and electrode coil portions are provided at the tips of these electrode shaft portions so as to face each other.

In conventional lamps, electrode shafts and external lead wires connected thereto are welded to the same side of the metal foil conductor.

(Issues to be solved by the invention @) However, such small metal halide lamps that are fixed on one side have to be lit with a higher lamp load in order to increase luminous efficiency compared to conventional double-end sealed lamps. When the input power is WL (watts) and the inner surface area of the arc tube is S (c), the lamp is lit with a high load WL/S of about 20 to 70.

For this reason, not only the temperature of the arc tube increases, but also the vapor pressure within the discharge space. Such high gas pressure, for example, the encapsulated metal halide, tends to leak through the gap between each of the electrically conductive members sealed in the crushing sealing part and the glass of the sealing part.

That is, the electrode shaft and the external lead wire are sealed to the crushing sealing part via a metal foil conductor, but these electrode shaft part, metal foil conductor, and external lead wire are adhered to the glass of the sealing part. This keeps the discharge space airtight.

However, during lighting, the temperature of the sealing part rises and the gas pressure of the metal halide in the discharge space increases to more than about 20 atmospheres, and this high-pressure gas causes the bond between the electrode shaft part and the glass of the sealing part to increase. Infiltrate by penetrating the surface. The intrusion of such high-pressure gas impedes the adhesion between the electrode shaft portion and the sealing portion glass, and generates a leak gap. This kind of leakage gap gradually progresses to the bonding surface between the metal foil conductor and the sealing glass, and further spreads to the bonding surface between the external lead wire and the sealing glass, and finally the electrode shaft and the metal A leak gap is created between the foil conductor, external lead wire, and the sealing glass to provide electrical continuity between the discharge space and the outside, and as a result, there are rare cases where metal halides in the discharge space leak to the outside. .

In this case, if the electrode shaft and the external lead wire are each joined to the same surface of the metal foil conductor, leakage occurs between the electrode shaft, the metal foil conductor, the external lead wire, and the glass sealing part. Since the gaps are generated on the same side, a leak gap that provides electrical continuity between the discharge space and the outside is generated at the shortest distance. Therefore, there is a problem that the time until leakage occurs is shortened, that is, the lamp life is shortened.

The present invention was made under these circumstances, and is a single-sealed metal that prolongs the lamp life by prolonging the time until leakage occurs even if the gas filled in the discharge space leaks. The aim is to provide a steam discharge lamp.

[Structure of the Invention] (Means for Solving the Problems) The present invention is characterized in that the electrode shaft portion and the external lead wire that are joined to the metal foil conductor are respectively joined to mutually opposite surfaces of the metal foil conductor. shall be.

(Function) According to the present invention, since the electrode shaft portion and the external lead wire are respectively bonded to opposite surfaces of the metal foil conductor, a leak gap occurs between the electrode shaft portion and the sealing glass. However, the creepage length of the actual contact area becomes longer until a leak gap occurs between the external lead wire and the sealing glass, and a leak gap that creates electrical continuity between the discharge space and the outside occurs. The length is longer than before. Therefore, the time until leakage occurs becomes longer, and the lamp life becomes longer.

(Example) The present invention will be described below based on an example shown in FIGS. 1 to 3.

The drawing shows an arc tube of a metal halide lamp with a lamp power of 150 W. In the drawing, reference numeral 1 denotes an arc tube bulb made of quartz glass, which is formed into an elliptical spherical shape with an internal volume of 0.5 cc. In such an elliptical spherical valve l, the long sleeve direction is the valve axis, and a flat crushing sealing part 2 is formed at one end in a direction perpendicular to the valve axis.

Inside the bulb l, a pair of electrodes 3a and 3b are arranged spaced apart and facing each other in the axial direction of the bulb, and these electrodes 3a and
, 3b are each sealed to the crush sealing portion 2.

The electrodes 3a, 3b are composed of electrode shaft parts 4a, 4b and electrode coil parts 5a, 5b.
The electrode coil parts 5as and 5b are made of, for example, pure rhenium wire with a wire diameter of 0.5 mm, and the electrode coil parts 5as and 5b are made of thoriated tungsten wire with a wire diameter of 0.5 mm, for example, and are wrapped around the bent tips of the electrode shaft parts 4a and 4b three to four times. It is made up of a roll.

The electrode coil parts 5a and 5b facing each other are spaced apart from each other by about 61 points along the valve axis direction.

These electrode shaft portions 4a and 4b are made of a metal foil conductor 6a such as Mo or the like sealed to the crushing sealing portion 2, respectively.
[Connected to ib.

In this case, each electrode shaft part 4a, 4b is arranged so as to be on the opposite side to the side surface of the respective metal foil conductor [ia, 6b. That is, as shown in FIG. 2, one electrode shaft portion 4a is welded to the rear surface of one metal foil conductor 6a, while the other electrode shaft portion 4b is welded to the front surface of the other metal foil conductor 6b. This is what is being done.

External lead wires 7a and 7b are connected to these metal foil conductors 6a and fib, respectively, and these external lead wires 7a and 7b are led to the outside from the end surface of the crush sealing portion 2.

In this case, each of the external lead wires 7a, 7b is connected to the metal foil conductor 6a, 6b to which they are connected, on the opposite side of the electrode shaft portions 4a, 4b connected to the metal foil conductor 8a, 6b. has been done. That is, one external lead wire 7a is welded to the front surface of one metal foil conductor 6a, while the other external lead wire 7b is welded to the rear surface of the other metal foil conductor cb. Therefore, when viewed from one metal foil conductor 6a, the electrode shaft portion 4 connected to it
a and the external lead wire 7a are connected to opposite sides of each other, and when viewed from the other metal foil conductor 6b, the electrode shaft portion 4b connected to this and the external lead wire 7b are also connected to the opposite sides of the conductor 6b. This is what is being done.

In addition, inside the valve l, there is a rare gas for starting, a predetermined amount of mercury, 5n12, Nal, T I Is I n I
% NaBr, LiBr, and other metal halides are enclosed.

Further, in such a single-sealed metal halide lamp, the lamp current (2) during stable lighting is 1.8A, and the lamp input power W at this time is set to be 150W. The inner surface area S of the arc tube is approximately 3.50 cm, and the lamp load per unit surface area of the arc tube is approximately 43 W/c.
-.

The operation of the embodiment with such a configuration will be explained.

When forming the crush sealing part 2 at the end of the bulb 1, the metal foil conductors 6a and 6b, to which the electrodes 3a and 3b and the external lead wires 7a and 7b are connected in advance, are inserted into the still open opening of the bulb. The valve opening wall is heated with a burner or the like to soften it. Next, with a pincher (not shown), the softened valve wall is removed by arrow A shown in FIG.
,, is crushed in the direction A, thereby closing the opening and sealing the metal foil conductors 8a and 6b at the same time.

In this case, the metal foil conductors 8a and 6b are sandwiched between the glasses, and there is a tendency for the electrode shaft portion 4a, which is joined to one side of the metal foil conductor 6a shown in the figure, to be tilted in the direction shown by the imaginary line. .

In this embodiment, one electrode shaft portion 4a is welded to one surface of one metal foil conductor 6a, while the other electrode shaft portion 4b is welded to one surface of the other metal foil conductor 6b. These electrode shaft parts 4a, 4b
have opposite inclination directions.

Therefore, the electrode coil parts 5a, 5b are connected to the electrode shaft part 4.
Even if they are deviated laterally from the bulb axis due to the inclinations of a and 4b, they will be deviated in the direction of the symmetrical position with respect to the bulb center, so that the arc center will almost coincide with the bulb center.

Therefore, the light emitting characteristics are stable, and since the arc does not approach the bulb wall unevenly, the bulb l is not locally heated, resulting in a long life.

Each external lead wire 7a, 7b is connected to the metal foil conductor 6a, 6b to which it is connected.
Since the electrode shaft portions 4a and 8b are connected to the surface opposite to the electrode shaft portions 4a and 4b, it takes a long time for the gas in the discharge space to leak.

That is, one electrode shaft portion 4a is connected to one metal foil conductor 6a.
The external lead wire 7a connected thereto is welded to the front surface of the metal foil conductor 6a. Further, the other electrode shaft portion 4b is welded to the front surface of the other metal foil conductor 6b, while the other external lead wire 7b connected thereto is welded to the rear surface of this metal foil conductor 6b. . Therefore, in the unlikely event that a leak occurs, these electrode shaft portions 4a, 4b and the metal foil conductor 8a
, 6b and the external lead wires 7a, 7b, respectively, and the leakage gaps that occur at the contact surfaces between the sealing portion glass are generated on alternate surfaces along the direction of the lead wires, thereby separating the discharge space from the outside. The creepage distance of the leak gap to be electrically conductive is substantially increased. Therefore, the time it takes for the gas in the discharge space to leak becomes longer, that is, the lamp life is extended.

In particular, in small sealed discharge lamps that are lit under a high load WL/S of about 20 to 70, the gas pressure in the discharge space during lighting is as high as about 20 atm or more. However, the electrode shaft portions 4a, 4b and the external lead wires 7a, 7b are connected to metal foil conductors 6a, 7b, respectively.
By connecting to the surface opposite to 6b, it is possible to prevent leakage from occurring at an early stage, resulting in a long life.

In the above embodiment, as shown in FIG. 2, one electrode shaft portion 4a is welded to the rear surface of one metal foil conductor 6a, and the other electrode shaft portion 4b is welded to the rear surface of the other metal foil conductor 6b. Although the electrode is welded to the front surface to prevent eccentricity of the arc due to the inclination of the electrode, the present invention is not limited to this point.

That is, FIG. 4 shows another embodiment of the present invention, in which both electrode shaft portions 4a and 4b are welded to the rear surfaces of metal foil conductors Oa and Ob, respectively, whereas the external lead wire 7a and 7b are welded to the front surfaces of metal foil conductors 6a and 6b, respectively.

Furthermore, the present invention is not limited to metal halide lamps, but may be any discharge lamp in which a crushed seal is formed only at one end of the bulb. You can.

[Effects of the Invention] As explained above, according to the present invention, since the electrode shaft portion and the external lead wire are respectively connected to the opposite surfaces of the metal foil conductor, there is no leakage that causes conduction between the discharge space and the outside. The length of the gap is longer than before. Therefore, the time until leakage occurs becomes longer, and the lamp life becomes longer.

[Brief explanation of drawings]

1 to 3 show one embodiment of the present invention, in which FIG. 1 is a sectional view of a small metal halide lamp, FIG. 2 is a sectional view taken along the line ■-■ in FIG. FIG. 4 is a cross-sectional view of a small metal halide lamp showing another embodiment of the present invention. l... Arc tube bulb, 2... Crushing sealing part, 3a,
3b... Electrode, 4a, 4b... Electrode shaft portion, 5a,
5b... Electrode coil portion, 8a, 8b... Metal foil conductor, ? a, 7b...External lead wire.

Claims (1)

[Claims] A crushed sealing part is formed at one end of the arc tube, a pair of metal foil conductors is sealed to this crushed sealing part, an electrode shaft part and an external lead wire are joined to these metal foil conductors, and the electrode shaft part In a single-sealed metal vapor discharge lamp in which an electrode coil portion is provided at the tip of the electrode coil portion and these electrode coil portions are opposed to each other in the discharge space, the electrode shaft portion and the external lead wire joined to the metal foil conductor are each made of metal. A single-sealed metal vapor discharge lamp characterized by bonding foil conductors on opposite sides.