JPS62219454A - Double base-type metallic vapor discharge lamp - Google Patents

Abstract

PURPOSE:To avoid discharge in an outer tube to prevent current-supply conductors from being fused, by housing a luminous tube into the outer tube and then forming insulation covering on at least one of the current-supply conductors, which are arranged in pairs between the pressed sealing parts of the outer tube and the luminous tube. CONSTITUTION:A luminous tube 13, which is formed by putting mercury and inert gas into a transmitting container having electrodes 14a and 14b, is housed into an outer tube 17, which has the pressed sealing parts 18a and 18b on both its ends and the inside vacuumized, to compose a double base-type metallic vapor discharge lamp such as a metal halide lamp. Then, insulation covering 23 is formed on at least one of current-supply conductors 20a and 20b which are arranged between the pressed sealing parts 18a and 18b of the outer tube 17 and the luminous tube. Thus, discharge generated inside the outer tube, between the current-supply conductors 20 and 20b, is avoided when a vacuum degree inside the outer tube 17 is lowered. Therefore, the current-supply conductors 20 can be prevented from being fused, with the outer tube 17 prevented from being broken during their life.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a double-ended metal vapor discharge lamp.

BACKGROUND OF THE INVENTION In recent years, high-pressure metal vapor discharge lamps such as metal halide lamps and high-pressure sodium lamps have been increasingly used as light sources for indoor lighting.

Particularly in the field of store lighting, there is a demand for the development of compact lamps that can easily control light distribution and that can be miniaturized in order to improve the illumination effect on displayed products.

A double-ended metal vapor discharge lamp meets this demand, and taking a metal halide lamp as an example, it has a structure as shown in FIG. In the figure, reference numeral 1 denotes an arc tube made of quartz, and a pair of electrodes 2m and 2b are hermetically sealed at both ends, and mercury, a rare gas, and a predetermined metal halide are sealed inside. Reference numeral 3 denotes an outer tube made of high silica-containing glass, such as quartz, which has crush sealing parts 4% and 4b at both ends, and the inside thereof is evacuated to a vacuum. Electrodes 2 & , 2b are each made of molybdenum foil 51
L, 6b, current supply conductors sa, eb, molybdenum foil 7&, 7b, external lead wire aa,
It is electrically connected to the caps 91k and 9b via ah. 10 is a getter for adsorbing and removing impurity gas in the outer bulb a, and 11 and 12 are heat insulating films coated on the outer wall surface of the arc tube near the electrodes.

In such lamps, the outer bulb is compact and it is difficult to incorporate a starting aid circuit into the outer bulb, so a ballast with a built-in starter (not shown) is usually used to light the lamp. That is, when the power is turned on, the secondary voltage of the ballast and the high voltage pulse generated by the starter are applied between the electrodes 21L and 2b, and discharge starts between the electrodes 2a and 2b, starting the lamp. .

Problems to be Solved by the Invention As mentioned above, the inside of the outer bulb of a double-ended metal vapor discharge lamp is evacuated to a vacuum, but impurity gas is released from the lamp components during the life of the lamp. , the degree of vacuum inside the outer tube gradually decreases.

If the lamp does not start under these conditions, for example, the lamp may malfunction due to an increase in the starting voltage, the lamp may go out due to an increase in the lamp voltage, or the lamp may fail due to a momentary drop in the power supply voltage. When the light is turned off, a high voltage pulse from the ballast is applied between the current supply conductors slL and eb, causing discharge between the current supply conductors 62L and eb.
In other words, discharge within the outer tube easily occurs. If such discharge occurs within the outer tube, the current supply conductors 62L and eb may be fused or the outer tube 3 may be damaged.

A similar discharge inside the outer tube also occurs due to leakage of the gas filled in from the arc tube 1, and is particularly dangerous in this case because the gas filled is easily dischargeable.

The present invention has been made to solve the above-mentioned problems, and provides a double-ended metal vapor discharge lamp that prevents discharge within the outer bulb and is free from damage during its life.

Means for Solving the Problems The present invention provides a light emitting tube comprising a light-transmitting heat-resistant container having a pair of electrodes and at least mercury and a rare gas sealed therein; and an outer tube for accommodating the tube, and at least one of a pair of current supply conductors disposed between the crushing sealing part and the arc tube is coated with an insulating coating.

Effect: The above configuration can prevent discharge inside the outer tube.
This can prevent the current supply conductor from fusing and the outer tube from being damaged.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a double-ended metal halide lamp according to the present invention, and the lamp power is 160W.
The light is lit using a ballast with a built-in starter at a power supply voltage of 200V. In FIG. 1, 13 is an arc tube made of quartz, and a pair of electrodes 1jLL and 14b are molybdenum foil 16a.

15b for airtight sealing. Inside the arc tube 13, mercury, thulium iodide, dysprosium iodide,
Holmium iodide, sodium iodide, and thallium iodide are sealed, and argon and krypton 86, a radioactive isotope of krypton, are also sealed at a predetermined pressure as a starting rare gas. The distance between the electrodes was 17.5 [1 m,
The inner diameter of the arc tube was 12.5M, and a heat insulating film 16 containing zirconium oxide as a main component was coated on the outer wall of the arc tube near the electrodes.

1 is an outer tube made of quartz with crush seals 1 at both ends.
Molybdenum foils 192L and 19b are used for the crushing sealing portion of the current supply conductor 20.
&, 20b are hermetically sealed. The inner diameter of the outer tube is 20m
The inside is evacuated to vacuum.

Electrodes 14&, 14b are molybdenum foil 15+L.

15b, current supply conductor 202L, 20b, molybdenum foil 191L, 19b, external lead wire 211L, 2
It is electrically connected to the bases 222L and 22b via 1b. 23 is an insulating tube made of quartz, which covers one current supply conductor 202L.

Note that 24 is a getter whose main component is a zirconium-aluminum alloy.

Here, since the current supply conductor 20& is covered with the insulating tube 23, the current supply conductor 20a.

20b, that is, discharge within the outer tube, can be prevented, and the outer tube will not be damaged during its life.

Hereinafter, specific examples of the present invention will be explained.

In the lamp configured as described above, the wall thickness of the insulating tube 23 is 0.
．． Using a 6M quartz tube, the pressure of the gas sealed inside the outer tube was set to 1X10 to 50 T, assuming that the degree of vacuum inside the outer tube would decrease.
We made a number of prototype lamps that varied within the range of Orr, and after lighting them for over an hour, we momentarily cut off the power to turn off the lamps, and then turned on the power again until the lamps restarted. We observed whether an outer-tube discharge occurred.

For comparison, a similar experiment was also conducted on the lamp of the conventional structure shown in FIG. In these experiments, argon was used as the gas sealed inside the outer tube.

The table below shows the results of these experiments.

(Left below) As is clear from the above table, in lamps with conventional structure, glow discharge occurs within the outer bulb until restart when the gas pressure inside the outer bulb is within the range of 0.01 to 6 Torr. It can be seen that when the sealing pressure exceeds 5 Torr, arc discharge occurs within the outer tube. This discharge within the outer tube occurs between the current supply conductors ea and eb, and when arc discharge occurs, the current supply conductor may be fused by repeating the experiment.

On the other hand, in the lamps of the examples of the present invention, no discharge occurred in the outer bulb regardless of the pressure of the gas sealed in the outer bulb, and of course there was no case where the current supply conductor was fused.

Although quartz is used as the insulating tube in the above embodiment, heat-resistant glass other than quartz may be used, and similar effects can be obtained with heat-resistant ceramics such as alumina and zirconia. Furthermore, the present invention can also be practiced with high pressure sodium lamps and high pressure mercury lamps.

Furthermore, in the above implementation), an insulating tube is used as the insulating coating, but for example, a heat-resistant insulating paste containing alumina, silica, zirconia, magnesia, etc. as a main component is applied to the current supply conductor to form an insulating coating. It may be something.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention provides an insulating coating to at least one of a pair of current supply conductors disposed between the outer tube crush seal and the arc tube, thereby reducing the discharge within the outer tube. Therefore, it is possible to provide a double-ended metal vapor discharge lamp which is free from damage during its life.

[Brief explanation of drawings]

FIG. 1 is a front view of a double-ended metal vapor discharge lamp according to an embodiment of the present invention, and FIG. 2 is a front view of a conventional double-ended metal vapor discharge lamp. 13... Luminous tube, 17... mark, outer tube, 20m,
20b... Current supply conductor, 23... Insulating tube.

Claims (1)

[Scope of Claims] An arc tube comprising a light-transmitting container having a pair of electrodes and at least mercury and a rare gas sealed therein, and an outer tube having crushing seals at both ends and housing the arc tube. Prepare,
A double-ended metal vapor discharge lamp characterized in that at least one of a pair of current supply conductors disposed between the crushing sealing part and the arc tube is coated with an insulation coating.