JPH0656757B2 - Double-ended metal vapor discharge lamp - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a double-ended metal vapor discharge lamp.

2. Description of the Related Art In recent years, the use of high-pressure metal vapor discharge lamps represented by metal halide lamps and high-pressure sodium lamps as a light source for indoor lighting has been increasing. In particular, in the field of store lighting, in order to enhance the lighting effect on the displayed products, it is desired to develop a compact lamp that can easily control the light distribution and can downsize the fixture.

The double-ended metal vapor discharge lamp responds to such a demand, and has a structure shown in FIG. 2 when a metal halide lamp is taken as an example. In the figure, reference numeral 1 denotes an arc tube made of quartz, and a pair of electrodes 2a and 2b are hermetically sealed at both ends, and mercury, a rare gas and a predetermined metal halide are sealed inside. Reference numeral 3 is an outer tube made of high-silica-containing glass, for example, quartz, having crushing sealing portions 4a and 4b at both ends, and the inside is evacuated to a vacuum. Electrodes 2a and 2b are molybdenum foil 5a and
5b, current supply conductors 6a, 6b, molybdenum foils 7a, 7b of the outer tube sealing portion, and external lead wires 8a, 8b are electrically connected to the caps 9a, 9b. Reference numeral 10 is a getter for adsorbing and removing the impure gas in the outer tube 3, 11a, 11
Reference numeral b is a heat insulating film applied to the outer wall surface of the arc tube in the vicinity of the electrodes.

In such a lamp, since the outer bulb is compact and it is difficult to incorporate a starting auxiliary circuit in the outer bulb, the lamp is usually lit by using a starter built-in ballast (not shown). That is, when the power is turned on, the secondary voltage of the ballast and the high voltage pulse generated by the starter superimposed on it are applied between the power supplies 2a and 2b, the discharge is started between the electrodes 2a and 2b, and the lamp is started. To do.

Problems to be Solved by the Invention As described above, the outer tube of the double-ended metal vapor discharge lamp is evacuated to a vacuum, but during the life of the lamp, impure gas is released from the constituent members of the lamp, The degree of vacuum inside the outer tube gradually decreases. If the lamp does not start under these conditions, for example, a rise in the starting voltage causes a fault, a rise in the lamp voltage causes extinction, and a momentary drop in the power supply voltage causes the lamp to turn off. In such a case, the high voltage pulse from the ballast is applied between the current supply conductors 6a and 6b, so that the current supply conductor 6a
A discharge between a and 6b, that is, a discharge in the outer tube is easily generated. When such discharge in the outer tube occurs, the current supply conductor 6a,
6b may be melted and the outer tube 3 may be damaged.

A similar discharge in the outer tube is also caused by leakage of the enclosed gas from the issuing tube 1, and in this case, the enclosed gas is an easily dischargeable gas, which is more dangerous.

As a result of various studies to solve the above-mentioned problems, the inventors have found that the outer tube discharge can be prevented by covering the current supply conductor with an insulating tube. An example of this is shown in FIG. 3, in which members common to those in FIG. 2 are designated by the same reference numerals. In FIG. 3, reference numeral 12 is an insulating tube that covers the current supply conductor 6a, and is made of a heat resistant insulating material such as quartz, alumina, or zirconia. Since this insulating tube completely covers the current supply conductor, even if the degree of vacuum in the outer tube 3 is lowered, no discharge will occur from the current supply conductor 6a, and discharge in the outer tube can be prevented. .

However, during the production of a large number of lamps having such a configuration, the insulating tube is damaged due to vibration, impact, etc. during the manufacturing process, during transportation, or during use, and the current supply conductor 6a is exposed inside the outer tube 3, so It was found that the intended purpose of preventing discharge could not be achieved in some cases.

The cause of damage to the insulating tube is described in more detail. The inner diameter of the insulating tube is made somewhat larger than the wire diameter of the current supplying conductor in order to insert the current supplying conductor into the insulating tube. It was found that when added to the lamp, the insulating tube made strong contact with the current supply conductor and eventually chipped from the end. Since the current supply conductor is exposed in the outer tube at the portion where the insulating tube is lacking, it is impossible to completely prevent discharge in the outer tube.

The present invention has been made to solve the above problems, and provides a double-ended metal vapor discharge lamp that does not cause discharge in the outer bulb and damage to the lamp during the life of the lamp.

Means for Solving the Problems The present invention provides an arc tube in which at least mercury and a rare gas are enclosed in a translucent container having a pair of electrodes, and the arc tube having a crushed sealing portion at both ends. An outer tube for accommodating, at least one of a pair of current supply conductors disposed between the crushing seal portion and the arc tube is covered with an insulating tube of the same material as the outer tube, and The insulating tube is fixed to the outer tube at the crushed and sealed portion.

Action With the above configuration, it is possible to prevent damage to the insulating tube due to vibration, shock, and the like, and further to prevent discharge in the outer tube and fusing of the current supply conductor and damage to the outer tube.

Embodiment Hereinafter, one embodiment 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, which has a lamp power of 150 W.
Therefore, the light source is lit at a power supply voltage of 200 V using a ballast with a built-in starter. In FIG. 1, 13 is an arc tube made of quartz, and a pair of electrodes 14a and 14b are hermetically sealed by using molybdenum foils 15a and 15b. Mercury, thulium iodide, dysprosium iodide, holmium iodide, sodium iodide, and thallium iodide are enclosed in the arc tube 13, and the radioactive isotopes krypton 85 of argon and krypton 85 are used as starting rare gases. It is sealed at a predetermined pressure. Distance between electrodes 17.5m
m, the inner diameter of the arc tube is 12.5 mm, and the heat insulating film 16 containing zirconium oxide as a main component is applied to the outer wall of the arc tube near the electrodes.

Reference numeral 17 denotes an outer tube made of quartz, and has crushed sealing parts 1 at both ends.
8a and 18b, and molybdenum foils 19a and 19b are used for the crushed sealing portion to supply current supply conductors 20a and 2b.
0b is hermetically sealed. The inner diameter of the outer tube is 20 mm, and the inside is evacuated to vacuum.

The electrodes 14a and 14b are molybdenum foils 15a and 15b, current supply conductors 20a and 20b, molybdenum foils 19a and 19, respectively.
b, the base 22a via the external lead wires 21a, 21b,
22b is electrically connected.

Reference numeral 24 is a getter whose main component is a zirconium-aluminum alloy.

Here, 23 is an insulating tube made of the same material as the outer tube 17, that is, made of quartz, and covers the current supply conductor 20a.
The insulating tube 23 has a wall thickness of 0.5 mm and has a length from the arc tube 13 to the molybdenum foil 19a of the outer tube sealing portion, and one end 23a shown by a broken line is the outer tube sealing section. At this time, the insulating tube 23 is fixed to the outer tube 17 because it is integrally sealed with the outer tube 17 at the crushing sealing portion 18a.

As described above, since the current supply conductor 20a is covered with the insulating tube 23, even if the vacuum degree in the outer tube 17 is lowered during the life of the lamp, the discharge between the current supply conductors 20a and 20b, that is, the discharge in the outer tube, It is possible to prevent the lamp from being damaged due to fusing of the current supply conductors 20a and 20b, and the insulating tube 23 is fixed to the outer tube 17 at the crushed sealing portion of the outer tube 17, so that vibration and impact may occur. The insulating tube 23 is not damaged and the effect of preventing the discharge inside the outer tube is not impaired.

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

In the lamp having the above structure, assuming that the degree of vacuum inside the outer tube is lowered, argon is introduced into the outer tube at 1 × 10 ^{−4 to} 5
A lot of lamps enclosed within the range of 0 Torr were prototyped, these lamps were turned off for 1 hour or more, then the power was momentarily turned off to turn off the lamps, and then the power was turned on again until the lamp restarted. It was observed whether or not a discharge inside the outer tube occurred. Next, after performing a vibration test on these lamps, the presence or absence of discharge in the outer tube was similarly observed. The conditions of the vibration test are a vibration frequency of 10 to 100 Hz, an acceleration of 2 G, and a vibration time of 2 hours. The results of the discharge test in the outer tube before and after the vibration test are shown in Table 1 columns A and B.

Also, for comparison, the same experiment was performed on a lamp having the structure shown in FIG. The results are shown in Table 1, columns C and D.
Shown in the column. As a conventional example, the same experiment was conducted on the lamp having the configuration shown in FIG. In this case, no vibration test was conducted. The results are shown in column E of Table 1.

As is apparent from Table 1, in the lamp according to the present invention, none of the lamps in the insulating tube was damaged by the vibration test, and none of the lamps caused the discharge in the outer tube regardless of the pressure of the enclosed gas in the outer tube.

On the other hand, in the lamp having the insulating tube shown in FIG. 3, the discharge in the outer tube could be prevented before the vibration test.
The vibration test caused damage such as chipping or cracking of the insulating tube in the majority of the lamps, and discharge in the outer tube was generated from this damaged portion, leading to fusing of the current supply conductor.

As described above, it has been found that the lamp according to the present invention can surely prevent the discharge in the outer tube. This is because the insulation tube is fixed to the outer tube at the outer tube sealing part, so even if vibration or shock is applied to the lamp, the insulation tube and the current supply conductor do not come into strong contact and damage to the insulation tube is prevented. Because you can.

As shown in the above embodiment, the quartz tube which is the same material as the outer tube is used for the insulating tube. However, if the material of the outer tube and the outer tube are different, even if the outer tube is crushed and sealed, the insulating tube may be fixed. Since the thermal expansion coefficients of the two are different, they cannot be firmly fixed to each other, the insulating tube is cracked and the intended purpose cannot be achieved, and cracks and leaks of the crushed seal portion are likely to occur, which is not desirable.

In this embodiment, quartz is used for the outer tube and the insulating tube, but other high silica-containing glass such as Vycor or hard glass having high heat resistance may be used. The present invention can also be implemented for high pressure sodium lamps and high pressure mercury lamps.

As described above, according to the present invention, at least one of the pair of current supply conductors arranged between the collapsible sealing portion of the outer tube and the arc tube is covered with an insulating tube made of the same material as the outer tube. In addition, by fixing the insulating tube to the outer tube at the crushing sealing portion, it is possible to provide a double-ended metal vapor discharge lamp that prevents discharge in the outer tube and damage to the lamp due to the discharge in the outer tube throughout the life. It is a thing.

[Brief description of drawings]

FIG. 1 is a front view of a double-ended metal vapor discharge lamp which is an embodiment of the present invention, FIG. 2 is a front view of a double-ended metal vapor discharge lamp which is a comparative example, and FIG. 3 is a conventional example. It is a front view of a base metal vapor discharge lamp. 13 ... Arc tube, 14a, 14b ... Electrode, 17 ... Outer tube, 18a, 18b ... Crushing sealing part, 22a, 22b ...
... base.

Claims (1)

[Claims] 1. An arc tube having at least mercury and a rare gas sealed in a translucent container having a pair of electrodes, and an outer tube having a crushing seal portion at both ends and accommodating the arc tube. ,
At least one of a pair of current supply conductors arranged between the crushing seal portion and the arc tube is covered with an insulating tube made of the same material as the outer tube, and the insulating tube is the crushing seal portion. A double-ended metal vapor discharge lamp, which is fixed to the outer tube in.