JPH06162995A - Both base type high voltage sodium lamp - Google Patents

Abstract

PURPOSE:To provide a both base type high-voltage sodium lamp which is high in efficiency and excels in luminous flux maintenance factor, by incorporating a ceramic light emission tube within which sodium, mercury and a predetermined pressure of xenon gas are enclosed together with promethium into a quartz-made outer ball within which specific gas is enclosed. CONSTITUTION:In a both base type high-voltage sodium lamp, a light emission tube 1 arranged within a quartz-made outer ball 2 provided with a base 6 on both ends is made of a translucent alumina tube having predetermined diameter and length within which a predetermined amount of sodium, mercury and xenon gas of 6X10<3> to 3.3X10<4>Pa and promethium gas as rare gas for starting are enclosed. Incidentally, rare gas, nitrogen gas or mixed gas of a predetermined pressure are enclosed within the outer ball for cooling the light emission tube 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-ended high pressure sodium lamp.

[0002]

2. Description of the Related Art A double-ended high-pressure sodium lamp is about 1/7 the size of a conventional BT-type outer bulb and is very compact, and the fixture and ballast are shared with the double-ended metal halide lamp. As a lamp that can be used, its application is expected.

Since the outer bulb of this double-capacity high-pressure sodium lamp is very compact, the temperature of the wall of the arc tube during lighting rises above the limit temperature for use, leading to an increase in lamp voltage and blackening of the outer bulb. There was something that caused it. The blackening of the outer sphere is
This is a phenomenon that when the tube wall temperature rises above the use limit temperature, Al ₂ O _3, which is a component of the arc tube, decomposes and evaporates to a lower oxide, and adheres to the inner surface of the outer bulb as a black substance.

If such a phenomenon occurs during the lighting of the lamp, it causes the lamp to go out and the luminous flux to deteriorate. Therefore, a lamp has been developed in which a gas is enclosed in the outer bulb in order to suppress the rise in the tube wall temperature.

[0005]

If a gas is enclosed in the outer bulb, the temperature rise of the tube wall of the arc tube can be suppressed by the heat conduction effect of the gas, but at the same time,
The heat loss will increase and the lamp efficiency will decrease.
That is, without reducing the lamp efficiency, inside the outer bulb,
Encapsulating gas is not possible. However,
If the decrease in efficiency can be compensated by another means, the gas can be enclosed in the outer sphere apparently without decreasing the efficiency.

As one method of compensating for the decrease in efficiency, there is a method of increasing the filling pressure of xenon gas filled as a starting gas in the arc tube. It is generally known that high-pressure sodium lamps increase in lamp efficiency when the filling pressure of xenon gas is increased. However, when the xenon filling pressure is increased, the starting voltage is increased and the starting performance of the lamp is deteriorated. Therefore, a method of using a proximity auxiliary conductor is generally known in order to improve startability. However,
When a proximity auxiliary conductor is attached to a lamp with gas enclosed in the outer bulb and the lamp is attempted to be lit, the gas enclosed in the outer bulb is generated between the proximity conductor and the lead wire due to the pulse voltage at startup. There are various problems such as discharge and lamp failure.

[0007]

SUMMARY OF THE INVENTION The present invention has been made under such circumstances, and in order to improve the starting performance in the arc tube, promethium is enclosed and starting is performed without using a proximity auxiliary conductor. It is intended to provide a double-ended high pressure sodium lamp with high efficiency, long life and excellent luminous flux maintenance rate.

[0008]

The double-capped high-pressure sodium lamp of the present invention compensates the lamp luminous flux reduced by the arc tube cooling gas enclosed in the outer bulb by increasing the enclosure pressure of the xenon gas enclosed in the arc tube. In order to avoid the discharge in the outer bulb at the time of starting, which is a problem with the above, it is characterized in that promethium is enclosed in the arc tube as an alternative to the proximity auxiliary conductor.
The promethium encapsulated in the arc tube has the function of promoting the excitation of other inclusions, lowering the starting voltage and facilitating the starting of the lamp.

[0009]

EXAMPLES The present invention will be described below based on examples.

FIG. 1 shows an embodiment of a 250 W double-barrel type high-pressure sodium lamp used in the experiment. The arc tube 1 placed inside a quartz outer bulb 2 having a base 6 at both ends has an inner diameter of 6.8 m.
It is composed of a translucent alumina tube having a length of m and a length of 85 mm, and 4 mg of sodium, 20 mg of mercury and xenon gas as a rare gas for starting are enclosed inside. In the outer bulb 2, for cooling the arc tube, argon gas is used at room temperature.
Enclosed with 5.3 × 10 ⁴ Pa.

[0011] The lamp having the above-mentioned structure was changed to various charging pressures of xenon gas, and 3 kinds of 6 kinds each containing 1 mg of promethium and not sealed were prototyped, and a JEL standard test ballast with a lamp power of 250 W was produced. A start-up test was carried out using the results shown in Table 1. The efficiency is 25
It is an average value of three lights at 0 W, and those which could not be started by the test ballast were forcibly turned on and measured.

[0012]

[Table 1]

From the results of the experiment, the following was found.

(1) Those without enclosing promethium cannot be lit when the xenon encapsulation pressure exceeds 6.7 × 10 ³ Pa.

(2) Those containing promethium can be turned on if the xenon filling pressure is 3.3 × 10 ⁴ Pa or less.

(3) There is no difference in efficiency between the case where promethium is enclosed and the case where promethium is not enclosed.

From the above, it was found that the encapsulation pressure of xenon which can be turned on by encapsulating promethium is 3.3 × 10 ⁴ Pa or less. Furthermore, when the gas filled in the outer sphere was a rare gas other than nitrogen or argon or a mixed gas thereof, the same experiment was carried out, and in the case of argon,
Almost the same result was obtained.

Further, when a lighting test was conducted on a part of the prototype lamp in a cycle of lighting for 5.5 hours and extinguished for 0.5 hours, blackening of the outer bulb did not occur after about 8,000 hours had elapsed. No increase in lamp voltage was observed.

[0019]

As described above, according to the present invention, it is possible to obtain a double-ended high-pressure sodium lamp having a high efficiency and an excellent luminous flux maintenance rate.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a double-ended metal mold high pressure sodium lamp according to the present invention.

[Explanation of symbols]

 1 arc tube 2 quartz outer tube 3 getter 4 support wire 5 lead wire 6 base

Claims (1)

[Claims] 1. A quartz outer sphere in which bases are provided at both ends and a rare gas, a nitrogen gas, or a mixed gas thereof is sealed inside,
Sodium, mercury and 6 × 10 ^{3 to} 3.3 × 10 ⁴ P
A double-ended high-pressure sodium lamp characterized by incorporating a translucent ceramic arc tube in which promethium ( ¹⁴⁷ Pm) is enclosed together with the xenon gas of a.