JPH02201862A - High pressure sodium lamp - Google Patents

Abstract

PURPOSE:To achieve a reduced starting voltage and a restarting voltage by sealing a given amount of promethium into a light emitting tube. CONSTITUTION:0.2 to 50 microcuries of promethium per tube volume of 1cm<3> is sealed into a light emitting tube 1 contained within an outer tube 2, together with sodium, buffer metal and rare gas for starting. The radiations emitted from the promethium cause electron excitation, resulting in improved starting and restarting characteristics. Actual measurements indicate that in cold condition, the average starting voltage is 2320V and the average restarting voltage is 3860V. This means that a lamp base 3 can be of ordinary screw-in type, and no special wiring is required for instantaneous re-activation, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to high pressure sodium lamps and to high pressure sodium lamps with improved starting and restarting characteristics.

Conventional technology High-pressure sodium lamps usually have a structure in which an arc tube is provided inside the outer tube and a screw-in cap such as E39 at the end of the outer tube.

It is becoming popular mainly in factories.

Generally, starting a high pressure sodium lamp requires applying a high voltage of several thousand ports. Furthermore, in order to restart the lamp immediately after the lamp goes out, a high voltage of 10 kilovolts or more is required for a 400 watt class lamp. Therefore, in a general type or straight tube type lamp such as a B type or BT type, when the lamp is restarted, discharge may occur inside the cap or between the arc tube support wires in the outer bulb.

Problems to be Solved by the Invention In order to solve these problems, in the past, the electric wire for applying high voltage during restart was placed at the top of the outer tube on the opposite side from the base.

The present invention provides a high-pressure sodium lamp that can be started and restarted immediately after extinguishing without the need for special lead wires.

Means for Solving the Problems The high-pressure sodium lamp of the present invention includes an arc tube provided in an outer bulb, a screw-type cap at the end of the outer bulb, and sodium, a buffer metal, and a starting rare metal in the arc tube. Gas and 0.2 to 50 microcuries of promethium (Pm) per ci of internal volume are sealed.

The radiation generated by the promethium enclosed within the working arc tube provides electronic excitation to improve the starting and restarting characteristics of the high-pressure sodium lamp.

Embodiment In FIG. 1, the arc tube 1 is made of polycrystalline alumina with an inner diameter of 7.5+1111 mm, a total length of 117 mm+, and an internal volume of 4 mm.
．． It is 6 cd. Inside the arc tube 1, there is a sodium amalgam consisting of 4 cm of sodium and 16 cm of mercury as a buffer metal, and 3 x 10"P xenon gas as a starting rare gas.
Along with a, there is also one capsule in which ceramic is impregnated with 2.5 microcuries of promethium. This arc tube has an outer tube 2 with a diameter of 120 an and a total length of 285 R1.
incorporated within. The inside of the outer tube 2 is evacuated to a high vacuum. An E39 screw-type cap 3 is attached to the outer tube 2. Ten such lamps were prepared.

Furthermore, 10 lamps with the same specifications as the above lamps but without promethium added were also prepared.

To measure the lamp starting voltage and restarting voltage, use the mercury lamp 4.
Using a 00W ballast, a high-voltage pulse voltage with a half-value width of 20 microseconds was applied, and the peak value was increased. The restart voltage was measured within 10 seconds immediately after the lamp was turned off after being turned on for 30 minutes or more. This is to avoid the effect of the lamp restart voltage rapidly decreasing over time. The starting voltage of the promethium-filled lamp according to the present invention when cold was 2320V on average, with a variation of 1450 to 3360V. In addition, the restart voltage is 3860V on average, 2860~
It was 4450V. On the other hand, in the same experiment as above,
In the lamps without promethium, the average cold starting voltage was 2830V with a variation of 1780 to 3920V, and the restart voltage immediately after extinguishing was 12080V on average with a variation of 10500 to 17640V.

In this way, compared to lamps without promethium, the starting voltage of lamps filled with promethium is almost the same in cold conditions, but the restart voltage immediately after the lamp is turned off is higher than that of the lamp without promethium. This value is lower than E390 gold pressure resistance 45
00V, and E390 gold could be used. As a result, the lamp according to the present invention does not require a special igniter even in applications where restart is important, and unlike conventional lamps, it is not necessary to install a special lead wire for applying high voltage from the top of the outer bulb. It has the advantages of simple configuration.

Note that the movement characteristics of the lamp filled with promethium were equivalent to those of the lamp not filled with promethium.

In addition, in an arc tube filled with less than 0.2 microcrystal of promethium per 1 c of internal volume of the arc tube, the restart voltage immediately after turning off exceeds the allowable withstand voltage of E390 gold, 4500 V, so a special cap such as a pie post type cap is used. structure must be used. On the other hand, with arc tubes filled with promethium exceeding the same <50 microcuries, there is a problem with lamp disposal after the rated lamp life has ended.
There are problems in practical use, such as limitations on where to dispose of them.

Therefore, the amount of promethium sealed is 1 d of arc tube internal volume.
A range of 0.2 to 50 microcuries per liter is preferred.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention provides an arc tube with an internal volume of 1 cd.
By adding 0.2 to 50 microcuries of promethium per lamp, it is possible to lower not only the starting voltage of high-pressure sodium lamps but also the restarting voltage, so special wiring is required for instant restarts and other applications. Also, a normal screw-in type cap can be used.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a high-pressure sodium lamp which is an embodiment of the present invention. 1... Arc tube, 2... Outer tube, 3...
...The cap. Name of agent: Patent attorney Shigetaka Awano and 1 other person

Claims (1)

[Claims] An arc tube is provided in the outer bulb, a screw-type cap is provided at the end of the outer bulb, and sodium, a buffer metal, a starting rare gas, and 0.2 to 50% gas per cm^3 of internal volume are contained in the arc tube.
A high-pressure sodium lamp characterized by containing microcurie promethium (Pm).