US1709858A - Luminescent tube - Google Patents

Description

Patented Apr. 23, 1929.

UNITED STATES PATENT OFFICE.

LUMINESCENT TUBE.

No Drawing.

This invention relates to luminescent tubes, ronsisting generally of a suitably bent glass ube filled with a conducting gas, and having lIl electrode at each end.

The objects of the present invention are improve the colour of the light radiated, and also to enable the tube to emit actinie rays, which are useful for a variety of purposes.

It consists essentially of the improved construction and method of manufacture, hereinafter described in detail.-

The electrodes may be formed from a suitable metal such as tungsten, molybdenum,

iron, nickel or cadmium, of a high degree of purity, of any convenient shape, and may for instance be in the form shown in my United States Patent No. 1,600,595, dated 21st day of September, 1926.

Prior to insertion in the tube, the electrodes are preferably cleaned or scavenged in an atmosphere of hydrogen and nitrogen gas, by heating the said electrodes in such atmosphere to a temperature of say 700 to 800 C.

for a period of from 5 to 6 minutes. The

electrodes are then sealed in a glass tube, in which a few drops of clean mercury have previously been dropped, the tube is then pumped to a high degree of vacuum say by the vacuum pump, the vacuum being in the neighbourhood of say .0001 mm. of mercury.

A small quantity of neon or other conducting gas at a. pressure of l to 3 mm. of mercury is then introduced in the tube.

The electric current is then passed through the tube at an amount of about 2 00 to 500 milliamperes for the purpose of scavenging or cleansing the tube. The tube is then again pumped to a high vacuum.

The operation of exhaustion and filling with'neon gas may be repeated a second time if desired.

Application filed August 26, 1927. Serial No. 215,752.

Argon gas is then introduced in the tube at a pressure varying from to 1 mm. At the same time neon gas is also introduced at a pressure from 2.5 mm. to 4 mm. of mercury, making a total gas pressure of 2% mm. to 5 mm. of the resulting mixture. The tube is then cut off from the pump and sealed, and is then ready for operation.

If it is desired to make use of actinic rays including violet or ultra-violet rays, the tube should be made from quartz or Pyrex glass.

It Will be found that in operation, in place of the usual orange colour, the light emitted will be blue.

As many changes could be made in the above construction, and many apparently Widely different embodiments of my invention, within the scope of the claims, constructed Without departing from the spirit or scope thereof, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative, and not in a limiting sense.

What I claim as my invention is:

1. Luminescent tube comprising a transparent tube adapted to permit the passage of actinic rays, a gaseous filling therein comprising a mixture of argon and noon. and mer- 7 cury vapour, and electrodes for the tube.

2. A luminescent tube comprising a tube, having a filling of argon, noon and mercury vapour.

3. The herein described method of manufacturing luminescent tubes comprising first scavenging the electrodes, then introducing the electrodes into the tube, then adding a few drops of mercury, then scavenging the tube and then filling the same with a mixture of neon and argon.

In Witness whereof I have hereunto set my hand.

PAUL FRANQOIS J OSEPII LEBRUN.