US1726107A - Electric discharge tube - Google Patents

Description

Patented Aug. 27, 1929.

UNITED STATES PATENT OFFICE.

GUSTAV LUDWIG HERTZ, OF EINDHOVEN, NETHERLANDS, ASSIGNOR TO N. V. PHIL- IPS GLOEILAMPENFABRIEKEN, 0F EINDHOVEN, THE NETHERLANDS.

nnncrnrc mscmnen TUBE.

N0 Drawing. Application filed February 18,1925, Serial- Ne. 10,105, and in the Netherlands April 1, 1924. I

This invention relates to electric discharge tubes and more particularly to electric discharge tubes having a positive column light for lighting purposes. I

It is known to introduce into such discharge tubes a gaseous filling of neon, whereby the light radiated by the said tubes acquires red colour.

It is also known to introduce into discharge tubes having a positive column light a little mercury in the form of a mercury drop, in addition to a gaseous filling of neon. By reason of the heating to which the tube during the discharge is exposed, the mercury volatilizes and at a certain temperature the vapour pressure of the mercury increases such that the mercury vapour begins to participate in the discharge and the positive light emitted by the discharge-tube is even produced essentially by radiation of mercury atoms with the result that the red colour changes to a blue one. Discharge tubes of this kind have the disadvanta e that if for any reason the temperature 0 the tube becomes too' low (for example by reason of a low temperature of the surrounding open air), the vapour pressure of the mercury may acquire such a low value that the mercury practically no longer takes part in the discharge and theblue mercury light changes to the red neon light.

Now it has been found that the said dis advantage is reduced or eliminated, if instead of neon some other rare gases are used,

for example argon, but krypton and xenon also give favourable result According to the invention a gaseous fill-- ing is introduced into a discharge tube with positive column light, which gaseous filling comprises arggn and mercury vapor. The gaseous filling may consist of ar on, kr ton, xenon and mercury vapor. referabl y a gaseous filling of argon and mercury, the argon pressure of whlch is above 4 millimetres of mercury will be used. Discharge tubes according to the invention are capable of still producing mercury li ht at temperatures at which a discharge tu e having positwo light and filled with neon and mercury alread produces neon light. This is a very remar able phenomenon, as the exciting potential of argon is lower than that of neon.

One would therefore expect that at a temperature at which a neon mercury discharge tube produces neon light, an argon mercury ciency of discharge tubes according to the invention will likewise be greater than that. of discharge tubes having a positive light and a gaseous filling of neon and mercury.

' What I claim is;

1. A' discharge tube for positive column light, the gaseous filling of which comprises argon and mercury vapor.

2. A discharge tube for positive column light, the gaseous filling of which consists o argon, krypton, xenonand mercury vapor.

3. A discharge tube for ositive column light, the gaseous filling 0 which consists o argon having a pressure above 4 millimetres of mercury pressure and of mercury vapor.

. In testimon whereof I afiix my signature, at the city January, 1925.

- GUSTAV LUDWIG HERTZ.

o Eindhoven, this 20th day of