HIGH-VACUUM VALVES

Evening Post, Volume CXII, Issue 104, 29 October 1931, Page 23

HIGH-VACUUM VALVES

DISPUTE OVER INVENTION

There has been a good deal of dispute between tho de Forest interests and the General Electric Company of America in regard to the so-called "gassy" valve originally used by De Forest and tho high-vacuum valve later brought forward jy Langmuir, states an English journal. The Langmuir patent was granted in 1925, and has passed by gradual stages through the several Courts, finally reaching the Supreme Couht. In view of tho very high value placed m the patent by the American General Electric Company, the fight for its validity has been a very energetic one.

The basis of the Langmuir patent is tho production of a valve for radio purposes from which all traces of gas have been removed to tho highest degree attainable by known modern methods. Valves in which a trace of gas is allowed to remain are classified aa "gassy" or "soft," and aro apt to becomo unstable in use, and are limited in their ability to control higher currents.

Although De Forest in 1908 obtained a patent on a three-electrode valve fairly highly evacuated, the American General Electric Company claim that the researches of Dr. Langmuir during the years from 1913, whon the first application was filed, to 1925, when the patent was issued, had perfected the design )f the valve to such a pitch that it was not to be considered merely as a question of degreo, but the valve was to bo regarded as being entirely different in kind. To what extent De Forest realised that the difficulties and uncertainties of the "soft" valve could be got over by concentrating upon an extremely high degreo of vacuum is a matter which tho American Courts no doubt had to consider "cry carefully. Apparently they have decided that, the development from a "soft" valve to a "hard" one is merely n matter of degree, while the Langmuir attorneys naturally contended that the modern "hard" valve was utterly different from the "soft" valve in its nature, and that it constituted a totally new stepin invention.