 In August 1948 German physicists Herbert F. Mataré (1912–2011) and Heinrich Welker (1912–1981), working at Compagnie des Freins et Signaux Westinghouse in Aulnay-sous-Bois, France applied for a patent on an amplifier based on the minority carrier injection process which they called the "transistron".Since Bell Labs did not make a public announcement of the transistor until June 1948, the transistron was considered to be independently developed.Mataré had first observed transconductance effects during the manufacture of silicon diodes for German radar equipment during WWII.