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The French government gained the right to manufacture Audions in 1912 when de Forest failed to renew his French patents for lack of $125. Langmuir had long suspected that certain assumed limitations on the performance of various low-pressure and vacuum electrical devices, might not be fundamental physical limitations at all, but simply due to ...
The first Audions had only two electrodes, and on October 25, 1906, [22] de Forest filed a patent for the diode vacuum tube detector, that was granted U.S. patent number 841387 on January 15, 1907. Subsequently, a third "control" electrode was added, originally as a surrounding metal cylinder or a wire coiled around the outside of the glass tube.
American Marconi sued de Forest for infringing the original Fleming patent. The U.S. courts eventually ruled that both Fleming's and de Forest's patents were valid, which led to an impasse, as it meant neither could legally manufacture three-element vacuum tubes.
John Ambrose Fleming developed a vacuum tube diode. Lee de Forest placed a screen, added a "grid" electrode, creating the triode. [55] Early radios ran the entire power of the transmitter through a carbon microphone. In the 1920s, the Westinghouse company bought Lee de Forest's and Edwin Armstrong's patent.
The name "triode" appeared later, when it became necessary to distinguish it from other kinds of vacuum tubes with more or fewer elements (diodes, tetrodes, pentodes, etc.). There were lengthy lawsuits between De Forest and von Lieben, and De Forest and the Marconi Company, who represented John Ambrose Fleming, the inventor of the diode. [22]
The patent increased AT&T's control over the manufacture and distribution of long-distance telephone services and allowed the Bell System to build the United States' first coast-to-coast telephone line. Thanks to the pressures of World War I, AT&T and RCA owned all useful patents on vacuum tubes. RCA staked a position in wireless communication ...
According to the patent office, the agency granted 1,020 patents from 2010 through the first quarter of 2024 that were both funded at least in part by the U.S. government and involved at least one ...
Especially after the rise of broadcasting, they were a major profit source for the company. RCA's strong patent position meant that the company effectively set the selling prices for vacuum tubes in the U.S., which were significantly higher than in Europe, where Lee de Forest had allowed a key patent to lapse.