Lee De Forest

Lee De Forest, (August 26, 1873 ? June 30, 1961) was an American inventor with over 300 patents to his name. De Forest invented the Audion, a vacuum tube that takes relatively weak electrical signals and amplifies them. De Forest is one of the fathers of the "electronic age," as the Audion helped to usher in the widespread use of electronics.

Middle years

De Forest invented the Audion in 1906 by improving the "diode" vacuum tubes being used at the time. In 1907, he filed a patent for a three-electrode version of the Audion. It was later called the De Forest valve, and is known now as a triode. De Forest's innovation was the insertion of a third electrode, the grid or gate, in between the cathode (filament) (or connected to the filament) and the anode (plate) of the previously invented diode. The resulting triode or three-electrode vacuum tube could be used as an amplifier for electrical signals, and, equally important, as a fast (for its time) electronic switching element, later applicable in digital electronics (such as computers). The triode would be a good candidate for the most important innovation in electronics in the first half of the 20th century, between Nikola Tesla's and Guglielmo Marconi's progress in radio in the 1890s and the invention in 1948 of the transistor. The triode version of the Audion was patented (patent number US879532). http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=879532.WKU.&OS=PN/879532&RS=PN/879532

Related Topics:
1906 - 1907 - De Forest valve - Triode - Electrode - Grid - Gate - Cathode - Filament - Anode - Plate - Diode - Vacuum tube - Amplifier - Digital - Computer - Electronics - Nikola Tesla - Guglielmo Marconi - Transistor - Patent

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The United States District Attorney sued De Forest (in 1913) for fraud on behalf of his shareholders, stating that his claim of regeneration was an "absurd" promise (he was later acquitted). De Forest filed a patent in 1916 that became the cause of a contentious lawsuit with the prolific inventor Edwin Armstrong, whose patent for the regenerative circuit had been issued in 1914. The lawsuit lasted twelve years, winding its way through the appeals process and ending up at the Supreme Court. The Court ruled in favor of De Forest, although the view of most historians is that the judgement was incorrect. In 1916, De Forest, from his own news radio station, broadcast the first radio advertisement (for his own products) and the first presidential election report by radio. He went on to lead the first radio broadcasts of music (featuring opera star Enrico Caruso) and many other events, but could receive little backing.

Related Topics:
United States - District Attorney - 1913 - 1916 - Edwin Armstrong - Regenerative circuit - 1914 - Supreme Court - Radio - Advertisement - President - Election - Enrico Caruso

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In the early 1920s, it was reported that he stole the invention of talking movies from Theodore Willard Case, a colleague of his from Yale. In 1922, De Forest improved on the work of German inventors and developed the Phonofilm process. It recorded sound directly onto film as parallel lines. These lines photographically recorded electrical impulses from a microphone, and were translated back into sound waves when projected. This system, which synchronized sound directly onto film, was used to record stage performances (such as in vaudeville), speeches, and musical acts. De Forest established his "De Forest Phonofilm Corporation", but could interest no one in Hollywood in his invention at that time. Several years after the Phonofilm Company folded, Hollywood decided to use a different method but eventually came back to the methods De Forest originally proposed. Even today, when looking in the Encyclopedia Britanica, Lee De Forest is cited as the inventor of sound on film. But it has been speculated that he took these ideas from an old friend.

Related Topics:
1920s - 1922 - Photograph - Microphone - Sound - Hollywood

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