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Lee De Forest

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Lee De Forest patented a three-electrode version of the Audion.

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 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.

He was involved in several patent lawsuits (and he spent his fortune from his inventions on legal bills). He had four marriages, several failed companies, was defrauded (by business partners), and once indicted for mail fraud (later acquitted). He had a brother and a sister.

Contents

Early years

Born in Iowa to a Congregational minister (who hoped that his son would become a minister like himself ). Lee De Forest's father accepted the position of President of Talladega College (a Black school) in Alabama, where Lee spent most of his young life. Most citizens of the white community resented his father's efforts to educate blacks. De Forest had several friends from among the black children of the town.

De Forest went to Mount Hermon School and then enrolled at the Sheffield School of Science at Yale University in 1893. As an inquisitive inventor, he tapped into the electrical system at Yale one evening and completely blacked out the campus, leading to his suspension. However, he was eventually allowed to complete his studies. He paid some of his tuition with mechanical and gaming inventions, and received his Bachelor's degree in 1896.

He remained at Yale for graduate studies, and earned his Ph.D. in 1899 with a doctoral dissertation on radio waves.

De Forest was interested in wireless telegraphy which led to his invention of the Audion tube, in 1906, and he developed an improved wireless telegraph receiver. He filed a patent for a two-electrode device for detecting electromagnetic waves. The audion tube is a vacuum tube which allowed for voice amplification for radio reception. De Forest said he didn't know why it worked; it just did.

He was a charter member of the Institute of Radio Engineers, the predecessor of the IEEE.

Middle years

De Forest invented the audion in 1906 improving the "diode" vacuum tubes being used at the time. In 1907, he filed a patent for a three-electrode version of the Audion, known now as a triode. It was later called the De Forest valve. 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 already invented diode. The resulting triode or three-electrode vacuum tube could be used as an amplifier for audio signals, and, equally important, as a fast (for its time) electronic switching element, 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 with Patent number US879532. [1] (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)

The United States District Attorney sued De Forest (in 1913) for fraud on behalf of his shareholders, stating that regeneration was an "absurd" promises (later he was 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, had the first radio advertisement (for his products) and the first presidential election reported 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.

In the early 1920s, it is reported that he stole the invention of talking movies from Theodore Willard Case, a colleage of his from Yale. In 1922, De Forest improved on the work of German inventors and developed the Phonofilm. Phonofilm process recorded sound directly onto the film stock as parallel lines. Lines photographically record electrical impulses from a microphone and are translated back into sound waves when projected. The Phonofilm system of recording synchronized sound directly onto film stock was used to record stage performances (such as in vaudeville), speeches, and musical acts. He started the "De Forest Phonofilm Corporation", but could interest no one in Hollywood in his invention at the 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 Encylopedia Britanica, Lee De Forest is named the inventor of sound on film. But it has been debated that he took these ideas from an old friend.

Later years

Lee De Forest sold one of his business interests to 's RCA (owner of the assets of American Marconi).
Enlarge
Lee De Forest sold one of his business interests to David Sarnoff's RCA (owner of the assets of American Marconi).

He sold one of his radio manufacturing firms in 1931 to RCA. In 1934, the courts sided with de Forest against Armstrong (though the technical community did not agree with the courts). De Forest won the court battle, but public opinion he lost (as Armstrong committed suicide in 1954). Public opinion would not take him seriously as an inventor or trust him as a colleague. For the initially rejected (but later adopted) movie sound method, de Forest was given an Academy Award (Oscar) in 1959/1960 for "his pioneering inventions which brought sound to the motion picture" and a star on the Hollywood Walk of Fame.

He died in Hollywood in 1961 and was interred in San Fernando Mission Cemetery in Los Angeles, California.

Patent

External links and references

  • IEEE History Center Lee De Forest (http://www.ieee.org/organizations/history_center/legacies/deforest.html)
  • National Inventors Hall of Fame's Lee De Forest (http://www.invent.org/hall_of_fame/40.html)
  • Complete Lee De Forest (http://www.leedeforest.org/)
  • Eugenii Katz's Lee De Forest (http://chem.ch.huji.ac.il/~eugeniik/history/deforest.htm)

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