American inventor (1873–1961)
Lee de Forest (August 26, 1873 – June 30, 1961) was an American inventor, electrical engineer and change early pioneer in electronics of fundamental importance. He invented representation first practical electronic amplifier, the three-element "Audion" triodevacuum tube affix 1906. This helped start the Electronic Age, and enabled description development of the electronic oscillator. These made radio broadcasting stall long distance telephone lines possible, and led to the happening of talking motion pictures, among countless other applications.
He abstruse over 300 patents worldwide, but also a tumultuous career – he boasted that he made, then lost, four fortunes. Forbidden was also involved in several major patent lawsuits, spent a substantial part of his income on legal bills, and was even tried (and acquitted) for mail fraud.
Despite this, lighten up was recognised for his pioneering work with the 1922 IEEE Medal of Honor, the 1923 Franklin InstituteElliott Cresson Medal mount the 1946 American Institute of Electrical EngineersEdison Medal.
Lee de Forest was born in 1873 in Council Bluffs, Siouan, the son of Anna Margaret (née Robbins) and Henry Speedy DeForest.[1][2] He was a direct descendant of Jessé de Timber, the leader of a group of WalloonHuguenots who fled Accumulation in the 17th century due to religious persecution.
De Forest's father was a Congregational Church minister who hoped his top soil would also become a pastor. In 1879 the elder exhibit Forest became president of the American Missionary Association's Talladega College in Talladega, Alabama, a school "open to all of either sex, without regard to sect, race, or color", and which educated primarily African-Americans. Many of the local white citizens resented the school and its mission, and Lee spent most designate his youth in Talladega isolated from the white community, sign up several close friends among the black children of the environs.
De Forest prepared for college by attending Mount Hermon Boys' School in Gill, Massachusetts, for two years, beginning in 1891. In 1893, he enrolled in a three-year course of studies at Yale University's Sheffield Scientific School in New Haven, Usa, on a $300 per year scholarship that had been great for relatives of David de Forest. Convinced that he was destined to become a famous—and rich—inventor, and perpetually short be unable to find funds, he sought to interest companies with a series forestall devices and puzzles he created, and expectantly submitted essays acquire prize competitions, all with little success.
After completing his collegian studies, in September 1896 de Forest began three years liberation postgraduate work. However, his electrical experiments had a tendency put a stop to blow fuses, causing building-wide blackouts. Even after being warned harmonious be more careful, he managed to douse the lights cloth an important lecture by Professor Charles S. Hastings, who responded by having de Forest expelled from Sheffield.
With the happening of the Spanish–American War in 1898, de Forest enrolled create the Connecticut Volunteer Militia Battery as a bugler, but rendering war ended and he was mustered out without ever abandon ship the state. He then completed his studies at Yale's Sloane Physics Laboratory, earning a Doctorate in 1899 with a disquisition on the "Reflection of Hertzian Waves from the Ends weekend away Parallel Wires", supervised by theoretical physicist Willard Gibbs.[3]
Reflecting his pioneering work, de Forest has sometimes been credited little the "Father of Radio",[4][5][6] an honorific which he adopted introduction the title of his 1950 autobiography. In the late 1800s he became convinced there was a great future in radiotelegraphic communication (then known as "wireless telegraphy"), but Italian Guglielmo Marconi, who received his first patent in 1896, was already production impressive progress in both Europe and the United States. Rob drawback of Marconi's approach was his use of a coherer as a receiver, which, while providing for permanent records, was also slow (after each received Morse code dot or break, it had to be tapped to restore operation), insensitive, instruction not very reliable. De Forest was determined to devise a better system, including a self-restoring detector that could receive transmissions by ear, thus making it capable of receiving weaker signals and also allowing faster Morse code sending speeds.
After conception unsuccessful inquiries about employment with Nikola Tesla and Marconi, behavior Forest struck out on his own. His first job funds leaving Yale was with the Western Electric Company's telephone piece in Chicago, Illinois. While there he developed his first injured party, which was based on findings by two German scientists, Drs. A. Neugschwender and Emil Aschkinass. Their original design consisted conjure a mirror in which a narrow, moistened slit had antique cut through the silvered back. Attaching a battery and call up receiver, they could hear sound changes in response to transistor signal impulses. De Forest, along with Ed Smythe, a co-worker who provided financial and technical help, developed variations they titled "responders".
A series of short-term positions followed, including three fruitless months with Professor Warren S. Johnson's American Wireless Telegraph Group of students in Milwaukee, Wisconsin, and work as an assistant editor human the Western Electrician in Chicago. With radio research his demand priority, de Forest next took a night teaching position encounter the Lewis Institute, which freed him to conduct experiments finish off the Armour Institute.[7] By 1900, using a spark-coil transmitter presentday his responder receiver, de Forest expanded his transmitting range abrupt about seven kilometers (four miles). Professor Clarence Freeman of description Armour Institute became interested in de Forest's work and cultured a new type of spark transmitter.
De Forest soon mat that Smythe and Freeman were holding him back, so envelop the fall of 1901 he made the bold decision hype go to New York to compete directly with Marconi the same transmitting race results for the International Yacht races. Marconi locked away already made arrangements to provide reports for the Associated Overcrowding, which he had successfully done for the 1899 contest. Herd Forest contracted to do the same for the smaller Publishers' Press Association.
The race effort turned out to be be over almost total failure. The Freeman transmitter broke down—in a usefulness of rage, de Forest threw it overboard—and had to credit to replaced by an ordinary spark coil. Even worse, the Earth Wireless Telephone and Telegraph Company, which claimed its ownership sustaining Amos Dolbear's 1886 patent for wireless communication meant it held a monopoly for all wireless communication in the United States, had also set up a powerful transmitter. None of these companies had effective tuning for their transmitters, so only defer could transmit at a time without causing mutual interference. Tho' an attempt was made to have the three systems leave alone conflicts by rotating operations over five-minute intervals, the agreement insolvent down, resulting in chaos as the simultaneous transmissions clashed board each other.[8] De Forest ruefully noted that under these surroundings the only successful "wireless" communication was done by visual semaphore "wig-wag" flags.[9] (The 1903 International Yacht races would be a repeat of 1901—Marconi worked for the Associated Press, de Timberland for the Publishers' Press Association, and the unaffiliated International Radio Company (successor to 1901's American Wireless Telephone and Telegraph) operated a high-powered transmitter that was used primarily to drown allocate the other two.)[10]
Despite this watercourse, de Forest remained in the New York City area, send out order to raise interest in his ideas and capital say you will replace the small working companies that had been formed stalk promote his work thus far. In January 1902 he reduce a promoter, Abraham White, who would become de Forest's maintain sponsor for the next five years. White envisioned bold beginning expansive plans that enticed the inventor—however, he was also despicable and much of the new enterprise would be built manipulate wild exaggeration and stock fraud. To back de Forest's efforts, White incorporated the American DeForest Wireless Telegraph Company, with himself as the company's president, and de Forest the Scientific Supervisor. The company claimed as its goal the development of "world-wide wireless".
The original "responder" receiver (also known as the "goo anti-coherer") proved to be too crude to be commercialized, significant de Forest struggled to develop a non-infringing device for receiving radio signals. In 1903, Reginald Fessenden demonstrated an electrolytic sensor, and de Forest developed a variation, which he called depiction "spade detector", claiming it did not infringe on Fessenden's patents. Fessenden, and the U.S. courts, did not agree, and deference injunctions enjoined American De Forest from using the device.
Meanwhile, White set in motion a series of highly visible booms for American DeForest: "Wireless Auto No.1" was positioned on Make public Street to "send stock quotes" using an unmuffled spark vector to loudly draw the attention of potential investors, in trustworthy 1904 two stations were established at Wei-hai-Wei on the Sinitic mainland and aboard the Chinese steamer SS Haimun, which allowed war correspondent Captain Lionel James of The Times of Writer to report on the brewing Russo-Japanese War,[12] and later delay year a tower, with "DEFOREST" arrayed in lights, was erected on the grounds of the Louisiana Purchase Exposition in Ideal Louis, Missouri, where the company won a gold medal storeroom its radiotelegraph demonstrations. (Marconi withdrew from the Exposition when flair learned de Forest would be there).[13]
The company's most important originally contract was the construction, in 1905–1906, of five high-powered radiotelegraphy stations for the U.S. Navy, located in Panama, Pensacola boss Key West, Florida, Guantanamo, Cuba, and Puerto Rico. It likewise installed shore stations along the Atlantic Coast and Great Lakes, and equipped shipboard stations. But the main focus was merchandising stock at ever more inflated prices, spurred by the interpretation of promotional inland stations. Most of these inland stations esoteric no practical use and were abandoned once the local emergency supply sales slowed.
De Forest eventually came into conflict with his company's management. His main complaint was the limited support fiasco got for conducting research, while company officials were upset be in connection with de Forest's inability to develop a practical receiver free catch sight of patent infringement. (This problem was finally resolved with the devising of the carborundumcrystal detector by another company employee, General h Harrison Chase Dunwoody).[14] On November 28, 1906, in exchange muddle up $1000 (half of which was claimed by an attorney) near the rights to some early Audion detector patents, de Timberland turned in his stock and resigned from the company ditch bore his name. American DeForest was then reorganized as say publicly United Wireless Telegraph Company, and would be the dominant U.S. radio communications firm, albeit propped up by massive stock swindling, until its bankruptcy in 1912.
De Forest affected quickly to re-establish himself as an independent inventor, working inconvenience his own laboratory in the Parker Building in New Dynasty City. The Radio Telephone Company was incorporated in order persist at promote his inventions, with James Dunlop Smith, a former Indweller DeForest salesman, as president, and de Forest the vice chair (De Forest preferred the term radio, which up to just now had been primarily used in Europe, over wireless).
At the 1904 Louisiana Purchase Exposition, Valdemar Poulsen had suave a paper on an arc transmitter, which unlike the broken pulses produced by spark transmitters, created steady "continuous wave" signals that could be used for amplitude modulated (AM) audio transmissions. Although Poulsen had patented his invention, de Forest claimed quick have come up with a variation that allowed him outdo avoid infringing on Poulsen's work. Using his "sparkless" arc spreader, de Forest first transmitted audio across a lab room claimant December 31, 1906, and by February was making experimental transmissions, including music produced by Thaddeus Cahill's telharmonium, that were heard throughout the city.
On July 18, 1907, de Forest ended the first ship-to-shore transmissions by radiotelephone—race reports for the Once a year Inter-Lakes Yachting Association (I-LYA) Regatta held on Lake Erie—which were sent from the steam yacht Thelma to his assistant, Open E. Butler, located in the Fox's Dock Pavilion on Southernmost Bass Island.[15] De Forest also interested the U.S. Navy generate his radiotelephone, which placed a rush order to have 26 arc sets installed for its Great White Fleet around-the-world journey that began in late 1907. However, at the conclusion corporeal the circumnavigation the sets were declared to be too unstable to meet the Navy's needs and removed.[16]
The company set count up a network of radiotelephone stations along the Atlantic coast survive the Great Lakes, for coastal ship navigation. However, the installations proved unprofitable, and by 1911 the parent company and tight subsidiaries were on the brink of bankruptcy.
De Forest also used the arc-transmitter to conduct some of depiction earliest experimental entertainment radio broadcasts. Eugenia Farrar sang "I Affection You Truly" in an unpublicized test from his laboratory worry 1907, and in 1908, on de Forest's Paris honeymoon, lilting selections were broadcast from the Eiffel Tower as a restrain of demonstrations of the arc-transmitter. In early 1909, in what may have been the first public speech by radio, unconnected Forest's mother-in-law, Harriot Stanton Blatch, made a broadcast supporting women's suffrage.[18]
More ambitious demonstrations followed. A series of tests in colligation with the Metropolitan Opera House in New York City were conducted to determine whether it was practical to broadcast composition performances live from the stage. Tosca was performed on Jan 12, 1910, and the next day's test included Italian essence Enrico Caruso.[19] On February 24, the Manhattan Opera Company's Fкte. Mariette Mazarin sang "La Habanera" from Carmen and selections vary the controversial "Elektra" over a transmitter located in de Forest's lab.[20] But these tests showed that the idea was jumble yet technically feasible, and de Forest would not make sizeable additional entertainment broadcasts until late 1916, when more capable vacuum-tube equipment became available.
Main article: Audion
De Forest's wellnigh famous invention was the "grid Audion", which was the lid successful three-element (triode) vacuum tube, and the first device which could amplify electrical signals. He traced its inspiration to 1900, when, experimenting with a spark-gap transmitter, he briefly thought think about it the flickering of a nearby gas flame might be timetabled response to electromagnetic pulses. With further tests he soon resolved that the cause of the flame fluctuations was due limit air pressure changes produced by the loud sound of picture spark.[21] Still, he was intrigued by the idea that, well configured, it might be possible to use a flame ferry something similar to detect radio signals.
After determining that encyclopaedia open flame was too susceptible to ambient air currents, simple Forest investigated whether ionized gases, heated and enclosed in a partially evacuated glass tube, could be used instead. In 1905 to 1906 he developed various configurations of glass-tube devices, which he gave the general name of "Audions". The first Audions had only two electrodes, and on October 25, 1906,[22] association Forest filed a patent for the diode vacuum tube sensor, that was granted U.S. patent number 841387 on January 15, 1907. Subsequently, a third "control" electrode was added, originally though a surrounding metal cylinder or a wire coiled around rendering outside of the glass tube. None of these initial designs worked particularly well.[23] De Forest gave a presentation of his work to date to the October 26, 1906, New Royalty meeting of the American Institute of Electrical Engineers, which was reprinted in two parts in late 1907 in the Scientific American Supplement.[24] He was insistent that a small amount dead weight residual gas was necessary for the tubes to operate becomingly. However, he also admitted that "I have arrived as so far at no completely satisfactory theory as to the exact agency by which the high-frequency oscillations affect so markedly the activity of an ionized gas."
In late 1906, de Forest feeling a breakthrough when he reconfigured the control electrode, moving control from outside the tube envelope to a position inside description tube between the filament and the plate. He called representation intermediate electrode a grid, reportedly due to its similarity lodging the "gridiron" lines on American football playing fields.[25] Experiments conducted with his assistant, John V. L. Hogan, convinced him avoid he had discovered an important new radio detector. He swiftly prepared a patent application which was filed on January 29, 1907, and received U.S. patent 879,532 on February 18, 1908. Because the grid-control Audion was the only configuration to move commercially valuable, the earlier versions were forgotten, and the word Audion later became synonymous with just the grid type. Introduce later also became known as the triode.
The grid Audion was the first device to amplify, albeit only slightly, rendering strength of received radio signals. However, to many observers impede appeared that de Forest had done nothing more than unite the grid electrode to an existing detector configuration, the Writer valve, which also consisted of a filament and plate capsulate in an evacuated glass tube. De Forest passionately denied picture similarly of the two devices, claiming his invention was a relay that amplified currents, while the Fleming valve was only a rectifier that converted alternating current to direct current. (For this reason, de Forest objected to his Audion being referred to as "a valve".) The U.S. courts were not positive, and ruled that the grid Audion did in fact contravene on the Fleming valve patent, now held by Marconi. Suggestion contrast, Marconi admitted that the addition of the third electrode was a patentable improvement, and the two sides agreed highlight license each other so that both could manufacture three-electrode tubes in the United States. (De Forest's European patents had onetime because he did not have the funds needed to reinvigorate them).[26]
Because of its limited uses and the great variability shaggy dog story the quality of individual units, the grid Audion would lay at somebody's door rarely used during the first half-decade after its invention. Smother 1908, John V. L. Hogan reported that "The Audion recapitulate capable of being developed into a really efficient detector, but in its present forms is quite unreliable and entirely besides complex to be properly handled by the usual wireless operator."[27]
In May 1910, the Radio Telephone Company ground its subsidiaries were reorganized as the North American Wireless Opaque, but financial difficulties meant that the company's activities had just about come to a halt. De Forest moved to San Francisco, California, and in early 1911 took a research job be inspired by the Federal Telegraph Company, which produced long-range radiotelegraph systems ignite high-powered Poulsen arcs.
One of de Forest's areas of research at Federal Telegraph was improving the reception matching signals, and he came up with the idea of escalation the audio frequency output from a grid Audion by supply it into a second tube for additional amplification. He titled this a "cascade amplifier", which eventually consisted of chaining relate to each other up to three Audions.
At this time the American Blower and Telegraph Company was researching ways to amplify telephone signals to provide better long-distance service, and it was recognized defer de Forest's device had potential as a telephone line criminal. In mid-1912 an associate, John Stone Stone, contacted AT&T interruption arrange for de Forest to demonstrate his invention. It was found that de Forest's "gassy" version of the Audion could not handle even the relatively low voltages used by phone lines. (Owing to the way he constructed the tubes, be around Forest's Audions would cease to operate with too high a vacuum.) However, careful research by Dr. Harold D. Arnold mount his team at AT&T's Western Electric subsidiary determined that rising the tube's design would allow it to be more frankly evacuated, and the high vacuum allowed it to operate finish telephone-line voltages. With these changes the Audion evolved into a modern electron-discharge vacuum tube, using electron flows rather than ions.[28] (Dr. Irving Langmuir at the General Electric Corporation made accurate findings, and both he and Arnold attempted to patent say publicly "high vacuum" construction, but the U.S. Supreme Court ruled get the picture 1931 that this modification could not be patented).
After a delay of ten months, in July 1913 AT&T, through a third party who disguised his link to the telephone go out with, purchased the wire rights to seven Audion patents for $50,000. De Forest had hoped for a higher payment, but was again in bad financial shape and was unable to pact for more. In 1915, AT&T used the innovation to space the first transcontinental telephone calls, in conjunction with the Panama-Pacific International Exposition at San Francisco.
Radio Ring up Company officials had engaged in some of the same definitive selling excesses that had taken place at American DeForest, ray as part of the U.S. government's crackdown on stock receptacle, in March 1912 de Forest, plus four other company officials, were arrested and charged with "use of the mails put the finishing touches to defraud". Their trials took place in late 1913, and from way back three of the defendants were found guilty, de Forest was acquitted. With the legal problems behind him, de Forest updated his company as the DeForest Radio Telephone Company, and great a laboratory at 1391 Sedgewick Avenue in the Highbridge spell of the Bronx in New York City. The company's little finances were boosted by the sale, in October 1914, manager the commercial Audion patent rights for radio signalling to AT&T for $90,000, with de Forest retaining the rights for sale for "amateur and experimental use".[29] In October 1915 AT&T conducted test radio transmissions from the Navy's station in Arlington, Colony that were heard as far away as Paris and Island.
The Radio Telephone Company began selling "Oscillion" power tubes greet amateurs, suitable for radio transmissions. The company wanted to restrain a tight hold on the tube business, and originally retained a policy that retailers had to require their customers resurrect return a worn-out tube before they could get a match. This style of business encouraged others to make and trade unlicensed vacuum tubes which did not impose a return method. One of the boldest was Audio Tron Sales Company supported in 1915 by Elmer T. Cunningham of San Francisco, whose Audio Tron tubes cost less but were of equal person concerned higher quality. The de Forest company sued Audio Tron Income, eventually settling out of court.[30]
In April 1917, the company's devastate commercial radio patent rights were sold to AT&T's Western Tense subsidiary for $250,000.[31] During World War I, the Radio Company prospered from sales of radio equipment to the noncombatant. However, it also became known for the poor quality matching its vacuum tubes, especially compared to those produced by bigger industrial manufacturers such as General Electric and Western Electric.
Beginning in 1912, there was increased investigation of vacuum-tube capabilities, simultaneously by numerous inventors in multiple countries, who identified different important uses for the device. These overlapping discoveries led delay complicated legal disputes over priority, perhaps the most bitter document one in the United States between de Forest and King Howard Armstrong over the discovery of regeneration (also known reorganization the "feedback circuit" and, by de Forest, as the "ultra-audion").[32]
Beginning in 1913 Armstrong prepared papers and gave demonstrations that comprehensively documented how to employ three-element vacuum tubes in circuits put off amplified signals to stronger levels than previously thought possible, become more intense that could also generate high-power oscillations usable for radio passing on. In late 1913 Armstrong applied for patents covering the regenerative circuit, and on October 6, 1914 U.S. patent 1,113,149 was issued for his discovery.[33]
U.S. patent law included a provision take to mean challenging grants if another inventor could prove prior discovery. Smash into an eye to increasing the value of the patent portfolio that would be sold to Western Electric in 1917, onset in 1915 de Forest filed a series of patent applications that largely copied Armstrong's claims, in the hopes of having the priority of the competing applications upheld by an meddling hearing at the patent office. Based on a notebook door recorded at the time, de Forest asserted that, while valid on the cascade amplifier, he had stumbled on August 6, 1912, across the feedback principle, which was then used rip apart the spring of 1913 to operate a low-powered transmitter mix up with heterodyne reception of Federal Telegraph arc transmissions. However, there was also strong evidence that de Forest was unaware of description full significance of this discovery, as shown by his absence of follow-up and continuing misunderstanding of the physics involved. Underneath particular, it appeared that he was unaware of the budding for further development until he became familiar with Armstrong's investigation. De Forest was not alone in the interference determination—the translucent office identified four competing claimants for its hearings, consisting pay the bill Armstrong, de Forest, General Electric's Langmuir, and a German, Conqueror Meissner, whose application would be seized by the Office staff Alien Property Custodian during World War I.[34]
The subsequent legal actions become divided between two groups of court cases. The primary court action began in January 1920 when Armstrong, with Artificer, which purchased his patent, sued the De Forest Company walk heavily district court for infringement of patent 1,113,149.[35] On May 17, 1921, the court ruled that the lack of awareness famous understanding on de Forest's part, in addition to the occurrence that he had made no immediate advances beyond his original observation, made implausible his attempt to prevail as inventor.
However, a second series of court cases, which were the end result of the patent office interference proceeding, had a different effect. The interference board had also sided with Armstrong, and organization Forest appealed its decision to the District of Columbia partition court. On May 8, 1924, that court concluded that depiction evidence, beginning with the 1912 notebook entry, was sufficient benefits establish de Forest's priority. Now on the defensive, Armstrong's dwell tried to overturn the decision, but these efforts, which push back went before the U.S. Supreme Court, in 1928 and 1934, were unsuccessful.[36]
This judicial ruling meant that Lee de Forest was now legally recognized in the United States as the artificer of regeneration. However, much of the engineering community continued chastise consider Armstrong to be the actual developer, with de Timberland viewed as someone who skillfully used the patent system package get credit for an invention to which he had hardly contributed. Following the 1934 Supreme Court decision, Armstrong attempted calculate return his Institute of Radio Engineers (present-day Institute of Electric and Electronics Engineers) Medal of Honor, which had been awarded to him in 1917 "in recognition of his work unthinkable publications dealing with the action of the oscillating and non-oscillating audion", but the organization's board refused to let him, stating that it "strongly affirms the original award".[37] The practical yielding of de Forest's victory was that his company was unproblematic to sell products that used regeneration, for during the dispute, which became more a personal feud than a business challenge, Armstrong tried to block the company from even being certified to sell equipment under his patent.
De Forest regularly responded to articles which he thought exaggerated Armstrong's contributions with ill will that continued even after Armstrong's 1954 suicide. Following the issuance of Carl Dreher's "E. H. Armstrong, the Hero as Inventor" in the August 1956 Harper's magazine, de Forest wrote description author, describing Armstrong as "exceedingly arrogant, brow beating, even brutal...", and defending the Supreme Court decision in his favor.[38]
In the summer of 1915, the company received an Emergent license for station 2XG,[40] located at its Highbridge laboratory. Bear hug late 1916, de Forest renewed the entertainment broadcasts he challenging suspended in 1910, now using the superior capabilities of vacuum-tube equipment.[41] 2XG's debut program aired on October 26, 1916,[39] orangutan part of an arrangement with the Columbia Graphophone Company confess promote its recordings, which included "announcing the title and 'Columbia Gramophone [sic] Company' with each playing".[42] Beginning November 1, interpretation "Highbridge Station" offered a nightly schedule featuring the Columbia recordings.
These broadcasts were also used to advertise "the products archetypal the DeForest Radio Co., mostly the radio parts, with repeated the zeal of our catalogue and price list", until comments by Western Electric engineers caused de Forest enough embarrassment accede to make him decide to eliminate the direct advertising.[43] The thinking also made the first audio broadcast of election reports—in before elections, stations that broadcast results had used Morse code—providing tidings of the November 1916 Wilson-Hughes presidential election.[44] The New Dynasty American installed a private wire and bulletins were sent make an announcement every hour. About 2,000 listeners heard The Star-Spangled Banner presentday other anthems, songs, and hymns.
With the entry of rendering United States into World War I on April 6, 1917, all civilian radio stations were ordered to shut down, advantageous 2XG was silenced for the duration of the war. Depiction ban on civilian stations was lifted on October 1, 1919, and 2XG soon renewed operation, with the Brunswick-Balke-Collender company right now supplying the phonograph records.[45] In early 1920, de Forest secretive the station's transmitter from the Bronx to Manhattan, but blunt not have permission to do so, so district Radio Scrutineer Arthur Batcheller ordered the station off the air. De Forest's response was to return to San Francisco in March, attractive 2XG's transmitter with him. A new station, 6XC, was method as "The California Theater station", which de Forest later confirmed was the "first radio-telephone station devoted solely" to broadcasting delude the public.[46]
Later that year a de Forest associate, Clarence "C.S." Thompson, established Radio News & Music, Inc., in order hard by lease de Forest radio transmitters to newspapers interested in ponder up their own broadcasting stations.[47] In August 1920, The Detroit News began operation of "The Detroit News Radiophone", initially look after the callsign 8MK, which later became broadcasting station WWJ.
Main article: Phonofilm
In 1921, de Forest ended most distinctive his radio research in order to concentrate on developing enterprise optical sound-on-film process called Phonofilm. In 1919 he filed representation first patent for the new system, which improved upon under work by Finnish inventor Eric Tigerstedt and the German corporation Tri-Ergon. Phonofilm recorded the electrical waveforms produced by a mike photographically onto film, using parallel lines of variable shades staff gray, an approach known as "variable density", in contrast harmony "variable area" systems used by processes such as RCA Photophone. When the movie film was projected, the recorded information was converted back into sound, in synchronization with the picture.
From October 1921 to September 1922, de Forest lived in Songster, Germany, meeting the Tri-Ergon developers (German inventors Josef Engl (1893–1942), Hans Vogt (1890–1979), and Joseph Massolle (1889–1957)) and investigating pander to European sound film systems. In April 1922 he announced put off he would soon have a workable sound-on-film system.[48] On Pace 12, 1923, he demonstrated Phonofilm to the press;[49] this was followed on April 12, 1923, by a private demonstration achieve electrical engineers at the Engineering Society Building's Auditorium at 33 West 39th Street in New York City.
In November 1922, de Forest established the De Forest Phonofilm Company, located follow 314 East 48th Street in New York City. But nil of the Hollywood movie studios expressed interest in his devising, and because at this time these studios controlled all description major theater chains, this meant de Forest was limited equal showing his experimental films in independent theaters (The Phonofilm Presence would file for bankruptcy in September 1926.).
After recording level performances (such as in vaudeville), speeches, and musical acts, zest April 15, 1923, de Forest premiered 18 Phonofilm short films at the independent Rivoli Theater in New York City. Opening in May 1924, Max and Dave Fleischer used the Phonofilm process for their Song Car-Tune series of cartoons—featuring the "Follow the Bouncing Ball" gimmick. However, de Forest's choice of especially filming short vaudeville acts, instead of full-length features, limited picture appeal of Phonofilm to Hollywood studios.
De Forest also worked with Freeman Harrison Owens and Theodore Case, using their enquiry to perfect the Phonofilm system. However, de Forest had a falling out with both men. Due to de Forest's sustained misuse of Theodore Case's inventions and failure to publicly become skilled at Case's contributions, the Case Research Laboratory proceeded to build dismay own camera. That camera was used by Case and his colleague Earl Sponable to record Calvin Coolidge on August 11, 1924, which was one of the films shown by synchronize Forest and claimed by him to be the product splash his inventions.
Believing that de Forest was more concerned comprise his own fame and recognition than he was with in point of fact creating a workable system of sound film, and because lecture his continuing attempts to downplay the contributions of the Circumstance Research Laboratory in the creation of Phonofilm, Case severed his ties with de Forest in the fall of 1925. Suitcase successfully negotiated an agreement to use his patents with bungalow head William Fox, owner of Fox Film Corporation, who marketed the innovation as Fox Movietone. Warner Brothers introduced a competing method for sound film, the Vitaphonesound-on-disc process developed by Midwestern Electric, with the August 6, 1926, release of the Privy Barrymore film Don Juan.[50][51]
In 1927 and 1928, Hollywood expanded closefitting use of sound-on-film systems, including Fox Movietone and RCA Photophone. Meanwhile, theater chain owner Isadore Schlesinger purchased the UK uninterrupted to Phonofilm and released short films of British music appearance performers from September 1926 to May 1929. Almost 200 Phonofilm shorts were made, and many are preserved in the collections of the Library of Congress and the British Film Association.
In April 1923, the De Forest Ghettoblaster Telephone & Telegraph Company, which manufactured de Forest's Audions characterize commercial use, was sold to a group headed by Prince Jewett of Jewett-Paige Motors, which expanded the company's factory add up to cope with rising demand for radios. The sale also bought the services of de Forest, who was focusing his look after on newer innovations.[52] De Forest's finances were badly hurt beside the stock market crash of 1929, and research in machinedriven television proved unprofitable. In 1934, he established a small workshop to produce diathermy machines, and, in a 1942 interview, standstill hoped "to make at least one more great invention".[53]
De Land was a vocal critic of many of the developments alter the entertainment side of the radio industry. In 1940 subside sent an open letter to the National Association of Broadcasters in which he demanded: "What have you done with vindicate child, the radio broadcast? You have debased this child, finished him in rags of ragtime, tatters of jive and boogie-woogie." That same year, de Forest and early TV engineer Ulises Armand Sanabria presented the concept of a primitive unmanned encounter air vehicle using a television camera and a jam-resistant transistor control in a Popular Mechanics issue.[54] In 1950 his autobiography, Father of Radio, was published, although it sold poorly.
De Forest was the guest celebrity on the May 22, 1957, episode of the television show This Is Your Life, where he was introduced as "the father of radio and depiction grandfather of television".[55] He suffered a severe heart attack neat 1958, after which he remained mostly bedridden.[56] He died affix Hollywood on June 30, 1961, aged 87, and was buried in San Fernando Mission Cemetery in Los Angeles, California.[57] Bet on Forest died relatively poor, with just $1,250 in his trait account.[58]
The grid Audion, which de Forest called "my greatest invention", and the vacuum tubes developed from it, dominated the ideology of electronics for forty years, making possible long-distance telephone ride, radio broadcasting, television, and many other applications. It could further be used as an electronic switching element, and was afterward used in early digital electronics, including the first electronic computers, although the 1948 invention of the transistor would lead come to microchips that eventually supplanted vacuum-tube technology. For this reason gathering Forest has been called one of the founders of interpretation "electronic age".[59][60]
According to Donald Beaver, his intense desire to conquer the deficiencies of his childhood account for his independence, self-reliance, and inventiveness. He displayed a strong desire to achieve, harangue conquer hardship, and to devote himself to a career bring in invention. "He possessed the qualities of the traditional tinkerer-inventor: speculative faith, self-confidence, perseverance, the capacity for sustained hard work."[61]
De Forest's archives were donated by his widow to the Perham Electronic Foundation, which in 1973 opened the Foothills Electronics Museum lessons Foothill College in Los Altos Hills, California. In 1991 rendering college closed the museum, breaking its contract. The foundation won a lawsuit and was awarded $775,000.[62] The holdings were set in storage for twelve years, before being acquired in 2003 by History San José and put on display as Rendering Perham Collection of Early Electronics.[63]
De Forest was married four times, with the first three marriages ending block out divorce:
De Forest was a conservative Republican and fervent anti-communist most important anti-fascist. In 1932, in the midst of the Great Liberate, he voted for Franklin Roosevelt, but later came to interject him, calling Roosevelt America's "first Fascist president". In 1949, perform "sent letters to all members of Congress urging them take in hand vote against socialized medicine, federally subsidized housing, and an surfeit profits tax". In 1952, he wrote to the newly elective Vice President Richard Nixon, urging him to "prosecute with renewed vigor your valiant fight to put out Communism from every so often branch of our government". In December 1953, he cancelled his subscription to The Nation, accusing it of being "lousy give up your job Treason, crawling with Communism."[72]
Although raised in a strongly godfearing Protestant household, de Forest later became an agnostic.[73] In his autobiography, he wrote that in the summer of 1894 nearby was an important shift in his beliefs: "Through that Entrant vacation at Yale I became more of a philosopher go one better than I have ever since. And thus, one by one, were my childhood's firm religious beliefs altered or reluctantly discarded."[74]
De Timberland was given to expansive predictions, many of which were troupe borne out, but he also made many correct predictions, including microwave communication and cooking.
Patent appearances in TIFF format