Seminal Science

• Alexandre Edmont Becquerel discovers the photovoltaic effect in 1839: when two pieces of dissimilar metals are immersed in an electrolyte, an electrical current passes between them when one of the pieces is struck by light.

 
• Baron Jöns Jakob Berzelius (1779–1848), a distinguished Swedish chemist, isolates the element selenium (Se) in 1818.

 
• Willoughby Smith and his subordinate Louis May notice a remarkable property of the gray metallic form of selenium - that its electrical conductivity is greater in light than in darkness, and it increases as the illumination increases. The results of their investigations are published  in 1873). Thus the phenomenon of photoconductivity is discovered.

 
• Sir George Stokes, in 1852, explains the phenomenon fluorescence - the property of some substances to emit light of visible colour under the stimulation of light or other forms of electromagnetic radiation.

 
• Karl Braun (German physicist) builds the electron beam or cathode ray tube in 1897. The cathode ray tube allows the creation and display of an electron (cathode) beam on a phosphorescent screen that forms one face of the tube.

 

 


 

Technological Predecessors

• In 1843 English physicist Alexander Bain had patented the chemical (facsimile) telegraph. Electrified metal type letters were scanned by a pendulum device and reproduced on the other end of the telegraph wire by a synchronized pendulum on chemically treated paper. Bain's system was further improved by Bakewell and Italian priest Abbe Caselli.

 
• In 1878, M. Senlecq de Ardres designed the telectroscope intended to transmit telegraphically the image obtained in camera obscura and imprint it on paper. He was the first to suggest the use of selenium in a scanning device. Shelford Bidwell built a device  of this kind (the scanning phototelegraph) in 1881 where for the first time transmitter and receiver were synchronized. The device was based on the idea of constructing the image out of a series of lines.

• In London, 1904, Ambrose Flemming, professor of electrical engineering and consultant to the British Marconi Company, invented the diode vacuum tube building on the coherer and the light bulb (invented by Edison's team in 1879).

 
• In 1906, Lee de Forest added a third electrode between the cathode and anode of Flemming's vacuum tube thus inventing the triode (audion) which had the capacity to amplify the radio signal. The possibility for wireless telephony (transmission of voice) was created.

 
• After 1905 motion pictures prospered as a popular entertainment.

 
• In the 1920s radio became a popular medium.

 

Mechanical Television
 

Paul Nipkow, a German science student, files patents for an electric telescope in 1884.

 

 

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Nipkow's original diagram published in Elektrotechnische Zeitschrift, 6, 1885

Between 1923 and 1928, engineers at Bell Labs (Jenkins) and at General Electric (Alexanderson) experimented with mechanical television. In 1928 the GE station broadcast the melodrama The Queen's Messenger. By 1929, the Federal Radio Commission had licensed 22 radio stations to transmit pictures.

 

In Britain, the Scottish inventor John Logie Baird developed a complex system  of mechanical television (30 line picture, scanning at 12,5 frames per second) and started selling receivers (televisors) for public domestic sale. The BBC started experimentation with Baird's system and in July 1930 transmitted the world's first upscale television play - Pirandello's The Man with the Flower in his Mouth. By 1934 the system was perfected to do scanning of 240 lines and 25 frames per second.

 

20th September 1927 - "Stookie Bill"	Paramount Astoria Girls 1933, In same outfit as above and as on recording ©T H Bridgewater 1992	Betty Bolton singing, recorded between 1932 and 1935

From the experimental recordings of John Logie Baird
Source: http://www.dfm.dircon.co.uk/recordng.htm

Demonstrations of German television systems were made at the Berlin Broadcasting Exhibitions of 1928 and 1929. Regular transmissions started in Berlin in 1935 (on the basis of Baird's patent) after the Nazis came to power. 180 lines and 25 frames per second were achieved. Television coverage of the Berlin Olympics of 1936 was performed.

 

In Canada, a French Canadian radio station began experiments with mechanical television in 1926. In 1931 the station began regular transmissions.

 

Electronic Television
 

In 1907 Russian physicist Boris Rozing patented in London, Berlin and St. Petersburg a television cathode ray tube receiver and actually transmitted a signal to it the next year.


 

In 1908 British electrical engineer Campbell Swinton described a totally electronic television system based on cathode ray tubes both at the transmitter and receiver end.


 

Both these ideas were not pursued before and during World War I. The rudeimentary state of the cathode ray tube and the limited knowledge of electronic amplification made these suggestions appear unfeasible.


 

In 1923, Vladimir Zworykin, a Russian immigrant to the US and student of Boris Rozing, patented an all-electrical television system, including an electronic camera (iconoscope).






Zworykin left Westinghouse for RCA where he was hired by David Sarnoff of RCA to work on an all-electrical television system.
 

Philo Farnsworth patented the image dissector in 1927, an electrical pick-up tube that produced better images than Zworykin's.

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Television Diffusion

In the 1930s

In Germany there were around 1000 sets in the whole country, some of them sited in halls of 40-400 seats. Private sets (Volkfernsehen) were introduced only in 1939 at the outbreak of World War II.


 

In Britain television standard of 405 lines was adopted in 1937 and all-electrical television was established after a full-scale public experimental service in 1936 using both mechanical and electrical television. By the start of WW II only about 20,000 TV sets had been sold. Public concerns about high level of repeats, worries about obsolescence because of unsettled technical standards and disappointment with the low definition Baird (mechanical) transmissions.


 

In the US


 

•  In 1936, the FCC began making frequency allocations for television. It however delayed standard decisions (thus keeping TV broadcasting at the stage of experimentation). RCA commanding patent position created fears of monopoly.

 

• In 1939, a National Television System Committee was formed with the task to review the existing systems and propose national standards. Twenty-two standards (525 lines, FM audio, etc.) were approved in July 1941.
 
• Post war conditions: vast spare industrial capacity, in general and specifically in the area of radio, push to consumerism, privatized existence centred in the family home; industrialization of entertainment.

 
• By 1948 in the US there were four TV networks, 52 stations, about 1,000,000 sets in 29 cities. Between 1948 and 1952 a freeze on issuing new licenses was imposed due to interference. By 1949 RCA engineers had produced a colour system compatible with the 1941 NTSC standards. CBS had a rival system developed as early as 1940 which the FCC unsuccessfully tried to impose fearing RCA monopoly. In 1953 the RCA system was approved as the standard for colour television.

 

In 1950 there were around 10 million TV sets in the US.

In 1955 with 36.5 million sets, the US became the first televisual nation in the world.