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-------------------
History of television
(From
Wikipedia, the free encyclopedia)
The history of television technology can be divided along
two lines: those developments that depended upon both mechanical and electronic
principles, and those dependent only on electronic principles. From the latter
descended all modern televisions, but these would not have been possible
without the discoveries and insights garnered from the development of the
electromechanical systems.
Contents
* 1
Electromechanical television
* 2 Electronic
television
* 3 Color
television
* 4 Broadcast
television
o 4.1 United
States and Canada
o 4.2 United
States
o 4.3 Canada
o 4.4 France
o 4.5
Germany
o 4.6 United
Kingdom
o 4.7 Soviet
Union (USSR)
o 4.8 Later
development
o 4.9
Technological innovations
o 4.10
Overview
* 5 Television
sets
* 6 Television
inventors/pioneers
* 7 Television
museums
* 8 See also
* 9 References
* 10 Further
reading
* 11 External
links
Electromechanical television
Main article:
Mechanical television
The origins of what would become today's television system
can be traced back to the discovery of the photoconductivity of the element
selenium by Willoughby Smith in 1873, the invention of a scanning disk by Paul
Gottlieb Nipkow in 1884, John Logie Baird's demonstration of televised moving
images in 1926 and Philo Farnsworth's Image dissector in 1927.
The 20-year old German university student Nipkow proposed
and patented the first electromechanical television system in 1884,[1] although
he never built a working model of the system. Nipkow's spinning disk design is
credited with being the first television image rasterizer. Constantin Perskyi
had coined the word television in a paper read to the International Electricity
Congress at the International World Fair in Paris on August 25, 1900. Perskyi's
paper reviewed the existing electromechanical technologies, mentioning the work
of Nipkow and others. The photoconductivity of selenium and Nipkow's scanning
disk were first joined for practical use in the electronic transmission of
still pictures and photographs, and by the first decade of the 20th century
halftone photographs, composed of equally spaced dots of varying size, were
being transmitted by facsimile over telegraph and telephone lines as a
newspaper service.
However, it wasn't until 1907 that developments in
amplification tube technology made the design practical.[2] The first
demonstration of the instantaneous transmission of still silhouette images was
by Georges Rignoux and A. Fournier in Paris in 1909, using a rotating
mirror-drum as the scanner, and a matrix of 64 selenium cells as the
receiver.[3]
In 1911, Boris Rosing and his student Vladimir Kosma
Zworykin created a television system that used a mechanical mirror-drum scanner
to transmit, in Zworykin's words, "very crude images" over wires to
the electronic Braun tube (cathode ray tube) in the receiver. Moving images
were not possible because, in the scanner, "the sensitivity was not enough
and the selenium cell was very laggy".
On March 25, 1925, Scottish inventor John Logie Baird gave a
demonstration of televised silhouette images in motion at Selfridge's
Department Store in London. AT&T's Bell Telephone Laboratories transmitted
halftone still images of transparencies in May 1925. Charles Francis Jenkins
was able to demonstrate on June 13, 1925, the transmission of the silhouette
image of a toy windmill in motion from a naval radio station to his laboratory
in Washington, using a lensed disk scanner with 48 lines per picture,[4] 16
pictures per second. But if television is defined as the live transmission of
moving images with continuous tonal variation, Baird first achieved this
privately on October 2, 1925. But strictly speaking, Baird had not yet achieved
moving images on October 2. His scanner worked at only five images per second,
below the threshold required to give the illusion of motion, usually defined as
at least 12 images per second. By January, he had improved the scan rate to
12.5 images per second. Then he gave the world's first public demonstration of a
working television system to members of the Royal Institution and a newspaper
reporter on January 26, 1926 at his laboratory in London. Unlike later
electronic systems with several hundred lines of resolution, Baird's vertically
scanned image, using a scanning disk embedded with a double spiral of lenses,
had only 30 lines, just enough to reproduce a recognizable human face.
In 1927, Baird transmitted a signal over 438 miles (705 km)
of telephone line between London and Glasgow. In 1928, Baird's company (Baird
Television Development Company / Cinema Television) broadcast the first
transatlantic television signal, between London and New York, and the first
shore-to-ship transmission. He also demonstrated an electromechanical color,
infrared (dubbed "Noctovision"), and stereoscopic television, using
additional lenses, disks and filters. In parallel, Baird developed a video disk
recording system dubbed "Phonovision"; a number of the Phonovision
recordings, dating back to 1927, still exist.[5] In 1929, he became involved in
the first experimental electromechanical television service in Germany. In
November 1929, Baird and Bernard Natan of Pathe established France's first
television company, Television-Baird-Natan. In 1931, he made the first live
transmission, of the Epsom Derby. In 1932, he demonstrated ultra-short wave
television. Baird's electromechanical system reached a peak of 240 lines of
resolution on BBC television broadcasts in 1936, before being discontinued in
favor of a 405-line all-electronic system developed by Marconi-EMI.
Meanwhile in Soviet Russia, Leon Theremin had been
developing a mirror drum-based television, starting with 16 lines resolution in
1925, then 32 lines and eventually 64 using interlacing in 1926, and as part of
his thesis on June 7, 1926 he electrically transmitted and then projected
near-simultaneous moving images on a five foot square screen.[4] By 1927 he
achieved an image of 100 lines, a resolution that was not surpassed until 1931
by RCA, with 120 lines.
However, Herbert E. Ives of Bell Labs gave the most dramatic
demonstration of television yet on April 7, 1927, when he field tested
reflected-light television systems using small-scale (2 by 2.5 inches) and
large-scale (24 by 30 inches) viewing screens over a wire link from Washington
to New York City, and over-the-air broadcast from Whippany, New Jersey. The
subjects, who included Secretary of Commerce Herbert Hoover, were illuminated
by a flying-spot scanner beam that was scanned by a 50-aperture disk at 16
pictures per minute.
Electronic television
In 1911, engineer Alan Archibald Campbell-Swinton gave a
speech in London, reported in The Times (UK), describing in great detail how
distant electric vision could be achieved by using cathode ray tubes at both
the transmitting and receiving ends. The speech, which expanded on a letter he
wrote to the journal Nature in 1908, was the first iteration of the electronic
television method that is still used today. Others had already experimented
with using a cathode ray tube as a receiver, but the concept of using one as a
transmitter was novel.[6] By the late 1920s, when electromechanical television
was still being introduced, inventors Philo Farnsworth, Vladimir Zworykin and
Hungarian Kalman Tihanyi were already working separately on versions of
all-electronic transmitting tubes.
The decisive solution was first described in 1926 by
Tihanyi, and appeared in patent applications for his "Radioskop" he
filed in Hungary that same year. In 1928 Tihanyi was awarded patents for his
inventions in both France and Great Britain.[7] He applied for patents in the
United States in June of the following year, but the U.S. patent for his
display tube would not be granted until October 1938, and the patent for his
camera tube the following May.[8][9]
On September 7, 1927, Philo Farnsworth's Image Dissector
camera tube transmitted its first image, a simple straight line, at his
laboratory at 202 Green Street in San Francisco. [1] By 1928, Farnsworth had
developed the system sufficiently to hold a demonstration for the press,
televising a motion picture film. In 1929, the system was further improved by
elimination of a motor generator, so that his television system now had no
mechanical parts. That year, Farnsworth transmitted the first live human images
with his system, including a three and a half-inch image of his wife Elma
("Pem") with her eyes closed (possibly due to the bright lighting
required).
Farnsworth gave the world's first public demonstration of a
complete all-electronic television system on 25 August 1934 at the Franklin
Institute in Philadelphia. Other inventors had previously demonstrated
components of such a system, or had shown an electronic system using still
images or motion picture film. Manfred von Ardenne demonstrated an
all-electronic television system using cathode ray tubes at the Berlin Radio
Show in August 1931, but as he never built a camera tube, his system was
limited to using the CRT as a flying spot scanner to transmit motion picture
films and slides. Farnsworth became the first to use all-electronic cameras and
receivers to transmit and receive live, moving images. Unfortunately, his
cameras needed too much light, so his work came to a stop.
Vladimir Zworykin was also experimenting with the cathode
ray tube to create and show images. While at Westinghouse in 1923, he developed
an electronic camera tube. But in a 1925 demonstration, the image was dim, had
low contrast and poor definition, and was stationary.[10] The tube never got
beyond the laboratory stage, but RCA (which had acquired the Westinghouse
patent) believed the patent on Farnsworth's 1927 image dissector was written so
broadly that it would exclude any other electronic formation of an image. And
so RCA, armed with Zworykin's 1923 patent application, filed a patent interference
suit against Farnsworth. The U.S. Patent Office examiner disagreed in a 1935
decision, finding priority of invention for Farnsworth against Zworykin.
Farnsworth claimed that Zworykin's 1923 system would be unable to produce an
electrical image of the type to challenge to Farnsworth's patent. Zworykin was
unable or unwilling to introduce in evidence a working model of his tube that
was based on his 1923 patent description. In October 1939, after losing an
appeal in the courts and wishing to go forward with the commercial
manufacturing of television equipment, RCA agreed to pay Farnsworth US$1
million (the equivalent of $13.8 million in 2006) over a ten-year period, in
addition to license payments, to use Farnsworth's patents.[11]
However, while working at RCA in 1931, Zworykin had designed
an improved camera tube based on the technology developed by Tihanyi. Zworykin
called the new tube the iconoscope, and it would be the primary type of camera
tube used in the U.S. until replaced by the image orthicon tube in 1946.[12]
Tihanyi's patents for both his camera and display tubes would eventually be
acquired by RCA.[8][9]
In Britain Isaac Shoenberg used Zworykin's idea to develop
Marconi-EMI's own Emitron tube, which formed the heart of the cameras they designed
for the BBC. Using this, on November 2, 1936 a 405 line service was started
from studios at Alexandra Palace, and transmitted from a specially-built mast
atop one of the Victorian building's towers; it alternated for a short time
with Baird's mechanical system in adjoining studios, but was more reliable and
visibly superior. So began the world's first high-definition regular service.
The mast is still in use today.[citation needed]
Color television
Main article:
Color television
Broadcast television
Further
information: Timeline of the introduction of television in countries
United States and Canada
Below is a list showing when U.S. states and Canadian
provinces established their first commercially licensed television stations.
* Alabama (1949)
* Alberta (1954)
* Territory of
Alaska (1953)
* American Samoa
(1964)
* Arizona (1949)
* Arkansas (1953)
* British Columbia
(1953)
* California
(1947)
* Colorado (1952)
* Connecticut
(1948)
* Delaware (1949)
* Florida (1949)
* Georgia (1948)
* Guam (1956)
* Territory of
Hawaii (1952)
* Idaho (1953)
* Illinois (1943)
* Indiana (1949)
* Iowa (1949)
* Kansas (1953)
* Kentucky (1948)
* Louisiana (1948)
* Maine (1953)
* Manitoba (1954)
* Maryland (1947)
* Massachusetts
(1947)
* Michigan (1947)
* Minnesota (1948)
* Mississippi
(1953)
* Missouri (1947)
* Montana (1953)
* Nebraska (1949)
* Nevada (1953)
* New Brunswick
(1954)
* New Hampshire
(1954)
* New Jersey
(1948)
* New Mexico
(1948)
* New York (1941)
* Newfoundland
(1955)
* North Carolina
(1949)
* North Dakota
(1953)
* Northwest
Territories (1972)
* Nova Scotia
(1954)
* Ohio (1943)
* Oklahoma (1949)
* Ontario (1952)
* Oregon (1952)
* Pennsylvania
(1941)
* Prince Edward
Island (1955)
* Puerto Rico
(1954)
* Quebec (1952)
* Rhode Island
(1949)
* Saskatchewan
(1954)
* South Carolina
(1953)
* South Dakota
(1953)
* Tennessee (1948)
* Texas (1948)
* Utah (1948)
* Vermont (1954)
* Virginia (1947)
* U.S Virgin
Islands (1961)
* Washington
(1948)
* Washington D.C
(1945)
* West Virginia
(1949)
* Wisconsin (1947)
* Wyoming (1954)
* Yukon (1972)
Television aerial on a rooftop
Television aerial on a rooftop
United States
The first regularly scheduled television service in the
United States began on July 2, 1928. The Federal Radio Commission authorized
C.F. Jenkins to broadcast from experimental station W3XK in Wheaton, Maryland,
a suburb of Washington, D.C. But for at least the first eighteen months, only
silhouette images from motion picture film were broadcast.
Hugo Gernsback's New York City radio station began a
regular, if limited, schedule of live television broadcasts on August 14, 1928,
using 48-line images. Simultaneously, Gernsback published Television, the
world's first magazine about the medium.
General Electric's experimental station in Schenectady, New
York, on the air sporadically since January 13, 1928, was able to broadcast
reflected-light, 48-line images via shortwave as far as Los Angeles, and by
September was making four television broadcasts weekly. It is considered to be
the direct predecessor of current television station WRGB.
General Broadcasting System's WGBS radio and W2XCR
television aired their regular broadcasting debut in New York City on April 26,
1931, with a special demonstration set up in Aeolian Hall at Fifth Avenue and
Fifty-fourth Street. Thousands waited to catch a glimpse of the Broadway stars
who appeared on the six-inch (15 cm) square image, in an evening event to
publicize a weekday programming schedule offering films and live entertainers
during the four-hour daily broadcasts. Appearing were boxer Primo Carnera,
actors Gertrude Lawrence, Louis Calhern and Lionel Atwill, WHN announcer Nils
Granlund, the Forman Sisters, and a host of others.[13]
CBS's New York City station W2XAB began broadcasting their
first regular seven days a week television schedule on July 21, 1931, with a
60-line electromechanical system. The first broadcast included Mayor Jimmy
Walker, the Boswell Sisters, Kate Smith, and George Gershwin. The service ended
in February 1933. However, CBS considers it to be an ancestor of WCBS-TV, which
first went on the air on July 1, 1941 as one of the first two commercially licensed
television stations in the country (the other being the National Broadcasting
Company's WNBC). Don Lee Broadcasting's station W6XAO in Los Angeles went on
the air in December 1931. Using the UHF spectrum, it broadcast a regular
schedule of filmed images every day except Sundays and holidays for several
years. It later moved to VHF Channel 1 before World War 2, and to Channel 2 in
the post-war television realignment. It was commercially licensed in 1947 as
KTSL and is the direct ancestor of current station KCBS-TV.
By 1935, low-definition electromechanical television
broadcasting had ceased in the United States except for a handful of stations
run by public universities that continued to 1939. The Federal Communications
Commission saw television in the continual flux of development with no
consistent technical standards, hence all such stations in the U.S. were
granted only experimental and not commercial licenses, hampering television's
economic development. Just as importantly, Philo Farnsworth's August 1934
demonstration of an all-electronic system at the Franklin Institute in
Philadelphia pointed out the direction of television's future.
On June 15, 1936, Don Lee Broadcasting began a month-long
demonstration of high definition (240+ line) television in Los Angeles on W6XAO
(later KTSL) with a 300-line image from motion picture film. By October, W6XAO
was making daily television broadcasts of films. RCA demonstrated in New York
City a 343-line electronic television broadcast, with live and film segments,
to its licensees on July 7, 1936, and made its first public demonstration to
the press on November 6. Irregularly scheduled broadcasts continued through
1937 and 1938.[14] NBC began regularly scheduled broadcasts in New York on
April 30, 1939 with a broadcast of the opening of the 1939 New York World's
Fair. By June 1939, regularly scheduled 441-line electronic television
broadcasts were available in New York City and Los Angeles, and by November on
General Electric's station in Schenectady. From May through December 1939, the
New York City NBC station (W2XBS) of General Electric broadcast twenty to
fifty-eight hours of programming per month, Wednesday through Sunday of each
week. The programming was 33% news, 29% drama, and 17% educational programming,
with an estimated 2,000 receiving sets by the end of the year, and an estimated
audience of five to eight thousand. A remote truck could cover outdoor events
from up to 10 miles (16 km) away from the transmitter, which was located atop
the Empire State Building. Coaxial cable was used to cover events at Madison
Square Garden. The coverage area for reliable reception was a radius of 40 to
50 miles (80 km) from the Empire State Building, an area populated by more than
10,000,000 people (Lohr, 1940).
The FCC adopted NTSC television engineering standards on May
2, 1941, calling for 525 lines of vertical resolution, 30 frames per second
with interlaced scanning, 60 fields per second, and sound carried by frequency
modulation. Sets sold since 1939 which were built for slightly lower resolution
could still be adjusted to receive the new standard. (Dunlap, p31). The FCC saw
television ready for commercial licensing, and the first such licenses were
issued to NBC and CBS owned stations in New York on July 1, 1941, followed by
Philco's station in Philadelphia, then licensed as WPTZ and eventually licensed
again as the present-day KYW-TV. After the U.S. entry into World War II, the
FCC reduced the required minimum air time for commercial television stations
from 15 hours per week to 4 hours. Most TV stations suspended broadcasting. On
the few that remained, programs included entertainment such as boxing and
plays, events at Madison Square Garden, and illustrated war news as well as
training for air raid wardens and first aid providers. In 1942, there were
5,000 sets in operation, but production of new TVs, radios, and other
broadcasting equipment for civilian purposes was suspended from April 1942 to
August 1945 (Dunlap).
Canada
The Canadian Broadcasting Corporation (CBC) adopted the
American NTSC 525-line B/W 60 field per second system as its broadcast
standard. It began television broadcasting in Canada in September 1952. The
first broadcast was on September 6, 1952 from its Montreal, Quebec station
CBFT. The premiere broadcast was bilingual, spoken in English and French. Two
days later, on September 8, 1952, the Toronto, Ontario station CBLT went on the
air. This became the English-speaking flagship station for the country, while
CBFT became the French language flagship after a second English language
station was licensed to CBC in Montreal later in the decade. The CBC�s first
privately owned affiliate television station, CKSO in Sudbury, Ontario,
launched in October 1953 (at the time, all private stations were expected to
affiliate with the CBC, a condition that was relaxed in 1960�61 when CTV,
Canada's second national English language network, was formed).
France
In November 1929, Bernard Natan established France's first
television company, Television-Baird-Natan. On April 14, 1931, was the first
transmission with a thirty-line standard by Rene Barthelemy. On December 6,
1931, Henri de France created the Compagnie Generale de Television (CGT). In
December 1932, Bathelemy carried out an experimental program in black and white
(definition: 60 lines) one hour per week, "Paris Television", which
gradually became daily from early 1933.
The first official channel of French television appeared on
February 13, 1935, date of the official inauguration of television in France which
was broadcast in 60 lines from 8:15 to 8:30 pm. The program was of the actress
Beatrice Bretty from the studio of Radio-PTT Vision at 103 rue de Grenelle in
Paris. The broadcast had a range of 100 km (62 miles). On November 10, George
Mandel, Minister of PTT, inaugurated the first broadcast in 180 lines from the
transmitter of the Eiffel tower. On the 18th, Susy Wincker, first announcer
since June, carried out a demonstration for the press from 5:30 to 7:30 pm.
Broadcasts became regular from January 4, 1937 from 11:00 to 11:30 am and 8:00
to 8:30 pm during the week, and from 5:30 to 7:30 pm on Sundays. In July 1938,
a decree defined for three years a standard of 455 lines VHF (whereas three
standards are used for the experiments: 441 lines for Gramont, 450 lines for
the Compagnie des Compteurs and 455 for Thomson). In 1939, there were about
only 200 to 300 individual television sets, some of which were also available
in a few public places.
With the entry of France into World War II the same year,
broadcasts ceased and the transmitter of the Eiffel tower was sabotaged. On
September 3, 1940, French television was seized by the German occupation
forces. A technical agreement was signed by the Compagnie des Compteurs and
Telefunken, and a financing agreement for the resuming of the service is signed
by German Ministry of Post and Radiodiffusion Nationale (Vichy's radio). On May
7, 1943 at 3:00 evening broadcasts. The first broadcast of Fernsehsender Paris
(Paris Television) was transmitted from rue Cognac-Jay. These regular
broadcasts (5 1/4 hours a day) lasted until August 16, 1944. One thousand
441-line sets, most of which were installed in soldiers' hospitals, picked up
the broadcasts.
In 1944, Rene Barthelemy developed an 819-line television
standard. During the years of occupation, Barthelemy reached 1015 and even 1042
lines. On October 1, 1944, television service resumed after the liberation of
Paris. The broadcasts were transmitted from the Cognacq-Jay studios. In October
1945, after repairs, the transmitter of the Eiffel Tower was back in service.
On November 20, 1948, Mitterrand decreed a broadcast standard of 819 lines;
broadcasting begins at the end of 1949 in this definition. France is the only
European country to adopt it (others will choose 625 lines).
Germany
Electromechanical broadcasts began in Germany in 1929, but
were without sound until 1934. Network electronic service started on March 22,
1935, on 180 lines using telecine transmission of film, intermediate film
system, or cameras using the Nipkow Disk. Transmissions using cameras based on
the iconoscope began on January 15, 1936. The Berlin Summer Olympic Games were
televised, using both fully electronic iconoscope-based cameras and
intermediate film cameras, to Berlin and Hamburg in August 1936. Twenty-eight
public television rooms were opened for anybody who did not own a television
set. The Germans had a 441-line system on the air in February 1937, and during
World War II brought it to France, where they broadcast from the Eiffel Tower.
The American Armed Forces Radio Network at the end of World War II, wishing to
provide US TV programming to the occupation forces in Germany, used US TV
receivers made to operate at 525 lines and 60 fields. US broadcast equipment
was modified; they changed the vertical frequency to 50 Hz to avoid power line
wiggles, changed the horizontal frequency from 15,750 Hz to 15,625 Hz a 0.5
microsecond change in the length of a line. With this signal, US TV receivers
with only an adjustment to the vertical hold control had a 625 line, 50 field
scan, which became the German standard.
United Kingdom
The first British television broadcast was made by Baird
Television's electromechanical system over the BBC radio transmitter in
September 1929. Baird provided a limited amount of programming five days a week
by 1930. On August 22, 1932, BBC launched its own regular service using Baird's
30-line electromechanical system, continuing until September 11, 1935. On
November 2, 1936 the BBC began broadcasting a dual-system service, alternating
between Marconi-EMI's 405-line standard and Baird's improved 240-line standard,
from Alexandra Palace in London, making the BBC Television Service (now BBC
One) the world's first regular high-definition television service. The
government, on advice from a special advisory committee, decided that
Marconi-EMI's electronic system gave the superior picture, and the Baird system
was dropped in February 1937. TV broadcasts in London were on the air an
average of four hours daily from 1936 to 1939. There were 12,000 to 15,000
receivers. Some sets in restaurants or bars might have 100 viewers for sport
events (Dunlap, p56).The outbreak of the Second World War caused the BBC
service to be suspended on September 1, 1939, resuming from Alexandra Palace on
June 7, 1946.
The first live broadcast from the European continent was
made on 27 August 1950. The first live signal to Britain from the United States
was broadcast via the Telstar satellite on 23 July 1962.
Soviet Union (USSR)
The Soviet Union began offering 30-line electromechanical
test broadcasts in Moscow on October 31, 1931, and a commercially manufactured
television set in 1932. The first experimental transmissions of electronic
television took place in Moscow on March 9, 1937, using equipment manufactured
and installed by RCA. Regular broadcasting began on December 31, 1938.
Later development
The first regular television transmissions in Canada began
in 1952 when the CBC put two stations on the air, one in Montreal, Quebec on September
6, and another in Toronto, Ontario two days later.
Technological innovations
The first live transcontinental television broadcast took
place in San Francisco, California with U.S. President Harry Truman's speech at
the Japanese Peace Treaty Conference on September 4, 1951, using AT&T's
transcontinental cable and microwave radio relay system.[15][16][17] The first
live coast-to-coast commercial television broadcast in the U.S. took place on
November 18, 1951 on the premiere of See It Now, which showed a split screen
view of the Brooklyn Bridge in New York City and the Golden Gate Bridge in San
Francisco. In 1958, the CBC completed the longest television network in the
world, from Sydney, Nova Scotia to Victoria, British Columbia. Reportedly, the
first continuous live broadcast of a breaking news story in the world was
conducted by the CBC during the Springhill Mining Disaster which began on
October 23 of that year.
Programming is broadcast on television stations (sometimes
called channels). At first, terrestrial broadcasting was the only way
television could be distributed. Because bandwidth was limited, government
regulation was normal.
In the U.S., the Federal Communications Commission in 1941
allowed stations to broadcast advertisements, but insisted on public service
programming commitments as a requirement for a license. By contrast, the United
Kingdom chose a different route, imposing a television licence fee on owners of
television reception equipment, to fund the BBC, which had public service as
part of its Royal Charter.
The development of cable and satellite means of distribution
in the 1970s pushed businessmen to target channels towards a certain audience,
and enabled the rise of subscription-based television channels, such as HBO and
Sky.
Overview
Practically every country in the world now has developed at
least one television channel. Television has grown up all over the world,
enabling every country to share aspects of their culture and society with
others.
Television sets
In television's electromechanical era, commercially made
television sets were sold from 1928 to 1934 in the United Kingdom,[18] United
States, and Russia.[19] The earliest commercially made sets sold by Baird in
the UK in 1928 were radios with the addition of a television device consisting
of a neon tube behind a mechanically spinning disk (the Nipkow disk) with a
spiral of apertures that produced a red postage-stamp size image, enlarged to
twice that size by a magnifying glass. The Baird "Televisor" was also
available without the radio. The Televisor sold in 1930�1933 is considered the
first mass-produced set, selling about a thousand units.[20]
The first commercially made electronic television sets with
cathode ray tubes were manufactured by Telefunken in Germany in 1934,[21][22]
followed by other makers in France (1936),[23] Britain (1936),[24] and America
(1938).[25][26] The cheapest of the pre-World War II factory-made American
sets, a 1938 image-only model with a 3-inch (8 cm) screen, cost US$125, the equivalent
of US$1,863 in 2007. The cheapest model with a 12-inch (30 cm) screen was $445
($6,633).[27]
An estimated 19,000 electronic television sets were
manufactured in Britain, and about 1,600 in Germany, before World War II. About
7,000�8,000 electronic sets were made in the U.S.[28] before the War Production
Board halted manufacture in April 1942, production resuming in August 1945.
Television usage in the United States skyrocketed after
World War II with the lifting of the manufacturing freeze, war-related
technological advances, the gradual expansion of the television networks
westward, the drop in set prices caused by mass production, increased leisure
time, and additional disposable income. While only 0.5% of U.S. households had
a television set in 1946, 55.7% had one in 1954, and 90% by 1962.[29] In
Britain, there were 15,000 television households in 1947, 1.4 million in 1952,
and 15.1 million by 1968.
For many years different countries used different technical
standards. France initially adopted the German 441-line standard but later
upgraded to 819 lines, which gave the highest picture definition of any
analogue TV system, approximately double the resolution of the British 405-line
system. However this is not without a cost, in that the cameras need to produce
four times the pixel rate (thus quadrupling the bandwidth), from pixels
one-quarter the size, reducing the sensitivity by an equal amount. In practice
the 819-line cameras never achieved anything like the resolution that could
theoretically be transmitted by the 819 line system, and for color, France
reverted to the same 625 lines as the European CCIR system.
Eventually most of Europe switched to the 625-line PAL
standard, once more following Germany's example, with France adopting SECAM. Meanwhile
in North America the original NTSC 525-line standard from 1941 was retained,
although analog television will be totally replaced for broadcast purposes in
February 2009.
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