Television (TV), sometimes shortened to tele
or telly, is a telecommunication medium used
for transmitting moving images in monochrome
(black and white), or in colour, and in two
or three dimensions and sound. The term can
refer to a television set, a television program
("TV show"), or the medium of television transmission.
Television is a mass medium for advertising,
entertainment and news.
Television became available in crude experimental
forms in the late 1920s, but it would still
be several years before the new technology
would be marketed to consumers. After World
War II, an improved form of black-and-white
TV broadcasting became popular in the United
States and Britain, and television sets became
commonplace in homes, businesses, and institutions.
During the 1950s, television was the primary
medium for influencing public opinion. In
the mid-1960s, color broadcasting was introduced
in the US and most other developed countries.
The availability of multiple types of archival
storage media such as Betamax, VHS tape, local
disks, DVDs, flash drives, high-definition
Blu-ray Discs, and cloud digital video recorders
has enabled viewers to watch pre-recorded
material—such as movies—at home on their
own time schedule. For many reasons, especially
the convenience of remote retrieval, the storage
of television and video programming now occurs
on the cloud. At the end of the first decade
of the 2000s, digital television transmissions
greatly increased in popularity. Another development
was the move from standard-definition television
(SDTV) (576i, with 576 interlaced lines of
resolution and 480i) to high-definition television
(HDTV), which provides a resolution that is
substantially higher. HDTV may be transmitted
in various formats: 1080p, 1080i and 720p.
Since 2010, with the invention of smart television,
Internet television has increased the availability
of television programs and movies via the
Internet through streaming video services
such as Netflix, Amazon Video, iPlayer, Hulu,
Roku and Chromecast.
In 2013, 79% of the world's households owned
a television set. The replacement of early
bulky, high-voltage cathode ray tube (CRT)
screen displays with compact, energy-efficient,
flat-panel alternative technologies such as
LCDs (both fluorescent-backlit and LED), OLED
displays, and plasma displays was a hardware
revolution that began with computer monitors
in the late 1990s. Most TV sets sold in the
2000s were flat-panel, mainly LEDs. Major
manufacturers announced the discontinuation
of CRT, DLP, plasma, and even fluorescent-backlit
LCDs by the mid-2010s. In the near future,
LEDs are expected to be gradually replaced
by OLEDs. Also, major manufacturers have announced
that they will increasingly produce smart
TVs in the mid-2010s. Smart TVs with integrated
Internet and Web 2.0 functions became the
dominant form of television by the late 2010s.Television
signals were initially distributed only as
terrestrial television using high-powered
radio-frequency transmitters to broadcast
the signal to individual television receivers.
Alternatively television signals are distributed
by coaxial cable or optical fiber, satellite
systems and, since the 2000s via the Internet.
Until the early 2000s, these were transmitted
as analog signals, but a transition to digital
television is expected to be completed worldwide
by the late 2010s. A standard television set
is composed of multiple internal electronic
circuits, including a tuner for receiving
and decoding broadcast signals. A visual display
device which lacks a tuner is correctly called
a video monitor rather than a television.
== Etymology ==
The word television comes from Ancient Greek
τῆλε (tèle), meaning 'far', and Latin
visio, meaning 'sight'. The first documented
usage of the term dates back to 1900, when
the Russian scientist Constantin Perskyi used
it in a paper that he presented in French
at the 1st International Congress of Electricity,
which ran from 18 to 25 August 1900 during
the International World Fair in Paris. The
Anglicised version of the term is first attested
in 1907, when it was still "...a theoretical
system to transmit moving images over telegraph
or telephone wires". It was "...formed in
English or borrowed from French télévision."
In the 19th century and early 20th century,
other "...proposals for the name of a then-hypothetical
technology for sending pictures over distance
were telephote (1880) and televista (1904)."
The abbreviation "TV" is from 1948. The use
of the term to mean "a television set" dates
from 1941. The use of the term to mean "television
as a medium" dates from 1927. The slang term
"telly" is more common in the UK. The slang
term "the tube" or the "boob tube" derives
from the bulky cathode ray tube used on most
TVs until the advent of flat-screen TVs. Another
slang term for the TV is "idiot box". Also,
in the 1940s and throughout the 1950s, during
the early rapid growth of television programming
and television-set ownership in the United
States, another slang term became widely used
in that period and continues to be used today
to distinguish productions originally created
for broadcast on television from films developed
for presentation in movie theaters. The “small
screen”, as both a compound adjective and
noun, became specific references to television,
while the “big screen” was used to identify
productions made for theatrical release.
== History ==
=== 
Mechanical ===
Facsimile transmission systems for still photographs
pioneered methods of mechanical scanning of
images in the early 19th century. Alexander
Bain introduced the facsimile machine between
1843 and 1846. Frederick Bakewell demonstrated
a working laboratory version in 1851. Willoughby
Smith discovered the photoconductivity of
the element selenium in 1873. As a 23-year-old
German university student, Paul Julius Gottlieb
Nipkow proposed and patented the Nipkow disk
in 1884. This was a spinning disk with a spiral
pattern of holes in it, so each hole scanned
a line of the image. Although he never built
a working model of the system, variations
of Nipkow's spinning-disk "image rasterizer"
became exceedingly common. Constantin Perskyi
had coined the word television in a paper
read to the International Electricity Congress
at the International World Fair in Paris on
24 August 1900. Perskyi's paper reviewed the
existing electromechanical technologies, mentioning
the work of Nipkow and others. However, it
was not until 1907 that developments in amplification
tube technology by Lee de Forest and Arthur
Korn, among others, made the design practical.The
first demonstration of the live transmission
of images was by Georges Rignoux and A. Fournier
in Paris in 1909. A matrix of 64 selenium
cells, individually wired to a mechanical
commutator, served as an electronic retina.
In the receiver, a type of Kerr cell modulated
the light and a series of variously angled
mirrors attached to the edge of a rotating
disc scanned the modulated beam onto the display
screen. A separate circuit regulated synchronization.
The 8x8 pixel resolution in this proof-of-concept
demonstration was just sufficient to clearly
transmit individual letters of the alphabet.
An updated image was transmitted "several
times" each second. In 1921 Edouard Belin
sent the first image via radio waves with
his belinograph.
In 1911, Boris Rosing and his student Vladimir
Zworykin created a system that used a mechanical
mirror-drum scanner to transmit, in Zworykin's
words, "very crude images" over wires to the
"Braun tube" (cathode ray tube or "CRT") in
the receiver. Moving images were not possible
because, in the scanner: "the sensitivity
was not enough and the selenium cell was very
laggy".
By the 1920s, when amplification made television
practical, Scottish inventor John Logie Baird
employed the Nipkow disk in his prototype
video systems. On 25 March 1925, Baird gave
the first public demonstration of televised
silhouette images in motion, at Selfridge's
Department Store in London. Since human faces
had inadequate contrast to show up on his
primitive system, he televised a ventriloquist's
dummy named "Stooky Bill", whose painted face
had higher contrast, talking and moving. By
26 January 1926, he demonstrated the transmission
of the image of a face in motion by radio.
This is widely regarded as the first television
demonstration. The subject was Baird's business
partner Oliver Hutchinson. Baird's system
used the Nipkow disk for both scanning the
image and displaying it. A bright light shining
through a spinning Nipkow disk set with lenses
projected a bright spot of light which swept
across the subject. A Selenium photoelectric
tube detected the light reflected from the
subject and converted it into a proportional
electrical signal. This was transmitted by
AM radio waves to a receiver unit, where the
video signal was applied to a neon light behind
a second Nipkow disk rotating synchronized
with the first. The brightness of the neon
lamp was varied in proportion to the brightness
of each spot on the image. As each hole in
the disk passed by, one scan line of the image
was reproduced. Baird's disk had 30 holes,
producing an image with only 30 scan lines,
just enough to recognize a 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. In 1929, he became
involved in the first experimental mechanical
television service in Germany. In November
of the same year, Baird and Bernard Natan
of Pathé established France's first television
company, Télévision-Baird-Natan. In 1931,
he made the first outdoor remote broadcast,
of The Derby. In 1932, he demonstrated ultra-short
wave television. Baird's mechanical system
reached a peak of 240-lines of resolution
on BBC television broadcasts in 1936, though
the mechanical system did not scan the televised
scene directly. Instead a 17.5mm film was
shot, rapidly developed and then scanned while
the film was still wet.
An American inventor, Charles Francis Jenkins,
also pioneered the television. He published
an article on "Motion Pictures by Wireless"
in 1913, but it was not until December 1923
that he transmitted moving silhouette images
for witnesses; and it was on 13 June 1925,
that he publicly demonstrated synchronized
transmission of silhouette pictures. In 1925
Jenkins used the Nipkow disk and transmitted
the silhouette image of a toy windmill in
motion, over a distance of five miles, from
a naval radio station in Maryland to his laboratory
in Washington, D.C., using a lensed disk scanner
with a 48-line resolution. He was granted
U.S. Patent No. 1,544,156 (Transmitting Pictures
over Wireless) on 30 June 1925 (filed 13 March
1922).
Herbert E. Ives and Frank Gray of Bell Telephone
Laboratories gave a dramatic demonstration
of mechanical television on 7 April 1927.
Their reflected-light television system included
both small and large viewing screens. The
small receiver had a 2-inch-wide by 2.5-inch-high
screen. The large receiver had a screen 24
inches wide by 30 inches high. Both sets were
capable of reproducing reasonably accurate,
monochromatic, moving images. Along with the
pictures, the sets received synchronized sound.
The system transmitted images over two paths:
first, a copper wire link from Washington
to New York City, then a radio link from Whippany,
New Jersey. Comparing the two transmission
methods, viewers noted no difference in quality.
Subjects of the telecast included Secretary
of Commerce Herbert Hoover. A flying-spot
scanner beam illuminated these subjects. The
scanner that produced the beam had a 50-aperture
disk. The disc revolved at a rate of 18 frames
per second, capturing one frame about every
56 milliseconds. (Today's systems typically
transmit 30 or 60 frames per second, or one
frame every 33.3 or 16.7 milliseconds respectively.)
Television historian Albert Abramson underscored
the significance of the Bell Labs demonstration:
"It was in fact the best demonstration of
a mechanical television system ever made to
this time. It would be several years before
any other system could even begin to compare
with it in picture quality."In 1928, WRGB,
then W2XB, was started as the world's first
television station. It broadcast from the
General Electric facility in Schenectady,
NY. It was popularly known as "WGY Television".
Meanwhile, in the Soviet Union, Léon 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. As part of his thesis, on 7 May 1926,
he electrically transmitted, and then projected,
near-simultaneous moving images on a five-foot
square screen. By 1927 he achieved an image
of 100 lines, a resolution that was not surpassed
until May 1932 by RCA, with 120 lines. On
25 December 1926, Kenjiro Takayanagi demonstrated
a television system with a 40-line resolution
that employed a Nipkow disk scanner and CRT
display at Hamamatsu Industrial High School
in Japan. This prototype is still on display
at the Takayanagi Memorial Museum in Shizuoka
University, Hamamatsu Campus. His research
in creating a production model was halted
by the United States after Japan lost World
War II.Because only a limited number of holes
could be made in the disks, and disks beyond
a certain diameter became impractical, image
resolution on mechanical television broadcasts
was relatively low, ranging from about 30
lines up to 120 or so. Nevertheless, the image
quality of 30-line transmissions steadily
improved with technical advances, and by 1933
the UK broadcasts using the Baird system were
remarkably clear. A few systems ranging into
the 200-line region also went on the air.
Two of these were the 180-line system that
Compagnie des Compteurs (CDC) installed in
Paris in 1935, and the 180-line system that
Peck Television Corp. started in 1935 at station
VE9AK in Montreal. The advancement of all-electronic
television (including image dissectors and
other camera tubes and cathode ray tubes for
the reproducer) marked the beginning of the
end for mechanical systems as the dominant
form of television. Mechanical television,
despite its inferior image quality and generally
smaller picture, would remain the primary
television technology until the 1930s. The
last mechanical television broadcasts ended
in 1939 at stations run by a handful of public
universities in the United States.
=== Electronic ===
In 1897, English physicist J. J. Thomson was
able, in his three famous experiments, to
deflect cathode rays, a fundamental function
of the modern cathode ray tube (CRT). The
earliest version of the CRT was invented by
the German physicist Ferdinand Braun in 1897
and is also known as the "Braun" tube. It
was a cold-cathode diode, a modification of
the Crookes tube, with a phosphor-coated screen.
In 1906 the Germans Max Dieckmann and Gustav
Glage produced raster images for the first
time in a CRT. In 1907, Russian scientist
Boris Rosing used a CRT in the receiving end
of an experimental video signal to form a
picture. He managed to display simple geometric
shapes onto the screen.In 1908 Alan Archibald
Campbell-Swinton, fellow of the Royal Society
(UK), published a letter in the scientific
journal Nature in which he described how "distant
electric vision" could be achieved by using
a cathode ray tube, or Braun tube, as both
a transmitting and receiving device, He expanded
on his vision in a speech given in London
in 1911 and reported in The Times and the
Journal of the Röntgen Society. In a letter
to Nature published in October 1926, Campbell-Swinton
also announced the results of some "not very
successful experiments" he had conducted with
G. M. Minchin and J. C. M. Stanton. They had
attempted to generate an electrical signal
by projecting an image onto a selenium-coated
metal plate that was simultaneously scanned
by a cathode ray beam. These experiments were
conducted before March 1914, when Minchin
died, but they were later repeated by two
different teams in 1937, by H. Miller and
J. W. Strange from EMI, and by H. Iams and
A. Rose from RCA. Both teams succeeded in
transmitting "very faint" images with the
original Campbell-Swinton's selenium-coated
plate. Although others had experimented with
using a cathode ray tube as a receiver, the
concept of using one as a transmitter was
novel. The first cathode ray tube to use a
hot cathode was developed by John B. Johnson
(who gave his name to the term Johnson noise)
and Harry Weiner Weinhart of Western Electric,
and became a commercial product in 1922.In
1926, Hungarian engineer Kálmán Tihanyi
designed a television system utilizing fully
electronic scanning and display elements and
employing the principle of "charge storage"
within the scanning (or "camera") tube. The
problem of low sensitivity to light resulting
in low electrical output from transmitting
or "camera" tubes would be solved with the
introduction of charge-storage technology
by Kálmán Tihanyi beginning in 1924. His
solution was a camera tube that accumulated
and stored electrical charges ("photoelectrons")
within the tube throughout each scanning cycle.
The device was first described in a patent
application he filed in Hungary in March 1926
for a television system he dubbed "Radioskop".
After further refinements included in a 1928
patent application, Tihanyi's patent was declared
void in Great Britain in 1930, so he applied
for patents in the United States. Although
his breakthrough would be incorporated into
the design of RCA's "iconoscope" in 1931,
the U.S. patent for Tihanyi's transmitting
tube would not be granted until May 1939.
The patent for his receiving tube had been
granted the previous October. Both patents
had been purchased by RCA prior to their approval.
Charge storage remains a basic principle in
the design of imaging devices for television
to the present day. On 25 December 1926, at
Hamamatsu Industrial High School in Japan,
Japanese inventor Kenjiro Takayanagi demonstrated
a TV system with a 40-line resolution that
employed a CRT display. This was the first
working example of a fully electronic television
receiver. Takayanagi did not apply for a patent.On
7 September 1927, American inventor 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. By 3 September 1928, Farnsworth
had developed the system sufficiently to hold
a demonstration for the press. This is widely
regarded as the first electronic television
demonstration. In 1929, the system was improved
further by the 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).
Meanwhile, Vladimir Zworykin was also experimenting
with the cathode ray tube to create and show
images. While working for Westinghouse Electric
in 1923, he began to develop an electronic
camera tube. But in a 1925 demonstration,
the image was dim, had low contrast, and poor
definition, and was stationary. Zworykin's
imaging tube never got beyond the laboratory
stage. But RCA, which acquired the Westinghouse
patent, asserted that the patent for Farnsworth's
1927 image dissector was written so broadly
that it would exclude any other electronic
imaging device. Thus RCA, on the basis of
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 his patent. Zworykin
received a patent in 1928 for a color transmission
version of his 1923 patent application; he
also divided his original application in 1931.
Zworykin was unable or unwilling to introduce
evidence of a working model of his tube that
was based on his 1923 patent application.
In September 1939, after losing an appeal
in the courts, and determined to go forward
with the commercial manufacturing of television
equipment, RCA agreed to pay Farnsworth US$1
million over a ten-year period, in addition
to license payments, to use his patents.In
1933, RCA introduced an improved camera tube
that relied on Tihanyi's charge storage principle.
Dubbed the "Iconoscope" by Zworykin, the new
tube had a light sensitivity of about 75,000
lux, and thus was claimed to be much more
sensitive than Farnsworth's image dissector.
However, Farnsworth had overcome his power
problems with his Image Dissector through
the invention of a completely unique "multipactor"
device that he began work on in 1930, and
demonstrated in 1931. This small tube could
amplify a signal reportedly to the 60th power
or better and showed great promise in all
fields of electronics. Unfortunately, a problem
with the multipactor was that it wore out
at an unsatisfactory rate.At the Berlin Radio
Show in August 1931, Manfred von Ardenne gave
a public demonstration of a television system
using a CRT for both transmission and reception.
However, Ardenne had not developed a camera
tube, using the CRT instead as a flying-spot
scanner to scan slides and film. Philo Farnsworth
gave the world's first public demonstration
of an all-electronic television system, using
a live camera, at the Franklin Institute of
Philadelphia on 25 August 1934, and for ten
days afterwards. Mexican inventor Guillermo
González Camarena also played an important
role in early TV. His experiments with TV
(known as telectroescopía at first) began
in 1931 and led to a patent for the "trichromatic
field sequential system" color television
in 1940. In Britain, the EMI engineering team
led by Isaac Shoenberg applied in 1932 for
a patent for a new device they dubbed "the
Emitron", which formed the heart of the cameras
they designed for the BBC. On 2 November 1936,
a 405-line broadcasting service employing
the Emitron began at studios in 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.
This was the world's first regular "high-definition"
television service.The original American iconoscope
was noisy, had a high ratio of interference
to signal, and ultimately gave disappointing
results, especially when compared to the high
definition mechanical scanning systems then
becoming available. The EMI team, under the
supervision of Isaac Shoenberg, analyzed how
the iconoscope (or Emitron) produces an electronic
signal and concluded that its real efficiency
was only about 5% of the theoretical maximum.
They solved this problem by developing, and
patenting in 1934, two new camera tubes dubbed
super-Emitron and CPS Emitron. The super-Emitron
was between ten and fifteen times more sensitive
than the original Emitron and iconoscope tubes
and, in some cases, this ratio was considerably
greater. It was used for outside broadcasting
by the BBC, for the first time, on Armistice
Day 1937, when the general public could watch
on a television set as the King laid a wreath
at the Cenotaph. This was the first time that
anyone had broadcast a live street scene from
cameras installed on the roof of neighboring
buildings, because neither Farnsworth nor
RCA would do the same until the 1939 New York
World's Fair.
On the other hand, in 1934, Zworykin shared
some patent rights with the German licensee
company Telefunken. The "image iconoscope"
("Superikonoskop" in Germany) was produced
as a result of the collaboration. This tube
is essentially identical to the super-Emitron.
The production and commercialization of the
super-Emitron and image iconoscope in Europe
were not affected by the patent war between
Zworykin and Farnsworth, because Dieckmann
and Hell had priority in Germany for the invention
of the image dissector, having submitted a
patent application for their Lichtelektrische
Bildzerlegerröhre für Fernseher (Photoelectric
Image Dissector Tube for Television) in Germany
in 1925, two years before Farnsworth did the
same in the United States. The image iconoscope
(Superikonoskop) became the industrial standard
for public broadcasting in Europe from 1936
until 1960, when it was replaced by the vidicon
and plumbicon tubes. Indeed, it was the representative
of the European tradition in electronic tubes
competing against the American tradition represented
by the image orthicon. The German company
Heimann produced the Superikonoskop for the
1936 Berlin Olympic Games, later Heimann also
produced and commercialized it from 1940 to
1955; finally the Dutch company Philips produced
and commercialized the image iconoscope and
multicon from 1952 to 1958.American television
broadcasting, at the time, consisted of a
variety of markets in a wide range of sizes,
each competing for programming and dominance
with separate technology, until deals were
made and standards agreed upon in 1941. RCA,
for example, used only Iconoscopes in the
New York area, but Farnsworth Image Dissectors
in Philadelphia and San Francisco. In September
1939, RCA agreed to pay the Farnsworth Television
and Radio Corporation royalties over the next
ten years for access to Farnsworth's patents.
With this historic agreement in place, RCA
integrated much of what was best about the
Farnsworth Technology into their systems.
In 1941, the United States implemented 525-line
television. Electrical engineer Benjamin Adler
played a prominent role in the development
of television.The world's first 625-line television
standard was designed in the Soviet Union
in 1944 and became a national standard in
1946. The first broadcast in 625-line standard
occurred in Moscow in 1948. The concept of
625 lines per frame was subsequently implemented
in the European CCIR standard. In 1936, Kálmán
Tihanyi described the principle of plasma
display, the first flat panel display system.
=== Color ===
The basic idea of using three monochrome images
to produce a color image had been experimented
with almost as soon as black-and-white televisions
had first been built. Although he gave no
practical details, among the earliest published
proposals for television was one by Maurice
Le Blanc, in 1880, for a color system, including
the first mentions in television literature
of line and frame scanning. Polish inventor
Jan Szczepanik patented a color television
system in 1897, using a selenium photoelectric
cell at the transmitter and an electromagnet
controlling an oscillating mirror and a moving
prism at the receiver. But his system contained
no means of analyzing the spectrum of colors
at the transmitting end, and could not have
worked as he described it. Another inventor,
Hovannes Adamian, also experimented with color
television as early as 1907. The first color
television project is claimed by him, and
was patented in Germany on 31 March 1908,
patent № 197183, then in Britain, on 1 April
1908, patent № 7219, in France (patent № 390326)
and in Russia in 1910 (patent № 17912).Scottish
inventor John Logie Baird demonstrated the
world's first color transmission on 3 July
1928, using scanning discs at the transmitting
and receiving ends with three spirals of apertures,
each spiral with filters of a different primary
color; and three light sources at the receiving
end, with a commutator to alternate their
illumination. Baird also made the world's
first color broadcast on 4 February 1938,
sending a mechanically scanned 120-line image
from Baird's Crystal Palace studios to a projection
screen at London's Dominion Theatre. Mechanically
scanned color television was also demonstrated
by Bell Laboratories in June 1929 using three
complete systems of photoelectric cells, amplifiers,
glow-tubes, and color filters, with a series
of mirrors to superimpose the red, green,
and blue images into one full color image.
The first practical hybrid system was again
pioneered by John Logie Baird. In 1940 he
publicly demonstrated a color television combining
a traditional black-and-white display with
a rotating colored disk. This device was very
"deep", but was later improved with a mirror
folding the light path into an entirely practical
device resembling a large conventional console.
However, Baird was not happy with the design,
and, as early as 1944, had commented to a
British government committee that a fully
electronic device would be better.
In 1939, Hungarian engineer Peter Carl Goldmark
introduced an electro-mechanical system while
at CBS, which contained an Iconoscope sensor.
The CBS field-sequential color system was
partly mechanical, with a disc made of red,
blue, and green filters spinning inside the
television camera at 1,200 rpm, and a similar
disc spinning in synchronization in front
of the cathode ray tube inside the receiver
set. The system was first demonstrated to
the Federal Communications Commission (FCC)
on 29 August 1940, and shown to the press
on 4 September.CBS began experimental color
field tests using film as early as 28 August
1940, and live cameras by 12 November. NBC
(owned by RCA) made its first field test of
color television on 20 February 1941. CBS
began daily color field tests on 1 June 1941.
These color systems were not compatible with
existing black-and-white television sets,
and, as no color television sets were available
to the public at this time, viewing of the
color field tests was restricted to RCA and
CBS engineers and the invited press. The War
Production Board halted the manufacture of
television and radio equipment for civilian
use from 22 April 1942 to 20 August 1945,
limiting any opportunity to introduce color
television to the general public.As early
as 1940, Baird had started work on a fully
electronic system he called Telechrome. Early
Telechrome devices used two electron guns
aimed at either side of a phosphor plate.
The phosphor was patterned so the electrons
from the guns only fell on one side of the
patterning or the other. Using cyan and magenta
phosphors, a reasonable limited-color image
could be obtained. He also demonstrated the
same system using monochrome signals to produce
a 3D image (called "stereoscopic" at the time).
A demonstration on 16 August 1944 was the
first example of a practical color television
system. Work on the Telechrome continued and
plans were made to introduce a three-gun version
for full color. However, Baird's untimely
death in 1946 ended development of the Telechrome
system.
Similar concepts were common through the 1940s
and 1950s, differing primarily in the way
they re-combined the colors generated by the
three guns. The Geer tube was similar to Baird's
concept, but used small pyramids with the
phosphors deposited on their outside faces,
instead of Baird's 3D patterning on a flat
surface. The Penetron used three layers of
phosphor on top of each other and increased
the power of the beam to reach the upper layers
when drawing those colors. The Chromatron
used a set of focusing wires to select the
colored phosphors arranged in vertical stripes
on the tube.
One of the great technical challenges of introducing
color broadcast television was the desire
to conserve bandwidth, potentially three times
that of the existing black-and-white standards,
and not use an excessive amount of radio spectrum.
In the United States, after considerable research,
the National Television Systems Committee
approved an all-electronic system developed
by RCA, which encoded the color information
separately from the brightness information
and greatly reduced the resolution of the
color information in order to conserve bandwidth.
As black-and-white TVs could receive the same
transmission and display it in black-and-white,
the color system adopted is [backwards] "compatible".
("Compatible Color", featured in RCA advertisements
of the period, is mentioned in the song "America",
of West Side Story, 1957.) The brightness
image remained compatible with existing black-and-white
television sets at slightly reduced resolution,
while color televisions could decode the extra
information in the signal and produce a limited-resolution
color display. The higher resolution black-and-white
and lower resolution color images combine
in the brain to produce a seemingly high-resolution
color image. The NTSC standard represented
a major technical achievement.
Although all-electronic color was introduced
in the U.S. in 1953, high prices, and the
scarcity of color programming, greatly slowed
its acceptance in the marketplace. The first
national color broadcast (the 1954 Tournament
of Roses Parade) occurred on 1 January 1954,
but during the following ten years most network
broadcasts, and nearly all local programming,
continued to be in black-and-white. It was
not until the mid-1960s that color sets started
selling in large numbers, due in part to the
color transition of 1965 in which it was announced
that over half of all network prime-time programming
would be broadcast in color that fall. The
first all-color prime-time season came just
one year later. In 1972, the last holdout
among daytime network programs converted to
color, resulting in the first completely all-color
network season.
Early color sets were either floor-standing
console models or tabletop versions nearly
as bulky and heavy; so in practice they remained
firmly anchored in one place. The introduction
of GE's relatively compact and lightweight
Porta-Color set in the spring of 1966 made
watching color television a more flexible
and convenient proposition. In 1972, sales
of color sets finally surpassed sales of black-and-white
sets. Color broadcasting in Europe was not
standardized on the PAL format until the 1960s,
and broadcasts did not start until 1967. By
this point many of the technical problems
in the early sets had been worked out, and
the spread of color sets in Europe was fairly
rapid. By the mid-1970s, the only stations
broadcasting in black-and-white were a few
high-numbered UHF stations in small markets,
and a handful of low-power repeater stations
in even smaller markets such as vacation spots.
By 1979, even the last of these had converted
to color and, by the early 1980s, B&W sets
had been pushed into niche markets, notably
low-power uses, small portable sets, or for
use as video monitor screens in lower-cost
consumer equipment. By the late 1980s even
these areas switched to color sets.
=== Digital ===
Digital television (DTV) is the transmission
of audio and video by digitally processed
and multiplexed signals, in contrast to the
totally analog and channel separated signals
used by analog television. Due to data compression
digital TV can support more than one program
in the same channel bandwidth. It is an innovative
service that represents the first significant
evolution in television technology since color
television in the 1950s. Digital TV's roots
have been tied very closely to the availability
of inexpensive, high performance computers.
It was not until the 1990s that digital TV
became feasible.In the mid-1980s, as Japanese
consumer electronics firms forged ahead with
the development of HDTV technology, the MUSE
analog format proposed by NHK, a Japanese
company, was seen as a pacesetter that threatened
to eclipse U.S. electronics companies' technologies.
Until June 1990, the Japanese MUSE standard,
based on an analog system, was the front-runner
among the more than 23 different technical
concepts under consideration. Then, an American
company, General Instrument, demonstrated
the feasibility of a digital television signal.
This breakthrough was of such significance
that the FCC was persuaded to delay its decision
on an ATV standard until a digitally based
standard could be developed.
In March 1990, when it became clear that a
digital standard was feasible, the FCC made
a number of critical decisions. First, the
Commission declared that the new ATV standard
must be more than an enhanced analog signal,
but be able to provide a genuine HDTV signal
with at least twice the resolution of existing
television images.(7) Then, to ensure that
viewers who did not wish to buy a new digital
television set could continue to receive conventional
television broadcasts, it dictated that the
new ATV standard must be capable of being
"simulcast" on different channels.(8)The new
ATV standard also allowed the new DTV signal
to be based on entirely new design principles.
Although incompatible with the existing NTSC
standard, the new DTV standard would be able
to incorporate many improvements.
The final standards adopted by the FCC did
not require a single standard for scanning
formats, aspect ratios, or lines of resolution.
This compromise resulted from a dispute between
the consumer electronics industry (joined
by some broadcasters) and the computer industry
(joined by the film industry and some public
interest groups) over which of the two scanning
processes—interlaced or progressive—would
be best suited for the newer digital HDTV
compatible display devices. Interlaced scanning,
which had been specifically designed for older
analogue CRT display technologies, scans even-numbered
lines first, then odd-numbered ones. In fact,
interlaced scanning can be looked at as the
first video compression model as it was partly
designed in the 1940s to double the image
resolution to exceed the limitations of the
television broadcast bandwidth. Another reason
for its adoption was to limit the flickering
on early CRT screens whose phosphor coated
screens could only retain the image from the
electron scanning gun for a relatively short
duration. However interlaced scanning does
not work as efficiently on newer display devices
such as Liquid-crystal (LCD), for example,
which are better suited to a more frequent
progressive refresh rate.Progressive scanning,
the format that the computer industry had
long adopted for computer display monitors,
scans every line in sequence, from top to
bottom. Progressive scanning in effect doubles
the amount of data generated for every full
screen displayed in comparison to interlaced
scanning by painting the screen in one pass
in 1/60-second, instead of two passes in 1/30-second.
The computer industry argued that progressive
scanning is superior because it does not "flicker"
on the new standard of display devices in
the manner of interlaced scanning. It also
argued that progressive scanning enables easier
connections with the Internet, and is more
cheaply converted to interlaced formats than
vice versa. The film industry also supported
progressive scanning because it offered a
more efficient means of converting filmed
programming into digital formats. For their
part, the consumer electronics industry and
broadcasters argued that interlaced scanning
was the only technology that could transmit
the highest quality pictures then (and currently)
feasible, i.e., 1,080 lines per picture and
1,920 pixels per line. Broadcasters also favored
interlaced scanning because their vast archive
of interlaced programming is not readily compatible
with a progressive format. William F. Schreiber,
who was director of the Advanced Television
Research Program at the Massachusetts Institute
of Technology from 1983 until his retirement
in 1990, thought that the continued advocacy
of interlaced equipment originated from consumer
electronics companies that were trying to
get back the substantial investments they
made in the interlaced technology.Digital
television transition started in late 2000s.
All governments across the world set the deadline
for analog shutdown by 2010s. Initially the
adoption rate was low, as the first digital
tuner-equipped TVs were costly. But soon,
as the price of digital-capable TVs dropped,
more and more households were converting to
digital televisions. The transition is expected
to be completed worldwide by mid to late 2010s.
=== Smart TV ===
The advent of digital television allowed innovations
like smart TVs. A smart television, sometimes
referred to as connected TV or hybrid TV,
is a television set or set-top box with integrated
Internet and Web 2.0 features, and is an example
of technological convergence between computers,
television sets and set-top boxes. Besides
the traditional functions of television sets
and set-top boxes provided through traditional
broadcasting media, these devices can also
provide Internet TV, online interactive media,
over-the-top content, as well as on-demand
streaming media, and home networking access.
These TVs come pre-loaded with an operating
system.Smart TV should not to be confused
with Internet TV, Internet Protocol television
(IPTV) or with Web TV. Internet television
refers to the receiving of television content
over the Internet instead of by traditional
systems—terrestrial, cable and satellite
(although internet itself is received by these
methods). IPTV is one of the emerging Internet
television technology standards for use by
television broadcasters. Web television (WebTV)
is a term used for programs created by a wide
variety of companies and individuals for broadcast
on Internet TV. A first patent was filed in
1994 (and extended the following year) for
an "intelligent" television system, linked
with data processing systems, by means of
a digital or analog network. Apart from being
linked to data networks, one key point is
its ability to automatically download necessary
software routines, according to a user's demand,
and process their needs. Major TV manufacturers
have announced production of smart TVs only,
for middle-end and high-end TVs in 2015. Smart
TVs are expected to become dominant form of
television by late 2010s.
=== 3D ===
3D television conveys depth perception to
the viewer by employing techniques such as
stereoscopic display, multi-view display,
2D-plus-depth, or any other form of 3D display.
Most modern 3D television sets use an active
shutter 3D system or a polarized 3D system,
and some are autostereoscopic without the
need of glasses. Stereoscopic 3D television
was demonstrated for the first time on 10
August 1928, by John Logie Baird in his company's
premises at 133 Long Acre, London. Baird pioneered
a variety of 3D television systems using electromechanical
and cathode-ray tube techniques. The first
3D TV was produced in 1935. The advent of
digital television in the 2000s greatly improved
3D TVs. Although 3D TV sets are quite popular
for watching 3D home media such as on Blu-ray
discs, 3D programming has largely failed to
make inroads with the public. Many 3D television
channels which started in the early 2010s
were shut down by the mid-2010s.According
to DisplaySearch 3D televisions shipments
totaled 41.45 million units in 2012, compared
with 24.14 in 2011 and 2.26 in 2010. As of
late 2013, the number of 3D TV viewers started
to decline.
== Broadcast systems ==
=== 
Terrestrial television ===
Programming is broadcast by television stations,
sometimes called "channels", as stations are
licensed by their governments to broadcast
only over assigned channels in the television
band. At first, terrestrial broadcasting was
the only way television could be widely distributed,
and because bandwidth was limited, i.e., there
were only a small number of channels available,
government regulation was the norm. In the
U.S., the Federal Communications Commission
(FCC) allowed stations to broadcast advertisements
beginning in July 1941, but required public
service programming commitments as a requirement
for a license. By contrast, the United Kingdom
chose a different route, imposing a television
license fee on owners of television reception
equipment to fund the British Broadcasting
Corporation (BBC), which had public service
as part of its Royal Charter.
WRGB claims to be the world's oldest television
station, tracing its roots to an experimental
station founded on 13 January 1928, broadcasting
from the General Electric factory in Schenectady,
NY, under the call letters W2XB. It was popularly
known as "WGY Television" after its sister
radio station. Later in 1928, General Electric
started a second facility, this one in New
York City, which had the call letters W2XBS
and which today is known as WNBC. The two
stations were experimental in nature and had
no regular programming, as receivers were
operated by engineers within the company.
The image of a Felix the Cat doll rotating
on a turntable was broadcast for 2 hours every
day for several years as new technology was
being tested by the engineers. On 2 November
1936, the BBC began transmitting the world's
first public regular high-definition service
from the Victorian Alexandra Palace in north
London. It therefore claims to be the birthplace
of TV broadcasting as we know it today.
With the widespread adoption of cable across
the United States in the 1970s and 80s, terrestrial
television broadcasts have been in decline;
in 2013 it was estimated that about 7% of
US households used an antenna. A slight increase
in use began around 2010 due to switchover
to digital terrestrial television broadcasts,
which offered pristine image quality over
very large areas, and offered an alternate
to cable television (CATV) for cord cutters.
All other countries around the world are also
in the process of either shutting down analog
terrestrial television or switching over to
digital terrestrial television.
=== Cable television ===
Cable television is a system of broadcasting
television programming to paying subscribers
via radio frequency (RF) signals transmitted
through coaxial cables or light pulses through
fiber-optic cables. This contrasts with traditional
terrestrial television, in which the television
signal is transmitted over the air by radio
waves and received by a television antenna
attached to the television. In the 2000s,
FM radio programming, high-speed Internet,
telephone service, and similar non-television
services may also be provided through these
cables. The abbreviation CATV is often used
for cable television. It originally stood
for Community Access Television or Community
Antenna Television, from cable television's
origins in 1948: in areas where over-the-air
reception was limited by distance from transmitters
or mountainous terrain, large "community antennas"
were constructed, and cable was run from them
to individual homes. The origins of cable
broadcasting are even older as radio programming
was distributed by cable in some European
cities as far back as 1924. Earlier cable
television was analog, but since the 2000s,
all cable operators have switched to, or are
in the process of switching to, digital cable
television.
=== Satellite television ===
Satellite television is a system of supplying
television programming using broadcast signals
relayed from communication satellites. The
signals are received via an outdoor parabolic
reflector antenna usually referred to as a
satellite dish and a low-noise block downconverter
(LNB). A satellite receiver then decodes the
desired television program for viewing on
a television set. Receivers can be external
set-top boxes, or a built-in television tuner.
Satellite television provides a wide range
of channels and services, especially to geographic
areas without terrestrial television or cable
television.
The most common method of reception is direct-broadcast
satellite television (DBSTV), also known as
"direct to home" (DTH). In DBSTV systems,
signals are relayed from a direct broadcast
satellite on the Ku wavelength and are completely
digital. Satellite TV systems formerly used
systems known as television receive-only.
These systems received analog signals transmitted
in the C-band spectrum from FSS type satellites,
and required the use of large dishes. Consequently,
these systems were nicknamed "big dish" systems,
and were more expensive and less popular.The
direct-broadcast satellite television signals
were earlier analog signals and later digital
signals, both of which require a compatible
receiver. Digital signals may include high-definition
television (HDTV). Some transmissions and
channels are free-to-air or free-to-view,
while many other channels are pay television
requiring a subscription.
In 1945, British science fiction writer Arthur
C. Clarke proposed a worldwide communications
system which would function by means of three
satellites equally spaced apart in earth orbit.
This was published in the October 1945 issue
of the Wireless World magazine and won him
the Franklin Institute's Stuart Ballantine
Medal in 1963.The first satellite television
signals from Europe to North America were
relayed via the Telstar satellite over the
Atlantic ocean on 23 July 1962. The signals
were received and broadcast in North American
and European countries and watched by over
100 million. Launched in 1962, the Relay 1
satellite was the first satellite to transmit
television signals from the US to Japan. The
first geosynchronous communication satellite,
Syncom 2, was launched on 26 July 1963.The
world's first commercial communications satellite,
called Intelsat I and nicknamed "Early Bird",
was launched into geosynchronous orbit on
6 April 1965. The first national network of
television satellites, called Orbita, was
created by the Soviet Union in October 1967,
and was based on the principle of using the
highly elliptical Molniya satellite for rebroadcasting
and delivering of television signals to ground
downlink stations. The first commercial North
American satellite to carry television transmissions
was Canada's geostationary Anik 1, which was
launched on 9 November 1972. ATS-6, the world's
first experimental educational and Direct
Broadcast Satellite (DBS), was launched on
30 May 1974. It transmitted at 860 MHz using
wideband FM modulation and had two sound channels.
The transmissions were focused on the Indian
subcontinent but experimenters were able to
receive the signal in Western Europe using
home constructed equipment that drew on UHF
television design techniques already in use.The
first in a series of Soviet geostationary
satellites to carry Direct-To-Home television,
Ekran 1, was launched on 26 October 1976.
It used a 714 MHz UHF downlink frequency so
that the transmissions could be received with
existing UHF television technology rather
than microwave technology.
=== Internet television ===
Internet television (Internet TV) (or online
television) is the digital distribution of
television content via the Internet as opposed
to traditional systems like terrestrial, cable,
and satellite, although the Internet itself
is received by terrestrial, cable, or satellite
methods. Internet television is a general
term that covers the delivery of television
shows, and other video content, over the Internet
by video streaming technology, typically by
major traditional television broadcasters.
Internet television should not be confused
with Smart TV, IPTV or with Web TV. Smart
television refers to the TV set which has
a built-in operating system. Internet Protocol
television (IPTV) is one of the emerging Internet
television technology standards for use by
television broadcasters. Web television is
a term used for programs created by a wide
variety of companies and individuals for broadcast
on Internet TV.
== Sets ==
A television set, also called a television
receiver, television, TV set, TV, or "telly",
is a device that combines a tuner, display,
an amplifier, and speakers for the purpose
of viewing television and hearing its audio
components. Introduced in late 1920's in mechanical
form, television sets became a popular consumer
product after World War II in electronic form,
using cathode ray tubes. The addition of color
to broadcast television after 1953 further
increased the popularity of television sets
and an outdoor antenna became a common feature
of suburban homes. The ubiquitous television
set became the display device for recorded
media in the 1970s, such as Betamax and VHS,
which enabled viewers to record TV shows and
watch prerecorded movies. In the subsequent
decades, TVs were used to watch DVDs and Blu-ray
Discs of movies and other content. Major TV
manufacturers announced the discontinuation
of CRT, DLP, plasma and fluorescent-backlit
LCDs by the mid-2010s. Televisions since 2010s
mostly use LEDs. LEDs are expected to be gradually
replaced by OLEDs in near future.
=== Display technologies ===
==== Disk ====
The earliest systems employed a spinning disk
to create and reproduce images. These usually
had a low resolution and screen size and never
became popular with the public.
==== CRT ====
The cathode ray tube (CRT) is a vacuum tube
containing one or more electron guns (a source
of electrons or electron emitter) and a fluorescent
screen used to view images.
It has a means to accelerate and deflect the
electron beam(s) onto the screen to create
the images. The images may represent electrical
waveforms (oscilloscope), pictures (television,
computer monitor), radar targets or others.
The CRT uses an evacuated glass envelope which
is large, deep (i.e. long from front screen
face to rear end), fairly heavy, and relatively
fragile. As a matter of safety, the face is
typically made of thick lead glass so as to
be highly shatter-resistant and to block most
X-ray emissions, particularly if the CRT is
used in a consumer product.
In television sets and computer monitors,
the entire front area of the tube is scanned
repetitively and systematically in a fixed
pattern called a raster. An image is produced
by controlling the intensity of each of the
three electron beams, one for each additive
primary color (red, green, and blue) with
a video signal as a reference. In all modern
CRT monitors and televisions, the beams are
bent by magnetic deflection, a varying magnetic
field generated by coils and driven by electronic
circuits around the neck of the tube, although
electrostatic deflection is commonly used
in oscilloscopes, a type of diagnostic instrument.
==== DLP ====
Digital Light Processing (DLP) is a type of
video projector technology that uses a digital
micromirror device. Some DLPs have a TV tuner,
which makes them a type of TV display. It
was originally developed in 1987 by Dr. Larry
Hornbeck of Texas Instruments. While the DLP
imaging device was invented by Texas Instruments,
the first DLP based projector was introduced
by Digital Projection Ltd in 1997. Digital
Projection and Texas Instruments were both
awarded Emmy Awards in 1998 for invention
of the DLP projector technology. DLP is used
in a variety of display applications from
traditional static displays to interactive
displays and also non-traditional embedded
applications including medical, security,
and industrial uses. DLP technology is used
in DLP front projectors (standalone projection
units for classrooms and business primarily),
but also in private homes; in these cases,
the image is projected onto a projection screen.
DLP is also used in DLP rear projection television
sets and digital signs. It is also used in
about 85% of digital cinema projection.
==== Plasma ====
A plasma display panel (PDP) is a type of
flat panel display common to large TV displays
30 inches (76 cm) or larger. They are called
"plasma" displays because the technology utilizes
small cells containing electrically charged
ionized gases, or what are in essence chambers
more commonly known as fluorescent lamps.
==== LCD ====
Liquid-crystal-display televisions (LCD TV)
are television sets that use LCD display technology
to produce images. LCD televisions are much
thinner and lighter than cathode ray tube
(CRTs) of similar display size, and are available
in much larger sizes (e.g., 90-inch diagonal).
When manufacturing costs fell, this combination
of features made LCDs practical for television
receivers. LCD's come in two types: those
using cold cathode fluorescent lamps, simply
called LCDs and those using LED as backlight
called as LEDs.
In 2007, LCD televisions surpassed sales of
CRT-based televisions worldwide for the first
time, and their sales figures relative to
other technologies accelerated. LCD TVs have
quickly displaced the only major competitors
in the large-screen market, the plasma display
panel and rear-projection television. In mid
2010s LCDs especially LEDs became, by far,
the most widely produced and sold television
display type. LCDs also have disadvantages.
Other technologies address these weaknesses,
including OLEDs, FED and SED, but as of 2014
none of these have entered widespread production.
==== OLED ====
An OLED (organic light-emitting diode) is
a light-emitting diode (LED) in which the
emissive electroluminescent layer is a film
of organic compound which emits light in response
to an electric current. This layer of organic
semiconductor is situated between two electrodes.
Generally, at least one of these electrodes
is transparent. OLEDs are used to create digital
displays in devices such as television screens.
It is also used for computer monitors, portable
systems such as mobile phones, handheld games
consoles and PDAs.
There are two main families of OLED: those
based on small molecules and those employing
polymers. Adding mobile ions to an OLED creates
a light-emitting electrochemical cell or LEC,
which has a slightly different mode of operation.
OLED displays can use either passive-matrix
(PMOLED) or active-matrix (AMOLED) addressing
schemes. Active-matrix OLEDs require a thin-film
transistor backplane to switch each individual
pixel on or off, but allow for higher resolution
and larger display sizes.
An OLED display works without a backlight.
Thus, it can display deep black levels and
can be thinner and lighter than a liquid crystal
display (LCD). In low ambient light conditions
such as a dark room an OLED screen can achieve
a higher contrast ratio than an LCD, whether
the LCD uses cold cathode fluorescent lamps
or LED backlight. OLEDs are expected to replace
other forms of display in near future.
=== Display resolution ===
==== LD ====
Low-definition television or LDTV refers to
television systems that have a lower screen
resolution than standard-definition television
systems such 240p (320*240). It is used in
handheld television. The most common source
of LDTV programming is the Internet, where
mass distribution of higher-resolution video
files could overwhelm computer servers and
take too long to download. Many mobile phones
and portable devices such as Apple's iPod
Nano, or Sony's PlayStation Portable use LDTV
video, as higher-resolution files would be
excessive to the needs of their small screens
(320×240 and 480×272 pixels respectively).
The current generation of iPod Nanos have
LDTV screens, as do the first three generations
of iPod Touch and iPhone (480×320). For the
first years of its existence, YouTube offered
only one, low-definition resolution of 320x240p
at 30fps or less. A standard, consumer grade
VHS videotape can be considered SDTV due to
its resolution (approximately 360 × 480i/576i).
==== SD ====
Standard-definition television or SDTV refers
to two different resolutions: 576i, with 576
interlaced lines of resolution, derived from
the European-developed PAL and SECAM systems;
and 480i based on the American National Television
System Committee NTSC system. SDTV is a television
system that uses a resolution that is not
considered to be either high-definition television
(720p, 1080i, 1080p, 1440p, 4K UHDTV, and
8K UHD) or enhanced-definition television
(EDTV 480p). In North America, digital SDTV
is broadcast in the same 4:3 aspect ratio
as NTSC signals with widescreen content being
center cut. However, in other parts of the
world that used the PAL or SECAM color systems,
standard-definition television is now usually
shown with a 16:9 aspect ratio, with the transition
occurring between the mid-1990s and mid-2000s.
Older programs with a 4:3 aspect ratio are
shown in the US as 4:3 with non-ATSC countries
preferring to reduce the horizontal resolution
by anamorphically scaling a pillarboxed image.
==== HD ====
High-definition television (HDTV) provides
a resolution that is substantially higher
than that of standard-definition television.
HDTV may be transmitted in various formats:
1080p: 1920×1080p: 2,073,600 pixels (~2.07
megapixels) per frame
1080i: 1920×1080i: 1,036,800 pixels (~1.04
MP) per field or 2,073,600 pixels (~2.07 MP)
per frame
A non-standard CEA resolution exists in some
countries such as 1440×1080i: 777,600 pixels
(~0.78 MP) per field or 1,555,200 pixels (~1.56
MP) per frame
720p: 1280×720p: 921,600 pixels (~0.92 MP)
per frame
==== UHD ====
Ultra-high-definition television (also known
as Super Hi-Vision, Ultra HD television, UltraHD,
UHDTV, or UHD) includes 4K UHD (2160p) and
8K UHD (4320p), which are two digital video
formats proposed by NHK Science & Technology
Research Laboratories and defined and approved
by the International Telecommunication Union
(ITU). The Consumer Electronics Association
announced on 17 October 2012, that "Ultra
High Definition", or "Ultra HD", would be
used for displays that have an aspect ratio
of at least 16:9 and at least one digital
input capable of carrying and presenting native
video at a minimum resolution of 3840×2160
pixels.
=== Market share ===
North American consumers purchase a new television
set on average every seven years, and the
average household owns 2.8 televisions. As
of 2011, 48 million are sold each year at
an average price of $460 and size of 38 in
(97 cm).
== Content ==
=== 
Programming ===
Getting TV programming shown to the public
can happen in many different ways. After production,
the next step is to market and deliver the
product to whichever markets are open to using
it. This typically happens on two levels:
Original run or First run: a producer creates
a program of one or multiple episodes and
shows it on a station or network which has
either paid for the production itself or to
which a license has been granted by the television
producers to do the same.
Broadcast syndication: this is the terminology
rather broadly used to describe secondary
programming usages (beyond original run).
It includes secondary runs in the country
of first issue, but also international usage
which may not be managed by the originating
producer. In many cases, other companies,
TV stations, or individuals are engaged to
do the syndication work, in other words, to
sell the product into the markets they are
allowed to sell into by contract from the
copyright holders, in most cases the producers.First-run
programming is increasing on subscription
services outside the US, but few domestically
produced programs are syndicated on domestic
free-to-air (FTA) elsewhere. This practice
is increasing, however, generally on digital-only
FTA channels or with subscriber-only, first-run
material appearing on FTA. Unlike the US,
repeat FTA screenings of an FTA network program
usually only occur on that network. Also,
affiliates rarely buy or produce non-network
programming that is not centered on local
programming.
=== Genres ===
Television genres include a broad range of
programming types that entertain, inform,
and educate viewers. The most expensive entertainment
genres to produce are usually dramas and dramatic
miniseries. However, other genres, such as
historical Western genres, may also have high
production costs.
Popular culture entertainment genres include
action-oriented shows such as police, crime,
detective dramas, horror, or thriller shows.
As well, there are also other variants of
the drama genre, such as medical dramas and
daytime soap operas. Science fiction shows
can fall into either the drama or action category,
depending on whether they emphasize philosophical
questions or high adventure. Comedy is a popular
genre which includes situation comedy (sitcom)
and animated shows for the adult demographic
such as South Park.
The least expensive forms of entertainment
programming genres are game shows, talk shows,
variety shows, and reality television. Game
shows feature contestants answering questions
and solving puzzles to win prizes. Talk shows
contain interviews with film, television,
music and sports celebrities and public figures.
Variety shows feature a range of musical performers
and other entertainers, such as comedians
and magicians, introduced by a host or Master
of Ceremonies. There is some crossover between
some talk shows and variety shows because
leading talk shows often feature performances
by bands, singers, comedians, and other performers
in between the interview segments. Reality
TV shows "regular" people (i.e., not actors)
facing unusual challenges or experiences ranging
from arrest by police officers (COPS) to significant
weight loss (The Biggest Loser). A variant
version of reality shows depicts celebrities
doing mundane activities such as going about
their everyday life (The Osbournes, Snoop
Dogg's Father Hood) or doing regular jobs
(The Simple Life).
Fictional television programs that some television
scholars and broadcasting advocacy groups
argue are "quality television", include series
such as Twin Peaks and The Sopranos. Kristin
Thompson argues that some of these television
series exhibit traits also found in art films,
such as psychological realism, narrative complexity,
and ambiguous plotlines. Nonfiction television
programs that some television scholars and
broadcasting advocacy groups argue are "quality
television", include a range of serious, noncommercial,
programming aimed at a niche audience, such
as documentaries and public affairs shows.
=== Funding ===
Around the globe, broadcast TV is financed
by government, advertising, licensing (a form
of tax), subscription, or any combination
of these. To protect revenues, subscription
TV channels are usually encrypted to ensure
that only subscribers receive the decryption
codes to see the signal. Unencrypted channels
are known as free to air or FTA. In 2009,
the global TV market represented 1,217.2 million
TV households with at least one TV and total
revenues of 268.9 billion EUR (declining 1.2%
compared to 2008). North America had the biggest
TV revenue market share with 39% followed
by Europe (31%), Asia-Pacific (21%), Latin
America (8%), and Africa and the Middle East
(2%). Globally, the different TV revenue sources
divide into 45–50% TV advertising revenues,
40–45% subscription fees and 10% public
funding.
==== Advertising ====
TV's broad reach makes it a powerful and attractive
medium for advertisers. Many TV networks and
stations sell blocks of broadcast time to
advertisers ("sponsors") to fund their programming.
Television advertisements (variously called
a television commercial, commercial or ad
in American English, and known in British
English as an advert) is a span of television
programming produced and paid for by an organization,
which conveys a message, typically to market
a product or service. Advertising revenue
provides a significant portion of the funding
for most privately owned television networks.
The vast majority of television advertisements
today consist of brief advertising spots,
ranging in length from a few seconds to several
minutes (as well as program-length infomercials).
Advertisements of this sort have been used
to promote a wide variety of goods, services
and ideas since the beginning of television.
The effects of television advertising upon
the viewing public (and the effects of mass
media in general) have been the subject of
philosophical discourse by such luminaries
as Marshall McLuhan. The viewership of television
programming, as measured by companies such
as Nielsen Media Research, is often used as
a metric for television advertisement placement,
and consequently, for the rates charged to
advertisers to air within a given network,
television program, or time of day (called
a "daypart"). In many countries, including
the United States, television campaign advertisements
are considered indispensable for a political
campaign. In other countries, such as France,
political advertising on television is heavily
restricted, while some countries, such as
Norway, completely ban political advertisements.
The first official, paid television advertisement
was broadcast in the United States on 1 July
1941 over New York station WNBT (now WNBC)
before a baseball game between the Brooklyn
Dodgers and Philadelphia Phillies. The announcement
for Bulova watches, for which the company
paid anywhere from $4.00 to $9.00 (reports
vary), displayed a WNBT test pattern modified
to look like a clock with the hands showing
the time. The Bulova logo, with the phrase
"Bulova Watch Time", was shown in the lower
right-hand quadrant of the test pattern while
the second hand swept around the dial for
one minute. The first TV ad broadcast in the
UK was on ITV on 22 September 1955, advertising
Gibbs SR toothpaste. The first TV ad broadcast
in Asia was on Nippon Television in Tokyo
on 28 August 1953, advertising Seikosha (now
Seiko), which also displayed a clock with
the current time.
===== United States =====
Since inception in the US in 1941, television
commercials have become one of the most effective,
persuasive, and popular methods of selling
products of many sorts, especially consumer
goods. During the 1940s and into the 1950s,
programs were hosted by single advertisers.
This, in turn, gave great creative license
to the advertisers over the content of the
show. Perhaps due to the quiz show scandals
in the 1950s, networks shifted to the magazine
concept, introducing advertising breaks with
multiple advertisers.
US advertising rates are determined primarily
by Nielsen ratings. The time of the day and
popularity of the channel determine how much
a TV commercial can cost. For example, it
can cost approximately $750,000 for a 30-second
block of commercial time during the highly
popular American Idol, while the same amount
of time for the Super Bowl can cost several
million dollars. Conversely, lesser-viewed
time slots, such as early mornings and weekday
afternoons, are often sold in bulk to producers
of infomercials at far lower rates. In recent
years, the paid program or infomercial has
become common, usually in lengths of 30 minutes
or one hour. Some drug companies and other
businesses have even created "news" items
for broadcast, known in the industry as video
news releases, paying program directors to
use them.Some TV programs also deliberately
place products into their shows as advertisements,
a practice started in feature films and known
as product placement. For example, a character
could be drinking a certain kind of soda,
going to a particular chain restaurant, or
driving a certain make of car. (This is sometimes
very subtle, with shows having vehicles provided
by manufacturers for low cost in exchange
as a product placement). Sometimes, a specific
brand or trade mark, or music from a certain
artist or group, is used. (This excludes guest
appearances by artists who perform on the
show.)
===== United Kingdom =====
The TV regulator oversees TV advertising in
the United Kingdom. Its restrictions have
applied since the early days of commercially
funded TV. Despite this, an early TV mogul,
Roy Thomson, likened the broadcasting licence
as being a "licence to print money". Restrictions
mean that the big three national commercial
TV channels: ITV, Channel 4, and Channel 5
can show an average of only seven minutes
of advertising per hour (eight minutes in
the peak period). Other broadcasters must
average no more than nine minutes (twelve
in the peak). This means that many imported
TV shows from the US have unnatural pauses
where the UK company does not utilize the
narrative breaks intended for more frequent
US advertising. Advertisements must not be
inserted in the course of certain specific
proscribed types of programs which last less
than half an hour in scheduled duration; this
list includes any news or current affairs
programs, documentaries, and programs for
children; additionally, advertisements may
not be carried in a program designed and broadcast
for reception in schools or in any religious
broadcasting service or other devotional program
or during a formal Royal ceremony or occasion.
There also must be clear demarcations in time
between the programs and the advertisements.
The BBC, being strictly non-commercial, is
not allowed to show advertisements on television
in the UK, although it has many advertising-funded
channels abroad. The majority of its budget
comes from television license fees (see below)
and broadcast syndication, the sale of content
to other broadcasters.
===== Ireland =====
Broadcast advertising is regulated by the
Broadcasting Authority of Ireland,
==== Subscription ====
Some TV channels are partly funded from subscriptions;
therefore, the signals are encrypted during
broadcast to ensure that only the paying subscribers
have access to the decryption codes to watch
pay television or specialty channels. Most
subscription services are also funded by advertising.
==== Taxation or license ====
Television services in some countries may
be funded by a television licence or a form
of taxation, which means that advertising
plays a lesser role or no role at all. For
example, some channels may carry no advertising
at all and some very little, including:
Australia (ABC)
Belgium (RTBF)
Denmark (DR)
Ireland (RTÉ)
Japan (NHK)
Norway (NRK)
Sweden (SVT)
United Kingdom (BBC)
United States (PBS)The BBC carries no television
advertising on its UK channels and is funded
by an annual television licence paid by premises
receiving live TV broadcasts. Currently, it
is estimated that approximately 26.8 million
UK private domestic households own televisions,
with approximately 25 million TV licences
in all premises in force as of 2010. This
television license fee is set by the government,
but the BBC is not answerable to or controlled
by the government.
The two main BBC TV channels are watched by
almost 90% of the population each week and
overall have 27% share of total viewing, despite
the fact that 85% of homes are multichannel,
with 42% of these having access to 200 free
to air channels via satellite and another
43% having access to 30 or more channels via
Freeview. The licence that funds the seven
advertising-free BBC TV channels costs £147
a year (about US$200) as of 2018 regardless
of the number of TV sets owned; the price
is reduced by two thirds if only black and
white television is received. When the same
sporting event has been presented on both
BBC and commercial channels, the BBC always
attracts the lion's share of the audience,
indicating that viewers prefer to watch TV
uninterrupted by advertising.
Other than internal promotional material,
the Australian Broadcasting Corporation (ABC)
carries no advertising; it is banned under
the ABC Act 1983. The ABC receives its funding
from the Australian government every three
years. In the 2014/15 federal budget, the
ABC received A$1.11 billion. The funds provide
for the ABC's television, radio, online, and
international outputs. The ABC also receives
funds from its many ABC shops across Australia.
Although funded by the Australian government,
the editorial independence of the ABC is ensured
through law.
In France, government-funded channels carry
advertisements, yet those who own television
sets have to pay an annual tax ("la redevance
audiovisuelle").In Japan, NHK is paid for
by license fees (known in Japanese as reception
fee (受信料, Jushinryō)). The broadcast
law that governs NHK's funding stipulates
that any television equipped to receive NHK
is required to pay. The fee is standardized,
with discounts for office workers and students
who commute, as well a general discount for
residents of Okinawa prefecture.
=== Broadcast programming ===
Broadcast programming, or TV listings in the
United Kingdom, is the practice of organizing
television programs in a schedule, with broadcast
automation used to regularly change the scheduling
of TV programs to build an audience for a
new show, retain that audience, or compete
with other broadcasters' programs.
== Social aspects ==
Television has played a pivotal role in the
socialization of the 20th and 21st centuries.
There are many aspects of television that
can be addressed, including negative issues
such as media violence. Current research is
discovering that individuals suffering from
social isolation can employ television to
create what is termed a parasocial or faux
relationship with characters from their favorite
television shows and movies as a way of deflecting
feelings of loneliness and social deprivation.
Several studies have found that educational
television has many advantages. The article
"The Good Things about Television" argues
that television can be a very powerful and
effective learning tool for children if used
wisely.
=== Consumption ===
== 
Negative impacts ==
With high lead content in CRTs and the rapid
diffusion of new flat-panel display technologies,
some of which (LCDs) use lamps which contain
mercury, there is growing concern about electronic
waste from discarded televisions. Related
occupational health concerns exist, as well,
for disassemblers removing copper wiring and
other materials from CRTs. Further environmental
concerns related to television design and
use relate to the devices' increasing electrical
energy requirements.A 2017 study in The Journal
of Human Resources found that exposure to
cable television reduced cognitive ability
and high school graduation rates for boys.
This effect was stronger for boys from more
educated families. The article suggests a
mechanism where light television entertainment
crowds out more cognitively stimulating activities.
== See also
