Editing Color television (section)

===Early television===
Experiments with [[fax|facsimile]] image transmission systems that used radio broadcasts to transmit images date to the 19th century. It was not until the 20th century that advances in electronics and light detectors made television practical. A key problem was the need to convert a 2D image into a "1D" radio signal; some form of image scanning was needed to make this work. Early systems generally used a device known as a "[[Nipkow disk]]", which was a spinning disk with a series of holes punched in it that caused a spot to scan across and down the image. A single photodetector behind the disk captured the image brightness at any given spot, which was converted into a radio signal and broadcast. A similar disk was used at the receiver side, with a light source behind the disk instead of a detector.{{cn|date=August 2023}}

A number of such [[mechanical television]] systems were being used experimentally in the 1920s. The best-known was [[John Logie Baird]]'s, which was actually used for regular public broadcasting in Britain for several years. Indeed, Baird's system was demonstrated to members of the Royal Institution in London in 1926 in what is generally recognized as the first demonstration of a true, working television system.<ref>{{Cite web|url=https://www.bbc.co.uk/history/historic_figures/baird_logie.shtml|title=BBC - History - John Logie Baird|language=en-GB|access-date=25 June 2018}}</ref><ref>{{Cite book|title=John Logie Baird: A Life|last1=Kamm|first1=Antony|last2=Baird|first2=John|pages=69}}</ref> In spite of these early successes, all mechanical television systems shared a number of serious problems. Being mechanically driven, perfect synchronization of the sending and receiving discs was not easy to ensure, and irregularities could result in major image distortion. Another problem was that the image was scanned within a small, roughly rectangular area of the disk's surface, so that larger, higher-resolution displays required increasingly unwieldy disks and smaller holes that produced increasingly dim images. Rotating drums bearing small mirrors set at progressively greater angles proved more practical than Nipkow discs for high-resolution mechanical scanning, allowing images of 240 lines and more to be produced, but such delicate, high-precision optical components were not commercially practical for home receivers.{{citation needed|date=March 2011}}

It was clear to a number of developers that a completely electronic scanning system would be superior, and that the scanning could be achieved in a vacuum tube via electrostatic or magnetic means. Converting this concept into a usable system took years of development and several independent advances. The two key advances were [[Philo Farnsworth]]'s electronic scanning system, and [[Vladimir Zworykin]]'s [[Iconoscope]] camera. The Iconoscope, based on [[Kálmán Tihanyi]]'s early patents, superseded the Farnsworth-system. With these systems, the [[BBC]] began regularly scheduled black-and-white television broadcasts in 1936, but these were shut down again with the start of [[World War II]] in 1939. In this time thousands of television sets had been sold. The receivers developed for this program, notably those from [[Pye Ltd.]], played a key role in the development of [[radar]].

By 22 March 1935, 180-line black-and-white television programs were being broadcast from the [[Fernsehsender Paul Nipkow|Paul Nipkow TV station]] in [[Berlin]]. In 1936, under the guidance of the Minister of Public Enlightenment and Propaganda, [[Joseph Goebbels]], direct transmissions from fifteen mobile units at the [[1936 Summer Olympics|Olympic Games in Berlin]] were transmitted to selected small television houses ({{lang|de|Fernsehstuben}}) in Berlin and Hamburg.

In 1941, the first [[NTSC]] meetings produced a single standard for US broadcasts. US television broadcasts began in earnest in the immediate post-war era, and by 1950 there were 6&nbsp;million televisions in the United States.<ref>"Television", ''The World Book Encyclopedia'' 2003: 119</ref>