Editing Television (section)

===Mechanical===
{{main|Mechanical television}}
[[File:Nipkow disk.svg|right|upright=0.9|thumb|The [[Nipkow disk]]. This schematic shows the circular paths traced by the holes that may also be square for greater precision. The area of the disk outlined in black displays the region scanned.]]
[[Facsimile transmission]] systems for still photographs pioneered methods of mechanical scanning of images in the early 19th century. [[Alexander Bain (inventor)|Alexander Bain]] introduced the facsimile machine between 1843 and 1846. [[Frederick Bakewell]] demonstrated a working laboratory version in 1851.{{Citation needed|date=May 2015}} [[Willoughby Smith]] discovered the [[photoconductivity]] of the element [[selenium]] in 1873. As a 23-year-old German university student, [[Paul Gottlieb Nipkow|Paul Julius Gottlieb Nipkow]] proposed and patented the [[Nipkow disk]] in 1884 in [[Berlin]].<ref>Shiers, George and May (1997), ''Early Television: A Bibliographic Guide to 1940''. Taylor & Francis, pp. 13, 22. {{ISBN|978-0-8240-7782-2}}.</ref> This was a spinning disk with a spiral pattern of holes, 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 "[[rasterizer|image rasterizer]]" became exceedingly common.<ref>Shiers & Shiers, p. 13, 22.</ref> [[Constantin Perskyi]] had coined the word ''television'' in a paper read to the International Electricity Congress at the [[Exposition Universelle (1900)|International World Fair]] in Paris on 24 August 1900. Perskyi's paper reviewed the existing electromechanical technologies, mentioning the work of Nipkow and others.<ref>{{cite web|author=Constantin PERSKYI|url=https://www.histv.net/perskyi-1900|title=Télévision au moyen de l'électricité|agency=Congrès Inographs by Telegraph|work=The New York Times Sunday Magazine|date=20 September 1907|page=7}}</ref> 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.<ref name="Sending Photographs by Telegraph">[https://query.nytimes.com/gst/abstract.html?res=9A07E4DA1331E733A25757C2A9649C946697D6CF "Sending Photographs by Telegraph"], ''The New York Times'', Sunday Magazine, 20 September 1907, p. 7.</ref>

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 (electric)|commutator]], served as an electronic [[retina]]. In the receiver, a type of [[Kerr effect|Kerr cell]] modulated the light, and a series of differently 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.<ref>Henry de Varigny, "[http://histv2.free.fr/rignoux/rignoux1909.htm La vision à distance] {{Webarchive|url=https://web.archive.org/web/20160303231305/http://histv2.free.fr/rignoux/rignoux1909.htm |date=3 March 2016 }}", ''L'Illustration'', Paris, 11 December 1909, p. 451.</ref>

In 1911, [[Boris Rosing]] and his student [[Vladimir K. Zworykin|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 "[[Karl Ferdinand Braun|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".<ref>[https://books.google.com/books?id=gZcwhVyiMqsC&q=zworykin+rosing+selenium R. W. Burns, ''Television: An International History of the Formative Years''], IET, 1998, p. 119. {{ISBN|0-85296-914-7}}.</ref>

In 1921, [[Édouard Belin]] sent the first image via radio waves with his [[belinograph]].<ref name="Corporation1921">{{cite magazine|url=https://books.google.com/books?id=aSoDAAAAMBAJ&pg=PA21|author=Wilfred S. Ogden|date=December 1921|publisher=Bonnier Corporation|pages=21–22|title=How the World's First Wireless News-Picture Was Flashed Across the Atlantic Ocean, Paris get President Harding's portrait in twenty minutes|magazine=The Popular Science Monthly|issn=0161-7370|access-date=2 July 2014}}</ref>

[[File:John Logie Baird and Stooky Bill.png|thumb|[[John Logie Baird|Baird]] in 1925 with his televisor equipment and dummies "James" and "Stooky Bill" ''(right)'']]

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 [[Selfridges]]'s department store in [[London]].<ref>{{cite journal |title=Current Topics and Events |journal=Nature |volume=115 |issue=2892 |pages=504–508 |year=1925 |bibcode=1925Natur.115..504. |doi=10.1038/115504a0 |doi-access=free|issn=0028-0836 }}</ref> 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 had demonstrated before members of the Royal Institution the transmission of an image of a face in motion by radio. This is widely regarded as the world's first true public television demonstration, exhibiting light, shade, and detail.<ref>Television 1873–1927,''Television: The Official Organ Of The Television Society'', Vo1, No1, March 1928, Television Press Ltd, London, p11.</ref> Baird's system used the Nipkow disk for both scanning the image and displaying it. A brightly illuminated subject was placed in front of a spinning Nipkow disk set with lenses that swept images across a static photocell. The [[thallium sulfide]] (thalofide) cell, developed by [[Theodore Case]] in the U.S., 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.<ref>"The 'Televisor' – Successful test of a new apparatus," The Times (London), 28 January 1926, p. 9. "First on a receiver in the same room and then on a portable receiver in another room, the visitors were shown recognizable reception of the movements of the dummy head and of a person speaking."</ref> In 1927, Baird transmitted a signal over {{convert|438|mi|km}} of telephone line between London and [[Glasgow]].<ref>{{cite web |title=John Logie Baird (1888–1946) |url=http://www.bbc.co.uk/history/historic_figures/baird_logie.shtml#:~:text=On%2026%20January%201926%20he,the%20Baird%20Television%20Development%20Company. |publisher=[[BBC]] |access-date=7 April 2021}}</ref> Baird's original 'televisor' now resides in the Science Museum, South Kensington.

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-[[John Logie Baird|Baird]]-Natan. In 1931, he made the first outdoor remote broadcast of [[Epsom Derby|The Derby]].<ref>Baird, J.L., "[http://www.bairdtelevision.com/1932.html Television in 1932]", ''BBC Annual Report'', 1933.</ref> In 1932, he demonstrated [[ultra-short wave]] television. Baird's mechanical system reached a peak of 240 lines of resolution on [[BBC]] telecasts in 1936, though the mechanical system did not scan the televised scene directly. Instead, a [[17.5 mm film]] was shot, rapidly developed, and then scanned while the film was still wet. {{Citation needed|date=August 2019}}

A U.S. inventor, [[Charles Francis Jenkins]], also pioneered the television. He published an article on "Motion Pictures by Wireless" in 1913, transmitted moving silhouette images for witnesses in December 1923, and on 13 June 1925, 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 5 miles (8&nbsp;km), from a naval radio station in Maryland to his laboratory in Washington, D.C., using a lensed disk scanner with a 48-line resolution.<ref>"Radio Shows Far Away Objects in Motion", ''The New York Times'', 14 June 1925, p. 1.</ref><ref name="glinsky">{{cite book |last=Glinsky |first=Albert |title=Theremin: Ether Music and Espionage |url=https://archive.org/details/thereminethermus00glin |url-access=registration |publisher=University of Illinois Press |location=Urbana, IL |year=2000 |pages=[https://archive.org/details/thereminethermus00glin/page/41 41]–45 |isbn=978-0-252-02582-2}}</ref> He was granted [[United States Patent and Trademark Office|U.S. Patent]] No. 1,544,156 (Transmitting Pictures over Wireless) on 30 June 1925 (filed 13 March 1922).<ref>{{cite web |title=Case Files: Francis Jenkins (Phantoscope) |url=https://www.fi.edu/case-files/francis-jenkins-phantoscope |website=[[The Franklin Institute]] |date=27 May 2016 |access-date=28 March 2020 |archive-date=28 March 2020 |archive-url=https://web.archive.org/web/20200328180825/https://www.fi.edu/case-files/francis-jenkins-phantoscope |url-status=dead }}</ref>

[[Herbert E. Ives]] and [[Frank Gray (researcher)|Frank Gray]] of [[Bell Labs|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 (5 by 6&nbsp;cm). The large receiver had a screen 24&nbsp;inches wide by 30&nbsp;inches high (60 by 75&nbsp;cm). Both sets could reproduce 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 [[millisecond]]s. (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."<ref>Abramson, Albert, ''The History of Television, 1880 to 1941'', McFarland & Co., Inc., 1987, p. 101. {{ISBN|978-0-89950-284-7}}.</ref>

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 (AM)|WGY]] Television." Meanwhile, in the [[Soviet Union]], [[Leon Theremin]] had been developing a mirror drum-based television, starting with 16 lines resolution in 1925, then 32 lines, and eventually 64 using [[interlaced video|interlacing]] in 1926. As part of his thesis, on 7 May 1926, he electrically transmitted and then projected near-simultaneous moving images on a {{convert|5|ft2|adj=on}} screen.<ref name="glinsky"/>

By 1927 Theremin had achieved an image of 100 lines, a resolution that was not surpassed until May 1932 by RCA, with 120 lines.<ref>{{cite web | url=http://www.earlytelevision.org/rca_story_brewster.html | title=Early Electronic Television RCA TV Development: 1929–1949 | publisher=Early Television Museum | access-date=20 February 2016 | author=Brewster, Richard}}</ref>

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 [[Supreme Commander for the Allied Powers|SCAP]] after [[World War II]].<ref name="nhk.or.jp">[http://www.nhk.or.jp/strl/aboutstrl/evolution-of-tv-en/p05/ ''Kenjiro Takayanagi: The Father of Japanese Television''] {{webarchive|url=https://web.archive.org/web/20160101180643/http://www.nhk.or.jp/strl/aboutstrl/evolution-of-tv-en/p05/ |date=1 January 2016 }}, NHK (Japan Broadcasting Corporation), 2002. Retrieved 23 May 2009.</ref>

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.<ref>{{cite book |last1=McLean |first1=Donald F. |title=Restoring Baird's Image |date=2000 |publisher=IET |isbn=978-0-85296-795-9 |page=184 |url=https://books.google.com/books?id=1ISFkhG6cZQC&pg=PA184 |language=en}}</ref> 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]].<ref>{{cite web|url=http://www.earlytelevision.org/ve9ak.html |title=VE9AK entry at |publisher=Earlytelevision.org |access-date=2 March 2010}}</ref><ref>{{cite web|title=Peck Television Corporation Console Receiver and Camera|url=http://www.earlytelevision.org/peck.html|publisher=Early Television Museum|access-date=18 February 2012}}</ref> The advancement of all-electronic television (including [[Video camera tube#Image dissector|image dissectors]] and other camera tubes and [[cathode-ray tube]]s for the reproducer) marked the start 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 telecasts ended in 1939 at stations run by a lot of public universities in the United States.