A box by which we see images and hear sounds is called television. Let us know about its invention and development.
In 1862 Abbe Giovanna Caselli invented pantelgraph which sends the still images with wires. May and Smith the other scientists in 1873 started their experiments with selenium and light which shows that they can convert these images to electronic signals. In 1876 George Boston a civil servant made the drawing of selenium camera which makes people see by electricity. After that some engineers and scientists like Figuier, Senlecq and Paivia gave designs for telectroscope. A rudimentary system with light sensitive cells was build by George Carey in 1880. Graham Bell invented photo phone in which light is used to send sound but he wanted to invent a device that could also send images.
In 1884 Paul Nipkow invented a device called electric telescope or screening disk which transmits images using a rotating metal disk with 18 lines of resolution over wires but his mechanical system cannot transmit a clear picture while inventors had hope for more clearer and perfect picture.
After 1900 from the discussions and ideas the development of television was started. Two ways were taken by the scientists. Some started their invention according to Paul Nipkowâ€™s rotating metal disk and tried to build mechanical television whereas others worked on cathode ray tube for electronic television. Charles Jenkins an American and John Baird Scotsman goes for mechanical model whereas Philo Farnsworth in San Francisco and Vladimir Zworykin worked in Westinghouse goes for electronic model. Boris Rosing took cathode ray tube and Nipkowâ€™s revolving disk made first working mechanical television in 1906. But Campbell Swinton and Boris Rosing said to use cathode ray tube for electronic system for sending images and developed electronic scanning method to reproduce images. Vladimir patents his T.V camera “electric eye” as he calls it has contributed for television development in 1923. Later on he developed kinescope for picture display.
John Baird became first to send moving silhouette images on mechanical system which was according to Nipkowâ€™s disk. In 1930 he operates a television which has 30 lines of resolution and five frames in a second.
Philo Farnsworth patents the first electronic television system “image dissector” as he calls it in 1927.
The first license of television station was given to Charles Jenkins in 1928 and in 1936 there were 200 televisions around the world. Cables of copper and surrounded by aluminum covering were used to send signals of television and telephone. In 1937 klystron got recognition as it is high frequency amplifier which had made U.H.F T.V possible because it can generate high power needed for the spectrum.
Vladimir and RCA had experimental broadcast from the empire state building. Dumont
Company started making television sets.
In 1940 Peter Goldmark made color television with 343 lines and in 1943 Vladimir developed a tube named orthicon which is more sensitive and can record night outdoor events. In 1946 Goldmark demonstrated color television which gives color picture by a placing red-blue-green spin wheel in front of cathode ray tube. Electronic system replaced this mechanical system of Goldmark. But he was the first for broadcasting color television system.
In 1950 Vladimir developed camera tube known as vidicon which was more superior. After certain developments if scientists made a T.V that broadcasts colored images in 1967.