Television became available in crude experimental forms in the late 1920s. After World War II, an improved form 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 storage media such as VHS tape (1976), DVDs (1997), and high-definition Blu-ray Discs (2006) enabled viewers to watch recorded material such as movies. At the end of the first decade of the 2000s, digital television transmissions greatly increased in popularity.
In 1921 the 14-year-old Mormon had an idea while working on his father's Idaho farm. Mowing hay in rows, Philo realized an electron beam could scan a picture in horizontal lines, reproducing the image almost instantaneously. This would prove to be a critical breakthrough in Philo Farnsworth's invention of the television in 1927.
Earlier TV devices had been based on an 1884 invention called the scanning disk, patented by Paul Nipkow. Riddled with holes, the large disk spun in front of an object while a photoelectric cell recorded changes in light. Depending on the electricity transmitted by the photoelectric cell, an array of light bulbs would glow or remain dark. Though Nipkow's mechanical system could not scan and deliver a clear, live-action image, most would-be TV inventors still hoped to perfect it.
Not Philo Farnsworth. In 1921 the 14-year-old Mormon had an idea while working on his father's Idaho farm. Mowing hay in rows, Philo realized an electron beam could scan a picture in horizontal lines, reproducing the image almost instantaneously. It would prove to be a critical breakthrough.
But young Philo was not alone. At the same time, Russian immigrant Vladimir Zworykin had also designed a camera that focused an image through a lens onto an array of photoelectric cells coating the end of a tube. The electrical image formed by the cells would be scanned line-by-line by an electron beam and transmitted to a cathode-ray tube.
Rather than an electron beam, Farnsworth's image dissector device used an "anode finger" -- a pencil-sized tube with a small aperture at the top -- to scan the picture. Magnetic coils sprayed the electrons emitted from the electrical image left to right and line by line onto the aperture, where they became electric current. Both Zworykin's and Philo's devices then transmitted the current to a cathode-ray tube, which recreated the image by scanning it onto a fluorescent surface.
Farnsworth applied for a patent for his image dissector in 1927. The development of the television system was plagued by lack of money and by challenges to Farnsworth's patent from the giant Radio Corporation of America (RCA). In 1934, the British communications company British Gaumont bought a license from Farnsworth to make systems based on his designs. In 1939, the American company RCA did the same. Both companies had been developing television systems of their own and recognized Farnsworth as a competitor. World War II interrupted the development of television. When television broadcasts became a regular occurrence after the war, Farnsworth was not involved. Instead, he devoted his time to trying to perfect the devices he had designed.
Television or TV is a telecommunication medium used for transmitting sound with moving images in monochrome (black-and-white), or in color, and in two or three dimensions. It can refer to a television set, a television program, or the medium of television transmission. Television is a mass medium, for entertainment, education, news and advertising.
One of the most popular inventions of 21st century has been surrounded by controversies. Television, which has become an indispensible part of our lives, is a result of several discoveries.
Early development stages of television witnessed various inventors employing combination of electronic, optical and mechanical technologies for capturing, transferring and broadcasting visual images. Towards the end of 1800s, images were transferred through fax machine for the first time. Soon after telephone came into being, electrically powered transmission of moving TV images, known as telephonoscope, was started. Science fiction writers were of the view that light would pass via wires like sound some day. And many people have worked hard to offer this exquisite instrument of entertainment.
Revolutionary works of Michael Faraday and Joseph Henry in 1831, launch of pantelegraph by Abbe Caselli and works by inventors and scientists Sheldon Bidwell, George Carey, Edison, Bell and Eugen Goldstein, all made way to Nipkow invention.
Paul Gottlieb Nipkow from Germany developed rotating disc technology known as Nipkow disc. In the year 1884, this young student patented electromagnetic TV system, employing scanning disk with various holes spiraling to center, for the purpose of rasterization. Holes on the disk were situated at equivalent angular intervals in way that the disc allowed light to pass through each hole in one rotation over light receptive selenium sensor that produced electrical pulses. But the design could only be used for transmission of halftone images.
Eventually, designs that used rotating mirror-drum scanner for capturing images and CRT as displaying device came into being. However, moving images were still not available due to bad sensitivity of selenium sensors. In year 1907, Boris, Russian scientist employed CRT in his experimental TV’s receiver. He made use of mirror drum scanner for transmitting geometric shapes to CRT.
After some decades, in 1920s, a Scots inventor named John Baird patented the technology that used various transparent rods for broadcasting images to be viewed and delivered on TV sets. The back lit figures were replaced by 30-line resolution. John clarified that his patented technology was based on Nipkow’s invention. He transmitted first ever televised images of moving objects, human faces and real time moving entities in the years 1924, 1925 and 1926 respectively. Baird was the first person to invent Phonovision, video recording mechanism. By using traditional audio recording mechanism, he modulated output signals of TV camera, down to audio range while capturing signals on wax audio discs. Some of his recordings stayed alive and were decoded to viewable pictures in 1990s with signal processing technologies.
