By student SM 5 -22 Shipit’ko Oleg
Television (TV) is a telecommunication medium for transmitting and receiving moving images that can be monochrome (blackand-white) or colored, with or without accompanying sound.
Commercially available since the late 1920 s, the television set has become commonplace in homes, businesses and institutions, particularly as a vehicle for advertising, a source of entertainment, and news. Since the 1970 s the availability of video cassettes, laserdiscs, DVDs and now Blu-ray Discs, have resulted in the television set frequently being used for viewing recorded as well as broadcast material. In recent years Internet television has seen the rise of television available via the Internet. The broadcast television system is typically disseminated via radio transmissions on designated channels in the 54– 890 MHz frequency band. Signals are now often transmitted with stereo or surround sound in many countries. Until the 2000 s broadcast TV programs were generally transmitted as an analog television signal, but in 2008 the USA went almost exclusively digital.
History In its early stages of development, television employed a combination of optical, mechanical and electronic technologies to capture, transmit and display a visual image. By the late 1920 s, however, those employing only optical and electronic technologies were being explored. All modern television systems relied on the latter, although the knowledge gained from the work on electromechanical systems was crucial in the development of fully electronic television.
In 1884 Paul Gottlieb Nipkow, a 23 -year-old university student in Germany, patented the first electromechanical television system which employed a scanning disk, a spinning disk with a series of holes spiraling toward the center, for rasterization. The holes were spaced at equal angular intervals such that in a single rotation the disk would allow light to pass through each hole and onto a light-sensitive selenium sensor which produced the electrical pulses. As an image was focused on the rotating disk, each hole captured a horizontal "slice" of the whole image.
Using a Nipkow disk, Scottish inventor John Logie Baird succeeded in demonstrating the transmission of moving silhouette images in London in 1925, and of moving, monochromatic images in 1926. Baird's scanning disk produced an image of 30 lines resolution, just enough to discern a human face, from a double spiral of lenses. This demonstration by Baird is generally agreed to be the world's first true demonstration of television, albeit a mechanical form of television no longer in use. Remarkably, in 1927 Baird also invented the world's first video recording system, "Phonovision": by modulating the output signal of his TV camera down to the audio range, he was able to capture the signal on a 10 inch wax audio disc using conventional audio recording technology. A handful of Baird's 'Phonovision' recordings survive and these were finally decoded and rendered into viewable images in the 1990 s using modern digital signalprocessing technology. «Baird's scanning disk produced an image of 30 lines resolution, just enough to discern a human face»
The Lumière brothers, Auguste Marie Louis Nicolas (19 October 1862, Besançon, France – 10 April 1954, Lyon) and Louis Jean (5 October 1864, Besançon, France – 6 June 1948, Bandol), were among the earliest filmmakers in history. (Appropriately, "lumière" translates as "light" in English. ) The Lumières held their first private screening of projected motion pictures in 1895. Their first public screening of films at which admission was charged was held on December 28, 1895, at Salon Indien du Grand Café in Paris. This history-making presentation featured ten short films, including their first film, Sortie des Usines Lumière à Lyon (Workers Leaving the Lumière Factory). Each film is 17 meters long, which, when hand cranked through a projector, runs approximately 50 seconds.
Оne of the first films of brothers Lumière
