Рет қаралды 78
In 100 years, the TV has taken many shapes and sizes. Here's the history of the television, from the 1920s to today.
The first demonstration of instantaneous 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, served as an electronic retina. In the receiver, a type of Kerr cell modulated the light and a series of variously angled mirrors attached to the edge of a rotating disc scanned the modulated beam onto the display screen. A separate circuit regulated synchronization. The 8×8 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.
In May 1914, Archibald Low gave the first demonstration of his television system at the Institute of Automobile Engineers in London. He called his system 'Televista'. The events were widely reported worldwide and were generally entitled Seeing By Wireless. The demonstrations had so impressed Harry Gordon Selfridge that he included Televista in his 1914 Scientific and Electrical Exhibition at his store.[15][16] It also interested Deputy Consul General Carl Raymond Loop who filled a US consular report from London containing considerable detail about Low's system.[17][18] Low's invention employed a matrix detector (camera) and a mosaic screen (receiver/viewer) with an electro-mechanical scanning mechanism that moved a rotating roller over the cell contacts providing a multiplex signal to the camera/viewer data link. The receiver employed a similar roller. The two rollers were synchronised. It was unlike any other TV system of the 20th Century and in some respects, Low had a digital TV system 80 years before modern digital TV. World War One began shortly after these demonstrations in London and Low became involved in sensitive military work, and so he did not apply for a patent until 1917. His "Televista" Patent No. 191,405 titled "Improved Apparatus for the Electrical Transmission of Optical Images" was finally published in 1923; delayed possibly for security reasons. The patent states that the scanning roller had a row of conductive contacts corresponding to the cells in each row of the array and arranged to sample each cell in turn as the roller rotated. The receiver's roller was similarly constructed and each revolution addressed a row of cells as the rollers traversed over their array of cells. Loops report tells us that... "The receiver is made up of a series of cells operated by the passage of polarized light through thin slats of steel, and at the receiver the object before the transmitter is reproduced as a flickering image" and "The roller is driven by a motor of 3,000 revolutions per minute, and the resulting variations of light are transmitted along an ordinary conducting wire.
In 1927, Baird transmitted a signal over 438 miles (705 km) of telephone line between London and Glasgow. 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-Baird-Natan. In 1931, he made the first outdoor remote broadcast, of the Derby.[21] In 1932, he demonstrated ultra-short wave television. Baird Television Limited's mechanical systems reached a peak of 240 lines of resolution at the company's Crystal Palace studios, and later on BBC television broadcasts in 1936, though for action shots (as opposed to a seated presenter) the mechanical system did not scan the televised scene directly. Instead, a 17.5mm film was shot, rapidly developed, and then scanned while the film was still wet.#USATV_HISTORY