A more important application of cable television promises to be its employment for the surveillance of industrial processes in locations not readily accessible to human beings. Early developments of television began on its first attempts at television date from the discovery that the magnitude of electric currents passing through crystalline selenium could be controlled by the amount of light falling on it. Television was invented by the American inventor G.R. Carey in 1875 when he devised a system in which the image of the scene to be transmitted was projected on a rectangular array of selenium cells, each of which was connected to a light bulb in a corresponding array by a pair of wires (Fink, 1975). Essentially, the same idea is employed beginning the 1960s in the operation of animated cartoon advertisements. In 1880, the French electrical engineer, Maurice Leblanc, added the second common feature, namely the transmission of the signals from successive picture elements in sequence through a single electrical channel (Zworykin, 1978). A practical method of realizing Leblanc’s suggestion was devised by the German television pioneer, Paul Gottlieb Nipkow in 1884. Nipkow, employing a single photosensitive cell, placed a rotating disk with a series of holes equal in area to a picture element, arranged along a spiral in front of the cell and projected the scene on it (Fink, 1975). Nipkow’s invention was followed by numerous other ingenious mechanical scanning devices, primarily designed to increase the optical efficiency of the television system. However, it was only Lee De Forest who succeeded in obtaining usable television pictures in 1907, with De Forest’s invention of the amplifying tube. After this, thedevelopment of mechanical methods of television was rapid.
Overview of Media Specialty