A.A. Campbell-Swinton (1863–1930)

The first man to envision a completely electronic television system, Campbell-Swinton was a Scottish consulting electrical engineer born in Edinburgh, and educated at the expensive Fettes College. He was one of the first to explore the medical applications of radiography, opening the first radiographic laboratory in Britain in 1896. He first described an electronic basis of producing television in a 1908 letter to Nature.

In 1911, Campbell-Swinton expanded on his 1908 proposal for an all-electronic television system in his presidential lecture to the Röntgen Society of London. The Times of London reprinted the lecture eight days later. Swinton described a design using cathode-ray tubes to both capture the light and display the image. Basic cathode-ray tubes at this time had been invented, and much similar to today, they were relatively large vacuum tubes with a long neck on one end and a flat screen on the other. An electron gun in the neck could shoot a stream of electrons toward the flat end of the tube which was covered with an internal coating of light-emitting phosphor. Swinton reasoned, by scanning, or sweeping the electron stream back and forth in rows from top to bottom while varying the intensity of the electron stream, a moving image could be drawn in the same manner as with Nipkow's disks.

A 1912 diagram of Swinton's proposed television system

Although a Russian, Boris Rosing had proposed as early as 1907 to use a cathode-ray tube to display an image as the "receiver", Swinton's proposed system was unique in that it also included a modified version of a cathode ray tube to be used to capture the light, or as the "transmitter". If the flat end could be given a sandwich of metal, a non-conducting material and some kind of photoelectric material, light focused on the flat end with a lens would produce a positive charge on the inside of the surface. By sweeping the electron stream across the flat end, again in rows, the charges could be read and the image could be turned into an electrical signal that could be sent via a line wire to the "receiver".

In 1915, Campbell-Swinton's television system was featured in Hugo Gernsback’s Electrical Experimenter magazine. He was elected a Fellow of the Royal Society in 1915.

While Swinton's foresight was near perfect, his description lacked many key details. Swinton, nor anyone else at the time, knew how to make such a system work. Approximately two decades would pass before inventors such as Kálmán Tihanyi, Philo Farnsworth, and Vladimir Zworykin would use Swinton's ideas as a starting point to patent workable fully electronic television systems. In April 1924, Swinton also provided an update of his television ideas in an article in Wireless World.

Further reading

Paul Marshall, One Hundred Years of All-Electronic Television, December 16, 2018