II. INVENTION AND EARLY DEVELOPMENT
There was no single moment when TV was invented, and it is very difficult to pick out the contribution of any individual as of more significance than any other. Regular TV broadcasting began in 1936 in Britain, but the development of TV relied on the coming together of a number of developments in related fields, such as telegraphy and electronics, over the previous 60 years. This convergence of innovations happened only when organizations such as the Radio Corporation of America (RCA), Electrical and Musical Industries, Ltd. (EMI), and the British Broadcasting Corporation (BBC)—institutions with sufficient capital to fund research and development—realized that TV might be the basis of prestige, power, and profit.
A. The Early Innovators
As early as the 1880s, a number of problems were widely recognized as needing to be solved in order to create the transmission of images. The term “television” does not appear to have been used until the beginning of the 20th century and even then, the aim of innovators was not to provide the news and entertainment medium we know today, but rather to develop a more advanced form of telecommunication than the telegraph and the telephone, using pictures as well as sound.
One problem facing developers was the need for a transducer (energy converter) that could turn light into electricity. The ability of the element selenium to do this was recognized in 1873, and spurred the search for more effective photoelectric materials. More efficient photoelectric cells were developed in the early 20th century.
Just as crucial was the problem of scanning: the breaking-up of a moving image into smaller, transferrable parts. In 1884 Paul Nipkow, a German engineer, produced an early version of mechanical TV, which provided a primitive solution to the problem of scanning. Nipkow drilled a spiral of holes in a disc, which was made to rotate. Light passing through these holes registered on a selenium cell. A similar disc rotated at the receiving end of the system, and the light projected by the selenium cell reproduced the original shape silhouetted by the light. Besides scanning, the Nipkow system also had the vital feature of synchronization, in that the two discs rotated at the same speed.
In Britain, the Scottish engineer John Logie Baird is often credited with the invention of TV. In fact, although Baird was responsible for some important early innovations, and provided the first public demonstration of a 30-line image in 1926, his mechanical system was superseded by electronic systems in the 1930s. At the centre of developments in electronic TV was the cathode ray tube, developed in the late 19th century. This is simply a vacuum tube inside which a beam of high-energy electrons focuses on a fluorescent screen to give light. An early Russian innovator, Boris Rozing, modified the cathode ray tube to display images from a mechanical scanner in 1907.
It was in the 1920s that developments in TV began to proceed quickly. The immense success of radio in the post-1918 period led companies to realize that great profits could be made from the manufacture of communications goods. During this era, TV began to be conceived of as a broadcasting technology rather than as a form of telecommunications, as people began to pursue new forms of leisure activity within the home.
B. Zworykin’s Kinescope
Important developments in electronic TV systems were made by two inventors: Vladimir K. Zworykin and Philo T. Farnsworth. In the United States in 1927, Farnsworth patented an electronic camera tube, the image dissector, and went on to develop improvements in the electronic synchronization of cameras and receivers. Farnsworth was something of a maverick, and attempted to work independently of large institutions. It was the corporations, however, that were to determine the technology of TV. Zworykin had been Boris Rozing’s student in St Petersburg, Russia, but had moved to the United States and in the 1920s worked for the giant US electronics companies Westinghouse and RCA, who were collaborating on developing broadcasting technology. In 1923 Zworykin outlined ideas for a TV camera tube that used electrons to scan across a target that had been charged by exposure to light. He failed to produce a workable system, but was eventually commissioned by RCA to extend European developments in cathode-ray technology, and in 1929 he patented a prototype of modern picture (that is, TV set) tubes called the “kinescope”. By 1931 Zworykin’s team at RCA had developed the type of camera tube he had envisaged eight years earlier, and called it an iconoscope.
C. Early Broadcasting
In the early 1930s in Britain, the work of Zworykin and his team was extended at EMI’s laboratories in Hayes, near London, in a transatlantic partnership with RCA. Separate research also made progress in Germany and the Netherlands, and the resolution of images (indicated by the number of scanned lines on the screen) improved rapidly. The world’s first high-definition, regular TV service was begun by the BBC from London in 1936, using both the EMI electronic system, of 405 lines, and the mechanical system Baird had developed, which by this point was of 240 lines.
In 1937 a British government committee rejected Baird’s design for the electronic system, which was good enough to last until the introduction of a 625-line system, phased in from the late 1950s onward. Meanwhile, in the United States, after protracted battles between the RCA-owned National Broadcasting Company (NBC) and rival developers of TV systems, the US government’s Federal Communications Commission (FCC) accepted NBC’s 525-line, 30 pictures per second standard in 1941. This technology is still the basis of the US system today, having been modified to include a compatible colour system in 1954.