Before the modern, all-electronic system was developed, mechanical systems were developed. Based on inventions by Alexander Graham Bell, Paul Nipkow, C. Frances Jenkins, and John L. Baird, these mechanical systems used spinning discs with a spiral of holes passing in front of an electric eye to create a scanned image. The pulses were transmitted and received in the home by a bulky set that used a disc with an identical spiral and a flickering neon bulb. The discs in both the studio’s camera and in the home would run at the same speed. The sets at home produced images with anywhere from 30 to 60 lines of resolution-one line per hole in the scanning spiral of the disc. This was a very blurry and low-definition picture. But the novelty was so great for the times, 1928 to 1933, that sets were actually sold.
The mechanical system ultimately failed because the novelty of its low-quality pictures soon wore off.
In 1930, Philo T. Farnsworth, a young American inventor, patented an electronic television. In 1934 RCA demonstrated its “iconoscope,” a camera tube very similar to Farnsworth’s image dissector. RCA claimed it was based on a device Zworykin tried to patent in 1923 — even though the Russian had used Nipkow’s old spinning disk design up until the time he visited Philo’s lab.
The first all-electronic American systems in 1932 used only 120 scanning lines at 24 frames per second. This produced a blurry image. The number of scan lines quickly increased. The year 1936 marked the first public demonstrations of television. The demonstrations of 1936 used the 343-line system.
In 1941, the United States implemented 525-line television. The world’s first 625-line television standard was designed in the Soviet Union in 1944, and became a national standard in 1946. The first broadcast in 625-line standard occurred in 1948 in Moscow. The concept of 625 lines per frame was subsequently implemented in the European CCIR standard.
The brighter, larger pictures did not come until the early 1950′s. The picture tubes were made of delicate glass and were limited to a small size due to their delicate structure, a vacuum and risk of implosion. With few exceptions, a 12-inch diagonal picture was the largest available and many sets used 9- and 5 inch tubes.
Although the first national color cast occurred on January 1, 1954, it was not until the late 1960′s that color sets started selling in large numbers.
For many years different countries used different technical standards. France initially adopted the German 441-line standard but later upgraded to 819 lines, which gave the highest picture definition of any analogue TV system, approximately double the resolution of the British 405-line system.
Throughout the 1960′s, television sets used exclusively vacuum tube electronics. This resulted in relatively heavy and unreliable TVs. In addition, vacuum tubes were poorly suited to color television, as it required a large amount of tubes which caused further reliability problems. Because vacuum tubes only allowed for very simple NTSC/PAL filtering, the picture quality of early color sets was rather poor.
In the 1970′s, electronic tuners began appearing in high-end TVs in place of traditional dials, and they would gradually become standard along with remote controls. Remotes had first appeared in the 1950′s with Zenith’s Space Command Control, but these were mechanical devices that emitted a high-pitched audio frequency that the TV detected. The first electronic remote controls did not appear until the 1980′s.
The first LCD TVs were introduced in 1988, small, handheld devices with a B&W screen that could not display the full NTSC resolution of 480 lines.
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