Did You Know? The First Live Television Broadcast Demonstration Was in 1926

IEEE Milestone honors John Baird’s electromechanical TV system

28 March 2017

In January 1926 a blurry, black-and-white image of a ventriloquist dummy’s face flickered on a screen at inventor John Logie Baird’s workshop in London. It is considered to be the first demonstration of live television.

With his new electromechanical TV system, Baird broadcast a live image of the dummy for members of the Royal Institution of Great Britain. Though other TV systems were in the works, the possibility that moving images might be broadcast via radio waves was regarded as a distant prospect until Baird’s demonstration.

The event was honored in January with an IEEE Milestone. Administered by the IEEE History Center and supported by donors, the Milestone program recognizes outstanding technical developments around the world.

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Born in Scotland in 1888, Baird was an electrical and mechanical engineer as well as a serial entrepreneur. In 1915 he began working at Clyde Valley Electrical Co., in Scotland, but instead of focusing just on his work there, he often invented things. He started several ventures, with varying degrees of success, making socks, boot polish, floor cleaner, and other products.

In the early 1920s he turned his attention to television. Drawing on developments in the field of electronics such as the vacuum tube invented in 1907 by Lee de Forest, he devised a television system—the first that could broadcast images via radio signals.

Baird relied on the scanning disk invented in 1844 by German technician Paul Nipkow. The rotating Nipkow disk had a spiral of holes bored into it. When the disk rotated, the holes would sweep over an image from top to bottom, slicing the image into lines of information. Behind the disk were selenium photocells, which reacted to the light passing through the disk. The light from each of the slices was converted to a varying electric signal in the photocell, and that signal was then transmitted wirelessly to a receiver. At the receiver, incoming information was reassembled into a crude picture.

A number of groups explored ways of applying the Nipkow disk to imaging technology, but it was Baird who first demonstrated its application to television. His system used the Nipkow disk for both scanning and displaying the image. A bright light shining through the spinning disk projected a bright spot of light that swept across the subject. A selenium photoelectric tube detected the light reflected from the subject and converted it into an electrical signal. That was transmitted by AM radio waves to a receiver. As each hole in the disk passed by, one line of the image was reproduced. Baird’s disk had 30 holes, producing an image with 30 lines—just enough to recognize a human face.

By 1927, a year after Baird’s live TV demonstration, he successfully transmitted moving images over telephone wires between London and Glasgow. He formed the Baird Television Ltd., in London. The BBC adopted Baird’s system for its first television broadcast service in 1930. By 1937, his system’s resolution rose from 30 lines to 240.

MILESTONE CEREMONY

The historic event was recognized on 27 January with a plaque placed on front of the building where Baird first demonstrated his invention. (The century-old building is now occupied by the Bar Italia café). The plaque reads:

Members of the Royal Institution of Great Britain witnessed the world’s first public demonstration of live television on 26 January 1926 in this building at 22 Frith Street, London. Inventor and entrepreneur John Logie Baird used the first floor as a workshop during 1924–1926, for various experimental activities, including the development of his television system. The BBC adopted Baird’s system for its first television broadcast service in 1930.

This article was written with assistance from the IEEE History Center, which is partially funded by donations to the IEEE Foundation.

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