John Logie Baird's Televisor
The Televisor, designed by the Scotsman John Logie Baird (1888-1946), was the first television receiver to be commercialized in Europe.
On January 26, 1926, after two years of research, Baird gave a public demonstration of his system at the Royal Institution in London. On March 6, 1928, a television signal was transmitted from London to New York for the first time, relayed via a ship in the mid-Atlantic. From September 1929 to 1935, Baird Television Ltd broadcast experimental programs with the help of the BBC. In 1930, the Televisor became commercially available (1,000 models were produced) and two transmitters were built, enabling pictures and sound to be broadcast simultaneously.
The images on the Televisor were often distorted and lacked definition. They were made up of 30 vertical lines, roughly 5 cm high and 2 cm wide. A magnifier allowed an image of around 15 cm x 6.4 cm to be displayed. The signals were picked up by a radio and an antenna; an external speaker reproduced the sound. The logo that appeared on the device was a globe with an open eye: "The Eye of the World."
The Televisor contained a vertical revolving disc designed by Paul Nipkow (patented in 1884) around 50 cm in diameter, with 30 holes, driven by a motor that ran at a rate of 750 rpm. It could receive 12.5 images per second. The disk was very thin, aluminum, and divided into five sections; it only became rigid under the action of centrifugal force. The 1st, 2nd, 3rd, 28th, 29th and 30th holes weren't square in shape like the others (0.8 x 0.8 mm), but were rectangular (0.8 x 1 mm). The image was read vertically and recreated on the right-hand side of the disc. This device could only receive images in Baird format.
Baird recorded some of the images that he had demonstrated in the early 1930s onto aluminum disks, called Phonovision disks. These images showed the moving head of a ventriloquist's dummy (so much light was needed to film that a dummy had been used instead of an actor), but there were also some sequences using actors.
Later on, the invention of the cathode ray tube would greatly improve the technology, making Baird's machines obsolete. The year 1936 saw the end of mechanical television, which was by then producing a resolution of 240 lines. But Baird was still one of the greatest pioneers in this area, along with René Barthélemy in France (using Weiller's wheel and Nipkow's disc) and Vladimir Zworykin in the United States (Iconoscope tube).
