Scottish engineer, J. L. Baird in 1926 was the first to televise moving object. However, current electronic television was invented by Russsian physicist Vladimir Zworykin, in 1928 and called it the iconoscope. BBC started the world's first public TV service from Alexandra Palace, London in 1936.

The TV has two main internal parts: the detection box and picture tube. The detection box consists of the tuner and detectors, whereas the picture box has 3 electron guns, shadow mask, deflection coil and phosphor coating of the screen. Radio waves carry the signals from the TV station which is picked up by the antenna. Electric currents produced by the waves is passed to a tuning circuit which picks out the signal for the desired television station.

The signal is made up of the chrominance and illuminance parts which carry information about the colour and the brightness respectively, and the synchronisation part controls the scanning of the electron beams across the screen, sound is the last. After detection, the chrominance and illuminance parts are sent to the electron guns, which in turn produce electron beams. The sound is sent to the loud speaker and the synchronisation part goes to deflection coils.

The electron beams are able to make it to the screen, because there is little air in the tube. There are three types of phosphor, which glows red, blue and green when the electron beams strike. The shadow mask ensures that each of the three electron beams only hits one type of phosphor. The electron beams build a picture by scanning the screen in horizontal lines.


This article was culled from the publications of Deen Communication Limited
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