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How does a plasma TV work?

Believe it or not the concept of plasma displays originates as long ago as the 1930s.

The principle is simple: instead of using a beam of electrons to create the lines on a TV screen, the plasma screen uses what are in effect tiny quick-acting fluorescent light cells to form a picture. In a modern colour plasma displays each pixel has three of these fluorescent lights, each one in a different primary colour, and fires them intelligently to create the desired colour. (LCD TVs use individual LCD shutters in each pixel to create a similar effect.)

But what is plasma? Essentially it is an electrically conductive gas that contains free-flowing ions (positively charged) and electrons (negatively charged). If you introduce more electrons by applying a voltage through the gas then they will begin to collide with atoms, knocking off electrons and turning them into ions. Then negatively charged particles will start to move towards the positively charged area, and vice versa. This causes the atomic equivalent of a motorway pile up, with particles smashing into each other and the xenon and neon gases used in plasma screens releasing photons of light. Most of this light is ultraviolet light which is invisible, but this is turned into visible light by painting the tiny cells with phosphoric material.

The result is that plasma displays are far shallower than older TVs, you can mount them on a wall and conveniently hide them behind a well-placed curtain. They can also be scaled up by adding more pixels and enough computing firepower to run them. The biggest plasma TV we found was 152 inches, around 3 metres long, and will set you back over $600,000.

If you want to find out how many pixels are squeezed into the world's largest TV, click here.

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