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Unlike LCD TVs, plasma TVs have no backlight. Instead, each pixel behaves like three tiny fluorescent tubes, one for each of the primary colours: red, green, and blue. These tubes, or cells, contain a gas that turns into a plasma when a voltage is applied. From this excited state, the gas then ‘discharges’ as it returns to the gaseous state, emitting a burst of energy in the form of photons. These photons collide with coatings, known as phosphors, on the cell walls and are the part of the screen that actually emits light. Each of the three cells in a pixel uses a slightly different phosphor in order to produce the relevant primary colour.
This process means that plasma pixels require excitation before they will produce light, and that they then do so for only an instant. The TV has to excite the pixels many tens of times per second in order to produce an image, and must vary the number of times per second in order to produce different brightness levels.
There are a number of benefits to producing the picture in this way. Since, for example, the light sources are (almost) on the surface of the screen, they emit light in all directions. This provides a wide viewing angle: viewers can watch the picture from one side without seeing a drop in contrast or colour accuracy. The rapid strobing of the pixels also results in sharper motion depiction than with LCDs — that is, there’s no blur during fast motion, so news tickers or fast serves in a tennis game resolve clearly.
One major benefit of plasma screens is that they only produce light when they need to. Where LCDs have to struggle to block the light from their backlight, plasmas simply don’t excite the pixels that are meant to be dark. In a dark room, this means plasmas can display very dark blacks. In bright rooms, however, a plasma screen shows up ambient illumination more strongly than an LCD — and this is essentially plasma’s biggest shortcoming.
When used in ideal conditions, therefore, plasma screens produce excellent pictures. LCDs, on the other hand, perform better than plasmas in day-lit rooms. Plasmas also use a lot of power — or, at least, they did traditionally: Recent developments have reduced plasma TVs’ power consumption, but they still use more power than LCDs.
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Keywords:
plasma tv, buy, guide, plasma, Reviews, TV, Tvs, Plasma TV Reviews |
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