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Display (technology)




Assignment

The first thing one thinks of with a screen is, of course, television. Not so as far as the motor car is concerned, where the television functions are still in the nursery stage. TV programmes can, until High-Definition-TV is established, be received better with a Cathode-Ray-Tube device (CRT). For a tube large enough to be rationally usable, the car simply does not have enough space. On the other hand, the latest DVD formats work well together with flat screens.The invention of liquid crystals is already more than one hundred years old. Nonetheless, they had a long journey to make before they became indispensable for us in everyday life. Now that they're here, and also becoming more and more apparent in motor vehicles, it is time to briefly examine the principle of LCD.

Function

In motor cars, the plasma television screen is possibly, also interesting. It differs substantially from LCD, e.g., because the colours are directly (actively) generated, whereas LCDs are back-lit, (passively) and only allow certain colour pixels through. That's why LCD has a constant brightness, while with plasma, the overall brightness is reduced if the total current intake becomes too high. Because of the not always exactly achieved colours, spectral filters which can unfavourably affect the attainable brightness are used. The word 'Plasma' originates, by the way, from the inert gas which in single cells, is enclosed between two glass plates and by specific control with high tension, discharges. On the phosphorus layer of the rear plate a luminous point, made up of certain portions of red, green and blue is generated. All in all, this technology is more suitable for wide-screen and high contrast displays, in areas which are not too bright.In the case of LC-technology, molecules from long, stretched out rods are, in certain liquid crystals, susceptible to electrical fields. As colour displays these three contain three times more transistors than they have pixels. Thereby, each transistor forms a junction point of the finest printed circuits, which have been vapour-deposited onto one of mostly two or three glass plates. The red, green and blue dots melt into one for the human eye, the colour depends on the intensity of the single basic colours. The remaining glass plates, or transparent foil, has the job of allowing the maximum amount of light, which is broken down in the liquid crystals oscillating in the area, to emerge as a sharp pointed light-source with as little colour shift as possible.

Although flat screens rather have a high factor of sharpness compared with CRTs, and do not flicker, they still do not yet achieve completely, their brightness and picture build-up speed. Plasma screens still have more picture errors than LCDs and also have a tendency to flicker, the picture quality is however, less dependent on the viewing angle. This factor can be quite decisive when the screen is mounted in the centre of the dashboard.


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