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Aktivmatrix
Active Matrix LCD's use three electronic
switches for each picture element, each one for the colours red, green
and blue, to maintain the field. The switch is usually a Thin Film Transistor
-TFT- which isolates the pixel from the influence of adjacent pixels and
so eliminates crosstalk. Addressing by transistors is advantageous because
once a pixel is switched on, the field can be maintained by the switch
until it is addressed once more. This allows faster LC material to be used,
so that 'smearing' is no longer a problem. The production of TFTs is similar
to those of semiconductor chips. The high number of rejections is the reason
for the high production costs which make the price of those displays extremely
unfavourable. (As an example, to produce a display with a resolution of
1024 x 768, 1024x768x3= 2, 36 million of transistors are requested). Obviously
LCD's do not suffer from any distortion in linearity and geometry, as every
pixel which is composed of the three colours red, green and blue, is situated
in a fixed order.
According to the technology used you have to reckon
on the following restrictions:
Missing Dots
Smearing when using fast changing videos and
motion pictures
Irregular lightning from the backlight