The Liquid Crystal Display is the most used type of display in modern portable electronic devices. It replaced the plasma display and the Vacuum fluorecent display in portable PCs, calculators and portable electronic games, since it has much lower power consumption.

The basic display is built up like this:

_________________  polarization filter 
-----------------  glass
=================  Transparent electrode
                   liquid crystals
=================  transparent electrode
-----------------  glass
=================  polarization filter 
-----------------  mirror or backlight

The polarization filter lets only light polarized the right way through. The glass is there to hold everything together. Since the LCD itself doesn't emit light an external lightsource is needed. Either we reflect light back by the use of a mirror or a backlight is used. Some LCDs have a combination of the two. By using a semi transparent mirror and a backlight, these LCDs are called hybrid LCDs. The backlight can be LEDs, electroluminescent backlight panels or fluorecent tubes. The electrodes are made from indium tin oxide.
The liquid consists of organic crystaline molecules. These crystals change the polarization of the light.

In polarized light the lightwaves only move in one direction. This means that if light moves through a horisontal filter the light will be horizontaly polarized(HP) A vertical filter only lets verticaly polarized(VP) through. This also means HP. light is blocked by a vertical filter. The crystals can change the polarization or let light it pass unchanged depending on orientation. This orientation changes if voltage is applied and thus we can change the light so that it is either blocked or not. Usualy AC is used since DC causes an electrolytic effect and over time breakes down the liquid.

By adjusting how much the crystals turn we can get several shades of grey. By adding colour filters we can make colour displays. The AMLCD(also called TFT) is a further development of this technology.

LCD is also the local version of the cd command(that's change directory if you're still wondering what the strange glowing box in front of you is, but you should probably know.). Unlike cd it operates on your computer and not the servers on Unix boxes.

Oh and it has an extra letter.

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