Liquid-crystal display
A liquid-crystal display (usually abbreviated to LCD) is a technology used in modern bit-mapped displays. It has a thin layer of pixels which can either let light through, or block it; it thus needs an additional light source (often a backlight, but sometimes there is a reflector behind the LCD, to allow the use of ambient light, entering the front of the device) to operate.
The pixel layer is sandwiched between two polarizing filter layers (usually oriented at right angles); light is thus normally blocked from passing through. When activated, the material in the pixels changes the polarization of the light passing through them (or not, depending on whether the pixel is 'usually off', or 'usually on'), allowing it to pass through the LCD in those pixels.
Modern colour LCDs include a more complex structure, created using 'photoresists' (which were also used to create chips). These are applied in an even, thin layer; after exposure to light, partially blocked in the desired pattern by a 'mask', the excess resist can be removed by a bath of solvent. The first to be applied is black, which is used to create a fine black grid, which separates the coloured sub-pixels from one another, thereby preventing light from leaking from one sub-pixel onto surrounding ones. This is followed by the red, green and blue sub-pixels themselves.
