LCD Structure

Backlight:

When the backlight shines through the liquid crystal display, the liquid crystals alternately block the light or let it through, which creates the image on the screen. For that reason, you'll need to beware of ultra-cheap LCD computer monitors because the backlights might not be evenly distributed, resulting in a brighter picture in only one spot on the monitor.

Polarizing Layers:

The light from the backlight passes through a polarizing layer, and it will pass through a second polarizing layer after passing through the rest of the display. The polarizing layers are arranged at a 90-degree angle, which means the light won't show through the screen unless the liquid crystals react to change the direction of the light so that it passes through the second polarizing layer.

Transistors:

A glass plate with transistors helps carry the electrical current to the liquid crystals, which prompts them to react and either block or show light.
Liquid Crystals: "LCD" stands for "liquid crystal display," and these crystals are the material that reacts to the electrical current, helping to create the image that you see. The crystals twist and untwist, and this action is what lets the light through.

Color Filter:

The crystals may block and unblock the backlight, but the screen is also composed of tiny filters-one red, one green and one blue-that create the colors you see. Each set of these three filters makes up a pixel. The transistors are associated with the pixels, and if a transistor ever burns out, the liquid crystal won't be able to react, which results in a "dead pixel."

A single-pixel LCD structure;

The sandwiched liquid crystal layer (typically on the order of 5 microns in thickness, or 1/20 of the width of human hair) is straddled by a pair of optical filters with orthogonal polarizations. When no voltage is applied across the crystal layer, incoming unpolarized light gets polarized as it passes through the entrance polarizer, then rotates by 900 as it follows the molecular spiral, and finally emerges from the exit polarizer, giving the exited surface a bright appearance. A useful feature of nematic liquid crystals is that their spiral untwists under the influence of electric field (induced by a voltage difference across the layer). The degree of untwisting depends on the strength of the electric field. With no spiral to rotate the wave polarization as the light travels through the crystal, the light polarization will be orthogonal to that of the exit polarizer, allowing no light passes through it. Hence, the pixel will exhibit a dark appearance.