LCD structure

About LCD structure

LCD comes from the first letter of liquid crystal display. It’s a passive display component, that means they do not emit light, just use the ambient light in the environment. By manipulating this light, only little power just be used. This has made LCDs the preferred technology for low power consumption.

All of us known about LCD using fields, But how it works and what’s the inner structure?

A display module consists of display panel and driving part.

Here is the monochrome display panel’s basic structure.

A liquid crystal cell consists of a thin layer (about 3~7 um) of a liquid crystal sand­wiched between two glass substrates with transparent elec­trodes deposited on their inside faces. Because the liquid crystal layer just liquid so it can’t sustain the pressure, so here are some spacers between two glass substrates.

Liquid crystal is a key material for a LCD.

For Twisted Nematic LCD, the two surfaces PI are rubbinged orthogonal to one another, forming a 90 degree twist from one surface to the other,

This helical structure has the ability to control light. A polarizer is applied to the front and an analyzer/reflector is applied to the rear of the cell. When randomly polarized light passes through the front polarizer it becomes linearly polarized. It then passes through the front glass and is rotated by the liquid crystal molecules and passes through the rear glass. If the analyzer is rotated 90 degrees to the polarizer, the light will pass through the analyzer and be reflected back through the cell. The observer will see the background of the display, which in this case is the silver gray of the reflector.

The LCD glass has transparent electrical conductors layer plated onto each side of the glass substrate in contact with the liquid crystal fluid and they are used as electrodes. These electrodes are made of Indium-Tin Oxide (ITO).

Below is a typical “8” electrode pattern.

More complex pattern’s principle is the same.