The Principle of LCD Liquid Crystal Displays
The principle of LCD liquid crystal displays is based on the unique properties of liquid crystal materials. Liquid crystals are substances that have a mesophase between a solid and a liquid. They possess the ability to change their molecular orientation in response to an external electric field. In an LCD, the liquid crystal layer is sandwiched between two polarizers. The backlight, which emits white light, is located behind the first polarizer. When the light from the backlight passes through the first polarizer, it becomes polarized, meaning the light waves are all vibrating in a particular direction.
The liquid crystal molecules, in their natural state without an applied voltage, are arranged in such a way that they allow the polarized light to pass through and maintain its polarization. However, when a voltage is applied to specific regions of the liquid crystal layer, the molecules reorient. This change in orientation causes the polarized light to be rotated or blocked depending on the degree of reorientation. The second polarizer, placed in front of the liquid crystal layer, is oriented in a way that it only allows light of a specific polarization to pass through. So, by controlling the voltage applied to different areas of the liquid crystal layer, the amount of light that can pass through the second polarizer and reach the viewer can be adjusted. This modulation of light intensity is used to create the different shades and patterns that form the images and text displayed on the LCD. To display color, color filters are incorporated, which separate the white light into its component colors (usually red, green, and blue) at each pixel location, and by varying the intensity of light for each color component, a full spectrum of colors can be generated.
