Liquid crystal display technology is well known as an advanced flat panel display technology. It has become a mainstream technology for many devices such as computer monitors, mobile devices and televisions.

The basic working principle of liquid crystal display

Before understanding how LCDs work, let's understand the structure of liquid crystal molecules. Liquid crystal molecules are actually long and thin organic molecules that can freely rotate in the direction of the long axis.

In liquid crystal displays, a layer of liquid crystal is overlaid between a backlight (usually a light-emitting diode; LED) and a transparent conductive layer. When a voltage is applied across the conductive layer, electrons flow and change the orientation of the liquid crystal molecules. Therefore, under the action of the electric field, the liquid crystal molecules form an optical image of a certain shape with the backlight source.

However, liquid crystal molecules can only switch between two states, which are polarized and non-polarized states. Just knowing the orientation of the liquid crystal molecules is not enough to construct the displayed image. So for each pixel we need to filter the backlight with three color filters (red, green, blue) to form the color of each pixel.

The structure of the liquid crystal display

Liquid crystal displays are made up of several layers stacked one on top of the other. Due to the limitations of liquid crystal molecules, the brightness and color of each liquid crystal cell are controlled by an electric field.

  • Liquid crystal layer

The liquid crystal layer is the most important layer in a display. It consists of two glass plates filled with liquid crystal molecules. When the electric field on the liquid crystal layer changes, the physical structure changes accordingly. This change in motion causes the orientation of the liquid crystal molecules to change, eventually presenting the desired image.

  • Transparent electrode layer

The transparent electrode layer is a layer controlled by an electric field. It is made of conductive material and acts as a transmission medium for electric current. Transparent electrode layers are arranged in a grid pattern on the surface of the glass plate to control the brightness and color of individual pixels.

  • Color filter

Color filters are an important part of LCD displays. They help filter the backlight so that light can pass through the liquid crystal molecules precisely. The material uses red, green, and blue filters to control the color of each pixel.

  • Backlight

The backlight is the bottommost layer of the display, formed by the light source behind the liquid crystal molecules. The backlight can be cold cathode fluorescent lamps (CCFLs) or light emitting diodes (LEDs), which provide the brightness and brightness required for the display.

How LCD Displays Display Images

The process by which an LCD monitor can display images is very simple. Once an image is input, the display creates an electric field across the liquid crystal molecules. The orientation of the liquid crystal molecules changes as the electric field in the liquid crystal changes. Next, the backlight passes through the color filter and the transparent electrode layer to achieve the color displayed by the filter by suppressing (or enhancing) the amount and color of the backlight. In the following stages, alternate optical rails are prepared at each pixel. In this process, the display of the backlight controls the direction of the liquid crystal molecules, and finally presents a complete image.

Conclusion

Liquid crystal display has become a common thing in people's life. Liquid crystal technology has brought many improvements in different types of devices, such as higher and higher resolutions and color depths in televisions and computer monitors. The technology has a relatively low failure rate, making it a relatively inexpensive and highly sought-after technology in the market. LCD monitors use simple principles to achieve complex output images, which is where the true charm of this technology lies.