If not polarized correctly, the light does not pass through the polarizer which creates an opaque LCD screen.īetween the two substrate layers lie liquid crystals. These filters allow only certain beams of light to pass through if they are polarized in a specific manner, meaning that the geometric waves of the light are appropriate for the filter. The outer sides of the glass substrates (closest to the surface or closest to the back) have filter layers called polarizers. In both these substrate layers, the electrodes are most frequently made of indium tin oxide (ITO) because they allow for transparency and have good conductive properties. In order to counteract the electrodes of the previously mentioned layer, this surface layer has counter (or common) electrodes on the side closer to the liquid crystals that close off the circuit that travels between the two layers. Just beneath this glass substrate is where the actual pixels and sub-pixels reside, forming the RGB color filter. On the surface level is the other glass substrate. Electrodes are conductors that channel electricity into or out of something, in this case, pixels. This layer also has pixel electrodes between the substrate and the liquid crystal layer. The TFTs in this layer are paired individually to each sub-pixel (refer to Architecture of a TFT Pixel below) from the other substrate layer of the device and control the amount of voltage applied to their respective sub-pixels. This silicon is then deposited on the actual glass substrate. It is made of amorphous silicon, a type of silicon with a non-crystalline structure. The TFT glass substrate layer is the deepest or back-most layer of a device’s circuit board.
1: A visual diagram of the different layers and components used in a TFT LCD display. The layer between the glass layers is a liquid crystal layer.įig. Two sandwiching layers consist of glass substrates, though one includes TFTs while the other has an RGB, or red green blue, color filter. The TFT LCD is built with three key layers. Modern-day high-resolution and -quality displays primarily use TFT technology within the LCDs. With this development, the cathode-ray tube, otherwise known as a CRT, began to fall into the past as the lighter, less bulky LCD took over in the field of displays. Since paired with flat panel technology, notably liquid crystal displays (LCD), TFT displays have grown extensively in popularity for display screens and LCD monitors like computer monitors and smartphones.
A TFT LCD, or a thin film transistor liquid crystal display, is one of the fastest growing forms of display technology today.