How a TFT LCD display work

- Dec 17, 2018-


How a TFT LCD display work?

 TFT "Thin Film Transistor", which generally refers to thin-film liquid crystal displays, but actually refers to thin film transistors (matrices) that "actively" control individual pixels on the screen. This is the origin of the so-called active matrix TFT (active matrix TFT). So how on earth did images come into being? The basic principle is very simple: the display screen consists of many pixels that can emit light of any color, so it can be achieved by controlling each pixel to display the corresponding color. In TFT LCD, backlight is generally used. In order to accurately control the color and brightness of each pixel, a shutter-like switch is installed after each pixel. The blinds are closed and the light does not pass through. Of course, technically,. LCD (Liquid Crystal Display) is not actually as simple as it was said to be, because it takes advantage of the properties of liquid crystals (liquid when heated, solid when cooled). 

Liquid crystals generally come in three forms: 

a clay-like laminated (Smectic) liquid crystal, a thin match rod; 

a filamentous (Nematic) liquid crystal;

a cholesterol-like (Cholestic) liquid crystal display, using a filamentous liquid crystal display. 

And when the external environment changes, its molecular structure changes, so it has different physical properties-that is, to allow light to pass through or block light-that is, the shutters just now. You know the three primary colors, so each pixel on the display screen needs to be composed of three similar basic components described above, controlling red, green, and blue respectively. 

The most common use is the twisted nematic TFT liquid crystal display (Twisted Nematic TFT LCD),) below, which explains how the TFT displays work.

There are grooves in the upper and lower layers, in which the upper grooves are arranged vertically and the lower layers are arranged horizontally. When the liquid crystal is in a natural state without adding voltage, the light emitted from the twisting of the luminescent figure 2a to the schematic diagram of the column TFT display passes through the interlayer, and a distortion of 90 degrees will occur, which will be able to pass smoothly through the lower layer. When a voltage is applied between the two layers, an electric field is generated, and the liquid crystal is perpendicular, so the light does not twist-the result is that the light cannot pass through the lower layer.


TFT pixel structure: 

According to the color, the color filter is divided into red, green and blue, and arranged on the glass substrate in turn to form a group of (dot pitch) corresponding to one pixel, each monochromatic filter called sub-pixel. That is, if a TFT display has a maximum resolution of 1280 × 1024, then at least 1280 × 3 × 1024 subpixels and transistors are required. For a 15-inch TFT display (1024 x 768), a pixel is about 0.0188 inches (equivalent to 0.30mm), and for an 18.1 inch TFT display (1280 x 1024), it is 0.011 inches (equivalent to 0.28mm). 

As you know, pixels are decisive for displays, and the smaller each pixel is, the greater the maximum resolution the display can achieve. However, due to the physical limitations of transistors, the current TFT pixel size is basically 0.0117 inches (0.297mm), so for a 15-inch display, the maximum resolution is only 1280 × 10 24.