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What is TFT display--Jingda display

2023-12-28

What is a TFT display screen? With the changes in the digital age, TFT displays are also widely used in various devices. Now let's understand what TFT is and its working principle.


Compared to regular LCD displays, TFT LCD can provide very clear images/text and has a shorter response time. The increasing application of TFT liquid crystal displays has brought better visual effects to products.


TFT liquid crystal display (Thin Film Transistor) refers to thin film transistors, which belong to a type of active-matrix liquid crystal display. Each LCD pixel is driven by a thin film transistor integrated behind the pixel, which can achieve high speed, high brightness, and high contrast. It is currently one of the excellent LCD color display devices.


Since TFT liquid crystal display has a liquid crystal layer between a glass substrate formed by TFT and transparent pixel electrodes and another glass substrate with a color filter (RGB) and a transparent counter electrode. Each pixel in the active matrix is paired with a transistor, including a capacitor, which enables each sub-pixel to retain its charge instead of sending the charge every time it needs to be replaced.


TFT generally refers to thin film liquid crystal displays, but in reality, it refers to thin film transistors (matrices). So how is the image generated?

The basic principle is simple: the display screen is composed of many pixels that can emit light of any color, and as long as each pixel is controlled to display the corresponding color, the goal can be achieved.


When light passes through the polarizer, it becomes linearly polarized light, with the polarization direction consistent with the vibration direction of the polarizer and the arrangement order of liquid crystal molecules on the upper and lower glass substrates. When light passes through the liquid crystal layer, due to refraction by the liquid crystal, linearly polarized light is decomposed into two beams of light. Due to the different propagation speeds (same phase) of these two beams of light, when they are combined, the vibration direction of the vibrating light will inevitably change. The light passing through the liquid crystal layer is gradually distorted.


When the light reaches the lower polarizer, its optical axis vibration direction is twisted 90 degrees and remains consistent with the vibration direction of the lower polarizer. In this way, the light passes through the lower polarizer to form a bright field. After applying voltage, the liquid crystal orientation and distortion disappear under the action of an electric field. At this point, the linearly polarized light passing through the upper polarizer no longer rotates in the liquid crystal layer and cannot pass through the lower polarizer to form a dark field. It can be seen that the liquid crystal itself does not emit light and can only be displayed under the modulation of an external light source. Throughout the display process, the liquid crystal acts as a voltage-controlled light valve.


Based on the structure of TFT, we have summarized the working principle of TFT as follows: 

When the display is powered on, the backlight emits white light, which illuminates the entire screen through the emission of the light guide plate. The diffusion film softens the light and ensures that the light can travel in the correct direction. Then, the polarizing film filters out light from other directions. Only allow vertically polarized light to pass through. TFT controls the voltage of sub-pixels as needed, affecting the degree of distortion of liquid crystal molecules and controlling the brightness of light.


Jingda Display Company can provide various TFT display sizes for you and our team has professional experience in this field.