How TFT LCD Works

The working principle of TFT LCD (Thin Film Transistor Liquid Crystal Display) is to control the display of each pixel on the screen based on thin film transistor technology. The following is a detailed analysis of its working principle:

1. Basic structure

The basic structure of TFT LCD display includes:

Backlight module: As a light source provider, it is usually composed of LED lamp tubes, reflectors, light guide plates, diffusers and prisms. These components work together to evenly distribute light behind the LCD screen and provide basic lighting for image display.

Liquid crystal module: It is composed of a layer of liquid crystal material sandwiched between two glass substrates. Liquid crystal molecules can change their arrangement direction under the action of electric field, thereby controlling the degree of light transmission.

Color filter: Located in front of the liquid crystal module, it is used to filter white light into red, green and blue primary colors to provide rich colors for the image.

Polarizer: It is divided into upper polarizer and lower polarizer. They convert the light emitted by the backlight module into polarized light, and control the light transmission through the rotation of liquid crystal molecules to achieve image brightness and color adjustment.

Glass substrate: It is the carrier of TFT and pixel electrode, and it is engraved with complex circuit traces to control the arrangement and voltage distribution of liquid crystal molecules.

Thin film transistor (TFT): TFT is one of the key technologies of TFT-LCD. It controls the light and color change of each pixel like a switch.

2. Working principle

The working principle of TFT LCD can be summarized as the following steps:

Electrical signal processing: Process the received electrical signal into the voltage required for TFT driving. This step is usually completed by the driver IC, which is responsible for receiving, processing and transmitting image signals, and its performance directly affects the display effect and response speed of TFT-LCD.

TFT drive: The voltage that adjusts the capacitance offset of liquid crystal molecules is generated through the TFT structure. Each pixel has a corresponding TFT structure to drive the liquid crystal molecules in the LCD to complete the refresh and update of the display. As a switching element, the performance of TFT transistor directly affects the display effect of TFT-LCD. When TFT is activated, it adjusts the arrangement state of liquid crystal molecules according to the received voltage signal.

Liquid crystal display: The offset of the capacitance of liquid crystal molecules is adjusted by using the TFT structure, thereby adjusting the light released by the liquid crystal capacitance to form a display image. The liquid crystal molecules rotate under the action of voltage, changing the degree of light transmission. At the same time, the color filter filters white light into red, green, and blue primary colors, and works together with the rotation angle of the liquid crystal molecules to form the final image.

3. Operation process

The display process of the TFT-LCD liquid crystal screen can be roughly divided into the following steps:

Backlight on: The backlight module is turned on to provide basic lighting for the liquid crystal screen.

Signal reception: The external image signal is transmitted to the driver IC of the TFT-LCD through the interface circuit.

Signal processing: The driver IC decodes, converts, and amplifies the received image signal to generate a signal to control the TFT switch state.

TFT switch control: The gate driver and the source driver work together to provide the correct voltage signal for each pixel of the TFT matrix. The gate driver is responsible for scanning line by line and activating each row of pixels; the source driver provides the corresponding voltage signal for each row of pixels according to the image data.

Liquid crystal molecule arrangement: Under the action of voltage, the liquid crystal molecules rotate, changing the degree of light transmission. At the same time, the color filter filters white light into red, green, and blue primary colors, and works together with the rotation angle of the liquid crystal molecules to form the final image.

Image display: After the above steps, the image is finally displayed on the TFT-LCD screen. Since the refresh rate of TFT-LCD is very fast, the human eye cannot perceive the process of line-by-line scanning, so the picture seen is continuous.

In summary, the working principle of TFT LCD is to use thin film transistors to control the display of each pixel on the screen, and to display and update the image by precisely controlling the arrangement and transmittance of liquid crystal molecules.

TFT LCD Displays product links for reference:
https://www.youritech.com/products/tft-displays/

Shenzhen Youritech Technology Co.,Ltd. focuses on the research and development ,design ,customization and production of LCD,OLED,touch screen and other products.

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