What are the working characteristics and driving methods of TFT color LCD display screens?
2023-08-21
Author: HuiXingLong
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The color TFT-LCD uses thin film transistors to generate voltage to control the direction of the liquid crystal display. It consists of a glass plate with a thin film field-effect transistor matrix circuit and a glass plate with a color filter, and liquid crystal is filled between the two glass plates. Each pixel in the display is divided by the horizontal and vertical common metal wires of the thin film transistor matrix circuit. Each pixel contains a thin film field-effect transistor and a capacitor, which is composed of a transparent indium tin oxide (ITO) electrode in the matrix circuit and a common 1TO electrode on the color filter. The liquid crystal sandwiched between the two electrodes acts as the dielectric in the capacitor.
&Nbsp& Nbsp& Nbsp& Nbsp; The display adopts a driving method of scanning one line at a time. When a positive pulse is applied to a horizontal scanning common wire (or gate line), all thin film transistors connected to the horizontal wire are turned on and in a conductive state. At this time, the capacitance on each pixel is charged to the voltage of its corresponding vertical common wire (or signal line). When it is the turn of other scanning lines to add positive pulses, the original scanning line will apply negative voltage, turning off all thin film transistors connected to the scanning line and presenting a non-conductive state.
&Nbsp& Nbsp& Nbsp& Nbsp; Therefore, the charge originally charged to each capacitor can maintain the time required for scanning one frame until the next time it is the line's turn to scan. If the display uses twisted nematic TN liquid crystal, it is best to use AC voltage to drive, which means that the polarity of the driving voltage for each screen must be opposite to the previous screen. The LCD in the display is like a light valve, and as the voltage on each pixel changes, the intensity of colored light passing through that pixel also changes.
&Nbsp& Nbsp& Nbsp& Nbsp; The TFT liquid crystal display screen is an active matrix display screen, so its driving method is completely different from TN and STN liquid crystal displays, using the source matrix dynamic driving method. The reason why TFT liquid crystal display screens can display realistic colors is due to the coordinated work of their internal color filters and TFT field-effect transistors.
