Detailed Introduction of TFT Display Screen’s Driving Method

The TFT display screen is the abbreviation of "Thin Film Transistor", which refers to the thin film liquid crystal display, but actually refers to the thin film transistor (matrix) - which can "actively" control each independent pixel on the screen, which That is the origin of the so-called active matrix TFT (active matrix TFT).


The driving method of TFT display screen 

Recently, many customers have asked about the driving method of TFT display screen. In fact, there are many types of display screens, so the driving methods of each different type of display screen are also different.

But no matter what type of device it is, or what different driving methods are used, the TFT display screen is to adjust the phase, voltage, peak value, frequency, timing, effective value, duty cycle, etc. applied to the pixel electrodes. A series of parameters and characteristics can be used to establish certain driving conditions, so as to realize the display.

Since each pixel of the active matrix liquid crystal display device of the TFT LCD SPI has a set of active devices, the driving of this device is the driving of the active device on each pixel.

The external circuit cannot directly apply the voltage to the liquid crystal pixel, and the voltage applied to the pixel is determined by the characteristics of the TFT transistor. When the on-off ratio of the transistor reaches more than 106Ω, a requirement for the on-off ratio of the liquid crystal function pixel can be satisfied.

The TFT display screen transistor works like this. When the gate G scan of the TFT is gated, VG will be connected to a positive high pulse. At this time, the source signal of the synchronous input address is an address data voltage VLD whose center value is VC and will always be lower than the amplitude of the VG strobe pulse, and the transistor of the TFT display screen is turned on.


There will be a path from the source to the drain that turns on the liquid crystal pixel, and the TFT display screen voltage is applied to the liquid crystal pixel electrode and the compensation capacitor electrode.

At this time, even if the applied electric field is removed, due to the action of the capacitor, the voltage applied on the pixel will remain for a considerable time until the next strobe.

If the capacitor value is set to make the pixel strobe reach the time of the half frame, and at the same time make the addressing signal of the second half frame invert with VC, it can be realized:

1. The driving wave on the pixel of the TFT display screen forms an AC form.

2. The number of driving channels is related to the characteristics of the TFT transistors, but has nothing to do with the response characteristics of the liquid crystal electro-optic. This will completely solve the big problem of LCD multiplexing.

3. There is no semi-gated waveform in the driving method, so there are no defects such as crossover effect and contrast reduction.

4. In addition, this kind of drive will not be affected by the electro-optical response speed of the TFT LCD SPI, and can display the image of the video activity without flickering or tailing.