Small tft display.TFT-LCD liquid crystal display screen is a thin film transistor liquid crystal display screen, that is, “true color” (TFT).

TFT LCD is equipped with a semiconductor switch for each pixel, and each pixel can be directly controlled by a point pulse, so each node is relatively independent and can be controlled continuously, which not only improves the reaction speed of the display screen, but also accurately controls the display color levels, so the color of TFT LCD is more real. TFT LCD screen is characterized by good brightness, high contrast, strong sense of hierarchy and bright color, but it also has some shortcomings such as power consumption and high cost.

The thin film field effect transistor belongs to a kind of active matrix liquid crystal display. It can “actively” control individual pixels on the screen, which can greatly improve the reaction time. Generally, the reaction time of TFT is relatively fast, about 80 milliseconds, and the visual angle is large, which can reach about 130 degrees.

Polarity conversion mode of TFT LCD screen:

The driving voltage of liquid crystal molecules can not be fixed at a certain value, otherwise, over time, liquid crystal molecules will polarize and gradually lose their optical rotation properties. Therefore, in order to avoid the destruction of the characteristics of liquid crystal molecules, the driving voltage of liquid crystal molecules must be changed, which requires the display voltage in the liquid crystal display screen to be divided into two polarities, one is positive polarity, the other is negative polarity. When the voltage of the display electrode is higher than that of the common (common electrode) electrode, it is called positive polarity; when the voltage of the display electrode is lower than the voltage of the common electrode, it is called negative polarity. Whether it is positive or negative, there will be a set of gray levels of the same brightness, so when the absolute value of the pressure difference between the upper and lower layers of glass is fixed, the gray scale is exactly the same. However, in these two cases, the steering of liquid crystal molecules is completely opposite, which can avoid the property damage caused by the steering of liquid crystal molecules when they are always fixed in one direction. There are four common ways to change polarity.

For the frame-by-frame inversion mode, all the adjacent points of the whole picture have the same polarity in the same frame, but the adjacent frame polarity is different; for the line-by-line inversion mode, they have the same polarity on the same row, while the polarity of the adjacent rows is different; for the column-by-column inversion mode, they have the same polarity on the same column, while the adjacent columns have different polarities. For the point-by-point inversion mode, each point is adjacent to its own upper, lower, left and right four points, the polarity is different.

At present, the common personal computer LCD screen, the use of panel polarity transformation, most of them are point-by-point conversion mode, why? The reason is that the display quality of point-by-point inversion is much better than other transformation methods. The table lists the performance comparison of four polarity conversion modes: frame-by-frame inversion, row-by-row inversion, column-by-column inversion and point-by-point inversion.

The so-called Flicker phenomenon is that the picture will have the feeling of flickering, but it is not a specially made visual effect, but because the gray scale of the displayed picture will change slightly every time the picture is updated, which makes people feel that the picture is flickering. This is most likely to happen using frame-by-frame inversion of polarity. Because the whole picture of frame-by-frame inversion is the same polarity, when the picture is positive this time, it will become negative next time. If there is a little error in common voltage, the same gray-scale voltage of positive and negative polarity will be different. Of course, the feeling of gray scale is different, as shown in figure 2. In the case of constantly switching pictures, due to the alternation of positive and negative polarity pictures, the Flicker phenomenon will appear. And the polarity transformation of other panels, although there will also be this Flicker phenomenon, but because unlike frame-by-frame inversion is the whole picture changes polarity at the same time, there is only one row or column, or even a point change polarity, in terms of the feeling of the human eye, it will not feel obvious.

The so-called Crosstalk phenomenon refers to the adjacent points, the data to be displayed will affect each other, so that the display of the picture will be incorrect. Although there are many causes of Ctosstalk phenomenon, as long as the polarity of adjacent points is different, the occurrence of this phenomenon can be reduced.