The type of liquid crystal display

Is called the liquid crystal display made of a liquid crystal display, in English called LCD (Liquid Crystal Display). Its kind of drive can be divided according to static drive (Static), simple matrix drive (SimpleMatrix) and active matrix drive (ActiveMatrix) three. The one simple matrix type is commonly known as passive (Passive), can be divided into a twisted nematic (Twisted Nematic, referred TN) and super twisted nematic (Super Twisted Nematic, referred STN) two kinds; while active matrix type places thin-film transistor type (Thin Film Transistor; TFT) is the current mainstream. TN TN type liquid crystal display technology can be said to be the most basic OLED Module, other types of liquid crystal displays can be said is modeled to be improved TN type. Similarly, its principle of operation is also simple than other techniques. TN The structure includes a vertical direction and the horizontal direction of the polarizer (Polarizer), which lines the groove having a middle mixed crystal material and a conductive glass substrate (Glass).

STN / DSTN STN type display principle is similar, except that a TN-type liquid crystal molecules are rotated 90 degrees to the incident light, the incident light can be rotated and the STN 180 to 270 degrees. TN display itself is only a simple two display brightness (or black and white), can not produce color changes. TN LCD used the "direct drive" can not display more pixels, and the screen contrast is small, slow response, perspective and we only +30 degrees (ie, viewing angle of about 60 degrees), the display quality is poor; it TN type LCD main purpose is to simply display the number of characters and words, such as: electronic watches and electronic calculators. STN improves the appearance of a narrow perspective on the shortcomings and improve the ratio, STN to "multi-task-driven" to increase the number of scan lines to improve pixel display, high quality more than TN. Then with the use of color filters, the color of any pixel of the display matrix (pixel) is divided into three sub-pixels (sub-pixel), respectively, through the color filters red, green, and blue, and then through the three primary colors ratio The harmony, can show full-color mode approximation colors. As STN display screen color contrast is still only reached 30:1 (compare the smaller screen more clear); reaction speed is 150ms (milliseconds), as a general operating display interface is acceptable but still not enough speed to play movies.

Since there are still many shortcomings STN, DSTN subsequent way through the dual-scan display, the DSTN dual scanning technology, so the effect is relatively STN display, it has greatly improved. DSTN response speed of up to 100ms, but they are "passive driven", changing the voltage of the electric field in the process repeated, each pixel recovery process is slow, rapid change in the screen, for example: display the broadcast of the game of tennis , will produce the so-called "tail" phenomenon. Especially when the tennis player hitting the moment, you can see on the screen drag the "ball track tail" phenomenon. However, DSTN cheap, power consumption is low, the number of PDA, etc., are still used as a display device DSTN. TFT TN and STN type liquid crystal displays are using a field voltage driving method, if the display size increase, the central portion of the electrode will lengthen the response time changes, the display speed can not keep up. In order to improve this problem, active matrix (active-matrix) drive is presented, active TFT liquid crystal display structure is more complex include: the backlight tubes, light guide plate, polarizer, filter plate, a glass substrate, with the film, the liquid crystal material and a thin mode transistors, etc. (Figure 3-2). TFT type liquid crystal display device in the conductive glass of fine lines painted on the mesh electrode by a thin film type transistors arranged in a matrix switch in each line intersects with a control gate, control gate of each display point with the drive signals for the move. Electrode of the transistor matrix display signals on or off by the liquid crystal molecules voltage, so that the liquid crystal molecular axis shift from "light" or "dark" contrast of the display to avoid dependence on the electric field effect, turn the transistor on and off in the rate of as the determining step. Therefore, TFT-LCD display quality than the TN / STN good, the screen display of up to 150:1 contrast, 30ms or faster reaction rate approximation. While the effect can be full color or true color display, products for PDA, notebook computers, lcd module, car navigation systems, digital cameras and LCD projectors.