There Are Several Types And Characteristics Of Liquid Crystal Displays

- Sep 24, 2019-

In general, that CRT display is now divided into a spherical picture tube and a pure flat picture tube. The so-called sphere is a sphere that is curved in both the horizontal and vertical directions. And the pure flat picture tube is completely in the horizontal or vertical direction, and the distortion is smaller than that of the spherical tube. the real-world spherical tube display is now extinct, and instead of a "plane right angle" picture tube, the plane right-angle picture tube is not actually a plane in a real sense, except that the tube has a smaller curvature than the spherical tube, close to the plane, and the four corners are at right angles, In that present market, in addition to the pure flat display and the liquid crystal display, the spherical tube display is a spherical tube display, because the price is mostly relatively cheap, therefore, the market is widely adopted in the low-grade model. Most of the liquid crystal displays of the present invention are tft-type liquid crystal displays. the type of liquid crystal display (I) Classification by physical structure The LCD can be divided into two-scan passive array display (DSTN-LCD) and thin film transistor array display (TFT-LCD) according to the physical structure. And fast DSTN (HPA), the performance is between the two. See Table 1 for specific parameters. Type Reaction time (ms) contrast angle of view DSTN 300 25:1 20 degrees HPA (HPA) 150 35:1 25 degrees TFT 80 100:1 45 degrees Table 1 Comparison of technical parameters of several LCD display types DSTN (Dual Scan Tachyose Nomingraph) Dual-scan twist array It is scanned by double scanning And the nematic liquid crystal display screen is used for achieving the purpose of completing the display. DSTN is a kind of super-twisted nematic display (STN). Because of the dual scanning technique of DSTN, the display effect is greatly improved. In the case of a notebook computer, STN was mainly used, followed by DSTN. The reaction time of STN and DSTN was slow, typically about 300 ms. According to the liquid crystal display principle, the principle of the STN is to change the arrangement of the liquid crystal molecules with the twist of more than 180 degrees by the electric field so as to change the optical rotation state, the applied electric field changes the electric field by a progressive scanning way, and the recovery process of each point is slow in the process of repeatedly changing the voltage in the electric field, So that the afterglow phenomenon can be generated. The user can feel the tail (afterglow), commonly known as the "pseudo-color". since the brightness and the contrast of each pixel point on the DSTN display screen cannot be independently controlled, the display effect is poor, the contrast and the brightness of the liquid crystal display formed by the liquid crystal are poor, the screen observation range is small, the color is rich, in particular the reaction speed is slow, It is not suitable for high-speed all-moving images, video playing, and the like, but is generally used only for text, table and static image processing, but is simple in structure and relatively low in price (the price is generally about $3,000 lower than that of the TFT notebook computer under the same configuration), and the energy consumption is less than that of the TFT-LCD, And the view angle is small, the content of the peeping screen can be prevented from reaching the secret function, the structure is simple, the volume of the whole machine can be reduced, and therefore, the small number of notebook computers still adopt the display device as the display device, and still occupy a certain market share. In fact, the DSTN-LCD is not a real color display, and it can only display a certain color depth, which is far from the color display characteristic of the CRT, and is thus called a "pseudo-color display". The working characteristic of DSTN is that the scanning screen is divided into upper and lower parts, and the CPU simultaneously refreshes the two parts in parallel (double-scanning), so that the refresh frequency is twice as fast as the single-scan (STN) redrawing of the whole screen, which improves the occupancy rate and improves the display effect. Since the DSTN is scanned at the same time and the two screens are scanned at the same time, the refresh is not synchronized in the upper and lower parts, so when the performance of the element is not good, a fuzzy horizontal bright line appears in the center of the display screen. However, the use of the DSTN-LCD's computer now has a high CPU and RAM rate and a stable performance, which has rarely been met. In addition, since the pixel information on the display screen of the DSTN is displayed by the transistors on the left and right sides of the screen to control a whole row of pixels, each pixel point can not emit light and is a passive image point, so that the reaction speed is not fast, a ghost is left after the screen is refreshed, the contrast and the brightness are low, The image is much darker than the CRT monitor. HPA is commonly referred to as a high-performance fixed address or a fast DSTN The improved type of DSTN can provide a faster reaction time, higher contrast and larger viewing angle than DSTN, because it has a cost similar to that of DSTN, and therefore has a certain advantage in the low-end notebook computer market. Thin Film Transistor The so-called thin film transistor means that each liquid crystal pixel point on the liquid crystal display is driven by a thin film transistor integrated thereafter. So that high-speed, high-brightness and high-contrast display screen information can be achieved. Because the number of pixel points required in a color display is four times that of a black-and-white display, a large number of pixels in the color display is increased, and if the double-scanning mode is still adopted, the screen can not work normally, and the active driving mode is used instead of the passive scanning mode to activate the pixels. such that a non-linear active element such as a thin-film transistor (tft), or a thin-film diode, or a metal-insulator-metal (mim) is integrated into the active technique in the display assembly for driving each pixel point so that each pixel can maintain a certain voltage, 100% of the cavitation is achieved, but this is no doubt that the power consumption of the device will be increased. The TFT belongs to an active matrix liquid crystal display (AM-LCD).