TFT-LCD Technology Introduction Thin film transistor liquid crystal display (TFT-LCD) is a flat panel display one of the most important fields, because of its many advantages, is the only display technology across all dimensions, is widely used in many fields, such as TV, notebook computer, monitor, mobile phone etc.. TFT plays a transmission and control electrical signal role in LCD, the voltage applied to the liquid crystal layer on the size determined by it. When a voltage is applied to the liquid crystal panel, liquid crystal molecules start to rotate, the light through the polarizer and liquid crystal layer can form a certain picture. TFT-LCD Panel structure: TFT-LCD in the theory and the technology process was better than those of TN and STN is much more complicated. Simply put, the basic structure of TFT-LCD is a two glass substrate sandwiched between a layer of liquid crystal layer, is mainly composed of a polarizer, a glass substrate, a common electrode, a pixel electrode, control of IC, the color filter film. Usually has a substrate color photoresist called CF substrate, the substrate TFT array is fabricated called array substrate. Backlight module in the LCD face plate is used as the light source. TFT-LCD panel structure of TFT and the basic structure of Figure 1 and 2 show Figure 1 TFT-LCD panel structure Figure 2 TFT-LCD panel structure
TFT-LCD pixel structure: TFT is located in the intersection of the scanning electrode and the signal electrode, drain and source of its electrode and the signal electrode and the pixel electrode is connected with the scanning electrode connected to the gate. TFT-LCD panel pixel structure schematic diagram shown in figure 3. The color filter film is composed of red, green, blue three colors of light resistance, the black matrix, the protective film and a public electrode consists of several parts. TFT-LCD mainly for three stage: Figure 3 TFT-LCD panel structure Front: Array process and semiconductor process some similar, but different is the thin film transistor fabricated on glass substrate instead of on wafer. Middle: the middle of the Cell is the glass substrate attaching the front Array substrate and a color filter, and in two of glass substrate drops of liquid crystal (LC) Posterior segment (assembly): module assembly process is Cell process after the panel and the other as a backlight unit, circuits, frame and other components assembly process.
Advanced TFT technology: Item Advantages Defect 1.(Transflective) Energy saving, outdoor display effect is good The process is complex, low yield M Multi domain vertical orientation / electrode pattern of vertical orientation (MVA/PVA) Wide viewing angle, high contrast ratio, short response time, does not need the friction process The process is complex, low yield 3. Conversion plane(ips) 4. Optically compensated bend (OCB) 5. The organic film high aperture ratio technique (HAR) 6. Field sequential color liquid crystal display technology (FIELD SEQUENTIAL) 7. Amorphous silicon gate driver and the active matrix display integrated technology (ASG) 8.4 Mask technology (4 MASK) Wide viewing angle, low color shift Fast response (including low temperature), wide viewing angle A high aperture ratio, high transmittance Fast response, wide color gamut range, low power consumption, simple manufacture process, high resolution, reduce costs Lower cost, more compact structure, higher mechanical reliability Yield improvement, cost reduction Complex processing, low yield, low power consumption, high transmittance Complex processing, low yield, requiring preset voltage Complex processing, low yield, increase the cost of materials The development of special IC and backlight unit High heat Low yield 1. Transflective A transflective type TFT-LCD can also guarantee the indoor and outdoor good information readability, it at the same time, through the advantages and reflectance of LCD together, each pixel including the part and a reflecting part.
In the indoor environment of low light conditions, TFT-LCD relies on the backlight unit light through the pixel transmission part illuminates the whole screen, and can obtain good brightness, contrast and color saturation and other display characteristics. In the outdoor environment, the light is sufficient, TFT-LCD relies on the screen reflection part reflects ambient light display, greatly reducing the energy consumption for the. Transflective technology diagram shown in Figure 4 2.multi domain vertical orientation technology (VA) Vertical alignment technology is a promising wide angle domain segmentation technology, which is realized by the formation of structures in the pixel electrode. The advantages of vertical orientation mode is a positive high contrast, can easily get more than 500:1 value. In addition, in the process does not require friction processing. VA LCD work in a normally black mode, greatly reducing the LCD panel a "bright spot" the possibility of. Figure 5 is a vertical orientation structure of LCD diagram. Fig. 5 Schematic diagram of a vertically oriented LCD structure 3.Conversion technology plane (IPS) In IPS technology, liquid crystal molecule long axis is not perpendicular to the substrate is parallel to the substrate. When the liquid crystal box after power on, the liquid crystal molecules in a plane parallel with the substrate, so called "in-plane switching" technology. Another technical features are not separately in the upper and lower substrates production of common electrode and the pixel electrode arrangement, but the common electrode and the pixel electrode
in a staggered array substrate, so as to obtain a wide viewing angle. Advanced- FFS (AFFS) technique is characterized by using the transparent public electrode is located below the pixel electrode, so as to obtain the edge electric field edge effectively, improve the aperture opening ratio, reduces the light leakage, and good perspective and contrast. Figure 7 is the IPS and AFFS technology principle diagram. Figure 6 IPS and the AFFS technical principle diagram 4. Optically compensated bend Technology (OCB) Optically compensated bend / optical compensation birefringence is a new technology of liquid crystal display technology of self compensation liquid crystal optical, originally developed by the Japanese Panasonic Corp. In the liquid crystal screen using OCB technology, the liquid crystal molecules are not twisted structure in TN mode, so only a relatively short time required for the liquid crystal molecules can reach the predetermined position, the response speed is very fast, has a response time is only 1ms ~ 5ms products, very suitable for dynamic image display. OCB-LCD also has a wide viewing angle, and compared with other wide view angle technique process more simple. 5. The organic film high aperture ratio technique (HAR) The organic film high aperture ratio technology uses organic transparent dielectric materials as the pixel storage capacitor dielectric, the pixel electrode and the scanning line and the data line with greater overlap, can make the product opening rate increased more than 10%, the rate increased more than 20%. 6. Field sequential color liquid crystal display technology (FIELD SEQUENTIAL) A frame (frame) color images are decomposed into R, G, B three color three color sub field (field), without the use of a color filter film, only according to the time order of high-speed switching RGB sub field for color display. Compared with the traditional field sequential color liquid crystal display, TFT-LCD does not require the use of color film, color performance range, resolution etc.. Figure 6 is a schematic diagram of the principle of ASG technology.
7. Amorphous silicon gate driver and the active matrix display technology (ASG) The Gate driver IC using the original production line of the existing a-si process integrated directly on the glass substrate, which can effectively make the screen becomes lighter, and can increase the display reliability, reduce the cost of. Fig. 7 shows the principle of ASG Technology 8. The 4 mask technique (4 MASK) TFT array substrate usually takes multiple mask use, 4 mask technology and 5 mask technology can reduce production line investment and product cost. The 4 mask technique using gray tone or half tone mask 5 mask technology in 2 mask instead of.