Thin Film Transistor Liquid Crystal Display
Thin film transistor liquid crystal display (English: Thin film transistor liquid crystal display, often abbreviated as TFT-LCD) is a type of most liquid crystal displays, which uses thin film transistor technology to improve image quality. Although TFT-LCD is collectively referred to as LCD, it is an active matrix LCD that is used in televisions, flat-panel displays and projectors.

Simply put, a TFT-LCD panel can be regarded as a layer of liquid crystal sandwiched between two glass substrates, the upper glass substrate is with color filters, and the lower glass is embedded with transistors. When the current passes through the transistor, the electric field changes, causing the liquid crystal molecules to deflect, thereby changing the polarization of the light, and then using the polarizer to determine the light and dark states of the pixels. In addition, the upper glass is bonded with the color filter, so that each pixel contains three colors of red, blue and green, and these red, blue and green pixels constitute the image on the panel.

Architecture
A common LCD is like the display panel of a calculator, whose picture elements are driven directly by voltage; when one unit is controlled, it does not affect other units. This approach becomes impractical when the number of pixels increases to extremely large numbers such as millions, noting that each pixel must have individual connecting lines for the red, green, and blue colors.
To avoid this dilemma, arranging pixels in rows and columns reduces the number of connecting lines to thousands. If all pixels in a column are driven by a positive potential and all pixels in a row are driven by a negative potential, the pixel at the intersection of the row and column will have the maximum voltage and be switched states. However, this method still has drawbacks, that is, although other pixels in the same row or column receive only a partial voltage, this partial switching will still make the pixels dark (for LCDs that do not switch to bright) . The solution is to add a transistor switch to each pixel so that each pixel can be controlled independently. The meaning of the low leakage current characteristic of the transistor is that the voltage applied to the pixel will not be arbitrarily lost before the picture is updated. Each pixel is a small capacitor with a transparent indium tin oxide layer in front and a transparent layer in the back, with insulating liquid crystals in it.

This circuit arrangement is similar to dynamic random access memory, except that the entire structure is not built on silicon wafers, but on glass, and many silicon wafer process technologies require temperatures that exceed the melting point of glass. The silicon substrate of ordinary semiconductors uses liquid silicon to grow a large single crystal, which has the good characteristics of transistors, and the silicon layer used in the thin film transistor liquid crystal display is to use silicide gas to create an amorphous silicon layer or a polycrystalline silicon layer. The manufacturing method is less suitable for making high-grade transistors.

type
TN
TN+film (Twisted Nematic + film) is the most common type,
Because of the low price and variety of products. On modern TN-type panels, the pixel response time is fast enough to greatly reduce the afterimage problem, and even the response time is fast in specifications, but this traditional response time is a standard set by ISO, only defined by full black The transition time to full white, but it does not mean the transition time between grayscales. The transition time between grayscales (which is actually more frequent transitions in normal liquid crystals) takes longer than defined by ISO. The current RTCOD (Response Time Compensation-Overdrive) technology allows manufacturers to effectively reduce the conversion time between different grayscales (G2G). However, the response time defined by ISO has not actually changed. Response time is now represented by G2G (Gray To Gray) numbers, such as 4ms and 2ms, which are commonplace on TN+Film products. This market strategy, with TN-type panels having a lower cost than VA-type panels, is already leading the trend of TN in the consumer market. TN-type monitors suffer from viewing angle limitations, especially in the vertical direction, and most cannot display the 16.7 million colors (24-bit true color) output by current graphics cards. In a special way, the RGB three colors use 6 bits as 8 bits, and it uses a downgrade method combined with adjacent pixels to approach the 24-bit color to simulate the desired grayscale. Some people also use FRC (Frame Rate Control) for liquid crystal displays, and the actual transmittance of pixels generally does not change linearly with the applied voltage.
In addition, B-TN (Best TN) is developed by Samsung Electronics. Improved TN color and response time.
STN
STN liquid crystal (Super-twisted nematic display) is the abbreviation of super twisted nematic liquid crystal. After TN liquid crystal was invented, people naturally thought of matrixing TN liquid crystal to display complex graphics. Relative to TN liquid crystal twisted 90 degrees, STN liquid crystal twisted 180 degrees to 270 degrees. In the early 1990s, color STN liquid crystal came out. One pixel of this liquid crystal is composed of three liquid crystal cells, covered with a layer of color filter, and the brightness of the liquid crystal cells can be controlled by voltage to generate color.

VA
CPA (Continuous Pinwheel Alignment) was developed by Sharp. High color reproduction, low yield and high price.
MVA (Multi-domain Vertical Alignment) was developed by Fujitsu in 1998 as a compromise between TN and IPS. At the time, it had fast pixel response, wide viewing angles, and high contrast, but at the expense of brightness and color reproducibility. Analysts predict that MVA technology will dominate the entire mainstream market, but TN has this advantage. Mainly because of the higher cost of MVA, and slower pixel response (it will increase significantly when the brightness changes small).
P-MVA (Premium MVA) was developed by AUO to improve MVA viewing angle and response time.
A-MVA (Advanced MVA) is developed by AUO.
S-MVA (Super MVA) is developed by Chi Mei Electronics.
PVA (Patterned Vertical Alignment) is developed by Samsung Electronics. Although the company calls it the technology with the best contrast at present, there are also
Same problem with MVA.
S-PVA (Super PVA) was developed by Samsung Electronics to improve the viewing angle and response time of PVA.
C-PVA is developed by Samsung Electronics.

IPS
IPS (In-PlaneSwitching) was developed by Hitachi in 1996 to improve the poor viewing angle and color reproducibility of TN-type panels. This improvement has increased the response time, which is the initial level of 50ms, and the cost of IPS-type panels is also extremely expensive.
In addition to the advantages of IPS technology, S-IPS (Super IPS) improves the update time of pixels. Color rendition is closer to CRTs and prices are lower, however contrast is still very poor and S-IPS is currently only used on larger monitors for professional purposes.

Super PLS
PLS (Plane to Line Switching) is developed by Samsung Electronics. In addition to the amazing viewing angle, it can also improve the screen brightness by 10%. The manufacturing cost is also 15% lower than that of IPS. Currently, the resolution provided is up to WXGA. (1280×800), MacBook Pro with Retina display also uses this kind of display screen produced by Samsung (resolution up to 2880×1800), and the rest still use IPS display screen, the main objects will be concentrated in intelligent Mobile phones and tablet PCs were mass-produced in 2011.

ASV
Sharp developed ASV (Advanced Super-V) technology to improve the viewing angle of TFT.

FFS
Modern electronics use FFS (Fringe FieldSwitching) technology. FFS technology is an advanced extension of IPS (In Plane Switching) wide viewing angle technology. It has the characteristics of low power consumption and high brightness. FFS can be extended to AFFS+ (Advanced FFS+) and HFFS (High aperture FFS) technology, AFFS+ has visibility in sunlight.

OCB
OCB (Optical Compensated Birefringence) is the technology of Japan's Panasonic.

Display industry
Because of the huge cost of building TFT factories, there may not be more than four or five major panel foundries. by monitor
According to the data of DisplaySearch, a research and investigation agency, the international market share ranking is higher than that of Samsung Electronics, LG Display, AUO, Innolux, Sharp, etc. Without system and ID assembly, front panel modules are usually divided into three categories in the factory , these three are the number of bright and dark spots, the gray level and color uniformity displayed by the panel, and the general production
quality. In addition, different panels of the same lot will still have a +/-2ms difference in response time. Panels judged to be the worst in quality are later sold to white-label manufacturers.
Panels of poor quality or sizes under 15 inches usually do not contain a digital signal compatible interface DVI, so their future suitability may be limited. The taller 17" or 19" models, for gamers and offices, may have dual display slots: analog D-sub and digital DVI; almost all professional screens will have DVI and The letter mode is turned 90 degrees. In any case, even if a DVI video signal is used, better video quality is not guaranteed: a good video card RAMDAC and a suitable and protected analog VGA cable will also provide the same display

quality.
plant generation
Generally speaking, several generations of a panel factory refer to the maximum size of the glass substrate during its production. The larger the size, the more panels can be cut, and the larger the production capacity, the higher the required technology. However, the length and width of each generation are not strictly defined, and there may be slight differences between panel manufacturers.