TFT LCD Display Types

- Mar 09, 2020-

TN


TN + film (Twisted Nematic + film) is the most common type, mainly due to the low price and diversity of products. On modern TN skin, the response time of the pixels is fast enough to greatly reduce the afterimage problem, and even the response time is already fast in the specifications. The transition time to full white does not indicate the transition time between gray levels. The transition time between gray levels (which is usually the more frequent switching of liquid crystals) takes longer than defined by ISO. The RTC-OD (Response Time Compensation-Overdrive) technology currently used allows manufacturers to effectively reduce the conversion time between different gray levels (G2G). However, the response time defined by ISO has not actually changed. The response time is now represented by G2G numbers, such as 4ms and 2ms, which are already commonplace on TN + Film products. This market strategy, having a lower cost TN skin than the VA type, is already leading the trend of TN in the consumer market. TN-type displays suffer from restrictions on viewing angles, especially in the vertical direction, and most of them cannot display 16.7 million colors (24-bit true colors) output by current graphics cards. In a special way, the RGB three colors use 6 bits as 8 bits. It uses a reduction method that combines adjacent pixels to approach 24-bits colors to simulate the required grayscale. Some people also use FRC (Frame Rate Control)


For liquid crystal displays, the actual transmittance of a pixel generally does not change linearly with the applied voltage.


B-TN (Best TN) was developed by Samsung. Improve TN color and response time.


VA CPA (Continuous Pinwheel Alignment) was developed by Sharp. High color reproduction, low output and expensive. MVA (Multi-domain Vertical Alignment) was developed by Fujitsu in 1998. It is intended as a compromise between TN and IPS. At the time, it had fast pixel response, wide viewing angles, and high contrast, but it had relatively lost brightness and color reproducibility. Analysts predict that MVA technology will dominate the mainstream market, but TN has this advantage. Mainly because of the higher cost of MVA and slower pixel response (it will increase dramatically with small changes in brightness).


P-MVA (Premium MVA) improves the viewing angle and response time of MVA. A-MVA (Advanced MVA) was developed by AUO. S-MVA (Super MVA) was developed by Chi Mei. VAextreme was developed by Chi Mei. PVA (Patterned Vertical Alignment) was developed by Samsung. Although Samsung claims that it has the best comparison technology at present, it also has the same problems as MVA. S-PVA (Super PVA) was developed by Samsung to improve PVA viewing angle and response time. C-PVA was developed by Samsung.


IPS IPS (In-Plane Switching) was developed by Hitachi in 1996 to change the poor viewing angle and color reproducibility of TN-type skin. This improvement has increased the response time. Its initial level is 50ms. The cost of IPS skin is also very expensive.


In addition to the advantages of IPS technology, S-IPS (Super IPS) also improves the pixel update time. Color reproducibility is closer to CRTs and prices are lower, but the contrast is still very poor. S-IPS is currently only used on larger displays for professional purposes.