FFS and VA

Technical advantages and disadvantages of FFS/ADS and VA
PSVA is a variation of traditional VA technology in liquid crystal alignment. The material and process need to be optimized and changed. Compared with FFS type horizontal direction allocation technology which can be realized by friction or polarized UV irradiation, PSVA has a considerable increase in both liquid crystal material cost and process cost.

Visual Angle
According to the traditional perspective definition only consider the impact of contrast, real professionals understand that this is a very comprehensive indicator. In particular, large size, brightness, contrast and color differences can greatly affect the viewing experience in front and side viewing angles. VA vertical direction matching technology USES 4 domain pixel electrodes, and the liquid crystal molecule flips in 4 directions to realize the self-redemption of the field of view. The attenuation of the side view brightness and contrast is improved compared with the normal view LCD technology such as TN, but the color deviation is still very insufficient, and the use of compensation film is still not optimistic. The 8 domain design increases the dispersion of liquid crystal molecules by applying different voltages to two 4 domain partitions in a pixel, which finally improves the color deviation. However, there is still a considerable gap even compared with the FFS class horizontal distributed LCD without compensation film. The genes of FFS/ADS horizontal alignment technology determine its innate excellence in perspective. It can achieve a side view display effect far superior to VA without using the compensation membrane.

Quality aspects
It can be seen from the pixel structure that another big disadvantage of VA class is that Vcom is located on the CF side, which is too far away from the pixel electrode, resulting in insufficient storage capacitance. Therefore, some additional Vcom wiring needs to be set on TFT to increase the storage capacitance, thus occupying the precious pixel opening area and ultimately affecting the transmittance. On the high resolution 8K product, the pixel opening area is already insufficient, and the extra storage capacitance that must be set further drags down the transmittance. The insufficient storage capacity is also very easy to occur screen flicker.

Color uniformity
VA class technology because of the liquid crystal molecules diffuse driving conditions, red, green, blue light efficiency under different grayscale change there is a big difference, gray-scale curve of red, green and blue (Gamma) can only separate modulation, in addition to increase the difficulty and cost in the process of designing and manufacturing, will enlarge backlight brightness, Gap uneven reasons such as color difference, thus affecting the brightness and color uniformity.