Overview
 
     Home
     Discovery of LCs
     LCs Introduction
     History of LCDs
     TFT basics
 
   LCD Modes
 
     ASV
     BiNem
     Cholesteric
     ECB
     SSFLC
     Guest-Host
     IPS
     LCoS
     MVA
     PDLC
     Pi-Cell
     PVA
     STN
     TN
     Transflective
 
  Acknowledgements

  LC Related Links

 
  About Author
 
 

[Advanced Super View (ASV, also Axially Symmetric Vertical Alignment ) mode]

The ASV mode was developed by Sharp. It is a VA mode where LC molecules orient perpendicular to the substrates in the off state. The bottom sub-pixel has continuously covered electrodes, while the upper one has a smaller area electrode in the center of the subpixel. When the field is on, the LC molecules start to tilt towards the center of the sub-pixels because of the electric field; As a result, a continuous pinwheel alignment (CPA) is formed; the azimuthal angle rotates 360 degrees continuously. The ASV mode is also called CPA mode. Because of the full circle rotation of the director, the viewing cone is very symmetric and viewing angle performance is excellent.

Figure 1. The working principle of ASV display.

Another working method for ASV mode is to employ polymer wall around each subpixel. In the off state, the molecules are vertically aligned. When the voltage is switched on, one umbilics defect will appear in each sub-pixel area, as shown in figure 2.

Figure 2. Another working method for ASV mode.

The real LCD using ASV mode gives a 170 degrees viewing cone with contrast ratio is larger than 10:1, the response time can reach 15ms with the over-shooting driving scheme. Recently, Sharp announced a Mega-Contrast ASV premium LCD with a contrast ratio as high as 1,000,000:1, declared as the highest contrast ratio in the LCD industry.


Further Readings and References:

Y. Ishii, S. Mizushima, and M. Hijikigawa, ^High performance TFT-LCD¨s for AVC applications, ̄ SID Digest, pp. 1090C1093. (2001)

T. Watanabe. Flat Panel Display 2000, p113 (2000).

Y,Yamada,K.Miyachi,M.Kubo,Y.Ishii and M.Hijikigawa, IDW'02, Proceedings, P203 (2002)

 

Last update: April, 2006
Questions? Contact author.