[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. 1090–1093. (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)
