Hak-Sun Chang

48.2: DCCII: Novel Method for Fast Response Time in PVA Mode

A modified DCC (Dynamic Capacitance Compensation), DCCII has been developed for the fast response time performance in PVA TFT-LCD TVs. DCCII applies a pre-tilt voltage to addressed pixels during the previous frame in addition to an overshoot voltage. In result, the response time less than 8 msec, has been obtained for all moving images through the DCCII technique.

P-93: High Performance 17.0″ SVGA OCB Panel with Fast Initial Bend Transition

Recently, the vigorous researches on the moving picture quality of TFT-LCDs have been made to overcome their drawbacks in replacing CRTs for TV application. Among them, the fast response OCB mode is thought to have the highest potential for TV application, even though its image quality still needs to be improved. In this regard, we have optimized the cell parameters of OCB mode to get wide viewing angle, high contrast ratio and transmittance as well as the fast response time. Based on these parameters, we have improved image qualities remarkably by adopting these to 17.0″ SVGA proto-panel, which shows the contrast ratio over 250, viewing angle over 80 degree for all direction except rubbing direction, response time under 7 ms including inter-gray scale and the transmittance of 90% of TN mode. Especially, by adopting new driving scheme, we considerably reduced the initial bend transition time, which is known as one of drawbacks in OCB mode. We are continuing further research to get the competitive image quality and good reliability, which is comparable to commercially used PVA or IPS mode.