P-179L: Late-News Poster: Analysis of Temperature Dependency on the Viscosity Coefficients and Flow-effect of Liquid Crystal, and their Influence on Response Time of OCB, ECB and VA Modes

Abstract

According to a popularization of LCD-TVs, realization of highperformance moving image LCD, such as field sequential color LCD, is required. This paper points out that we have clarified the temperature dependency of viscosity coefficients and flow effects that are great relevance to response of LC comparing among OCB, ECB and VA modes.From mentioned results, we have designed and realized the high-speed response prototyped OCBmode field sequential color TFT-LCD of 15-inch XGA in consideration of temperature dependency.

Response times in pi-cell liquid crystal displays

“…(1), are shown in figure 1 for the Pi-cell with different pretilt angle, respectively. From figure 1, we see that the rise time decreases as the driven voltage increases, but has no more change for low driven voltage and decreases fast as the pretilt angle increases, which is also confirmed partially by the previous experiment data [5,10]. For achieving faster rise time, it is driven by a high voltage, as the LC profile arrive the appropriate state of a grey-level, the voltage for this grey-level is added to hold the state, this method is also called as over-drive method.…”

“…Taking into account the flow effect, the dynamic equation for the cell switching in the bend state can be described by [7][8][9][10] ( ) ( )…”

“…The Pi-cell operates between the bend deformation at the critical voltage (Uc) and the near homeotropic state at high voltage. Many researchers [4][5][6][7][8][9][10] only studied the response times of the cell with various pretilt angles, which is switched between Uc and on-state voltage. However, the response time is sensitive with the different driven voltage and pretilt angle, but it has not analyzed in detail before.…”

Modes for Liquid Crystal Devices

“…The response time of a typical OCB cell is around 1-5 ms, with the potential of further decrease by improving the design and conditions of the LC molecules. Furthermore, this high-speed response due to the flow effect has been shown to be effective even at low temperatures [69].…”

“…Figure 6.19 shows a 15 in. panel that with improved clarity of video images, light efficiency, and color reproducibility [69,[78][79][80][81][82]. The subfield frequency in this case was set to 180 Hz or 360 Hz.…”