Jeong-Geun Yoo

Antiferroelectric liquid crystal display with high image quality

Abstract The antiferroelectric liquid crystal display (AFLCD) is a unique display that can at demonstrate a moving image perfectly the passive matrix driving scheme. We optimised driving the waveform and introduced a dual‐driving method. Also, by improving this driving method and using line inversion method, we realize the AFLC display of high image quality with 160(RGB) × 240, 32768 colors, crosstalk free and flicker free contrast ratio is greater than 60:1, and the brightness is above 200 cd/m2.

Suppression of the pretransition by polymer in antiferroelectric liquid crystals

We have investigated the temperature dependence of the contrast ratio when AFLCD is driven in real driving condition. Although the antiferroelectric phase is seen at m 30°C, the minimum driving temperature is higher. This is because the physical properties such as response time and the hysteresis are not enough for driving. We explained the temperature dependence of the response time and hysteresis characteristics related to the contrast ratio. The pretransition that causes a bad darkness in the low electric field decreases the contrast ratio and the tolerance of the driving voltage. This pretransition phenomenon is dominant at lower temperature. We have examined the effect of polymer addition in V-T double hysteresis curve. Small addition of polymer suppresses the pretransition effect. The falling time from ferroelectric to antiferroelectric state is faster by adding the polymer. The polymer addition mitigates the physical and thermal shock.