Surface Anchoring Energy Fast Qtensor Mothod picell Email

Surface Anchoring Energy가 추가된 Fast Q-tensor Mothod를 이용한 pi-cell 시뮬레이션 강완석*, 허승열*, 윤형진**, 이기동* *동아대학교 전자공학과, **㈜ 사나이시스템 E-mail : gdlee@dau. ac. kr Dong-A University 1/16 Display Device Lab

Contents ▷ Introduction ▷ Fast Q-tensor method ▷ The Results of Simulation ▷Conclusion Dong-A University 2/16 Display Device Lab

Introduction ▣ Next generation of LCD ▶ Large size Display, TV, Mobile Display, etc. 1) Wide viewing for family use 2) Fast response time for moving pictures Multi-domain Technology Dynamics simulator Defects Dong-A University 3/16 Display Device Lab

Introduction ▣ The generation of the Defect u Liquid crystal samples may contain defects where the director n is undefined, that is, where there is a discontinuity in the orientation of n. 1) non uniform electric field distribution (ex. PVA, S-IPS, FFS) 2) Phase transition (ex. Pi cell) Fig 1. Defects in a pi cell Fig 2. Defects in a PVA cell Fig 3. Defects in a S-IPS cell Fig 4. Defects in a FFS cell ⇒ We focus on dynamics simulator which can show the defects. Dong-A University 4/16 Display Device Lab

Introduction ▣ Comparison Vector Method Q-tensor Method Fast Q-tensor Method Ø In real nematics, n and –n are equivalent and give the same free energy density. -. Vector : different free energies for n and –n. -. Q tensor : same free energies for n and –n. Ø Fast Q-tensor method can calculate order parameter S (can show the defects). Dong-A University 5/16 Display Device Lab

Introduction ▪ LC Dynamics : Vector method, Q-tensor method, Fast Q-tensor method Vector method Dickman’s Qtensor method Fast Q-tensor method Normal Dynamics O O O Phase Transition X O O Defect X X O commercial use O O Is going etc. Dong-A University easy calculation 6/16 simple, short time for calculation Display Device Lab

Fast Q-tensor Method ▪ Q-tensor form of strain free energy ▪ Q-tensor form of electric free energy Dong-A University 7/16 Display Device Lab

Fast Q-tensor Method [fg]Q = strain term([fg]S) + voltage term([fg]V) + temperature term([fg]T) jk Dong-A University 9/16 Display Device Lab

Fast Q-tensor Method Dong-A University 10/16 Display Device Lab

Fast Q-tensor Method • Rapinni-Papular Equation W : anchoring strength Qjk : Q with strong anchoring Q’jk: Q of a LC director Dong-A University 11/16 Display Device Lab

Fast Q-tensor Method [fg]Qjk = strain term([fg]S) + voltage term([fg]V) + temperature term([fg]T) + surface term([fg]sur) Dong-A University 12/16 Display Device Lab

The Results of Simulation < A Simulated Structure > Electrodes < Liquid Crystal Parameter > Dong-A University K 11 14. 4 p N 10. 7 K 22 6. 9 p N 3. 7 Pretil 18. 3 p K 33 t N angle 5 13/16 Display Device Lab

The Results of Simulation < 강한 고정에너지를 고려한 pi-cell의 모델링 결과 > (a) 1. 53 V (a) 1. 55 V (a) 1. 6 V Dong-A University (a) 1. 8 V 14/16 Display Device Lab

The Results of Simulation < 약한 고정에너지를 고려한 pi-cell의 모델링 결과 > (a) 1. 55 V (a) 1. 53 V (a) 1. 6 V Dong-A University (a) 1. 8 V 15/16 Display Device Lab