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Reflective Bistable Chiral Splay Nematic Liquid Crystal Display

반사형 쌍안정 카이랄 스플레이 네마틱 액정표시소자

  • Kim, Tae-Hyung (School of Electrical Engineering, Pusan National University) ;
  • Lee, Joong-Ha (School of Electrical Engineering, Pusan National University) ;
  • Shen, Zheng-Guo (School of Electrical Engineering, Pusan National University) ;
  • Jang, Ji-Hyang (School of Electrical Engineering, Pusan National University) ;
  • Kim, Jeong-Soo (School of Electrical Engineering, Pusan National University) ;
  • Jhun, Chul-Gyu (School of Display Engineering, Hoseo University) ;
  • Kwon, Soon-Bum (School of Display Engineering, Hoseo University) ;
  • Yoon, Tae-Hoon (School of Electrical Engineering, Pusan National University) ;
  • Kim, Jae-Chang (School of Electrical Engineering, Pusan National University)
  • 김태형 (부산대학교 전자전기공학부) ;
  • 이중하 (부산대학교 전자전기공학부) ;
  • 신정국 (부산대학교 전자전기공학부) ;
  • 장지향 (부산대학교 전자전기공학부) ;
  • 김정수 (부산대학교 전자전기공학부) ;
  • 전철규 (호서대학교 디스플레이공학부) ;
  • 권순범 (호서대학교 디스플레이공학부) ;
  • 윤태훈 (부산대학교 전자전기공학부) ;
  • 김재창 (부산대학교 전자전기공학부)
  • Received : 2010.11.22
  • Accepted : 2011.02.07
  • Published : 2011.02.25

Abstract

Bistable chiral splay nematic liquid crystal display (BCSN LCD) is a memory type liquid crystal display using splay and $-\pi$ twist states as two stable states. When the cell thickness to pitch (d/p) ratio is 0.25, splay and $-\pi$ twist states have permanent memory time. However, when the transition from $-\pi$ twist state to splay state is caused by a fringe field, pixel regions show that the splay state is not perfect, but rather includes a contribution from the $-\pi$ twist state. In this paper, we propose a reflective BCSN LCD using $-\pi$ twist state in which the two stable states do not coexist. The fabricated reflective BCSN LC cell shows a high contrast ratio of over 30:1 and response times of 950 ms and 450 ms in vertical and fringe field switching, respectively. The proposed cell also shows wide viewing angle characteristics of $180^{\circ}$ in left- and right directions.

쌍안정 카이랄 스플레이 네마틱 액정표시소자는 스플레이 상태와 $-\pi$ 꼬인 상태를 쌍안정 상태로 사용하는 메모리 액정표시소자이다. 셀 갭/피치의 값이 0.25일 경우 완전한 쌍안정 상태를 갖지만, $-\pi$ 꼬인 상태에서 스플레이 상태로 전이시키기 위하여 fringe 전계를 인가할 경우 픽셀영역은 전계의 왜곡에 의해서 완전한 스플레이 상태가 아니라 $-\pi$ 꼬인 상태를 부분적으로 유지하게 된다. 본 논문에서는 화소영역에서 두 안정한 상태가 공존하지 않는 $-\pi$ 꼬인 상태를 어두운 상태로 사용하는 반사형 쌍안정 카이랄 스플레이 네마틱 액정표시소자를 제안한다. 제작된 반사형 액정표시소자는 30:1의 고명암비를 나타냈으며, 응답속도는 수직전압 8 V, fringe 전압 12 V의 구동 전압으로 각각 쓰기 응답시간이 950 ms, 리셋 응답시간이 450 ms였다. 또한 제안된 셀은 +C 광학 보상 필름을 사용하여 좌우 방향에서 $180^{\circ}$의 광시야각을 나타냈다.

Keywords

References

  1. R. A. Soref and M. J. Rafuse, “Electrically controlled birefringence of thin nematic film,” J. Appl. Phys. 43, 2029-2037 (1972). https://doi.org/10.1063/1.1661449
  2. M. Oh-e and K. Kondo, “Electro-optic characteristics and switching behavior of the in-plane switching mode,” Appl. Phys. Lett. 67, 3895-3897 (1995). https://doi.org/10.1063/1.115309
  3. S. H. Lee, S. L. Lee, and H. Y. Kim, “Electro-optic characteristics and switching principle of a nematic liquid crystal cell controlled by fringe-field switching,” Appl. Phys. Lett. 73, 2881-2883 (1998). https://doi.org/10.1063/1.122617
  4. F. S.-Y. Yeung, H.-S. Kwok, “Fast-response no-bias-bend liquid crystal displays using nanostructured surfaces,” Appl. Phys. Lett. 88, 063505-1~063503-3 (2006).
  5. D. W. Berreman and W. R. Heffener, “New bistable cholesteric liquid-crystal display,” Appl. Phys. Lett. 37, 109-111 (1980). https://doi.org/10.1063/1.91680
  6. D. W. Berreman and W. R. Heffner, “New bistable liquidcrystal twist cell,” J. Appl. Phys. 52, 3032-3039 (1981). https://doi.org/10.1063/1.329049
  7. A. J. Davidson, N. J. Mottram, “Flexoelectric switching in a bistable nematic device,” Physical Review E 65, 051710-1-051710-10 (2002). https://doi.org/10.1103/PhysRevE.65.051710
  8. S. H. Lee, and K.-H. Park, T.-H. Yoon, and J. C. Kim, “Bistable chiral-splay nematic liquid crystal device using horizontal switching,” Appl. Phys. Lett. 82, 4215-4217 (2003). https://doi.org/10.1063/1.1581368
  9. J.-X. Guo, Z.-G. Meng, M. Wong, and H.-S. Kwok, “Three-terminal bistable twisted nematic liquid crystal displays,” Appl. Phys. Lett. 77, 3716-3718 (2000). https://doi.org/10.1063/1.1328363
  10. C. D. Hoke and P. J. Bos, “Multidimensional alignment structure for the liquid crystal director field,” J. Appl. Phys. 88, 2302-2304 (2000). https://doi.org/10.1063/1.1287772
  11. C. G. Jhun, K. Chen, K. Kim, U.-S. Jung, J.-H. Moon, S.-B. Kwon, J. H. Lee, and J. C. Kim, “Gray scale of bistable chiral splay nematic device in the splay transition,” Mol. Cryst. Liq. Cryst. 527, 12/[168]~17/[173] (2010). https://doi.org/10.1080/15421406.2010.486353