DOI QR코드

DOI QR Code

A Study on Electro-optical Characteristics of the UV Aligned FFS Cell on the Organic Layer

  • Han, Jeong-Min (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University) ;
  • Ok, Chul-Ho (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University) ;
  • Hwang, Jeoung-Yeon (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University) ;
  • Kim, Byoung-Yong (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University) ;
  • Kang, Dong-Hun (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University) ;
  • Kim, Jong-Hwan (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University) ;
  • Kim, Young-Hwan (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University) ;
  • Han, Jin-Woo (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University) ;
  • Lee, Sang-Keuk (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University) ;
  • Seo, Dae-Shik (Department of Electrical & Electronic Engineering(C-724), College of Engineering, Yonsei University)
  • 발행 : 2007.07.26

초록

In this study, we investigated the electro-optical (EO) characteristic of fringe-field switching (FFS) mode cell by the two kinds of ultraviolet (UV) alignment method on the organic thin film (polyimide: PI). The suitable organic layers for FFS cell and the aligning capabilities of nematic liquid crystal (NLC) using the in-situ photoalignment method were studied; Disclination is observed after conventional photoalignment method for 1h, and in-situ photoalignment method for 1h. Monodomain alignment of the NLC can be observed via insitu photo alignment method for 2 h and 3 h. It is considered that NLC alignment is due to photo-depolymerization of the polymer with oblique non-polarized UV irradiation on PI surface. An unstable V-T curve of UV-aligned FFS-LCD with conventional photoalignment method can be achieved. However, a stable V-T curve of UV-aligned FFS-LCD with in-situ photoalignment method (1 h), and V-T curve of UV-aligned FFS-LCD with in-situ photo alignment method was much stable comparing with that of other UV-aligned FFSLCD's. As a result, more stable EO performance of UV-aligned FFS-LCD with in-situ photoalignment method for 3h is obtained than that of the other UV-aligned FFS-LCD's.

키워드

참고문헌

  1. M. Ohta, M. Oh-e, and K. Kondo, 'Development of Super- TFT -LCDs With In-plane Switching Display Mode', Asia Display' 95 Digest paper, p. 707, 1995
  2. Y. Koike, S. Kataoka, T. Sasaki, H, Chida, H. Tsuda, A. Takeda, K. Ohmuro, T. Sasaboysshi, and K. Okamoto, 'A Vertically Aligned LCD Providing Super-high Image Quality', IDW' 97 Digest paper, p. 159, 1997
  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., Vol. 73, p. 2881, 1998
  4. J. M. Geary, J. W. Goodby, A. R. Kmetz, and J. S. Patel, 'The mechanism of polymer alignment of liquid-crystal materials', J. Appl. Phys., Vol. 62, p. 4100, 1987
  5. D. S. Seo, K. Muroi, and S. Kobayashi, 'Generation of pretilt angles in nematic liquid crystal, 5CB, media aligned polyimide films prepared by spincoating and LB techniques: effect of rubbing', Mol. Cryst. Liq. Cryst., Vol. 213, p. 223, 1992
  6. M. Schadt, K. Schmitt, V. Kozinkov, and V. Chigrinov, 'Surface-induced parallel alignment of liquid crystals by linearly polymerized photopolymers', Jpn, J. Appl. Phys., Vol. 31, p. 2155, 1992
  7. J. Y. Hwang, D. S. Seo, O. B. Kwon, and D. H. Sub, 'Electro-optical characteristics of photo-aligned TN-LCD on PM4Ch surfaces', Liq. Cryst., Vol. 27, p. 1045, 2000
  8. J. Y. Hwang, D. S. Seo, O. Kwon, D. H. Sub, and E. J. Hahn, 'Investigation of electro-optical characteristics of photo-aligned TN-LCD on PCEMA surfaces', Liq. Cryst., Vol. 27, p. 1325, 2000
  9. J. L. West, X. Wang, Y. Ji, and J. R. Kelly, 'Polarized UV -Exposed Polyimide Films for Liquid-crystal Alignment', SID' 95 Digest paper, p. 703,1995
  10. K. W. Lee, A. Lien, J. H. Stathis, and S. H. Paek, 'Control and modification of nematic liquid crystal pretilt angles on polyimides', Jpn. J. Appl. Phys., Vol. 36, p. 3591, 1997
  11. D. S. Seo, L. Y. Hwang, and S. Kobayashi, 'Investigation of pretilt angl generation in nematic liquid crystal with slanted non-polarized UV light irradiation on polyimide surfaces', Liq. Cryst., Vol. 23, p. 923, 1997
  12. J. H. Kim, B. R. Acharya, Kumar, and K. R. Ha, 'A method for liquid crystal alignment using in situ ultraviolet exposure during imidization of polyimide', Appl. Phys. Lett., Vol. 23, p. 3372, 1998
  13. D. S. Seo and J. M. Han, 'Generation of pretilt angle in NLC and EO characteristics of photoaligned TN-LCD with oblique non-polarized UV light irradiation on polyimide surface', Liq. Cryst., Vol. 26, p. 959, 1999