Abstract

Pretilt angle and cell thickness are two extremely important parameters in predicting the behavior of vertically aligned negative nematic liquid crystal (LC) displays. The accurate estimation of pretilt angle and cell thickness is not a trivial task when these devices work in reflective mode, as in liquid crystal on silicon (LCOS) vertically aligned nematic (VAN) displays. Usual experimental setups are based on the proportionality between the retardation of the polarization components of the incident light and the product effective birefringence times thickness. However, any attempt to separate the two product variables is cancelled out by symmetry from reflection. This work shows a relatively simple method capable of separating both variables, allowing accurate, independent measurements of pretilt and thickness, as well as other configurations details, such as residual twist. A simulation model based on the properties of actual reflective displays has been developed. An experimental setup specifically designed for measuring LCOS VAN cells has been prepared. Initial comparisons between experimental measurements of intensity and theoretical results showed some discrepancies that could be explained assuming that the LC profile contains a residual twist from the manufacturing process. Including that twist in the model, an excellent agreement between theory and experiment has been achieved. Matching simulations and experimental results yield separate determinations of pretilt angle and thickness, and give good estimates for the residual twist angle.

© 2010 IEEE

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  1. R. Lu, Q. Hong, S.-T. Wu, K.-H. Peng, H.-S. Hsieh, "Quantitative comparison of color performances between IPS and MVA LCDs," J. Display Technol. 2, 319-326 (2006).
  2. X. J. Yu, H. S. Kwok, "Fast response film-compensated liquid crystal on silicon display," Appl. Phys. Lett. 89, 031104 (2006).
  3. N. Xiangyi, X. Haiqing, L. Ruibo, W. Thomas X., W. Shin-Tson, "Pretilt angle effects on liquid crystal response time," J. Display Technol. 2, 280-283 (2007).
  4. S. T. Tang, H. S. Kwok, "Transmissive liquid crystal cell parameters measurement by spectroscopic ellipsometry," J. Appl. Phys. 89, 80-85 (2001).
  5. K. Y. Han, T. Miyashita, T. Uchida, "Accurate measurement of pretilt angle in the liquid crystal cell by an improved crystal rotation method," Mol. Cryst. Liq. Cryst. 241, 147-157 (1994).
  6. J. S. Gwag, S. H. Lee, K. Park, W. S. Park, K. Han, C. G. Jhun, "Simple method for measuring the high pretilt angle of nematic liquid crystals," J. Appl. Phys. 8, 4936 (2003).
  7. B. G. Rho, J. S. Kim, J. K. Kim, "Simultaneous measurement of pretilt angle and cell gap of LC cells by using an improved crystal rotation method," Proc. Asia Display (1998) pp. 245-248.
  8. M. Kawamura, Y. Goto, S. Sato, "Novel real-time measurement of cell parameters in reflective liquid crystal cells by using a circularly homogeneously aligned liquid crystal cell," Proc. SPIE'03 (2003) pp. 250-257.
  9. D. Cuypers, H. De Smet, G. Van Doorselaer, J. Van Den Steen, A. Van Calster, "Measurement methodology for vertically aligned nematic reflective displays," Proc. SPIE'03 (2003) pp. 62.
  10. J. Li, C. Wen, S. Gauza, R. Lu, S. Wu, "Refractive indices of liquid crystals for display applications," J. Display. Technol. 1, 51-61 (2005).
  11. S. J. Hwang, S.-T. Lin, C.-H. Lai, "A novel method to measure the cell gap and pretilt angle of a reflective liquid crystal display," Opt. Commun. 260, 614-620 (2006).
  12. J. S. Hsu, B. J. Liang, S. H. Chen, "A simple method for determining the pretilt angle of a vertically aligned reflective LCD," IEEE Trans Electron. Devices 52, 918-921 (2005).
  13. B. Cerrolaza, M. A. Geday, J. M. Otón, X. Quintana, N. Bennis, "Measuring thickness and pretilt in reflective vertically aligned nematic liquid crystal displays," Mol. Cryst. Liq. Cryst. 494, 222-230 (2008).
  14. R. Clark Jones, "A new calculus for the treatment of optical systems," J. Opt. Soc. Amer. 31, 488-493 (1941).
  15. M. A. Geday, A. M. Glazer, "A new view of conoscopic illumination of optically active crystals," J. Appl. Cryst 35, 185-190 (2002).

2008 (1)

B. Cerrolaza, M. A. Geday, J. M. Otón, X. Quintana, N. Bennis, "Measuring thickness and pretilt in reflective vertically aligned nematic liquid crystal displays," Mol. Cryst. Liq. Cryst. 494, 222-230 (2008).

2007 (1)

N. Xiangyi, X. Haiqing, L. Ruibo, W. Thomas X., W. Shin-Tson, "Pretilt angle effects on liquid crystal response time," J. Display Technol. 2, 280-283 (2007).

2006 (3)

X. J. Yu, H. S. Kwok, "Fast response film-compensated liquid crystal on silicon display," Appl. Phys. Lett. 89, 031104 (2006).

S. J. Hwang, S.-T. Lin, C.-H. Lai, "A novel method to measure the cell gap and pretilt angle of a reflective liquid crystal display," Opt. Commun. 260, 614-620 (2006).

R. Lu, Q. Hong, S.-T. Wu, K.-H. Peng, H.-S. Hsieh, "Quantitative comparison of color performances between IPS and MVA LCDs," J. Display Technol. 2, 319-326 (2006).

2005 (2)

J. Li, C. Wen, S. Gauza, R. Lu, S. Wu, "Refractive indices of liquid crystals for display applications," J. Display. Technol. 1, 51-61 (2005).

J. S. Hsu, B. J. Liang, S. H. Chen, "A simple method for determining the pretilt angle of a vertically aligned reflective LCD," IEEE Trans Electron. Devices 52, 918-921 (2005).

2003 (1)

J. S. Gwag, S. H. Lee, K. Park, W. S. Park, K. Han, C. G. Jhun, "Simple method for measuring the high pretilt angle of nematic liquid crystals," J. Appl. Phys. 8, 4936 (2003).

2002 (1)

M. A. Geday, A. M. Glazer, "A new view of conoscopic illumination of optically active crystals," J. Appl. Cryst 35, 185-190 (2002).

2001 (1)

S. T. Tang, H. S. Kwok, "Transmissive liquid crystal cell parameters measurement by spectroscopic ellipsometry," J. Appl. Phys. 89, 80-85 (2001).

1994 (1)

K. Y. Han, T. Miyashita, T. Uchida, "Accurate measurement of pretilt angle in the liquid crystal cell by an improved crystal rotation method," Mol. Cryst. Liq. Cryst. 241, 147-157 (1994).

1941 (1)

R. Clark Jones, "A new calculus for the treatment of optical systems," J. Opt. Soc. Amer. 31, 488-493 (1941).

Appl. Phys. Lett. (1)

X. J. Yu, H. S. Kwok, "Fast response film-compensated liquid crystal on silicon display," Appl. Phys. Lett. 89, 031104 (2006).

IEEE Trans Electron. Devices (1)

J. S. Hsu, B. J. Liang, S. H. Chen, "A simple method for determining the pretilt angle of a vertically aligned reflective LCD," IEEE Trans Electron. Devices 52, 918-921 (2005).

J. Appl. Cryst (1)

M. A. Geday, A. M. Glazer, "A new view of conoscopic illumination of optically active crystals," J. Appl. Cryst 35, 185-190 (2002).

J. Appl. Phys. (2)

S. T. Tang, H. S. Kwok, "Transmissive liquid crystal cell parameters measurement by spectroscopic ellipsometry," J. Appl. Phys. 89, 80-85 (2001).

J. S. Gwag, S. H. Lee, K. Park, W. S. Park, K. Han, C. G. Jhun, "Simple method for measuring the high pretilt angle of nematic liquid crystals," J. Appl. Phys. 8, 4936 (2003).

J. Display Technol. (2)

N. Xiangyi, X. Haiqing, L. Ruibo, W. Thomas X., W. Shin-Tson, "Pretilt angle effects on liquid crystal response time," J. Display Technol. 2, 280-283 (2007).

R. Lu, Q. Hong, S.-T. Wu, K.-H. Peng, H.-S. Hsieh, "Quantitative comparison of color performances between IPS and MVA LCDs," J. Display Technol. 2, 319-326 (2006).

J. Display. Technol. (1)

J. Li, C. Wen, S. Gauza, R. Lu, S. Wu, "Refractive indices of liquid crystals for display applications," J. Display. Technol. 1, 51-61 (2005).

J. Opt. Soc. Amer. (1)

R. Clark Jones, "A new calculus for the treatment of optical systems," J. Opt. Soc. Amer. 31, 488-493 (1941).

Mol. Cryst. Liq. Cryst. (2)

B. Cerrolaza, M. A. Geday, J. M. Otón, X. Quintana, N. Bennis, "Measuring thickness and pretilt in reflective vertically aligned nematic liquid crystal displays," Mol. Cryst. Liq. Cryst. 494, 222-230 (2008).

K. Y. Han, T. Miyashita, T. Uchida, "Accurate measurement of pretilt angle in the liquid crystal cell by an improved crystal rotation method," Mol. Cryst. Liq. Cryst. 241, 147-157 (1994).

Opt. Commun. (1)

S. J. Hwang, S.-T. Lin, C.-H. Lai, "A novel method to measure the cell gap and pretilt angle of a reflective liquid crystal display," Opt. Commun. 260, 614-620 (2006).

Other (3)

B. G. Rho, J. S. Kim, J. K. Kim, "Simultaneous measurement of pretilt angle and cell gap of LC cells by using an improved crystal rotation method," Proc. Asia Display (1998) pp. 245-248.

M. Kawamura, Y. Goto, S. Sato, "Novel real-time measurement of cell parameters in reflective liquid crystal cells by using a circularly homogeneously aligned liquid crystal cell," Proc. SPIE'03 (2003) pp. 250-257.

D. Cuypers, H. De Smet, G. Van Doorselaer, J. Van Den Steen, A. Van Calster, "Measurement methodology for vertically aligned nematic reflective displays," Proc. SPIE'03 (2003) pp. 62.

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