Title:
PARAMETERS OPTIMIZATION FOR REFLECTIVE BTN DISPLAY USING THE POINCARE SPHERE METHOD
Document Type and Number:
WIPO Patent Application WO/2000/066682
Kind Code:
A1
Abstract:
Disclosed is a transparent upper substrate that faces a lower parallel sustrate with a polarizing sheet attached to the upper surface of the upper substrate. A first electrode is formed on the lower surface of the upper substrate and an upper alignment layer is formed on the first electrode. A light reflective second electrode is formed on the lower substrate and a lower alignment layer is formed on the second electrode. A ferroelectric liquid crystal layer is interposed between the upper and lower substrates with the retardation of the liquid crystal layer, the cone tilt angle of liquid crystal molecules, the polarizing direction of the polarizing sheet, and the alignment direction controllable to achieve gray scales.
Inventors:
PATEL JAY S (US)
ZHUANG ZHIZHONG (US)
KIM YOUNG JIN (US)
ZHUANG ZHIZHONG (US)
KIM YOUNG JIN (US)
Application Number:
PCT/US2000/012151
Publication Date:
November 09, 2000
Filing Date:
May 04, 2000
Export Citation:
Assignee:
PENN STATE RES FOUND (US)
PATEL JAY S (US)
ZHUANG ZHIZHONG (US)
KIM YOUNG JIN (US)
PATEL JAY S (US)
ZHUANG ZHIZHONG (US)
KIM YOUNG JIN (US)
International Classes:
C09K19/02; G02F1/139; (IPC1-7): C09K19/02
Foreign References:
| US5172257A | 1992-12-15 |
Attorney, Agent or Firm:
Monahan, Thomas J. (PA, US)
Download PDF:
Claims:
AMENDED CLAIMS [received by the International
Bureau on 27 October 2000 ; original claims 1-6 amended;
original claims 7-10 cancelled (2 pages)]
| 1. | A method for optimizing geometry of a liquid crystal display (LCD) to provide a high contrast ratio, said method comprising the steps of: (a) defining a geometry of the LCD using a method based on a Poincare sphere representation : and (b) obtaining a set of optimized parameters that simultaneously satisfy both bistable states of the LCD. |
| 2. | The method of claim 1. wherein said liquid crystal display comprises a reflective bistable twisted nematic (RBTN) display. |
| 3. | The method of claim 2, wherein the method optimizes polarization of a single polarizer reflective bistable twisted nematic. |
| 4. | The method of claim 1, wherein obtaining said optimized parameters comprises: (a) obtaining a first incident polarization angle from about 21.45 to 68.85: (b) obtaining a second incident polarization angle from about68.55 to 21.15; (c) obtaining a birefringence from about 137.6 nm to 956.93nm ; (d) obtaining a twisted angle for a first state from about 2.59° to 176.56° : and (e) obtaining a twisted angle for a second state from about357.41 ° to 503.8°. |
| 5. | The method of claim 1. wherein the optimized parameters comprise 67.38° and292. 62° twisted bistable states with 310.69 nm birefringence and a 24.25° incident polarization angle. |
Description:
6. A reflective bistable twisted nematic display having optimized parameters obtained from a method comprising the steps of : (a) defining a geometry of the LCD using a method based on a Poincare sphere representation : and (b) obtaining a set of optimized parameters that simultaneously satisfy both bistable states of the LCD.