An optical display employs a liquid crystal cell with a d.DELTA.n/.lambda. of approximately 0.2-0.8, allowing the cell's optical transmissivity to be modulated by an applied electric field through a dominant non-polarization rotation effect. For visible wavelengths, d.DELTA.n is approximately 0.1-0.4...http://www.google.com.au/patents/US5933207?utm_source=gb-gplus-sharePatent US5933207 - Reflective-type liquid crystal displays using mixed-mode twist nematic cells
