A multicolour projection display using nematic-cholesteric liquid crystal

A multicolour projection display with a bright screen and large information capacity has been developed using nematic-cholesteric (NC) liquid crystals (LCs). Through investigation of light scattering in the focal-conic state of the LC layer, the authors found that the transmittance depends on the light wavelength, because of diffraction scattering, and that the colour of light transmitted through the layer can be controlled by the birefringence and the thickness of the LC layer. A 640-*400-pixel multicolour projection display was fabricated using a two-layered LC panel, each layer passing green and red light under the focal-conic state. The Munsell chroma value was 6 for both of the projected colours. The projector also provides excellent white and black, because of the high transmittance of the nematic state and the subtractive mixture of complementary colours.<>