LIQUID CRYSTAL CELLS

摘要

1437797 Modulating light DAINIPPON INK & CHEMICALS Inc and DAINIPPON INK INSTITUTE OF CHEMICALS RESEARCH 12 July 1973 [15 July 1972] 33391/73 Heading H4F The turbidity of a layer of nematic liquid crystal material disposed between two plates is reduced by treating the internal surfaces of the plate with a fluorine containing surface active agent whereby the nematic material assumes a homotropic alignment (long molecular axes at 90 degrees to the plates). The surface active agent includes a hydrophobic saturated perfluoralkyl group and a hydrophilic group which may be anionic (carboxylate, sulphate, phosphate), neutral, e.g. -(CH 2 CH 2 O-) m H where m is 5-25, or preferably cationic, for example containing -N+R 3 .X- or -N+R 2 .HX, where R is a lower alkyl group and X- is an acid anion. The agent is deposited as a solution, followed by drying, either on the plates before assembly, or in the assembled cell. As particularly described the nematic layer exhibits induced birefringence in response to an electric field applied via conductive coatings on the plates but reference is made to ultrasonic activation of the liquid crystal material and to the production of a light scattering state.