Light control systems with a circular polarizer and a twisted nematic liquid crystal having a minimum path difference of lambda /2

摘要

PCT No. PCT/CH90/00251 Sec. 371 Date Jun. 20, 1991 Sec. 102(e) Date Jun. 20, 1991 PCT Filed Oct. 26, 1990 PCT Pub. No. WO91/06889 PCT Pub. Date May 16, 1991.A new mode of operation is proposed for light control systems consisting of a combination of liquid crystal cells and polarizers. The direct operation of liquid crystal cells with circularly-polarized light is advantageous in many respects. The circularly-polarized light is produced either with conventional circular polarizers or with monomeric or polymeric cholesteric liquid crystals. The new mode of operation is possible under certain conditions for all liquid crystal cells which hitherto had to be operated with linearly-polarized light.