LARGE APERTURE POLARIZED-LIGHT SOURCE AND NOVEL LIQUID-CRYSTAL DISPLAY OPERATING MODES

A wide aperture liquid crystal polarized light source (LC-PLS) is presented which converts unpolarized-into circular- and/or linearly polarized light with an efficiency better than 80%. Moreover, new operating modes for electro-optical field-effects on which liquid crystal displays (LCDs) are based are shown to increase the transmission of twisted nematic (TN)-LCDs by a factor of two. Besides, a 25% shift of the TN-LCD transmission-voltage characteristics towards lower voltages is achieved. One of the new, reflective LCD-operating modes is shown to avoid light absorption by thin film transistor structures in actively addressed LCD-projection systems. Within the bandpass region of the cholesteric liquid crystal filters the combination of LC-PLS with appropriate LCD-operating mode is shown to increase the transmission of LCD-projection systems three to five times compared with conventional LCD-projectors. © 1990 IOP Publishing Ltd.