AMORPHOUS TWISTED NEMATIC LIQUID-CRYSTAL DISPLAYS FABRICATED BY NONRUBBING SHOWING WIDE AND UNIFORM VIEWING-ANGLE CHARACTERISTICS ACCOMPANYING EXCELLENT VOLTAGE HOLDING RATIOS

A new twisted-nematic (TN)-liquid-crystal display (LCD) device has bee n prepared without rubbing, which is called the no-rubbing (NR) techni que. The device is shown to exhibit wide and uniform viewing-angle cha racteristics without showing a contrast inversion in the vertical dire ction of the cell. This characteristic is achieved in particular by fi lling chiral-molecular-doped nematic LCs (NLCs) in the isotropic phase into a cell. The substrate surfaces of the cells are either bare indi um-tin-oxide films or those coated with polymer materials such as poly imide. These films are optically and structurally isotropic in a quasi -macroscopic scale (say, 100 X 100 mum2). In particular, the polymer f ilms are capable of stabilizing and homogenizing the distribution of t he NLC directors at the surfaces. The TN-LCDs fabricated by the NR tec hnique, called amorphous TN-LCDs, are also featured by the excellent v oltage holding ratio which is necessary to achieve good active matrix driving, and, furthermore, the device exhibits a very small viewing an gular dependence in the electro-optic (EO) characteristics, which prov ides a significant benefit for achieving a good gray-scale operation. This rubbing-free technology may contribute not only to the significan t improvement of the EO performance of TN-LCDs but also to the simplif ication of the production process and in turn to the reduction of the production cost.