Frustration between Ferro- and Antiferro-Electricity and its Application to Liquid Crystal Displays

V型开关因其在快速响应AM-LCD中的潜在应用而引起了人们的关注。两家公司已经开发出一组与反铁电液晶原型密切相关的材料。这项研究的目的是了解什么是实际可用的V型开关出现的关键因素。两个要素是：(1)铁和反铁电之间的挫折，和(2)“双轴锚定”，即更容易极化的短轴(直观地说，苯环平面的平均方向)容易变得与基板垂直而不是平行的趋势。由于在V型开关材料中平行于倾斜面，即使在铁电SMC中，熔体也可能平行于电场出现，而聚酰亚胺取向膜上的双轴锚定起着重要作用，破坏了SS态的稳定；总锚定几乎与a…无关更多零点角度，指定SMC*倾斜锥体上的位置。由于摩擦导致的相对较弱的锚定必须迫使董事对齐。当手性扭转功率较大时，摩擦方向周围的分布可能变得较宽。第一个要素，即受挫，通过在整个开关范围内容易形成看不见的微区，确保了相对于倾斜方向的极端柔软性，从而确保了无滞后特性。双轴锚定可能破坏反铁电体SMC_A*结构。局域指向矢在V尖端呈现出多种取向分布，层内指向矢的朗之万式反转和高度集中的方位角旋转都不是V形转换所必需的。极大的自发极化和由此产生的定向场的极化电荷硬化是不必要的。近晶层的任何扭曲结构以及界面效应引起的指向矢都会严重降低V型开关的实际性能。较少

The V-shaped switching has attracted attention because of its potential applications to fast-response AM-LCDs. Two companies have developed a group of materials, which are closely related to the prototyped antiferroelectric liquid crystals. This research aims at understanding what are essential to the emergence of the practically usable V-shaped switching. Two essentials are: ( 1 ) the frustration between ferro- and antiferro-electricity, and ( 2 ) the "biaxial anchoring", i.e. a tendency that the more easily polarizable short axis (intuitively, the averaged direction of phenyl ring planes) is liable to become rather perpendicular than parallel to the substrate plates. Since it is parallel to the tilt plane in the V-shaped switching materials, the melatopes may emerge parallel to an electric field even in ferroelectric SmC*, and the biaxial anchoring on polyimide aligning films plays an important role, destabilizing the SS states; the total anchoring becomes almost independent of the a … More zimuthal angle specifying the position on the SmC* tilt cone. The relatively weak anchoring due to rubbing must force to align directors. When the chiral twisting power is large, the distribution around the rubbing direction may become broad. The first essential, i.e. the frustration assures the extreme softness with respect to the tilting direction and hence the hysteresis-free characteristics by easily forming invisible microdomains in the whole switching range. The biaxial anchoring may destroy the antiferroelectric SmC_A* structure. The local director shows a variety of orientational distributions at the tip of the V; neither Langevin-like reotientation nor highly collective azimuthal angle rotation of in-layer directors is essential to the V-shaped switching. Extremely large spontaneous polarization and the resultant polarization charge stiffening of the orientation field is not necessary. Any twisting structure of the smectic layer as well as the director caused by interface effects rather degrades the practical performance of the V-shaped switching. Less