Recently, the driving scheme of a fringe-field switching (FFS) liquid crystal display varies for the best of required performance. Although low-frequency driving can effectively give rise to reduce power consumption in portable displays, proper controlling of liquid crystal director in direct current is challenging. Particularly, under different polarity of applied electric fields, the transmittance difference along the location of electrodes becomes significant, hence giving rise to an image flickering issue. Here, we investigate how physical properties of a bulk liquid crystalline medium are involved to locally modulate the transmitting light, numerically and experimentally.

Surface anchoring strength of the alignment layer on liquid crystal (LC) determines electrooptic characteristics in the LC devices. This paper investigates how azimuthal and polar anchoring strength affects the electro-optic performance of a fringe-field switching (FFS) mode associated with electrode structure, cell gap and dielectric anisotropy of the LC by numerical simulation. Our important findings in the FFS mode are that both azimuthal and polar anchoring energy can considerably affect the operating voltage and also maximum transmittance when using a LC with positive dielectric anisotropy; however, when using a LC with negative dielectric anisotropy only azimuthal anchoring energy affects electro-optic characteristics. The study proposes an optimal design of an alignment layer for maximizing transmittance in the FFS mode.

Image-flickering due to flexoelectric effect in a low frequency driven fringe-field switching (FFS) LCD is troublesome. Maximization of transmittance in the FFS mode is achieved using LCs with negative dielectric anisotropy but still the flickering exists. The paper describes in detail on optimal solutions how it can be solved by controlling the ratio of electrode width to distance and thickness of passivation layer. The results greatly contribute to achieve high transmittance and image-flickering free FFS LCD. Author KeywordsFFS mode, image-flicker, flexoelectric effect, negative liquid crystal, fine-patterned electrode.

2015): Role of the elastic constants of a liquid crystal with positive dielectric anisotropy in the electro-optic characteristics of fringe-field switching mode, Liquid Crystals, We investigated how the electro-optic characteristics of the fringe-field switching (FFS) liquid crystal (LC) mode are affected by elastic constants of LCs. Unlike conventional liquid crystal (LC) devices, in which mainly the dielectric torque determines reorientation of LC, the field-induced LC reorientation in the fringe-field switching (FFS) mode is controlled first by dielectric torque and then by pure elastic torque between LCs so that the transmittance oscillates along the electrode positions. We find that elastic constants of the LC play an important role on the field-induced dynamics of the LC molecules such that the higher the splay constant is, the higher the light efficiency becomes, which is a unique characteristic of the FFS mode. The results present an important design of physical properties of LC to enhance better transmittance in the FFS mode.

We investigated how surface anchoring strength affects the electro-optic (EO) characteristics of a fringe-field switching (FFS) mode. Unlike IPS mode that only azimuthal anchoring mainly contributes to the EO performances, both azimuthal and polar anchoring energies play an important role such that the transmittance increases with decreasing magnitude of azimuthal energy but increasing polar anchoring energy in the FFS mode when using a LC with positive dielectric anisotropy. In addition, weak anchoring at the electrode edge may result in change in initial LC optic axis by applied voltage stress so local control of anchoring energy is proposed.