Our group has also researched an influence of DC offset on the image flicker in the FFS pixel and suggested a controllable method of the FE polarization to reduce the dependency of signal polarity on the positional brightness variation. They demonstrated the brightness variation depending on the signal polarity at low-frequency driving, and proposed methods to analyze and reduce the brightness variation. Therefore, the FE effects in the FFS LC mode have been studied by some researchers. This is a critical obstacle to reducing power consumption in the FFS LC mode even though the p-LC has many advantages such as low cost, low viscosity, high dielectric constant, and high reliability. Moreover, when a positive dielectric LC (p-LC) is used, this problem becomes more serious owing to the large deformational variation of the LC directors between the splay and the bend elasticity, which causes a polar angle distribution change of LC directors depending on the polarity of the driving field. However, this temporal brightness variation is more easily observed at lower-frequency driving and leads to severe flickering problems. This electro-optic variation has not been recognized at the frame rate of 60 Hz, which has been broadly applied to most LC displays so far, because of the perceptual integration of the intensity change in the human visual system. Since the reorientation of LC directors affected by the FE effect depends on the sign of the applied field (in contrast to the dielectric behavior, which does not show signal-polarity dependency), the brightness level is influenced by the polarity of the driving signal. However, the flexoelectric (FE) effect is easily observed in the FFS LC mode because the highly distorted and spatially asymmetric LC distribution on application of an electric field causes polarization by asymmetric splay and bend deformations in a cell. Because the power consumption to operate the LC display (LCD) panel is linearly proportional to the driving frequency, recently, a low-frequency driving method has been applied to reduce the power consumption. In particular, many efforts in the past decades have attempted to further reduce the power consumption, and this research will continue in the future. Introductionįringe-field switching (FFS) liquid crystal (LC) mode has been widely used for mobile phones, tablets, and high-end notebook displays owing to its high optical efficiency and low power consumption properties required for ultra-high resolution displays. To remove the transient blink, the elastic property adjustment of LCs was an effective solution because the FE switching dynamics between the splay-enhanced and bend-enhanced deformations are highly dependent on the elastic constants of LCs, which is the cause of momentary brightness drop. Based on the positional dynamic behaviors of LCs by using a high-speed camera, we found that the transient blink is highly related to the asymmetric responses of the splay-bend transitions caused by the flexoelectric (FE) effect. We analyzed a transient blinking phenomenon in a fringe-field switching liquid crystal (LC) mode that occurred at the moment of frame change even in the optimized DC offset condition for minimum image flicker.
Note the Boolean sign must be in upper-case.