Fringe-field Switching Liquid Crystal Display Research Articles

Reducing the Power Consumption of VR Displays with a Field Sequential Color LCD

To achieve 60 pixels per degree (PPD) and 100° field of view (FoV) while keeping a reasonably high aperture ratio for active-matrix liquid crystal displays (LCDs), field sequential color (FSC) is a promising approach. We evaluate the physical properties of a high birefringence nematic LC mixture and then use these data to simulate the performance of a fringe-field switching (FFS) LCD. Such an FFS LCD exhibits a fast average gray-to-gray response time (~1.5 ms) to enable FSC operation. By removing the spatial color filters, FSC operation triples the resolution density and optical efficiency, which are critical to high-resolution density and low power consumption virtual reality applications. Wide color gamut (96.2% of the DCI-P3 standard) and superior color uniformity are also demonstrated using such an FSC LCD.

Multi-layer protruded electrodes for reducing the operating voltage and gamma shift of fringe-field switching LCDs

ABSTRACTTo reduce the operating voltage and gamma shift of the nematic liquid crystal display (LCD), a single-domain-protruded fringe-field switching (PFFS) electrode structure is designed. In this work, a kind of nematic liquid crystal (NLC) is introduced firstly. Then, the operating voltage and gamma shift of the proposed PFFS LCD are investigated under various electrodes’ parameters. Besides, its light leakage and contrast ratio are also discussed. The results show that the operating voltage of the PFFS LCD is only 1.40 V, here the electrodes’ width is 2 μm and electrodes’ gap is 4 μm. The gamma shift of the PFFS LCD can be reduced to the indistinguishable level under various electrodes’ sizes, if the height of the insulation layer is proper. For contrast ratio, it is larger than 200:1 at full viewing-angle, and the zone of 500:1 covers 60° polar angle.

Image flickering reduction by dimer and polymer stabilization in FFS liquid crystal display

AbstractPower consumption of a liquid crystal display, when it is used to display static images, can be reduced by using low frequency driving. However, when the driving frequency is decreased, the brightness of the display may change with time, a phenomenon known as image flickering. One factor responsible for the flickering issue is flexoelectric effect which is sensitive to the polarity of the applied voltage. We show that the flickering in fringe field switching (FFS) LCD can be significantly reduced by doping a liquid crystal dimer and using polymer stabilization. We demonstrated that 2 Hz driving frequency can be used to display static images.

High-Performance and Low-Cost Aluminum Zinc Oxide and Gallium Zinc Oxide Electrodes for Liquid Crystal Displays

The majority of electro-optical devices use transparent conductive oxide (TCO) electrodes such as indium tin oxide (ITO) in their structure. In this study, we manufactured aluminum zinc oxide (AZO) and gallium zinc oxide (GZO) TCO films on glass substrates and demonstrate suitability of these materials for application as transparent electrodes of liquid crystal displays (LCD). We have established a deposition process for the fabrication of AZO and GZO coated glass substrates with average transmittance of 93% and 92% in the visible spectrum, and the sheet resistivity without annealing of ∼120 Ω/□. Using photolithographic patterning and wet etching of AZO and GZO films, we have successfully fabricated laboratory prototypes of twisted nematic, vertical alignment, in-plane switching, and fringe-field switching LCDs. The electro-optical performance of AZO and GZO prototypes is comparable to those of the ITO prototypes of identical design. The AZO and GZO have demonstrated great potential to compete with ITO as low-cost TCOs for display applications. Our findings validated by numerical analyses will be useful for the development of TCOs alternative for display and other optical or electro-optical applications.

Temperature-Dependent Behavioral Model of Active-Matrix Liquid Crystal Displays for All Types of Liquid Crystals

This paper proposes a temperature-dependent behavioral circuit model to predict optical characteristics of an active-matrix liquid crystal display with twisted-nematic (TN), patterned vertical alignment (PVA), and fringe-field switching (FFS) modes. The optical responses of liquid crystal displays (LCDs) are strongly affected by ambient temperature. We optimized time-constant parameters that describe the movement of liquid crystal molecules so that simulated optical responses of TN, PVA, and FFS LCDs best fit to the measured ones depending over the temperature range from 0 to 50 °C. We found that the time-constant parameters have a linear relationship with the ambient temperature, which enables us to anticipate the optical responses at any given temperature. The simulation results of the transient responses show excellent matches with the measurement ones regardless of ambient temperature.

Temperature-dependent behavioral model of pixels in active-matrix liquid crystal displays with fringe-field switching mode

This paper proposes a temperature-dependent behavioral circuit model to predict the optical char- acteristics of an active-matrix liquid crystal display with a fringe-field switching (FFS) mode. The optical responses of liquid crystal displays (LCDs) are strongly affected by their ambient temperature. We optimized the time-constant parameters that describe the movement of liquid crystal molecules so that simulated optical responses of FFS LCD provide the best fit to the measured responses over the temperature range of 0 to 50°C. It is found that these time-constant parameters have a linear relationship with the ambient temperature, which enables the prediction of optical responses at any given temperature. The simulation results of the transient responses show an excellent match with the measured results regardless of the ambient temperature. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.OE.54.9.093104)

Elimination of image flicker in a fringe-field switching liquid crystal display by applying a bipolar voltage wave

Recently, low-frequency driving of liquid crystal display (LCD) panels to minimize power consumption has drawn much attention. In the case in which an LCD panel is driven by a fringe-field at a low frequency, the image flickering phenomenon occurs when the sign of the applied electric field is reversed. We investigated image flickering induced by the flexoelectric effect in a fringe-field switching (FFS) liquid crystal cell in terms of the transmittance difference between frames and the ripple phenomenon. Experimental results show that image flicker due to transmittance difference can be eliminated completely and that the ripple phenomena can be reduced significantly by applying a bipolar voltage wave to the FFS cell.

Fringe-Field Switching (FFS) 액정 소자의 전기광학 특성, 응용 현황 및 향후 이슈

Recently, the fringe-field switching (FFS) mode in liquid crystal displays has been used mainly for high image quality and high-resolution liquid crystal displays (LCDs). In this review paper, the fundamental switching principle of the FFS mode, with its excellence over other LC modes in electro-optic performance, will be described. In addition, the development history, present technical issues, and future of the FFS LCD will be discussed.

Elimination of image flicker in fringe-field switching liquid crystal display driven with low frequency electric field.

Recently, a low frequency driving of a fringe-field switching-liquid crystal display (FFS-LCD) draws much attention to minimize the power consumption. In the low frequency driving of FFS-LCD, an image flickering effect occurs when the sign of the electric field is reversed. We suggested a method to eliminate the image flickering effect by doping small amount of bent-core liquid crystal (BLC) molecules. The BLC molecules have an opposite sign of flexoelectric polarization and reduce the flexoelectric polarization of the host liquid crystal. By adding 2.0 wt% of BLC, the total transmittance during a positive and a negative electric field could be balanced and the image flickering effect was not observed by eyes.

Past, present, and future of fringe-field switching-liquid crystal display

The fringe-field switching-liquid crystal display (FFS-LCD) mode recently became a major component of LCDs for high resolution, high-image quality, low power consumption, and touch screen suitability. This review paper discusses how the FFS technology was developed, how it evolved to its present status, and also about the future advances of the FFS mode in terms of performance and technologies.

Nanowire grid polarizer for energy efficient and wide-view liquid crystal displays

We report a liquid crystal display (LCD) using a nanowire grid polarizer (NWGP) to replace the bottom sheet linear polarizer (LP). The top LP and bottom NWGP configurations enable backlight recycling for enhancing optical efficiency while keeping a high contrast ratio and wide viewing angle. The electro-optic performance of this device configuration is studied based on the effective-medium theory and 4×4 matrix method. Results show that this configuration exhibits a 100:1 contrast ratio over 75° viewing cone in a film-compensated multidomain vertical alignment LCD and 10:1 over 65° viewing cone in a fringe-field switching LCD without any compensation film.

Intensifying the density of a horizontal electric field to improve light efficiency in a fringe-field switching liquid crystal display

The transmittance in fringe-field switching liquid crystal (LC) displays, which show a wide viewing angle, is dependent on the position along the electrode position. The reason for this is that the dielectric torque (and hence the twist angle) varies with position. This effect depends on the type of LC: a display using an LC with positive dielectric anisotropy has less transmittance than one with negative dielectric anisotropy. Furthermore, the transmittance decreases with decreasing cell gap. The difference between the LC types can be reduced and the transmittance can be improved greatly even for a low cell gap by optimizing the electrode structure to enhance the region of in-plane twist.

Fringe‐field switching transflective liquid crystal displays

This paper investgates the transflective liquid crystal displays (LCDs) associated with fringe‐field switching (FFS) mode to achieve high image quality. In the past, several cell structures were used to fabricate transflective FFS LCDs. Their structures and characteristics are carefully examined to find their merits and demerits. In addition, we attempt to optimize cell parameters to achieve a single driving circuit.