Jun Ho Jung

Liquid crystal display using combined fringe and in-plane electric fields

A high performance liquid crystal display using combined fringe and in-plane horizontal electric fields is proposed. The strong electric fields cause more liquid crystals to reorient almost in plane above and between the pixel electrodes. As a result, the operation voltage is lower and transmittance is higher than those of fringe field switching and in-plane switching modes, while preserving a wide viewing angle. Such a high performance device is particularly attractive for large panel liquid crystal displays.

P-132: Blue Phases Liquid Crystal Cell Driven by Strong In-Plane Electric Field

The polymer-stabilized blue phase liquid crystals are in the limelight of liquid crystal display area because of its fast response and wide viewing angle with alignment layer free. The conventional device is driven by in-plane field, which has thin electrodes only on bottom substrate and also due to low Kerr constant of LC, the driving voltage of the device is very high. We propose improved electrode structure which has partition-wall shaped electrodes. The proposed device has maximized horizontal electric field so that the driving voltage is decreased. Further, adoption of two transistors can lower driving voltage.

Abnormal behaviour in colour tracking characteristics of the fringe-field switching liquid crystal display

Colour tracking behaviour is observed in most liquid crystal displays. In in-plane switching and vertical alignment devices, the colour chromaticity in the normal direction changes linearly from bluish- to yellowish-white as the grey level is increased from the dark to white state. Interestingly, abnormal behaviour in colour tracking is observed in fringe-field switching devices using a liquid crystal with positive dielectric anisotropy, such that the colour chromaticity changes from bluish to yellowish up to a certain grey level, then turns around and becomes bluish-white as the grey level is further increased to the fully white state. According to our theoretical and experimental results, this ‘turn around’ effect in the colour tracking of the fringe-field switching mode is associated with the generation of a tilt angle of the liquid crystal molecules with increasing voltage in the electrode position where the light modulation is associated with the polarisation rotation.

P‐129: Study on Electro‐Optic Characteristics According to Length between Pixel Electrodes in the Fringe and In‐Plane Field Switching Mode

We have studied electro-optic characteristics of high performance liquid crystal display using combined fringe and in-plane horizontal electric fields, named as fringe and In-plane switching (FIS). The strong electric fields cause more liquid crystals to reorient above and between the pixel electrodes. Moreover, the operating voltage of FIS mode was decreased by using two thin film transistors (TFTs). To suggest novel structure of FIS mode, electro optic characteristics are analyzed as a function of length between pixel electrodes compared to IPS and FFS mode. Consequently FIS mode shows not only higher transmittance but also lower operating voltage than those of IPS and FFS mode while keeping wide viewing angle.

Study of Optimal Phase Retardation According to Electrode Structure in the Fringe-Field Switching Mode Using the Negative Liquid Crystal

The fringe-field switching (FFS) mode has unique characteristics such as high transmittance and wide viewing angle and its electro-optic characteristics strongly depend on pixel electrode width (w) and distance (l) between them. In this study, optimal phase retardation of the FFS mode using a liquid crystal (LC) with negative dielectric anisotropy depending on pixel electrode structure was investigated based on the simulation. The results shows that when the width of the pixel electrode and distance between electrodes are 3 μm and 4.5 μm, respectively, the cell shows transmittance 0.87 with optimal phase retardation value of LC cell 0.36 μ. As w and l are decreased to 1 μ and 1.5 μ, the cell shows transmittance of 0.90 with optimal phase retardation of LC cell 0.40 μ, indicating that the light modulation method is changed according to electrode structure.

P-200: Effect of the Magnitude of Dielectric Anisotropy on the Light Efficiency of Fringe-Field Switching Nematic Liquid Crystal Cell

The light efficiency of fringe-field switching (FFS) mode when using a liquid crystal (LC) with positive dielectric anisotropy was found to be dependent on dielectric anisotropy, such that the lower the dielectric anisotropy, it becomes higher. On the contrary, for the LC with negative dielectric anisotropy it is almost independent of magnitude of dielectric anisotropy. This paper investigates light efficiency of FFS mode dependent on the magnitude of dielectric anisotropy of the LC associated with rubbing angle and cell gap.