Hironori Shiroto

A Full-Color Video Rate FLC Display Based on Time Domain Color Switching with a TFT Array

Abstract This document introduces a full-color video rate FLC display which is based on time domain color switching with an amorphous Si TFT array. Research on particular polarization switching properties provided us with the technology for quick switching FLCs by using amorphous silicon TFTs. We created a prototype, and confirmed that it provided gray scale, short response time, high color purity, color balance adjustment, and a wide viewing angle. Our prototype demonstrated that it was possible to create a full-color video rate display based on this technology.

44.2: Super‐High‐Resolution FLC Display Based on Field Sequential Color Method with Low Driving Voltage

We investigated the effect of a storage capacitor (Cs) on the driving voltage in ferroelectric liquid crystal (FLC) displays by which a TFT array drives the FLCs. The addition of Cs enabled a decrease in the driving voltage. When spontaneous polarization (Ps) was large, the decrease in the driving voltage was larger than when Ps was small. We were able to use 5V as the driving voltage of an FLC display. According to the prototype we built based on the field sequential color (FSC) method, we were able to achieve the characteristics of super-high-resolution (318 ppi), high-speed response (300 μs), and high color purity (greater than the NTSC standard).

Surface Anchoring Influence on Polarization Switching Properties of Ssflcs

Abstract Polarization switching properties of SSFLCs in terms of the surface anchoring effect were investigated. Low frequency and low voltage triangular waveform applications on to low, medium and high pretilt cells suggest that the low pretilt chevron geometry cell provides stronger anchoring effect. Low pretilt quasi-bookshelf cell indicates whole LC molecules switchings including the interface area. This conclusion is also supported by the polarization switching study under the compression and expansion environment.

Threshold properties of SSFLC in terms of polarization structures

Abstract Bistability of the surface stabilized ferroelectric liquid crystal (SSFLC) is one of the most important factors of display perfomances. The electrooptical switching is based on the bistability which provides threshold characteristics to the SSFLC display device. The threshold properties of the SSFLC device which has a layer structure of liquid crystal molecules and provides an in-plane molecular switching are assumed to be governed by not only a surface anchoring but also a bulk structure itself. We show some experimental results which suggest a contribution of ferroelectric liquid crystals bulk structure to the electrooptical threshold properties. Layer structures: the bookshelf and the chevron geometries are one of the main bulk factors. Our experimental results clarified that the polarization switching behavior was intrinsically different between the bookshelf and the chevron structures. The bookshelf geometry also shows a possibility of gray shades.

The evaluation of polarization relaxation by means of charge holding ratio

Abstract A polarization switching is one of the most important factor of the characteristic properties of the surface stabilized ferroelectric liquid crystal displays. The polarization switching behaviour is conventionally investigated by an electrooptic measurement or a polarization switching current peak. We propose here new method for the polarization behaviour using the charge holding ratio. The new method is effective for an analysis of transient behaviour of the polarization switchings.