Hirokazu Furue

P-78: Characteristics and Driving Scheme of Polymer-Stabilized Monostable FLCD Exhibiting Fast Response Time and High Contrast Ratio with Gray-Scale Capability

We have fabricated a zig-zag defect-free surface-stabilized ferroelectric liquid crystal display (SSFLCD) by using a newly developed polyamide(PI) alignment film and by adopting polymer stabilization with a polymer network with mesogenic side chains. The fabricated polymer-stabilized (PS) SSFLCD exhibits high contrast ratio (230:1) and fast response speed (τ=40 μs) with perfect grayscale capability. The developed PI films were characterized by surface morphology study with an AFM and by switching characteristics of FLC cells. We suggest that the freedom of zig-zag defect of the SSFLC cells is attributed to the smoothness of the rubbed PI films. We have developed a new driving scheme for our monostable FLCD that has an asymmetric electrooptical characteristics. Further, we have developed a prototype experimental of field sequential full color LCD using our monostable FLCD.

Preliminary Study of Field Sequential Fullcolor Liquid Crystal Display using Polymer Stabilized Ferroelectric Liquid Crystal Display

Using a side-chain mesogenic polymer stabilized ferroelectric liquid crystal display (PS-FLCD) cell together with a two-dimensional array of red, green and blue light-emitting diodes (LEDs) as a modulated back light unit, we constructed a field sequential fullcolor (FSC) LCD. The PS-FLCD used in this research exhibits a high contrast ratio (230:1) with thresholdless monostability, grayscale capability, and a fast response speed (τ=40 µs). In the present research it is taken the advantages of the favorable characteristics of the PS-FLCD for implementing a FSC-LCD that has an 8×8 matrix format. The fabricated FSC-LCD, which is operated at the frame rate of 330 Hz, is shown to exhibit an excellent color gamut, color grayscale, and smearless moving color bars.

Mesogenic Polymer Stabilized Ferroelectric Liquid Crystal Display Exhibiting Monostability with High Contrast Ratio and Grayscale Capability.

We have fabricated a new ferroelectric liquid crystal (FLC) display that exhibits monostable electrooptical characteristics with high contrast ratio (160:1) owing to freedom from defects, grayscale capability without threshold, and fast response (70 µs). A FLC(ZLI-4654-100, Merck) is subjected to polymer stabilization by UV photocure of a mixture of doped monoacrylates with a mesogenic side chain particularly at a temperature where the LC medium is in the SmC* phase under the simultaneous application of a monopolar electric field.

Newly Developed Polymer-Stabilized Ferroelectric Liquid Crystals: Microsized Bistable Domains and Monostable V-Shaped Switching

We fabricated new polymer-stabilized ferroelectric liquid crystal displays (PS-FLCDs) by UV photocure of doped monoacrylates with a mesogenic side chain at a temperature where the LC medium is in the SmC* phase under the application of a bipolar square-pulsed AC electric field. Then, we investgated the effect of polymer density on the molecular alignment structure of the PS-FLC by observation of the microscopic textures and measurement of the electrooptical characteristics. The PS-FLC with low concentration of polymer (4 wt%) exhibits bistable electrooptical characteristics accompanied with microsized domain switching. On the other hand, the PS-FLC with high concentration of polymer (10 wt%) exhibits monostable V-shaped electrooptical performance without a threshold.

The effect of substrate surface smoothness on the chevron layer structure of surface-stabilized ferroelectric liquid crystals

Abstract For freedom from zigzag defects in SSFLCD, it is important to research in detail the effect of surface smoothness of substrate on the chevron layer structure. We have studied the effect of surface roughness of undercoating layer on the surface smoothness of alignment film and then the alignment structure of SSFLC. Furthermore, we suggest a model for explaining the freedom from defects in a SSFLC by investigating theoretically the free energy of Cl and C2 chevron structure.

Mesogenic polymer-stabilized FLCDs exhibiting asymmetric and symmetric (V-shape) electrooptic characteristics

Abstract We have succeeded in fabricating a novel FLCD, which exhibits symmetric electrooptic (EO) characteristic called V-shape EO performance, by choosing an appropriate photocuring condition such as applied voltage waveforms and the concentration of photocurable mesogenic monomers. Our mesogenic polymer stabilized (MPS)-V-FLCD shows high contrast ratio owing to zig-zag defect free, continuous grayscale without accompanying switching domains, and good switchability with TFTs due to free from the value of the spontaneous polarization.

Fabrication of Defect-Free Ferroelectric Liquid Crystal Displays Using Photoalignment and Their Electrooptic Performance

A photoalignment technique has been utilized for fabricating zigzag-defect-free ferroelectric liquid crystal displays (FLCDs) using polyimide RN-1199, -1286, -1266 (Nissan Chem. Ind.) and adopting oblique irradiation of unpolarized UV light. A rubbing technique was also utilized for comparison. It is shown that among these polyimide materials, RN-1199 is the best for fabricating defect-free cells with C-1 uniform states, but RN-1286 requires low energy to produce a photoaligned FLC phase. We have conducted an analytical investigation to clarify the conditions for obtaining zigzag-defect-free C-1 states, and it is theoretically shown that zigzag-defect-free C-1 state is obtained using a low azimuthal anchoring energy at a low pretilt angle, while a zigzag-defect-free C-2 state is obtained by increasing azimuthal anchoring energy above a critical value, also at a low pretilt angle. The estimated critical value of the azimuthal anchoring energy at which a transition from the C-1 state to the C-2 state occurs is 3×10-6 J/m2 for the FLC material FELIX M4654/100 (Clariant) used in this research; this value is shown to fall in a favorable range which is measured in an independent experiment.

Monostabilization of Surface-Stabilized Ferroelectric Liquid Crystal Using Polymer Stabilization

Surface-stabilized ferroelectric liquid crystals (SSFLCs) fabricated by adopting polymer stabilization in terms of the UV photocure of doped photocurable monoacrylates with mesogenic side chains at a temperature where the LC medium is in the SmC* phase under the simultaneous application of a monopolar electric field, exhibit monostable electrooptical characteristics with grayscale capability without threshold. We suggest a model for explaining the monostability of this polymer-stabilized SSFLC by investigating theoretically the free energy of the SSFLC before and after the photocure.

Applications of Biomaterials to Liquid Crystals

Nowadays, chemically synthesized proteins and peptides are attractive building blocks and have potential in many important applications as biomaterials. In this review, applications of biomaterials to thermotropic liquid crystals are discussed. The review covers the improvement of the performance of liquid crystal displays using liquid crystal physical gels consisting of a liquid crystal and amino acid-based gelators, and also new functionalization of liquid crystals. Moreover, the influence of DNA, which is one of the more attractive biomaterials, dispersed in thermotropic liquid crystals and its potential use in the liquid crystal industry is described. In addition, we found interesting results during electrooptical measurements of liquid crystals doped with DNA, and explain them from the point of view of biological applications. These recent approaches suggest that these biomaterials may be applicable in the electronic device industry and should be considered as an interesting material with their physical properties having the potential to create or refine an industrial product.

MODELING AND COMPUTER SIMULATION OF THE ELECTROOPTIC RESPONSE OF POLYMER-STABILIZED FERROELECTRIC LIQUID CRYSTAL CELLS

The dynamical electrooptic (EO) response of mesogenic side-chain polymer-stabilized ferroelectric liquid crystal cells has been investigated based on the continuum theory. From numerical calculations, the transition from the bistable EO response to the monostable EO response for pulse-applied voltages is clearly demonstrated with increasing degree of polymer stabilization, where free energy originating from the polymer stabilization is formulated and adopted. The reduction of the fall time constant is revealed in this transition. These behaviors are shown to be in qualitative agreement with the results of independent experimental measurements.