Katsunobu Awane

Ferroelectric Liquid Crystals Incorporating the Optically Active γ-Lactone Ring

Ferroelectric liquid crystals incorporating an optically active γ-lactone ring were prepared. They show enantiotropic smectic C phases which have very large spontaneous polarizations as large as ∼590 nC/cm 2 (5.9 mC/m 2 ). The large spontaneous polarizations are attributed to the structural features wherein a dipole and two chiral centers are fixed in the γ-lactone ring

Deviation of layer normal from rubbing direction in SSF-LC

Abstract Deviation angle δ of the layer normal away from the rubbing direction in surface-stabilized ferroelectric liquid crystal(SSF-LC) was studied using liquid crystal(LC) mixtures possessing smectic A(SmA) phase and cells with one rubbed substrate. The dependence of δ on the properties of LC, cell spacing, temperature, and external field suggested that δ originated from the twist in the nematic phase and electroclinic effect in SmA phase due to the surface field.

The states of surface-stabilized ferroelectric liquid crystal with high-pretilt aligning film

Surface-stabilized ferroelectric liquid crystal with high-pretilt (about 15°) aligning film rubbed in parallel showed three types of states: C1-uniform (C1U), C1-twisted (C1T), and C2 states. In the C1 state, the uniform state (C1U) showing extinction positions and the twisted state (C1T) showing no extinction position were observed. On the other hand, the C2 state showed only one state showing extinction positions. The properties of these three states were investigated and their orientational model will be discussed in combination with the molecular orientation on the surface of the aligning film.

A CCD Imager on Three Types of P-Wells

A 488×590-elment interline-transfer CCD imager for the 2/3-inch formal is described. It employs three types of p-wells (shallow, medium, and deep) for smearing suppression as well as for blooming suppression. The shallow p-well incorporates the photodiodes and is completely depleted for blooming suppression. The medium one does the CCD shift registers and also is completely depleted for smearing suppression. The deep one does the output circuitry and is not completely depleted for the stable MOS transistor operation. For 10-percent vertical-height illumination, the smear signal was as small as -73 dB of the illumination signal at a wavelength of 550 nm. Furthermore, this imager employs n+-n--p photodiodes to reduce the change of spectral response with a storage of signal charge.

Alignment Technique for Thin-Film-Transistor Liquid-Crystal Displays

In high-definition thin-film-transistor liquid-crystal displays (TFT-LCDs), it is important to establish the stability of liquid-crystal molecule alignment. In this paper, we describe the relation between pretilt angle and reverse tilt disclination in the high-definition TFT-LCD at 60°C. We conclude that a pretilt angle of more than 3° is required to prevent the occurrence of the reverse tilt disclination. Next, we consider this result, using a brief computer simulation on the electric field distribution in the TFT-LCD. Then, we describe the temperature dependence of the pretilt angle. We conclude that we can control the magnitude of pretilt angle by changing liquid crystal, polyimide material and process conditions, but the pretilt angle decreases at the same rate as the temperature becomes higher, without dependence on these parameters.

Effect of molecular structure of chiral fluorinated compounds on spontaneous polarization of ferroelectric liquid crystals

The trans and cis isomers derived from chiral 1-trifluoromethyl-3-phenyl-2-propen-1-ol were prepared as chiral dopants of ferroelectric liquid crystals. They were doped to an achiral compound possessing a smectic C phase, and the induced spontaneous polarization of the mixtures was investigated. The observed spontaneous polarization for the trans isomer is larger than that for the cis isomer. The signs and values of spontaneous polarization were explained by a model which examined the fitness of two typical conformers possessing positive and negative spontaneous polarization to the zigzag conformation of molecules in the smectic C phase.

Tilt Angle Behavior of Smectic C Phase in Binary Systems

The tilt angle behavior of the smectic C phase was studied in several binary systems. The concentration dependence of the tilt angle deviated from the linear relationship. The degree of the deviation was influenced by the difference in the molecular structure between the two components. The tilt angles were found to correlate to the ratio of the SC-SA transition temperature to the SA-N (or I) transition temperature.

Novel optically active dopants for ferroelectric liquid crystals

Abstract Optically active compounds derived from 1-(4-substituted-phenyl)ethanols were evaluated as a dopant for ferroelectric liquid crystals. The effects of the restriction of the rotational freedom around the chiral center on the spontaneous polarization and the response time will be discussed.

Relationship Between Molecular Structure and Spontaneous Polarization for Optically Active Γ -Lactone Derivatives

AbstractFerroelectric liquid crystal mixtures doped with the cis isomer of optically active γ -lactone derivatives show a higher spontaneous polarization (Ps) than those doped with the trans isomer. The relationship between the molecular structure and Ps will be discussed with respect to the molecular conformations and molecular arrangements in smectic C phase.