Kiyofumi Takeuchi

Physical Properties of Nematic Tolans

Abstract A series of 4-n-alkyl-4′-n-alkoxytolans, trans-4-n-alkylcyclohexyl-4′-n-alkyltolans and 4-n-alkyl-2′- or 3′-substituted 4′-n-alkoxytolans was prepared. Their mesomorphic and physical properties were measured. Some nematic mixtures of 4-n-alkyl-4′-n-alkoxy-tolans and other familiar series of nematic mixtures of two-ring systems having n-alkyl and n-alkoxy as terminal groups were prepared and their physical properties were compared. A nematic mixture of tolans has a high N-I transition temperature of 72[ddot]C, a high birefringence of 0.297 and a low viscosity of 19.1 c.p. at 20[ddot]C. The birefringence and the flow-aligned viscosity of trans-4-n-propylcyclohexyl-4′-n-butyltolan were determined by extrapolation and compared with those of trans-4-n-pentylcyclohexyl-4′-ethylbiphenyl and 4-n-propylphenyl 4′-n-propylcyclohexyl-benzoate. The influence of the introduction of 2′-, 3′-fluoro and 2′-, 3’ -methyl groups into 4-n-alkyl-4′-n-alkoxytolans on the dielectric constants was discussed.

Physical Properties of Novel Fluorinated Ethers and Ether Mixtures for Actively-Addressed, Twisted Nematic Liquid Crystal Displays

Abstract Several new classes of low polar, low viscous and optically weak anisotropic two- and three-ring fluorinated liquid crystals (LCs) with ether terminal groups are presented. Their material properties are investigated and compared with those of fluorinated LCs with alkenyl terminal groups. The 4-fluoro-phenylbicyclohexane ethers were found to exhibit dielectric anisotropies Δewhich are similar to those of the corresponding alkenyls with 1-propenyl and 3-pentenyl group, whereas the alkenyls with 4-pentenyl group exhibit considerably lower Δe-values. The optical and dielectric anisotropies of difluoro-ethers with odd numbers n of the methylene groups separating the ether oxygen from the rigid cores of the molecules are comparable, whereas compounds with odd n′s were found to exhibit lower vis-coelastic ratios γ/K and therefore shorter response times in twisted nematic liquid crystal displays (TN-LCDs) than their even counterparts. In mixtures designed for thin film transistor (TFT)-addressed TN-LCDs ...

Properties of novel UV-curable liquid crystals and their retardation films

— Novel UV-curable liquid crystals showing nematic phases at room temperature have been developed. The liquid crystals can be utilized to create retardation films with high quality and good thermal stability. The properties of novel UV-curable liquid crystals and the fabrication of various kinds of retardation films using them are discussed.

Synthesis and Some Properties of 3-Fluoro-4-Cyanophenyl 4′-n-alkylbenzoates

Abstract A series of 3-fluoro-4-cyanophenyl 4′-n-alkylbenzoates, which show monotropic nematic phases, was prepared and their transition temperatures and melting enthalpies were measured. The 3-fluoro-4-cyanophenyl 4′-n-propylbenzoate, 3-chloro-4-cyanophenyl 4′-n-propylbenzoate and 4-cyanophenyl 4′-n-propylbenzoate were mixed with a nematic mixture (A) of 4-n-alkoxyphenyl 4′-n-alkylcyclohexane-1′-carboxylates. 3-Fluoro-4-cyanophenyl 4′-n-propylbenzoate decreases the N-1 transition temperature less, increases the birefringence more, and increases the bulk viscosity less than 3-chloro-4-cyanophenyl 4′-n-propylbenzoate, and reduces the threshold voltage to the greatest extent. The dielectric anisotropies of 3-fluoro-4-cyanophenyl 4′-n-propylbenzoate and 4-cyanophenyl 4′-n-propylbenzoate determined from a series of solutions of the compounds in nematic mixture (A) are 35.9 and 29.6, respectively.

A Novel Liquid Crystal Display: A Randomly-Oriented Nematic Liquid Crystal Display (RON-LCD)

Abstract A novel liquid crystal display: a Randomly-Oriented Nematic Liquid Crystal Display (RON-LCD) is demonstrated and the electro-optical properties are discussed compared with those of a Polymer Network Liquid Crystal Display (PN-LCD). The Homeotropic-RON-LCD with an 8 μm network layer and a 2 μm no-network layer has sufficient opaqueness at off-state and can be driven by lower voltage than the d = 10 μm PN-LCD. The resistivity of RON-LCD is improved by using a liquid crystal PN-011.

Synthesis and Some Properties of 3,4-Difluorophenyl Trans-4′-Substituted Cyclohexane-1′-Carboxylates

Abstract A series of 3,4-difluorophenyl trans-4′-substituted cyclohexane-1′-carboxylates, which show nematic phases, was prepared and their transition temperatures, enthalpies and entropies were measured. 3,4-Difluorophenyl and 4-fluorophenyl trans-4′-n-pentylcyclohexane-1′-carboxylates were mixed separately with a nematic mixture A consisting of trans-4-n-alkyl-1-(4′-cyanophenyl)cyclohexanes. 3,4-Difluorophenyl trans-4′-n-pentylcyclohexane-1′-carboxylate reduces the threshold voltage more, decreases the N-I transition temperature more, reduces the bulk viscosity less and decreases the birefringence more than 4-fluorophenyl trans-4′-n-pentylcyclohexane-1′-carboxylate. 3,4-Difluorophenyl, 4-fluorophenyl, 3-fluorophenyl and phenyl trans-4′-{β-(trans-4”-n-propylcyclohexyl)-1”) ethylcyclohexane-1′-carboxylates were mixed separately with a mixture B consisting of 4-n-alkoxyphenyl frara-4′-n-alkylcyclohexane-l′-carboxylates and /ram-4-n-alkyl-l-(4′-cyanophenyl)cyclohexanes. The 3,4-difluorophenyl trans-4′-(β-(t...

Field Sequential Full Color LCDs using Polymer-stabilized V-shaped Ferroelectric Liquid Crystals

By doping photo-curable monomers showing properties of a low driving voltage into FLC media and performing an appropriate photo-curing, we succeeded in fabricating novel Polymer-stabilized FLCDs exhibiting V shaped switching (PSV-FLCDs) with τ = 100 μs to 200 μs and with a free from the temperature dependence of operating voltage within 3 mV/°C in the range from −5°C to 50°C. We also demonstrate a field sequential full color LCD with 4 inch diagonal and 254 ppi that is capable of displaying moving images without blurring and break.

Physical property of new liquid crystal materials and mixture design for active matrix LCD

Abstract We studied the physical properties of three series of new fluorinated liquid crystal components and prepared some mixtures by using these components. Decahydronaphthalenes have low Δn with relatively high T NI. Naphthalenes and Tetrahydronaphthalenes have large Δϵ and variety range of Δn (0.08–0.21). Moreover, we have revealed that the fluoro- substituent at C-1 position for the naphthalene and the tetrahydronaphthalene ring has effects to increase T NI and to reduce γ1 with good solubility. Then, we have designed some LC mixtures for AM-LCD having good performance with 4V-driving, quick response, high birefringence, low birefringence, wide temperature range and low driving voltage.

Synthesis and some Physical Properties of trans-4–{β-(trans-4′-n-Alkylcyclohexyl)-1′} -Ethylcyclohexane-1 -Carboxylates

Abstract A series of trans-4–(β-(trans-4′-n-alkylcyclohexyl)-1′}-ethylcyclohexane-1-carboxylates, which show nematic phases, was prepared. Their transition temperatures and enthalpies were measured. Their bulk viscosities and birefringences were determined by extrapolation. The influence of terminal halogeno and alkyl groups on the N-I transition temperatures and the C-N transition enthalpies for the trans-4–(β-(trans-4′-n-alkylcy-clohexy1)-1′)-ethylcyclohexane-1-carboxylates is discussed and compared with the influence for the 1–(trans-4′-n-alkylcyclohexyl)-2–(4”-halobiphenyl-4′-yl)ethanes. The bulk viscosity as a function of the third power of the van der Waals radius of the halogeno group and the birefringence as a function of the van der Waals radius of the halogeno group for the 4-halophenyl trans-4′-{β-(trans-4”-n-propylcyclohexyl)-1”}-ethylcyclohexane-1′-carboxylates are discussed.

Electro-Optical Properties of LCD Doped with Nanoparticles and with Optical Compensators: Ways for Fast Response

This paper consists of two Parts. In the Part 1, we report the experimental results and considerations of the reduction of operation voltage and response time of narrow-gap TN(NTN)-LCDs embedded with the nanoparticles of hydrophobic Aerosil silica. While, in the Part 2, we give a report of the reduction of response time, especially τoff for the decay process of optically compensated tunable birefringence (OCTB)-mode LCD.