Photostability of liquid crystals and alignment layers

Abstract— Photostability of liquid‐crystal (LC) materials and surface alignment layers was evaluated using a UV lamp and a blue laser beam. Both organic polyimide (PI) and inorganic silicon‐dioxide (SiO₂) alignment layers were studied under nitrogen environment. Two commercial TFT‐grade LC mixtures (low‐birefringence MLC‐9200‐000 and high‐birefringence TL‐216) were used for comparisons. Results indicate that SiO₂ alignment layers are much more robust than PI layers, and low birefringence LCs are more stable than the high‐birefringence ones. At the He‐Cd laser wavelength (λ = 442 nm), both LC mixtures and SiO₂ alignment layers are hardly damaged. To lengthen the lifetime of an LCD projector, inorganic SiO₂ alignment layers, high‐optical‐density UV filter, long cutoff‐wavelength blue filter, and short‐conjugation (low birefringence) LC materials should be considered.     

Refractive indices of liquid crystals for display applications

This paper reviews the extended Cauchy model and the four-parameter model for describing the wavelength and temperature effects of liquid crystal (LC) refractive indices. The refractive indices of nine commercial LCs, MLC-9200-000, MLC-9200-100, MLC-6608, MLC-6241-000, 5PCH, 5CB, TL-216, E7, and E44 are measured by the Multi-wavelength Abbe Refractometer. These experimental data are used to validate the theoretical models. Excellent agreement between experiment and theory is obtained.     

Fast Switching Liquid Crystals for Color-Sequential LCDs

High birefringence (0.3 < Deltan < 0.4) and relatively low-viscosity liquid crystal mixtures containing isothiocyanato tolane and isothiocyanato terphenyl liquid crystals are developed. A twisted-nematic (TN) 1.6-mum thin cell for color-sequential liquid crystal display with ~1-ms response time is demonstrated.     

Reflective direct-view displays using a dye-doped dual-frequency liquid crystal gel

A high-contrast, fast-response, and polarizer-free reflective display using a dye-doped dual-frequency liquid crystal gel is demonstrated. The high contrast ratio originates from the combination of light scattering from the microdomain polymer gel and absorption from the black dyes. The fast response is due to the frequency modulation of the dual-frequency liquid crystal.     

High performance room temperature nematic liquid crystals based on laterally fluorinated isothiocyanato-tolanes

High birefringence and low viscosity isothiocyanates liquid crystal single compounds and eutectic mixtures, based solely on laterally fluorinated aromatic rigid core structures, are reported. Extraordinarily high values of figure-of-merit were observed at room temperature and also elevated temperatures for the nematic mixtures we formulated. Potential applications of such mixtures for laser beam steering at /spl lambda/=1.55 /spl mu/m using optical phased arrays are emphasized.     

利用染料掺杂双频率液晶胶体材料制备反射式直视显示器

利用染料掺杂双频率液晶胶体材料制备了一种对比度高、响应速度快且无需偏光片的反射式显示器。器件的高对比度是由于聚合物胶体材料对光的散射和黑色染料分子对光的吸收。对双频率液晶材料进行频率调制使得器件产生较快的响应速度。     

Highly tunable large-core single-mode liquid-crystal photonic bandgap fiber

We demonstrate a highly tunable photonic bandgap fiber, which has a large-core diameter of 25 microm and an effective mode area of 440 microm2. The tunability is achieved by infiltrating the air holes of a photonic crystal fiber with an optimized liquid-crystal mixture having a large temperature gradient of the refractive indices at room temperature. A bandgap tuning sensitivity of 27 nm/degrees C is achieved at room temperature. The insertion loss is estimated to be less than 0.5 dB and caused mainly by coupling loss between the index-guided mode and the bandgap-guided mode.     

双氟二苯乙炔类液晶的高对比度垂面取向

通过在SiO2无机层上蒸镀长链醇的取向方法以及摩擦聚酰亚胺层的取向方法，证明了高双折射率、负介电各向异性双氟二苯乙炔液晶具有优良的垂面取向特性。添加5～10％的异硫氰基二苯乙炔不但改善了对比度，而且提高了质量因数。缺点是使阈值电压升高。     

IPS-LCD using a glass substrate and an anisotropic polymer film

A lightweight in-plane-switching liquid crystal display (IPS-LCD) using a single glass substrate and an anisotropic polymeric film is demonstrated. The liquid crystal molecules are aligned by the elongated polymer grain of the film. The alignment capability of the anisotropic film is comparable to a buffed polyimide layer. Compared to the LCD using two glass substrates, our new device exhibits a comparable contrast ratio (/spl sim/514:1), driving voltage, and response time because of good LC alignment. Such an anisotropic film can also function as a phase compensation film for widening the viewing angle. This technology is particularly attractive for making single-substrate displays and also has potential for a double-layered guest-host display and a flexible display using IPS LCDs.     

彩色顺序制液晶显示器的快速液晶开关

本文中,研究制成了含有液晶材料异硫氰酸根二苯乙炔和异硫氰酸根三联苯的较高双折射(0.3<△n<0.4)和相对低粘性的液晶混合物。制作了用于顺序制彩色液晶显示器的扭曲相列式液晶薄盒(TN),盒厚为1.6μm,研究证明了其响应时间为1ms。