We propose a reflective three-dimensional (3D) display using a cholesteric liquid crystal (ChLC) with an inner patterned retarder producing half-wave retardation. The inner patterned retarder, fabricated by selective ultra-violet exposure to the aligned reactive mesogen, divides the circularly polarized light reflected from the ChLC layer into two orthogonal circular polarizations. These reflected orthogonal polarizations construct stereoscopic 3D images without any optical components such as a polarizer and backlight unit.
We proposed a method to control pre-tilt angle of liquid crystals by coating vertical alignment reactive mesogen(RM) material on the planar alignment layer. The pre-tilt angle can be precisely and simply controlled in full range (0° ~ 90°). We also easily obtained a patterned alignment layer using this method.
An inverse four-domain twisted nematic (IFDTN) liquid crystal (LC) display was fabricated by enhancing the azimuthal anchoring energy of the alignment layers. By stacking a vertical alignment layer onto a planar alignment layer, we increased the azimuthal anchoring energy by approximately 17-fold times compared to that with vertical alignment only. Due to the enhanced azimuthal anchoring energy, we were able to achieve a four-domain twisted nematic LC structure without dopant via the application of an external voltage. A simulation of the LC molecular orientation with respect to the azimuthal anchoring energy, the viewing angle characteristics, and the switching behavior of the IFDTN LC are presented.
We report a cholesteric liquid crystal (ChLC) display with multicolor in a single-layered configuration using a multi-pitch stabilization by reactive mesogen (RM). The cholesteric pitches were modulated by temperature and stabilized at room temperature by polymerization of the RMs through ultraviolet (UV) exposure. In a single-layered ChLC display without any additional layer such as a color filter, multicolor was obtained by a multipitch stabilization through spartially selective UV expose at several temperatures.
We propose a novel method for a stable four-domain twisted nematic (4DTN) structure by injecting nematic liquid crystal in an isotropic phase under an applied electric field. In this method, no high pre-tilt angle is required to stabilize the 4DTN structure and thus the high transmittance and fast response are obtained. IntroductionThe twisted nematic (TN) liquid crystal display (LCD) mode has been widely used in various display applications due to its simple manufacturing process and high light efficiency. However, TN mode hardly used in the large size displays such as television sets due to its poor viewing angle characteristics and gray inversion problem [1]. To improve the viewing angle characteristics of the TN mode, the four-domain TN (4DTN) structures were proposed [2][3][4][5]. However, these methods inevitably required a high pretilt angle (about 20) to obtain a stable 4DTN structure. Hence, the conventional 4DTN modes exhibit low transmittance and/or slow response compared to the onedomain TN modes [6]. Moreover, complicated alignment processes are involved to obtain the high pre-tilt angle, apart from the multi-alignment processes.In this paper, we propose a novel method for fabricating a stable 4DTN structure with a conventional planar alignment layer for the TN modes. The stable 4DTN structure was fabricated by multiply rubbing the conventional planar alignment layer and injecting a nematic liquid crystal (NLC) in an isotropic phase under an applied electric field. In such situation, the 4DTN structures were electrically stabilized with cooling down to a nematic phase. Our electrically stabilized (ES) 4DTN exhibits the fast response equal to the TN mode and the high transmittance compared to the highly pre-tilted 4DTN modes. Figure 1 shows a schematic diagram of the cell configuration of our ES-4DTN structure. The planar alignment layer (Nissan chemical SE-7492) was spincoated on the indium-tin-oxide (ITO) coated glass substrate, and the pre-baked at 100 °C for 10 min to evaporate solvent followed by hard-baking at 210 °C for 2 h for perfect imidization. The reverse rubbing processes were carried out with rubbing mask with 150 m spacing. Two reverse-rubbed substrates were assembled perpendicular to each other to perform the 4DTN structure. ExperimentsThe cell thickness was maintained using spacers of 4.3 m. The NLC of MLC-6875 (E Merck) with positive dielectric anisotropy ( = 7.8) was injected into the assembled cell by capillary action in the isotropic phase with applying an external voltage of 20 V. After injection of the NLC, the cell was cooled down to room temperature under the applied voltage.Measurements of the electro-optic (EO) transmittance and the dynamic EO response were carried out with a digitized oscilloscope (Tektronix TDS754D), an arbitrary waveform generator (Stanford Research System DS345), and a He-Ne laser ( = 632.8 nm). The microscopic textures were observed with a charge-coupled devices (Samsung SDC-450) mounted in a polarizing microscope (Nikon Eclipse E600 POL). The mic...
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