In-plane switching of vertically aligned negative liquid crystals for high transmittance and wide viewing angle.

We propose a method for in-plane switching of vertically aligned negative liquid crystals (LCs) for high transmittance and wide viewing angle. By applying an in-plane electric field using a double-layered electrode structure, LC molecules can be rotated by the vertical as well as the in-plane components of the applied field over the entire region so that high transmittance can be achieved. The threshold voltage difference can be obtained simply by varying the electrode structure, which can reduce the off-axis gamma shift in a multidomain vertical alignment LC cell.

Ultrafast switching of randomly-aligned nematic liquid crystals.

We propose an ultrafast nematic liquid crystal (LC) device without alignment layers, where both the dark and bright states can be realized by applying an electric field. A vertical electric field is applied to vertically align the LCs for the dark state, whereas an in-plane electric field is applied to homogeneously align the LCs for the bright state. We achieved a total response time of less than 3 ms in the proposed device. This device may contribute, not only to a significant improvement of the switching speed in liquid crystal devices, but also to the simplification of the device fabrication by the omission of the alignment layer coating and the rubbing process.

Fast switching of long-pitch cholesteric liquid crystal device.

We propose a long-pitch cholesteric liquid crystal (ChLC) device capable of operation in both the dynamic mode and the memory mode. Fast switching between the homeotropic state and the focal conic state allows the display of moving pictures at a low operating voltage. In addition, we can write text messages on the proposed ChLC device by applying an external pressure locally to switch it from the focal conic state to the planar state.

Dual-mode operation of a twisted nematic liquid crystal cell by switching between dynamic and memory modes.

We propose a twisted nematic liquid crystal device that can be operated in dynamic or memory mode, based on the information content to be displayed at that time. +90°-twisted and -90°-twisted states are used as two stable states for operation in the memory mode. A vertical electric field is applied to realize gray levels for operation in the dynamic mode. The proposed device has a memory retention time of over a month for the memory mode and a response time of 12 ms for the dynamic mode. Contrast ratios of over 500∶1 can be obtained in both the dynamic and memory modes.

Switching of liquid-crystal devices between reflective and transmissive modes using long-pitch cholesteric liquid crystals.

We propose liquid-crystal (LC) devices capable of switching between reflective and transmissive modes using the scattering and transparent states of long-pitch cholesteric LCs (CLCs). Two different device configurations can be realized by changing the location of a CLC layer. Low-power operation without the parallax problem can be achieved using the bistable switching of CLCs. We believe that the proposed devices are potential candidates for highly efficient transflective displays.

Liquid crystal alignment on ion-beam-treated polyimide with a long alkyl side chain: near edge X-ray absorption fine structure spectroscopy analysis.

Liquid crystal alignment on ion-beam-treated polyimides with a long alkyl side chain was investigated using near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The long alkyl side chains and the asymmetric distribution and orientational order of the pi-bonds of the polyimide surface can be determined by analyzing the angular dependent resonance intensities of the NEXAFS measurements. Herein, we demonstrate that the pretilt angle of the LC cell made by our method decreases as more long alkyl side chains are destroyed. Additionally, the tilt direction of the LC molecules can be determined from the asymmetric distribution of pi-bonds of the polyimide created by the ion beam irradiation.

Fringe field switching of a twisted nematic liquid crystal device for a single-cell-gap transflective display.

We propose an optical configuration of a twisted nematic liquid crystal device driven by a fringe field for a single-cell-gap transflective display. The dark state of the reflective part is realized by a nematic liquid crystal layer with a twist angle of 63.6 degrees and retardation of 194 nm, while a quarter-wave plate is inserted for the dark state of the transmissive part. Wavelength dispersion of the liquid crystal layer is suppressed by introducing a half-wave plate. Different directions of electric fields rotate liquid crystals to 15 degrees for the bright state of the reflective part, but to -30 degrees for that of the transmissive part. With the proposed configuration, we can realize a high-brightness single-gamma transflective display in a single-cell-gap structure without any in-cell retardation layers.