We propose a method for fast switching of nematic liquid crystals with neither alignment materials nor alignment process. A three-terminal electrode structure is used to apply in-plane and vertical electric fields to randomly-aligned liquid crystals. A vertical field is applied to align liquid crystals vertically for the dark state, whereas an in-plane field is applied to align liquid crystals homogeneously for the bright state. We obtained the turn-on time of 1.2 ms and turn-off time of 0.5 ms in the three-terminal electrode structure with neither alignment materials nor alignment process. However, three-terminal electrode structure with neither alignment material nor alignment process shows low transmittance. For higher transmittance, we mixed reactive mesogen and nano-particles with anisotropic molecular shape to liquid crystals. As a result, we obtained a transmittance similar to the conventional fringe field switching mode and achieved the total response time of less than 3 ms.
We studied two types of bistable liquid crystal devices that can be operated in the memory mode as well as in
the dynamic mode. One of them is a pixel-isolated twist-splay nematic LC cell that has two stable states of π-
twist and splay. Polymer walls are formed at pixel boundaries by anisotropic phase separation between
nematic liquid crystals and reactive mesogens. Operation in the memory mode can be achieved through
bistable switching between the splay and π-twisted states. The other one is a bistable twisted-nematic mode
that has two stable states of -π/2 and +π/2 twist. Three-terminal electrodes are used to apply both vertical and
in-plane electric field to both devices. The proposed bistable modes has an infinite memory time and the fast
transition time compared to other bistable liquid crystal modes.
In this paper, we propose new pixel structures for high transmittance in the patterned vertical alignment mode.
We formed the protrusion or the slit on the top substrate to reduce the width of disclination lines at the
domain boundaries.
We propose a chiral-nematic liquid crystal (CN-LC) device that reflects the infrared light, where the planar
state is transparent over the entire visible wavelengths and the focal conic state scatters the light
achromatically. The proposed CN-LC device can be operated at a low voltage because of the long pitch. A
liquid crystal display (LCD) switchable between reflective and transmissive modes can be realized by
stacking a CN-LC layer and a nematic LC layer.
We propose a fast switching method for a homogeneous-aligned liquid crystal (LC) cell using 3-terminal
electrode structure. LCs are vertical-aligned momentarily before they are in-plane switched to show a bright
state, by which LCs are in a transient state rather than the stable state. The turn-on can be faster, whereas LCs
start to relax along the rubbing direction so that the relaxation is optically hidden. The turn-off time of about
0.6 ms could be obtained. Experimental results show that fast gray-to-gray response as well as turn-on and
turn-off can be achieved by using the proposed switching method.
We propose an optical configuration of a twisted-nematic liquid crystal (TNLC) device driven by an in-plane electric
field for a single-cellgap transflective display. The dark state of the reflective part is realized by a nematic liquid crystal
layer with the twisted angle of 63.6° and the retardation of 194 nm, while a quarter-wave plate is inserted for the dark
state of the transmissive part. Wavelength dispersion of the TNLC layer is suppressed by introducing a half-wave plate,
whose optimum angle is found by using the Muller matrix method. Different directions of electric fields rotate liquid
crystals to 15° for the bright state of the reflective part, but to -30° for that of the transmissive part. With the proposed
configuration, we can realize a single-gamma transflective display in single cellgap structure without any in-cell
retardation layers. By fabricating a 2.0" qCIF+ (176×RGB×220) prototype panel, we demonstrated both high
reflection/transmission and single gamma of the proposed configuration.
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