A Blue Phase Liquid Crystal and Device Thereof

KSU.351

Abstract:  Liquid crystal (LC) displays (LCDs) with motion picture response time (MPRT) to display fast action media have been sought after for LC displays – from mobile to LCD-TVs.  Compared to the cathode-ray tube, the motion artifacts observed with video or dynamic picture of several currently available LCD technologies such as S-PVA, S-IPS or OCB LCDs are still far from perfect.  One major factor is related to the slow dynamics of LC molecular reorientation in response to the field-on and field-off states.  To improve the slow dynamics of LC, one approach is using an electronic engine to drag the LC wagon.  Several techniques, including the scanning backlight, frame rate doubling, or black data insertion were developed recently to improve the hold type blur.  In contrast, there is a little progress toward the development of fast switching nematic LC materials capable of MPRT. This invention relates to a LC display comprising a blue phase-forming LC liquid crystal and a LC crystal cell with a pair of substrates. The LC cell has one of the substrates coated with indium-tin-oxide conductive electrodes and inter-digitally patterned, and the other substrate has no electrode. A blue phase liquid crystal is formulated with a nematic and chiral dopant to achieve a room temperature blue phase and is deposited between the pair of substrates that is separated with spacer to control the cell gap. Applying an electric field across the electrode enables the deformation of the optically isotropic LC medium in a 3-D structure and induction of a birefringence. The device can be built also on substrates that are flexible and with patterned structure to provide physical support to substrates against external stress and mechanical shock.

Applications:

•          Displays, spatial light modulators
•          Active optical elements, sensors

 Advantages:

•          Fast switching, improved dynamics of liquid crystals to display fast action media
•          No alignment layer
•          Active field control of birefringence
•          Flexible substrates also can be used – with patterned structure for physical support/ruggedizing

Inventors:  Dr. Liang-Chy (L.C.) Chien; Lu Lu, Jeoung Yeon Hwang