Adrian Derek Geisow

Controllable alignment of nematic liquid crystals around microscopic posts: Stabilization of multiple states

Nematic liquid crystal materials are rod-like molecules that align in a locally common direction called the director. This gives rise to anisotropic properties that are used in electro-optical devices such as displays, which usually consist of a sandwich of material between two substrates. The behavior of the director at the substrate surfaces is a critical design consideration, and a wide variety of surface treatments has been reported. Most are dominated by molecular interactions, e.g., high surface energy materials that give homogeneous alignment (the director parallel to substrate). The elastic properties of nematics can also be used to influence alignment by shaping the surface on the micron scale. The potential that this offers to engineer device properties is relatively unexplored; to date, the majority of results reported concentrate on essentially two-dimensional effects. Here we show that the three-dimensional configuration of nematics around microscopic posts results in multiple stable director orientations, and can be used in particular to implement bistable displays with a broad range of control over the optical and switching properties.

Bright color reflective displays with interlayer reflectors

A good solution to the reflective display of color has been a major challenge for the display industry, with very limited color gamuts demonstrated to date. Conventional side-by-side red, green and blue color filters waste two-thirds of incident light. The alternative of stacking cyan, magenta and yellow layers is also challenging--a 10% loss per layer compounds to nearly 50% overall. Here we demonstrate an architecture that interleaves absorbing-to-clear shutters with matched wavelength selective reflectors. This increases color gamut by reducing losses and more cleanly separating the color channels, and gives much wider choice of electro-optic colorants.

43.2: Colour Plastic Bistable Nematic Display Fabricated by Imprint and Inkjet Technology

Plastic displays require new manufacturing processes and techniques to achieve acceptable cost and performance. We present a novel additive, low temperature, atmospheric pressure, self-aligned means of fabricating a plastic, bistable, full colour LC display. By using imprinting rather than photolithographic patterning, a scalable, low cost manufacturing route is possible.

Designing liquid crystal alignment surfaces

We have previously shown that tilted micron-scale posts can be used to generate uniform liquid crystal alignment. By considering the geometry and symmetry of individual surface features in more detail, we have been able to demonstrate finer control of alignment, eliminate the need for tilted structures, and show multidomain alignment.

Color plastic bistable nematic display fabricated by imprint and ink-jet technology

— Plastic displays require new manufacturing processes and techniques to achieve acceptable cost and performance. A novel additive, low-temperature atmospheric-pressure self-aligned means of fabricating integrated plastic substrates for full-color LCDs and a bistable LC mode based on microstructure alignment are presented. By using imprinting rather than photolithographic patterning, a scalable, low-cost manufacturing route is possible. A 2-in.-diagonal 128 × 128-pixel display was made to demonstrate the principles involved, which has retained an image for in excess of 2 years.

Upward trend for flat displays

FOR OVER 100 years the cathode-ray tube has been the principal war of displaying viedo images. Since its invention in 1897 by Karl Ferdinand Braun, the popularity of the cathoderay tube has grown enormously – the number of units sold worldwide last year was estimated to be 150 million. But that popularity is on the wane, thanks to 20 years of investment in liquid crystal and plasma displays.