Electronic displays for the rendering of full-color images have to date relied solely on self-luminous display configurations. While self-luminous displays have evolved into effective devices for color imaging, they require relatively large amounts of power and, in general, do not respond naturally to changes in ambient illumination. These attributes place limiting constraints on future applications for self-luminous color displays, particularly in light of current trends toward mobile computing and the proliferation of color in hardcopy document imaging. Clearly, a low-power reflective color display technology is needed to broadly satisfy the needs of both mobile computing and electronic color imaging. Previous approaches to achieve a reflective color display have generally produced unsatisfactory results, typically yielding displays with a restricted set of primary colors and low luminance. In this contribution we determine the visual parameters required for effective, full color reflective displays. We analytically examine a number of contemporary liquid crystal technologies and associated optical configurations which hold promise for achieving reflective color displays. We conclude that reflective displays based on polymer-dispersed liquid crystals (PDLCs) and polymer-stabilized cholesteric texture liquid crystals (PSCT) are the most viable color-capable reflective technologies to date. A new type of PDLC offering highly selective and efficient spectral reflectance via Bragg reflection is described, and we show such materials can be configured as a full-color reflective display and optimized for color imaging applications.
Gregory P. Crawford, Thomas G. Fiske, Louis D. Silverstein, "Reflective Color Displays for Imaging Applications" in Proc. IS&T 3rd Color and Imaging Conf., 1995, pp 52 - 58, https://doi.org/10.2352/CIC.1995.3.1.art00014