We report on the recent advances made by our groups in the technology and applications of Holographically formed Polymer Dispersed Liquid Crystal (HPDLC) devices. In this paper we will briefly review some of the basic operating principles of HPDLC devices and their salient features as applied to display and image capture applications. The usability of HPDLC films in displays is enhanced by incorporating diffusion into the films. The photopic reflectance and reflection bandwidth of an HPDLC device can be improved by stacking multiple films of HPDLC material between one set of electrodes. HPDLC mirrors can be used to advantage in an electronic image capture system.
We have carried out experiments and simulations to optimize the materials and processes for fabricating holographically formed polymer dispersed liquid crystal (HPDLC) devices. Bright reflective HPDLC displays with peak reflection above 60% have been achieved with fast, sub-millisecond (tau) ON + (tau) OFF switching speed. The switching voltage has been reduced by more than a factor of 2 by selecting appropriate liquid crystal and polymer materials and by the addition of surfactants. The viewing angle of HPDLCs has been extended by a novel fabrication technique. We have fabricated color HPDLC demonstration displays by stacking red, green, and blue HPDLC layers and have achieved the widest color gamut that has ever been reported for a reflective display. The methods for making these novel color reflective displays and the measured are presented.
This paper reviews critical aspects of AMLCD design, concentrating on those areas that are particularly important for military applications. The impact of a range of design choices, particularly those associated with the active matrix and L.C. cell, on overall optical performance is described along with the trade-offs that must be made in order to meet the most demanding military and commercial specifications. The use of a common technology foundation to build displays for a range of high performance military and commercial uses is discussed.
This paper describes the system tradeoffs related to display type, resolution, and pixel structure, taking examples from the development of binary and grayscale high resolution AMLCDs. Performance is related to the match achieved between the human visual system, the display system and the task assigned. The active matrix liquid crystal display is compared to other technologies at the high acuity levels achieved in a 282 DPI monochrome grayscale and a 141 color groups per inch color grayscale AMLCD. The potential benefits to military aviators of very high resolution displays are outlined as well as the challenges to implement these systems.