Thomas G. Fiske

Reflective color LCDs based on H‐PDLC and PSCT technologies

— In this paper we determine the visual parameters required for effective, full-color reflective displays. We analytically examine a number of contemporary liquid crystal (LC) technologies and associated optical configurations which hold promise for achieving reflective color displays. We conclude that reflective displays based on holographically formed polymer-dispersed liquid crystals (H-PDLCs) and polymer-stabilized cholesteric-texture liquid crystals (PSCT) are the most viable color-capable reflective technologies to date.

Far‐infrared reflection–absorption spectroscopy of thin polyethylene oxide films

We report the temperature dependent far‐infrared spectrum of ultra‐thin films of polyethylene oxide (PEO). Using the orientational specificity of infrared and far‐infrared reflection–absorption spectroscopy and in‐situ recrystallization, we find that during spin coating the PEO helices are initially in the plane of the film, but on crystallization reorient to be normal to the substrate. A splitting of the C–O torsional mode near 109 cm−1 is identified as arising from a distortion of the normal helical structure of PEO. Comparison with transmission spectra of cast films demonstrates the value of far‐infrared reflection–absorption spectroscopy (FIRRAS) in the study of crystalline polymers in the far infrared.

49.3: H‐PDLC Color Separation Device for Image Capture Systems

A novel device for separation of color image components in image capture systems is described. The device is based upon temporal switching of HPDLC elements with tunable spectral passbands. The device may be operated as either a reflective RGB color separation mirror or a transmissive CMY color separation filter. A breadboard color image capture system using this device for color separation has been developed and tested as a proof of concept.

HPDLC color reflective displays

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.

The electronic document display : A 6.3-million-pixel AMLCD

This paper describes 6.3-million-pixel active-matrix displays in monochrome and color (1.6 million color groups) with a diagonal dimension of 33 cm (13 in.), first discussed by Martin et al. in 1993. 1 These displays have the largest number of pixels of any AMLCDs thus far reported. The monochrome display is intended for office-automation applications where there is a requirement for electronically controlled image reproduction with characteristics similar to those of a conventional laser print. This display achieves the resolution, luminance, and viewing angle required for these applications through a binary driving scheme.

Advances and applications for color HPDLC reflective technologies

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.

Resolution in information display

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.

Military displays based on a dual-use AMLCD technology

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.