We report on unique flexible ReflexTM displays based on bistable, reflective, cholesteric liquid crystal display
technology. Reflex displays are attractive for numerous applications because of the low power consumption and paper
like reflective color. As the possible applications grow for flexible, reflective displays the new methods to manufacture
these displays, such as web processing, also become important. We will report on several unique display types such as a
pressure induced writing display and a switchable color electronic skin display. In addition, the current status of
traditional Reflex displays will be discussed.
Flexible Cholesteric liquid crystal displays have been rapidly maturing into a strong contender in the flexible display
market. Encapsulation of the Cholesteric liquid crystal permits the use of flexible plastic substrates and roll-to-roll
production. Recent advances include ultra-thin displays, laser-cut segmented displays of variable geometry, and smart
card applications. Exciting technologies such as simultaneous laser-edge sealing and singulation enable high volume
production, excellent quality control and non-traditional display geometries and formats.
Bistable reflective cholesteric displays are a liquid crystal display technology developed to fill a market need for very low power displays. Their unique look, high reflectivity, bistability, and simple structure make them an ideal flat panel display choice for handheld or other portable devices where small lightweight batteries with long lifetimes are important. Applications ranging from low resolution large signs to ultra high resolution electronic books can utilize cholesteric displays to not only benefit from the numerous features, but also create enabling features that other flat panel display technologies cannot. Flexible displays are the focus of attention of numerous research groups and corporations worldwide. Cholesteric displays have been demonstrated to be highly amenable to flexible substrates. This paper will review recent advances in flexible cholesteric displays including both phase separation and emulsification approaches to encapsulation. Both approaches provide unique benefits to various aspects of manufacturability, processes, flexibility, and conformability.
This paper highlights recent advances toward flexible cholesteric displays including new night vision applications for military use and full color. Particular emphasis is paid to recently developed encapsulated cholesteric liquid crystals that are necessary for printing and coating the materials as well as prevent erasure of the image during flexing or handling the display. The paper presents recent results from encapsulation of cholesteric materials using polymerization induced phase separation and their progression towards thin flexible plastic based cholesteric displays. Several other key issues in the transition from smooth rigid glass substrates to flexible plastic substrates including spacing control and preparation of surfaces are discussed. Lastly, the night vision mode and night vision applications of cholesteric displays are also presented.
We developed a novel technology for the fabrication of reflective cholesteric liquid crystal displays coatable on a single
substrate using a layer-by-layer approach. Encapsulated cholesteric liquid crystals serving as an electro-optical layer and
transparent conducting polymer films serving as electrodes are coated and printed on a variety of unconventional
substrates, including ultra-thin plastic, paper, and textile materials to create conformable displays. The displays are
capable of offering excellent electro-optical properties of the bulk cholesteric liquid crystals, including full-color, IR
capability, bistability, low power, high brightness and contrast, combined with the ruggedness and pressure insensitivity
of the liquid crystal droplets embedded in a polymer matrix. Durability of encapsulated cholesteric liquid crystals and
single substrate approach allows for display flexing, folding, rolling and draping during image addressing without any
image distortion. Our single substrate approach with natural cell-gap control significantly simplifies the fabrication
process of the LCDs especially for large area displays. This paper will discuss the development, status, and merits of
this novel display technology.
Bistable reflective cholesteric displays are a liquid crystal display technology developed to fill a market need for very low power displays on a low-cost, high resolution passive matrix. Their unique look, high reflectivity, bistability, and simple structure make them an ideal flat panel display choice for handheld or other portable devices where small lightweight batteries with long lifetimes are important. We discuss recent advances in cholesteric display technology at Kent Displays such as progress towards single layer black and white displays, standard products, lower cost display modules, and various interface options for cholesteric display applications. It will be shown that inclusion of radio frequency (rf) control options and serial peripheral interface (spi) can greatly enhance the cholesteric display module market penetration by enabling quick integration into end devices. Finally, some discussion will be on the progress of the development of flexible reflective cholesteric displays. These flexible displays can dramatically change industrial design methods by enabling curved surfaces with displays integrated in them. Additional discussion in the paper will include applications of various display modes including signs, hand held instrumentation, and the electronic book and reader.
We discuss the state of the art of the bistable reflective cholesteric liquid crystal display technology. Numerous applications from low resolutions signs, to medium resolution instrumentation type displays, and high resolution electronic books are discussed. Different modes of the technology are discussed as being viable for the respective display applications. Special emphasis is paid to electronic book applications.
Reflective cholesteric liquid crystal displays (Ch-LCDs) are attracting more interest because power efficient displays are needed for the rapid growing mobile computation applications. Its capability of high-resolution full color with passive matrix drive method provides the market with a very powerful alternative display technology. In this paper, we will review the history of Ch-LCDs as well as the most recent developments.
We report a full color 1/4 VGA reflective cholesteric display with 4096 colors. The display can deliver a brightness approaching 40 percent reflected luminance, far exceeding all other reflective technologies. With its zero voltage bistability, images can be stored for days and months without ny power consumption. This property can significantly extend the battery life. The capability of displaying full color complex graphics and images is a must in order to establish a market position in this multimedia age. Color is achieved by stacking RGB cells. The top layer is blue with right chirality, the middle layer is green with left chirality, and the bottom layer is red with right chirality. The choice of opposite chirality prevents the loss in the green and red spectra from the blue layer on the top. We also adjusted the thickness of each layer to achieve color balance. We implement gray scale in each layer with pulse width modulation. This modulation method is the best choice consideration of lower driver cost, simpler structure with fewer cross talk problems. Various drive schemes and modulation methods will be discussed in the conference.
Bistable reflective cholesteric liquid crystal displays (Ch- LCDs) can be modified for compatibility with various classes of NVGs (Night Vision Goggles). Stacking near-infrared reflecting displays and visible reflecting displays can produce a novel dual use display module. Due to the optical clarity of the visible display in NVIS mode, the two displays are stacked on top of each other without any visual compromise. This module has high reflectivity and contrast in both the visible, and NVIS cases. The display is also bistable, enabling a low power device. This paper describes variations in this configuration including a single cholesteric layer for both viewing conditions. Various methods of contrast optimization, and multiple color capability are also discussed. Military applications of this unique display device for cockpits and handheld devices with night vision requirements are discussed.
The first monochrome, high resolution reflective 1/8 VGA liquid crystal displays have been built using various plastic substrates for body mounted and hand held applications. These displays have a contrast ratio of over 10:1 with a wide viewing angle. The reflectivity is about 40 percent and the frame update time is less than 2 seconds.
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