Cholesteric LCD Research Articles

P‐161: Wide‐view and Fast‐response Uniform Standing Helix Cholesteric LCD

We develop an experimentally validated numerical simulation model to characterize the electro‐optic properties of uniform standing helix (USH) cholesteric liquid crystal displays. Based on the proposed numerical model, the viewing angle properties are analyzed by taking the optical polarization rotation effect into consideration. Furthermore, we propose two compensation schemes to widen the viewing angle of an USH display and achieve contrast ratio >100:1 over 80° viewing cone.

An effective way to achieve full color cholesteric liquid crystal displays with single liquid crystal mixture and layer

AbstractTwo‐step ultraviolet exposure method to achieve flexible color cholesteric LCD with single liquid crystal mixture and layer was proposed. The first step for polymer wall formation via photo‐polymerization induced phase separation and second step for color rendering with the photo‐sensitive chiral dopant were independently carried out without the interference of ultraviolet reaction using proper band‐pass filer. This display has good color performance and mechanical stability, which can be also driven by simplified driving circuit so that it would be a substantive solution for color flexible displays.

P‐184L: Late‐News Poster: An Effective Way to Achieve Full Color Cholesteric Liquid Crystal Displays with Single Liquid Crystal Mixture and Layer

AbstractAn effective way to achieve flexible color cholesteric LCD with single LC mixture and layer was proposed. The 1st‐step for polymer wall formation and 2nd‐step for color rendering were independently carried out without the interference of UV reaction using proper band‐pass filer. This display has good color performance and mechanical stability, so that it would be a substantive solution for color flexible displays.

Liquid Crystal Biosensors

The liquid crystal (LCD) biosensor is a new research area of sensor technology, which integrates the modern biotechnology and advanced electronic sensing technology. The feasibility and the principle of the LCD biosensor were mainly introduced in this paper. The chitosan films exhibited cholesteric phase LCD texture which can be seen by using the polarizing microscope (POM), and there is a main endothermic peak and exothermic peak of chitosan LCD solution in the DSC heating curve and cooling curve respectively. Chitosan maybe will be used as a sensing material by using its LCD characteristics. The development prospects are predicted.

43.2: Energy and Area‐Efficient Driving Scheme in Cholesteric LCD by Embedded Fully Symmetric Self‐biased Switched‐Capacitor

AbstractThe paper‐like cholesteric liquid crystal display (Ch‐LCD) has become the next generation of electronic readers in consuming market. The embedded fully symmetric self‐biased switched‐capacitor (FSSBSC) with single‐inductor high voltage bipolar‐output (SIHBO) converter is proposed to achieve the energy and area‐efficient driving scheme. As the compact power management module, SIHBO converter can provide +/−35V bipolar outputs for row driving. In addition, the embedded FSSBSC is utilized to generate the different voltage levels for modulating the gray‐color in column driving scheme. This combination carries out the effective driving operation for Ch‐LCD through the demand of timing control unit. Simulated results show the achievement of +/‐35V output voltage in the SIHBO converter and the variety voltage levels generated from FSSBSC. The peak efficiency is derived of 85% with the integrated chip area of 6.53 mm2.

40.4: Generation of Uniform and Multitude Gray Scales on Cholesteric LCD by Using a Fast Low Voltage Driving Scheme

AbstractNew fast driving scheme of the Cholesteric LCD with low driving voltages and high image quality has been developed for driving black‐write as well as stable gray scales. Comparing to the dynamic driving scheme, this method could generate more grayscales in the same driving conditions. Combined with the multi‐selection method, even more middle tone gray levels can be distinguished. In addition, the uniformity of the gray scales is considerably better.

P‐116: A Multi‐Line Driving Scheme for R2R PM Ch‐LCD

AbstractA multi‐line driving scheme simultaneously addressing two or more lines on cholesteric LCD (Ch‐LCD) was proposed for faster addressing rate with low power consumption. The performance of the proposed driving scheme was experimentally evaluated on R2R PM Ch‐LCD and satisfactory results of fast update and fine image quality were achieved.

30.4: A Low Cost, Full Color Cholesteric LCD with Low Voltage and Crosstalk‐Free Drive Scheme

AbstractTo reduce the power consumption and improve the image quality of a full color Cholesteric LCD, low driving voltage Cholesteric LC and crosstalk‐free drive schemes have been respectively developed. The developed technologies were integrated into a 5″ full color QVGA Cholesteric LCD with a low‐cost single‐layer structure. The performance of the display validated the development approaches.

P‐130: An Advanced Cumulative Drive Scheme for Fast Refreshed Cholesteric LCD

AbstractFast refresh rate is desirable for inherently slow updated passive matrix (PM) cholesteric liquid crystal display (Ch‐LCD). This paper proposes a flexible cumulative drive scheme for fast and optimally refreshed PM Ch‐LCD. The proposed drive scheme was experimentally verified on a 5′ 100ppi PM Ch‐LCD and satisfactory results were obtained.

P‐135: A Low Power and Video Driving Scheme for Roll‐to‐Roll Cholesteric LCD

AbstractIn order to make Roll‐to‐Roll Cholesteric LCD more power saving and attractive, this paper proposes a low power and video driving scheme by applying the partial and cumulative updating waveforms. The performance of this new scheme is experimentally evaluated, and satisfactory results of local video rich gray‐level content could be obtained with much lower power.

P‐141: Real‐Time Dynamic Characteristics Measurement and Automatic Driving Parameters Extraction for Dynamic Driving Bistable Cholesteric LCD

AbstractTo obtain the dynamic driving parameters for cholesteric LCD in a systematic manner, its dynamic characteristics and then driving parameters should be measured and extracted respectively. Accordingly, this paper develops a real‐time dynamic characteristics measurement system and an automatic dynamic driving parameters extraction scheme. Satisfactory results can be obtained experimentally.

53.3: Flexible Color Cholesteric LCD with Single‐Layer Structure

AbstractA 10.4‐inch flexible single layer color cholesteric liquid crystal display (ChLCD) is demonstrated. The display is realized by the development of the pixelized vacuum filling (PVF) technique. The performance of the display is 3‐bit color and the resolution is QVGA. The display had passed the bending test over 10,000 times with 3 cm curvature.

6.2: Dynamic Driving Schemes for Cholesteric LCDs to Eliminate Data‐Dependent Defects

AbstractAn improved dynamic driving scheme is proposed to eliminate data‐pattern‐dependent defects in cholesteric LCD images by inserting a framing voltage pulse between each successive selected pixel voltage pulse, such that the effective selection time is independent of the preceding and following non‐selected pixel voltages.

Full‐color transflective cholesteric LCD with image‐enhanced reflector

Abstract— A full‐color bistable transflective cholesteric liquid‐crystal display (Ch‐LCD) was demonstrated by using an imbedded image‐enhanced reflector (IER) on top of each transmissive subpixel. The RGB colors were achieved by patterning conventional color filters on a black‐and‐white Ch‐LCD. In addition, the IER on top of each transmissive subpixel provides similar paths for the transmissive backlight and the reflected ambient light. A simple transflective Ch‐LCD was demonstrated.

P‐34: A Micro‐Power 100‐V Cholesteric Texture LCD Driver

AbstractA complete micro‐power high‐voltage driver for a 80×104 passive matrix cholesteric texture LCD is monolithically integrated in a 0.7μm CMOS I2T technology. It features 100V driving capability on all row and column outputs, comprises all necessary digitally programmable high‐voltage generators, and exhibits a total internal power consumption below 10mW from a 3V battery power supply. In parallel to this dedicated cholesteric texture LCD driver, a much more universal high‐voltage driver chip was also manufactured in the same 100V I2T technology. This multifunctional driver chip is intended to be used as a laboratory tool to develop different types of high‐voltage reflective bistable display systems and to design new display addressing schemes in order to achieve maximum optical performance at minimum power consumption.

P‐89: A Novel Dynamic Drive Scheme for Reflective Cholesteric Displays

AbstractWe have developed a novel dynamic drive scheme for cholesteric LCD utilizing 3 and 2 levels driver ICs for row and column, respectively. Stable gray scale has also been accomplished by using a pulse position modulation. By adopting this new drive scheme, we have developed 5.7″ folder type VGA cholesteric LCD showing addressing speed of 1msec/line.

Electro‐optic applications of soluble polypyrrole

AbstractThe optical transmittance of the film spin‐cast from the polypyrrole(PPy) solution in chloroform depended on the thickness of the film. The film with 80% transmittance showed a surface resistivity of 23kΩ/□. A TN‐LCD cell with rubbed PPy films as the LC alignment layers responded properly to an applied potential of 3.0V. Reflective mode cholesteric LCD cells made with black PPy film electrodes responded to AC fields to switch between the planar and focal conic states. PPy with imine structures introduced by deprotonation of doped PPy with NaOH solution was used as a diode material to exhibit a photo‐current on exposing to light.