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Bistable electrowetting display (EWD) is a promising low-power electronic paper technology, where power is consumed only during the switching between two stable states; however, it is not required for state maintenance once switched. In this paper, a bistable electrowetting device with non-planar designed controlling electrodes is fabricated by a fully conventional photolithography process. The device has potential for video display applications with a controllable gray scale. The novel electrode design realizes a lower driving voltage and a higher contrast between two stable states than the EWDs with planar electrodes reported previously.

Electrochromic devices have many important commercial applications ranging from electronic paper like displays, antiglare rear-view mirrors in cars, to energy-saving smart windows in buildings. Monovalent ions such as H+, Li+, and Na+ are widely used as insertion ions in electrochromic devices, but they have limitations such as instability, high cost, and hard handling. The utilization of multivalent ions as insertion ions has been overlooked probably because of the strong electrostatic interactions between ions and intercalation framework as well as the resulted difficulties of intercalation.The bivalent cation, Mg2+, has been proved to be efficient electrochromic insertion ions for the electrochromic processes of the nonstoichiometric W18O49 nanowires. Using Mg2+ based aqueous electrolyte, the electrochromic W18O49 nanowires shows a short coloration/bleaching time of 2.7/3.6 s, and a high tinting productiveness of 116 cm2/c, together with excellent cyclic constancy. The utilization of bivalent Mg2+ as insertion ions will benefit electrochromic devices with low cost, high stability and simple operation.

Electrowetting display (EWD) has promising prospects in the electronic paper industry due to it having superior characteristics, such as the ability to provide a comfortable reading experience and quick response. However, in real applications, there are also problems related to dielectric deterioration, excess power consumption, optical instability and narrow color gamut etc. This paper reviewed the existing challenges and recent progress made in terms of improving the optical performance and reliability of EWD. First, the principle of electrowetting applied in small and confined configurations is introduced and the cause of the failure of the dielectric layer is analyzed. Then, the function of the pixel structures is described to avoid display defects. Next, electric signal modulations are compared in terms of achieving good image quality and optical stability. Lastly, the methods are presented for color panel realization. It was concluded that multi-layer dielectrics, three-dimensional pixel structures, proper electric frequency-and-amplitude modulation and an RGB color panel are expected to resolve the current limitations and contribute to designing advanced reflective displays.

Partially addressable technology to realize a colorized image onto a glass substrate or plastic film in reflective electronic paper display is accomplished by the particle-moving method. This image panel includes upper and lower substrates with cells surrounded by rib patterns and filled with charged color particles. Mold substrate is prepared with the same condition as that of the lower substrate. The electric field between the mold and upper/lower substrates is used in this study, along with the image force of the conductive electrode. This addressable technology can be easily applied to any image panel, including transparent film. The feasibility of this technology is shown as a resultant reflective display panel with its fabrication process. We also ascertain that partially-addressed particles with a two-contrast color image are transferred from the mold substrate to the upper substrate of the panel via the particle-moving method.

A multi-functional electrochromic material which modulates light over a wide spectral range and stores electrical energy is an intriguing substance, which would lead to a variety of novel applications, such as smart windows for energy-efficient buildings, solar power storage, nonemissive displays, electronic paper, optoelectronic switches, and variable-reflectance mirrors/surfaces. Developing such a versatile material entails merging the electrochromic phenomenon with electrical-chemical energy conversions in an electrochromic-battery platform. However, the challenges related to transition metal oxide electrochromic-batteries include poor energy storage, low optical contrast, and high fabrication cost. Here, we demonstrate the synthesis of aqueous nanocrystalline colloidal molybdenum oxide in a matrix of tungsten molybdenum oxide (MoO3-W0.71Mo0.29O3) for solution-processed fully reversible switching electrochromic-battery electrodes. The hybrid material exhibits both 50% optical contrast modulation over a wide optical bandwidth and an improved Columbic efficiency. An 8 × 8 cm2 energy storing smart (ESS) window is assembled to demonstrate a functional prototype that can power an LED for more than 10 min when charged under −2.5 V for 1 min. The enhanced electrochromic performance, high energy storage capacity, simple solution processability, versatility for large area fabrication, and low cost make this nanocrystalline MoO3-W.71Mo.29O3 composite a promising material with the potential to be deployed ubiquitously in energy-efficient smart window architectures.

The electrophoretic display (EPD) is the main solution to electronic papers, but most of them can display the image or text in black and white particles only. The users may prefer the EPD showing multiple colors rather than the black/white content only. In this paper, we introduce the driving system for a color EPD, which is composed of three kinds of particles. The system aims at optimizing the visual quality based on a new driving waveform by equipping with an optimization method for color and tone reproduction. The experimental result shows that the proposed EPD driving system can display three-color pictures with promising visual quality.

In this study, we implemented a micro-encapsulated CLC electronic paper that is optically addressed and electrically erasable. The mechanism that forms spot diameters on the CLC films is discussed and verified through various experimental parameters, including the thickness of CLCs and Poly(2,3-dihydrothieno-1,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS), pump intensity, and pumping time. The opto-thermal effect, brought on by the PEDOT:PSS absorbing layer, causes the spot diameters on the cholesteric liquid crystal thin films to vary. According to our results, the spot diameter is larger for a sample with a thinner cholesteric liquid crystal layer with the same excitation conditions and same thickness of the PEDOT layer. The spot diameter is also larger for a sample with a thicker PEDOT under the same excitation conditions and same thickness of the cholesteric liquid crystal layer. We proposed a simple heat-conducting model to explain the experimental results, which qualitatively agree with this theoretical model.

Plasmonic structural colors have recently received a lot of attention. For many applications there is a need to actively tune the colors after preparing the nanostructures, preferably with as strong changes in the optical response as possible. However, to date, there is a lack of systematic investigations on how to enhance contrast in electrically induced color modulation. In this work we implement electrochromic films with plasmonic metasurfaces and compare systematically organic and inorganic materials, with the primary aim to maximize brightness and contrast in a reflective color display. We show nanostructures with good chromaticity and high polarization-insensitive reflectivity (similar to 90%) that are electrochemically stable in a nonaqueous solvent. Methods are evaluated for reliable and uniform electropolymerization of the conductive polymer dimethylpropylenedioxythiophene (PProDOTMe(2)) on gold. The resulting organic films are well-described by Lambert-Beer formalism, and the highest achievable contrast is easily determined in transmission mode. The optical properties of the inorganic option (WO3) require full Fresnel models due to thin film interference, and the film thickness must be carefully selected in order to maintain the chromaticity of the metasurfaces. Still, the optimized fully inorganic device reaches the highest contrast of approximately 60% reflectivity change for all primary colors. The switching time is about an order of magnitude faster for the organic films (hundreds of ms). The bistability is very long (hours) for the inorganic devices and comparable for the polymers, which makes the power consumption essentially zero for maintaining the same state. Finally, we show that switching of the primary colors in optimized devices (both organic and inorganic) provides almost twice as high brightness and contrast compared to existing reflective display technologies with RGB subpixels created by color filters.

The aim of this study was to understand to what extent people can read e-paper devices under various conditions of ambient illuminance that can occur indoors. In this study, 110 young to elderly subjects participated in an experiment to evaluate the effects of 14 different levels of ambient lighting on their reading from three different electronic devises and paper text. The participants were asked to undergo a timed read task and then to evaluate the readability of two eReader devices (a regular electronic display and one with a front light) in comparison with a backlit liquid crystal device and conventional paper text. The results indicated that backlit and front lit devices are easier to read at less than 200 lx and the reflective device is easier to read at levels above 500 lx.

Electrochromism, phenomenon of reversible color change induced by electrochemical redox reactions, is one of the prime candidates for full-color electronic paper. Recently, we reported Ag-deposition based multicolor electrochromic device showing color change between three primary colors of cyan, magenta, and yellow. These observed spectra include both absorbing and reflectance components. Therefore, it is necessary to separate these components in order to analyze coloration mechanism of the device. In this paper, coloration mechanisms of Ag deposition-based multicolor electrochromic device were investigated in terms of measurement of the actual absorption and actual reflection of the device. Morphologies of the deposited Ag nanoparticles were also investigated by FE-SEM, and then relationship between optical properties and deposited Ag morphologies was examined. As the results, color appearances of magenta and yellow state of the device were mainly dominated by absorption component of localized surface plasmon resonance of the deposited Ag nanoparticles. On the other hand, cyan state of the device was based on absorption as well as reflection component induced by thin film structure of the Ag deposit.

This paper presents an innovative and versatile selective liquid-metal plating (SLMP) process to realize a transparent stretchable circuit board (TSCB) with the capability of large deformation and self-healing. The TSCB consists of polydimethylsiloxane (PDMS) thin films and non-toxic liquid-metal patterns that are embedded into the PDMS substrate. Complex liquid-metal patterns with various aspect ratios are achieved by using the selective wetting behavior of the reduced liquid metal on the Au/Cr patterns of the PDMS substrate. The smallest liquid-metal pattern is approximately 3 μm in width. The TSCB integrated with a light-emitting diode exhibit stable performance, even though it is twisted more than 180° or is stretched up to ∼60% 6000 times. To evaluate the feasibility of the SLMP process, an electrical filter was fabricated on the PDMS substrate and the current–voltage (I–V) characteristics are successfully demonstrated under various conditions. The experimental results reveal that the proposed idea has the potential to enable advanced electronics such as wearable computers, wall-scale displays, electronic paper, and other stretchable electronics.

The inherent advantages of reflective e-paper displays (EPD) – wide viewing direction range and excellent readability even under bright sunlight – can be extended into low-light conditions by the addition of an integrated lighting unit (ILU) such as a front light. A methodology for predicting the viewing direction dependence of ambient contrast and color from display measurements and illumination models is here applied to reflective EPD where the ILU is switched on. The predictions can be used to optimize task lighting. The ILU improves the indoor performance of EPD without compromising their superior daylight performance.

This study investigated technologies related to a smart-card display and its wireless charging system, where the wireless receiver in the smart card receives not only the data but also the power required for the display circuitry. The goal of this research was to achieve the required energy transfer during the extremely short reading time when a person swipes his or her smart card. This paper describes the design considerations and the analysis procedures of the transmitter and receiver pair for an electronic paper (E-paper) display. A series of magnetic simulations as well as experimental tests were conducted to investigate the various design factors. The design considerations included the shape and effect of using ferromagnetic cores, the component design for frequency tuning, the geometric arrangements, and the number of turns of the coils. A novel design for power transmission is then proposed using a ferromagnetic core to enhance its energy efficiency. In experiments the transmitter unit prov...

As a special kind of binary image, halftone image is produced by digital halftoning and widely used in printing. In recent years, some consumer electronics apply halftone image for lost-cost liquid crystal display systems. However, few techniques are reported for securing the content of halftone images, although a variety of schemes have been developed for continuous-tone image encryption in literatures. This paper proposes an encryption scheme for digital halftone images based on the principle of reversible pairwise swapping. The encryption and decryption phases are symmetrical because of the reversibility. It also can be easily integrated into some emerging display technologies such as cholesteric liquid crystal display which is used in electronic paper book. This secure method is also applicable for binary image encryption. Extensive experimental results demonstrate the effectiveness and efficiency of the proposed method.

The electrophoretic display (EPD) has been widely applied on electronic readers (E-Readers) for displaying image/text contents. With a touch panel, the user can put annotations on the contents at will. However, none of the available E-Readers support the function of paintbrush, which allows the user to plot gray tone figures. This is because the EPD is a bistable display whose driving method is quite complicated. In this paper, we first discuss the issues of realizing paintbrush function on the EPD display controller and then propose a new signal processing engine for the paintbrush function. The engine contains four stages: 1) screening the detected pixel coordinates; 2) interpolating pixels; 3) performing image halftoning to generate more visual gray levels; and 4) driving the pixels to the target states. The experimental results show that the engine meets the real-time requirement to complete the pixel interpolation as well as produce the gray-tone traces.

Electrophoretic display (EPD) is one of the most prominent technologies used in electronic paper. EPDs have good paper-like readability in ambient sunlight, and their bistability characteristics allow them to use very little power. To understand the physical mechanism at work in EPDs in terms of optical phenomena and current responses, we investigated EPD charging behavior using a transient current, an intermediate-state current, a discharge current, and a current bump. After establishing the microcup EPD model, we developed recommendations for a shortened transition time. As our experiments show, the method can reduce the transition time by 20%.

In this study, the effects of ambient illuminance and light source on participants’ reading performance and visual fatigue during a long reading task were investigated using three electronic paper displays. Reading on electronic paper displays was also compared with reading on paper. In Experiment 1, 100 participants performed a reading task where the display area for the text was equated for the displays. The results indicated that participants’ visual performance and visual fatigue did not differ significantly among different electronic paper displays, ambient illuminance conditions, or light sources. In Experiment 2, another 60 participants performed the same reading task where the full screen of each electronic paper display was used to present the text. The results showed that reading speed differed significantly across different electronic paper displays and ambient illuminance levels. The reading speed was slower for displays with smaller screens and increased as the ambient illuminance increased. Changes in the critical flicker fusion frequency significantly differed across ambient illuminance levels. Implications of the results for the use of electronic paper displays are discussed.

To develop an all organic active matrix light emitting display required for large area thin display, electronic paper and electronic paints, Si-based thin film transistor has to be replaced with organic thin film transistor (OTFT). The most important issues in OTFT are the low charge carrier mobility and poor stability under ambient conditions, which critically depend on how organic thin films are grown on different substrates. Here we show that both these issues are correlated and can be overcome by certain surface morphology which can only be achieved through anisotropic growth. Careful control of different growth parameters can lead to unprecedented control on thin film morphology which has been shown to be engineered reversibly and reproducibly. High temperature and low evaporation rate increase the diffusive mobility of molecules, which are responsible for the stacking of molecules to higher length scales. By carefully choosing a temperature and evaporation rate, elongated rod-like grains were grown for achieving high performance and stable thin film transistors.

Mobile display devices that use ultra-thin (≤100 µm) glass substrates offer a combination of attractive characteristics: lightweight, high quality device fabrication process, thermal and dimensional stability, and mechanical flexibility. Electrowetting (EW) devices fabricated on ultra-thin glass are demonstrated in this paper. Water contact angle, which is the most critical parameter of EW devices, changes from ~165° to 80° when a 20 V direct current (or alternating current) voltage is applied. EW devices on ultra-thin glass show negligible hysteresis (~2°) and fast switching time of ~10 ms. EW device operation is maintained when the glass substrate is mechanically flexed. These results indicate the promise of narrow profile EW devices on ultra-thin glass substrate for mobile and other devices, including video rate flexible electronic paper.

In this article, we disclose a method to fabricate the three-dimensional (3D) image on an optically rewritable (ORW) electronic paper (e-paper) by deploying the lenticular lenses array on the top of the ORW e-paper. Unlike other autostereoscopic 3D liquid crystal displays, our autostereoscopic 3D ORW e-paper is actually a green technology, which is without electrode and voltage. No electricity is needed to maintain the 3D image on the ORW e-paper. We can easily change a 3D image by erasing and rewriting with photoalignment technology.

We have quantified the image quality of color electronic paper (e-paper) by subjective evaluations and clarified the requirements for improving the image quality. In the color e-paper field, various display types have been developed with the focus on improving the display performances or manufacture costs. However, color e-papers are still under development, and the image quality is not sufficient when compared with printed papers, photographs and conventional displays. With respect to the image quality of color e-paper in the future, it is very significant to clarify how reflectance, contrast ratio, National Television System Committee (NTSC) ratio, and other factors affect the image quality. Therefore, we have quantified the image quality factors such as color reproduction, tone reproduction, and surface texture. From our experimental results, we could clarify the significant factors and the practical range of image quality of color e-paper. For instance, both the reflectance of approximately 30% or higher, contrast ratio of approximately 8:1 or higher, and NTSC ratio of 20% or higher are the requirements for obtaining subjective evaluation score that is equivalent to that of newspapers, which are read very widely.

Projected image on a screen is not always vivid enough when it is projected in a bright room. We generally have to choose either vivid image in a dark room or dull image in a bright room. We have suggested a new projection system which can realize high contrast image projection in a bright room. It is consisted of electronic paper screen, projector, and light-emitting diode room light. The electronic paper (e-Paper) screen alternates its whole surface white/black with 120 Hz. Room lights are controlled with the same frequency of 120 Hz with the opposite phase as that of the e-Paper screen. We have confirmed that our new system has achieved higher contrast than the conventional projection system and also enough readability of paper documents in the room simultaneously. We have thus confirmed that our new system can bring an ideal condition, for audience, which can realize a vivid image projection in a bright room.

The display quality, as well as the speed of electrophoretic displays (EPDs), is highly affected by the design of driving waveforms. A typical driving waveform contains the phases of image erase, particle activation, and driving each pixel to the target gray level. Due to the difficulty of modeling a complete EPD device, the designers still lack a systematic approach to driving waveform design. In this paper, we study the property of the viscosity of the suspension, characterize the response latency of the device, and propose a new driving waveform. The experimental results show that the proposed approach can effectively reduce driving time while still maintaining good image quality.

We propose a new particle-insertion method for a reflective display based on the structure of a quick response-liquid powder display (QR-LPD). To compare this method with the reported simple loading method, two panels are fabricated in the same panel condition of which the width of ribs is 30 μm, the cell size is 220 μm 220 μm, the cell gap is 116-120 μm, the m value of the black particles is μC/g and that for the white particles is μC/g. This method excludes the non-moving particles, inserting only mobile particles into a substrate by using electric fields so that a panel fabricated by the particle-moving method can drive most of the particles in a cell. Also, most of the particles move at the threshold voltage of 40 V with enhanced reflectivity.

This study investigated the effects of bending curvature of simulated e-paper displays (−10 cm, plane and 10 cm) and ambient illuminance (50, 500, 6000 and 12,000 lx) on the visual performance of young and elderly users for simulated electronic-paper displays. In total, 24 people comprising 12 young and 12 elderly users participated in this study. Young users demonstrated significantly enhanced visual performance using the simulated electrophoretic ink (E ink) e-paper display with ambient illuminance set at 50 and 500 lx; however, participants did not demonstrate significantly different visual performance using the 2 simulated e-paper displays with ambient illuminance set at 6000 and 12,000 lx. The bending curvature did not exhibit significant effects on the visual performance of young participants under various ambient illuminances. The elderly participants exhibited significantly enhanced visual performance using the simulated E ink e-paper display only when ambient illuminance was set at 50 lx; however, participants did not exhibit significantly different visual performance using the two simulated e-paper displays with ambient illuminance set at other levels. Elderly users exhibited significantly enhanced visual performance when the bending curvature was set at 10 cm, with ambient illuminance set at 50 lx. Elderly users also demonstrated significantly enhanced visual performance under bending curvature settings of 10 cm and plane, with ambient illuminance set at 500 lx. However, the bending curvature of the simulated e-paper did not exhibit significant effects on the visual performance of elderly participants under ambient illuminance settings of 6000 and 12,000 lx.

An electrophoretic display (EPD) cell with a triple-layered microcavity structure was fabricated using a convenient dry film resist. The inherent structural advantage arising from the function of the middle channel layer as a background colored state enabled the EPD to operate with two different-colored states by using a single type of electronic-ink particles, thereby eliminating the possible agglomeration of oppositely charged ink particles and supporting the potential application of the proposed structure to color the electronic paper. The preliminary operation of this new EPD structure was demonstrated as white and blue display states on a rigid glass exhibiting a contrast ratio of 1.5 : 1 with saturation voltages of + 30 and -30 V, respectively. Successful demonstrations on both the indium-tin-oxide-patterned glass and flexible polyethylene substrates are also provided.

In-cell adaptive touch technology for use in an electrophoretic display (EPD) has been developed and implemented in 11.5 in. UXGA flexible electronic paper display. Here, two types of a-Si:H photo-sensor arrays fabricated on a stainless steel substrate at the process temperature of 250 °C have been used along with an overall capacitive sensor formed on top of the flexible panel. Thus, we can resolve the sensing issue of normal photo-sensor array as well as maintain the feature of low power consumption in the EPD. Moreover, new touch algorithm adapted depending upon the amount of light intensity has been applied to enhance touch sensitivity regardless of environmental light conditions.

This study investigated the effects of light source, ambient illuminance, character size, and interline spacing on visual performance and visual fatigue in using commercial electronic paper displays. Regarding visual performance the results showed that display type, character size, interline spacing had significant effects on search time. Electrophoretic electronic ink display had a shorter search time than chlorestic liquid crystal display. Searching time decreased as character size and interline spacing increased. Ambient illumination, display type, character size, and interline spacing had significant effects on accuracy. Accuracy was highest for 1500 lx ambient illumination. Accuracy of electrophoretic electronic ink display was greater than chlorestic liquid crystal display. Accuracy increased as character size and interline spacing increased. Regarding visual fatigue, results showed that light source and ambient illumination had non-significant effects on change of critical flicker fusion (CFF) and subjective visual fatigue. Results could be able to provide some guidelines for consumers to choose a suitable electronic paper according to lighting condition and set appropriate character size and interline spacing.

The intent of this study is to determine the minimum ambient illumination requirement for legible electronic-paper display. Not only the young but also the elderly were included as research subjects. Through the method of character-search task, the results indicated that the significant performance improvement of all subjects occurred at 52 lux on the search time and at 62 lux on the subjective visual fatigue. Therefore, the minimum ambient illumination requirement for legible electronic-paper display can be synthesized at 62 lux. This minimum point of ambient illumination for the young and the elderly represents that the reflective-type display started presenting its better legibility and the subjective visual fatigue started decreasing. As electronic-paper display technology applications gradually expand, product designers need notice this fundamental limit of electronic-paper display when they continue to create possible applications in the future.

The electrophoretic display (EPD) has become the main solution to electronic papers, but there are several limitations when it is being driven. First of all, the optical response curve of the EPD is nonlinear and temperature sensitive. In addition, the number of gray levels that can be displayed is also quite limited. The image quality is unsatisfactory if the images shown on the panel are not preprocessed to increase the number of visual gray levels and compensate the characteristics of the EPD. In this paper, we present an integrated image tool to automatically estimate the reflectance function curves under different ambient temperatures, perform adaptive image halftoning to improve visual quality, and calibrate the image to compensate the nonlinear response of EPD. The proposed approach has been verified on practical EPD panels and promising results have been achieved.

A novel microelectromechanical-systems (MEMS)-controlled paper-like transmissive flexible display device was modeled by a combination of a cantilever with a flat plate and was realized by roll-to-roll printing process for the first time. This model provides predictions as well as improvement suggestions to both mechanical and electrical designs. A newly developed roll-to-roll printing process which was composed of flexography, gravure, lift-off, and lamination techniques used to manufacture this device was proved applicable on flexible electronics with high-volume, low-cost, and large-area solutions. This 20 V-driven device provided distinguishable three primary colors with averaged transmittance of 50% in visible region for full color flexible display applications and showed commercialization compatibility. Its electrical, mechanical, and optical characteristics excelled previous similar works. The proved major advantages of mechanical reliability, low operation voltage, and process simplicity done by this work made the MEMS flexible display an important alternative to electrophoretic, electrowetting, and electrochromic systems.

Electrochromic (EC) type e-paper is attracted with colorfulness and clearness. We have been researching and developing the material for EC type e-paper. We developed novel EC Polymers for e-paper. Our EC polymers are kinds of conductive polymers (CP). CP has some characteristics. One is electrochromism, and the other is electrochemical polymerization. Electrochromism of CP has a good memory effect. And electrochemical polymerization is suitable for printable electronics, for instance, ink-jet, screen print, and so on. Our EC polymers are comprised with thiophene derivatives and pi-conjugated X unit. To our knowledge, this thiophene derivatives are novel structure for EC polymers. These EC polymers have the electrochromic characteristic which change from coloration state to clear state. And we can adjust the color which we want by changing only X unit. And we made segment matrix EC display with our EC polymers by ink-jet printing. Our EC polymers are suitable for printable electronics, flexible substrate, and roll-to-roll process. We introduce our developing technologies.

Electrophoretic displays (EPDs) have become the main solution to electronic paper because of its invariably reflective and bistable properties. With different requirements of display resolution, speed, and contrast ratio, the electronic paper (E-paper) designers may adopt different types of electrophoretic material and active matrix backplane for building the system. The driving waveforms should be also customized for accommodating different application specifications and environment temperature. In this paper, we present a configurable EPD controller which can support various application specifications. In addition to providing a new architecture of compacted waveform lookup tables, the controller supports partial image update and integrates a real-time halftoning engine for improving image quality. The design has been implemented on a field-programmable gate array (FPGA) and tested with several real EPDs.

The purpose of this paper is based on micro fabrication technology, while integrating planar waveguide technology and the scattering phenomenon generated by electro-statically actuator thin film, to develop a 2-dimensional display technology capable of being cleared and re-displayed. For thin film displacement, the restoration of inward elasticity needs to be overcome. During thin film displacement, attraction due to suction occurs when coming into contact with light waveguide; electrostatic force and elastic force are restored and mutually balanced, causing display to light up. On the other hand, when input voltage is released, electrostatic force stops and thin film is restored to original position, causing display to darken. The design structure uses SU-8 as supporting posts, and PDMS as the electrostatic thin film suspended above the glass substrate (light waveguide). The experimental results show that a waveguide with an electrode length of 250 μm (sub-pixel length), a micro-post height of 27 μm, and a PDMS film thickness of 16 μm requires an actuator voltage of 314 V; and a micro-post height of 27 μm, and a PDMS film thickness of 8 μm requires an actuator voltage of 189 V. Thus, with an arrayed micro-electrode design, electronic paper and panels with large color display area could be manufactured.

Writable cholesteric liquid crystal display (ChLCD) and the algorithm used to detect its image were developed. A hard tip such as the fingertip could be used to draw an image onto the surface of ChLCD. Two states i.e., focal conic state (dark state) as F-state, and planar state (bright state) as P-state were designated in this paper. F-state or P-state could be detected by measuring the capacitance of one pixel of test cell (12 mm times 15 mm/1 times 1). However, it could not be detected using the same method on a 4.1" ChLCD (241 mum times 241 mum/320 times 320) due to the effect of parasitic capacitance. The reason why we measured capacitances and detected F-state or P-state was to look for a method which could be applied to detect the drawn image on ChLCD. By using a writable ChLCD, a user should be able to draw an image on it, and then detect and save the drawn image. Therefore, the high frequency measurement and the algorithm were developed to detect the image on ChLCD. Moreover, color writable ChLCD was also introduced.

Visual performance and visual fatigue of electronic paper displays (electrophoretic display and cholesteric liquid crystal display) under ambient illuminances and light sources were studied and compared with paper. Forty-eight participants participated in a character-search task in the experiment. The results showed that search speed depends on the illuminance but not light source. Search speed increased as illumination increased from 300 lx (45.6 sec), 700 lx (44.18 sec) to 1500 lx (43.24 sec). The effect of medium display and polarity on accuracy was also significant. Accuracy was greater for electrophoretic display and positive polarity. However, the effect of illuminance and light source on visual fatigue was not statistically significant. Based on the results of this study, it seems that E-paper displays may need greater illumination (700 lx or higher).

To design various electronic papers, the panel designers may adopt different types of electrophoretic materials and active matrix backplanes for resolution, speed, and contrast ratio considerations. The electrical and optical characteristics are quite different under different design requirements so that a good display timing controller should provide an easy way to modify waveforms accordingly. In this paper, we present a configurable timing controller for active matrix electrophoretic displays (EPD). The design principle of driving waveforms is first discussed and the controller can support all variations of driving waveforms with pulse width modulation. The performance of the controller has been verified by several practical EPD systems.

A prototype of a novel mobile viewer system consisting of a mobile phone and a 13.1-inch 4096-color electronic paper display has been developed. The basic concept of the system, the technological study for realizing the concept, and the specifications of the prototype are described. Possible applications of the system are also proposed.

Electrical characteristics of the mechanically flexible driver LSI as thin as 35μm mounted directly on a flexible display panel were precisely analyzed. The high-voltage transistors on this LSI show the current decrease by 10-30% in high voltage region, comparing with that of an ordinary thickness LSI. These phenomena can be associated with a self-heating effect. We considered the thermal diffusion on the thin chip by changing material of the measurement stage. Moreover, we analyzed the transistor characteristics on the thin chip under convex and concave bending conditions. The drain current change by piezoresistive effect was observed.

We developed new principle of electronic paper that is one side (for 2D image) or double side (for stereoscopic 3D image) light printable rewritable matter with polarization dependent gray scale. It consists of one or two liquid crystal displays based on Optical Rewritable (ORW) technology, which is the development of rotation azo-dye photoalignment. Each ORW display uses bare plastic or polarizers as substrates. The conductor is not required, as the image is formed by rewritable states of azimuthal direction, which results in 2D pattern of the liquid crystal twist angle. Continuous grey image maintains proper performance even when the device is bent. Simple construction provides durability and low cost, thin substrates minimize parallax for 3D image. Fluorescent dye dopant of liquid crystal partly absorbs light in blue and re-emit in green specter range improving photopic reflection and enhancing color of the ORW e-paper.

Applications of amorphous oxide TFTs to electrophoretic display have been demonstrated. First, we focus attention on the low process temperature of amorphous In-Ga-Zn-O (a-IGZO) TFT and successfully fabricated a-IGZO TFT array onto poly-ethylene-naphthalate (PEN) films at room temperature. Subsequently, an a-IGZO TFT array was combined with electrophoretic display and we have successfully driven a flexible electrophoretic display by a-IGZO TFT. The image of the flexible display was not affected by bending. Secondly, taking advantage of the transparency of oxide TFT, we propose a novel display structure for electronic paper. In our display structure, an oxide TFT array is fabricated directly onto a color filter array, which facilitates good alignment of the color filter and the TFT array. This TFT and color filter array were laminated with electrophoretic frontplane and positioned at the viewing side of the display. In this structure, the electrophoretic display is driven from the viewing side of the display, which we call the "Front Drive" structure. We have successfully displayed QVGA 4 inch color electronic paper by the "Front Drive" structure.

Effects of character size under ambient illuminances and light sources on legibility of electronic paper displays (electrophoretic display and cholesteric liquid crystal display) were studied and compared with paper. Sixty subjects participated in a letter-search task in the experiment. The results showed that search speed depends on the illuminance but not light source. Search speed increased as the illuminance increase from 300, 700 to 1500 lx. Search speed also increased with the increase of character size, from character height of 1.4 mm (9.6 min visual angle), 2.2 mm (15.1 min visual angle) to 3.3 mm (22.7 min visual angle), and the increase leveled off at 4.3 mm (29.6 min visual angle). The effect of character size on accuracy was also significant. Accuracy increased with the increase of character size. However, the effect of illuminance and light source on accuracy was not statistically significant. Based on the results of this study, it seems that E-paper displays may need greater illumination (700 lx or higher), greater character size (3.3 mm or 22 min of visual angle).

We demonstrate a novel display structure for color electronic paper for the first time. Fully transparent amorphous oxide TFT array is directly deposited onto color filter array and combined with E Ink Imaging Film. Taking advantage of the transparent property of the oxide TFT, the color filter and TFT array are positioned at the viewing side of the display. This novel "Front Drive" display structure facilitates the alignment of the color filter and TFT dramatically.

The toner type paper‐like display (PLD) has been developed with two polymer particles having opposite polarity composed of polymer, colorant and external additives (nano‐sized silica). Nano‐sized silica with triboelectric charge was used for the charge control agent (CCA) and influenced on the electrostatic properties of the silica‐coated polymer particles. The surface morphology and the cohesiveness of silica‐coated polymer particles were changed with the silica coating time. From these results, it was verified that the PLD cell using silica‐coated particles (200 seconds) shows a good white appearance and low driving voltage.

A complete model for the internal particle distribution of electrophoretic image displays (EPIDs) is presented. From this model, simulation formulas for electrical and optical properties are calculated. These formulas incorporate both time dependence and voltage dependence. They make it possible to optimize display properties since the model is built up with physical parameters. Results are shown that prove that this model is indeed capable of complete optical and electrical transient simulation. The importance of centrifugation during display manufacturing is proven as a way to improve the switching speed of the display.