A novel spectrum‐sequential display design with a wide color gamut and reduced color breakup

Abstract— The advantage of RGB color‐sequential displays is that they have no color filters, but the disadvantage is that they need to run at high refresh rates (> >180 Hz) to prevent flicker and color breakup. An alternative color‐sequential display, which can operate at relatively low refresh rates (～ 100 Hz) without disturbing color breakup or flicker, has been developed. The display has two color filters per pixel (cyan and magenta) on the LCD panel and the backlight can generate two types of spectra (blue‐green and green‐red), which results in a wide gamut four‐primary display, effectively. One part of the paper describes the color reproduction, including color‐filter design, gamut mapping, and multi‐primary conversion. The other part deals with the reduced perception of color breakup on the novel spectrum‐sequential display compared to conventional color‐sequential displays.     

Electron‐beam curing of color filters for flexible‐display applications

Abstract— Color filters spin‐coated on plastic and glass substrates have been cured by electron‐beam radiation instead of by the conventional thermal‐heating method. The electron‐beam curing of the color filters has many advantages over the thermal curing method. Electron‐beam curing is, in principle, a non‐thermal method where low‐temperature (<100°C) curing of color filters on plastic substrates can be realized for the manufacturing process of flexible display panels. A color‐filter resist having a 1.5‐μm thickness was spin‐coated on plastic (polycarbonate) and glass (corning 1737) substrates. The effect of the electron‐beam radiation conditions, such as electron‐beam energy (0.3–1.0 keV), radiation dosage (10–200 kGy), and ambient oxygen has been characterized. The degree of curing was analyzed by using the characteristic absorption peaks at 808 and 1405 cm^?1 in the FT‐IR spectrum. These two peaks originate from the carbon double bonds (>C=C<) of the multi‐functional acrylate monomer which exist in the color‐filter resist. By electron‐beam radiation, the spin‐coated color filter can be effectively polymerized at g (glass transition temperature) of the plastic substrates. The electron beam can solve the problems of the conventional thermal curing method, such as thermal deformation of a plastic substrate and difficulty in achieving dimensional control of a color‐filter pattern due to a large coefficient of thermal expansion (20–70 ppm/°C) compared to that of a glass substrate.     

Synthesis and application of an alkylated pyrazole‐based azo dye for electrofluidic display

Electrofluidic display (EFD) is one of the most promising reflective displays for its full color and video speed. Colored EFD oil, normally formulated by soluble organic dyes in non‐polar solvent, dominates the color, electro‐optical behavior, and reliability performances for EFD devices. In this paper, a novel yellow electrofluidic dye with excellent solubility in non‐polar EFD solvent was achieved based on the introduction of long alkyl chain into pyrazole azo dye. The resulting EFD device fabricated by the dye showed excellent application properties, such as fast switching speed (17.8 ms), high aperture ratio (68.5%), low threshold voltage (24v), good light stability (240 h under accelerated conditions), and low backflow phenomenon.     

Micro‐cavity design of bottom‐emitting AMOLED with white OLED and RGBW color filters for 100% color gamut

Abstract— Two optical structures used for a bottom‐emitting white organic light‐emitting diode (OLED) is reported. An RGBW color system was employed because of its high efficiency. For red, green, and blue (RGB) subpixels, the cavity resonance was enhanced by the use of a dielectric mirror, and for the white (W) subpixel, the mirror was removed. The optical length of the cavities was controlled by two different ways: by the thickness of the dielectric filter on top of the mirror or by the angle of oblique emission. With both methods, active‐matrix OLEDs (AMOLEDs) that reproduced a color gamut exceeding 100% of the NTSC (National Television System Committee) standard were fabricated. More importantly, the transmission of a white OLED through R/G/B color filters was significantly higher (up to 50%) than that of a conventional structure not employing a mirror, while at the same time as the color gamut increased from ～75 to ～100% NTSC.     

Room‐temperature deposition of thin‐film indium tin oxide on micro‐fabricated color filters and its application to flat‐panel displays

Abstract— Direct deposition of indium tin oxide (ITO) thin film on color filters is of practical use in the fabrication of state‐of‐the‐art flat‐panel displays. Room‐temperature dc magnetron sputtering of thin‐film ITO and issues related to the integration of ITO‐on‐glass panels containing micro‐fabricated color filters and other functional materials have been investigated. The resulting polycrystalline ITO exhibited good adhesion to the underlying color filters, as well as good optical transparency and high electrical conductivity. Application of this ITO deposition technology to color liquid‐crystal and organic light‐emitting diode displays will also presented.     

Reduction of defects and improvement in the performance of blue phosphor for thick‐dielectric electroluminescent displays using Color‐by‐Blue

Abstract— Defect‐free large‐area inorganic thick‐dielectric EL (TDEL) displays using Color by Blue (CBB) technology have been successfully developed. We have achieved the world's highest blue‐phosphor luminance of 900 cd/m² for a single‐pixel device by using CBB and by optimizing the e‐beam gun configuration and the flow rate of H₂S in the vacuum chamber. By analyzing the defects on panels with triple‐pattern phosphors and CBB panels, we also found that the number of defects on CBB panels can be drastically reduced compared with those on triple‐pattern panels. The defect‐free 17‐in. VGA CBB panels show better characteristics, a high peak luminance of 600 cd/m² and a high contrast ratio of 1000:1, compared with those of triple‐pattern panels.     

RuleSIM: a toolkit for simulating the operation and improving throughput of rule‐based spam filters

This paper introduces RuleSIM, a toolkit comprising different simulation tools specifically designed to aid researchers concerned about spam‐filtering throughput. RuleSIM allows easily designing, developing, simulating and comparing new scheduling heuristics using different filters and sets of e‐mails. Simulation results can be both graphically analysed, by using different complementary views, and quantitatively compared through several measures. Moreover, the underlying RuleSIM API can be easily integrated with third‐party Java optimization platforms to facilitate debugging and achieve better configurations for rule scheduling. RuleSIM is free software distributed under the terms of GNU Lesser General Public License, and both source code and documentation are publicly available at https://github.com/rulesim/v2.0 . Copyright © 2015 John Wiley & Sons, Ltd.     

The influence of the hole transport layers on the performance of blue and color tunable quantum dot light‐emitting diodes

The performance of the blue quantum dot light‐emitting diodes (QLEDs) is largely affected by the hole transport layers (HTLs). As a consequence of the deep valance band level of blue quantum dots (QDs), hole injection is relatively difficult in blue QLEDs. To favor the hole injection, HTLs with high hole mobility and deep‐lying highest occupied molecular orbital level are desired. In this work, various HTLs and their influence on the performance of blue QLEDs are demonstrated. Devices with poly(N‐vinylcarbazole) (PVK) HTL exhibit the highest external quantum efficiency while devices with poly[9,9‐dioctylfluorene‐co‐N‐(4‐(3‐methylpropyl))‐diphenylamine] (TFB) exhibit the lowest driving voltage. By combining the advantages of PVK and TFB, the blue QLEDs with TFB/PVK bilayered HTL simultaneously exhibit a low driving voltage of 2.6 V and a high external quantum efficiency of 5.9%. Moreover, the exciplex emission at the interface of HTL/QDs is also observed, and the emission intensity can be tuned by modulating the hole injection. By utilizing PVK doped with 25% poly(3‐hexylthiophene) (P3HT) as HTL, exciplex emission is significantly enhanced at low driving voltage while QD emission is dominant at high driving voltage. By combining the exciplex emission and the QD emission, the emission color can be effectively tuned from red to blue as the driving voltage changing from 2 to 10 V.     

Rapid design closure of microwave components by means of feature‐based optimization and adjoint sensitivities

In this article, fast design closure of microwave components using feature‐based optimization (FBO) and adjoint sensitivities is discussed. FBO is one of the most recent optimization techniques that exploits a particular structure of the system response to “flatten” the functional landscape handled during the optimization process, which leads to reducing its computational complexity. When combined with gradient‐based search involving adjoint sensitivities, the design cost becomes even lower, allowing us to find the optimum design using just a few electromagnetic (EM) simulations of the structure at hand. Here, operation and performance of the algorithm is demonstrated using a waveguide filter and a miniaturized microstrip rat‐race coupler (RRC). Comparative studies indicate considerable savings that can be achieved even compared with adjoint‐based gradient search. In case of RRC, numerical results are supported by experimental validation.     

Color tuning of indium phosphide quantum dots for cadmium‐free quantum dot light‐emitting devices with high efficiency and color saturation

Semiconductor quantum dots (QDs) promise facile color tuning and high color saturation in quantum‐dot light‐emitting devices (QD‐LEDs) by controlling nanoparticle size and size distribution. Here, we demonstrate how this promise can be practically realized for the cadmium‐free InP/ZnSe/ZnS multishell quantum dots. We developed a set of synthesis conditions and core/shell compositions that result in QDs with green, yellow, and red emission color. The QD‐LEDs employing these QDs show efficient electroluminescence (EL) with luminance up to 1800 cd/m² and efficiency up to 5.1 cd/ A . The color coordinates calculated from the EL spectra clearly demonstrate the outstanding color saturation as an outcome of the narrow particle size distribution. These results prove that the performance gap between cadmium‐free and cadmium‐based QDs in QD‐LEDs is shrinking rapidly.     

Fractional‐order–dependent global stability analysis and observer‐based synthesis for a class of nonlinear fractional‐order systems

This paper focuses on proposing novel conditions for stability analysis and stabilization of the class of nonlinear fractional‐order systems. First, by considering the class of nonlinear fractional‐order systems as a feedback interconnection system and applying small‐gain theorem, a condition is proposed for L₂‐norm boundedness of the solutions of these systems. Then, by using the Mittag‐Leffler function properties, we show that satisfaction of the proposed condition proves the global asymptotic stability of the class of nonlinear fractional‐order systems with fractional order lying in (0.5, 1) or (1.5, 2). Unlike the Lyapunov‐based methods for stability analysis of fractional‐order systems, the new condition depends on the fractional order of the system. Moreover, it is related to the H_∞‐norm of the linear part of the system and it can be transformed to linear matrix inequalities (LMIs) using fractional‐order bounded‐real lemma. Furthermore, the proposed stability analysis method is extended to the state‐feedback and observer‐based controller design for the class of nonlinear fractional‐order systems based on solving some LMIs. In the observer‐based stabilization problem, we prove that the separation principle holds using our method and one can find the observer gain and pseudostate‐feedback gain in two separate steps. Finally, three numerical examples are provided to demonstrate the advantage of the novel proposed conditions with the previous results.     

Control performance‐based fault detection and fault‐tolerant control schemes for a class of nonlinear systems

The objective of this paper is to develop performance‐based fault detection (FD) and fault‐tolerant control (FTC) schemes for a class of nonlinear systems. To this end, the representation forms of nonlinear systems with faults and the controller parameterization forms are studied first with the aid of the nonlinear factorization technique. Then, based on the stable kernel representation and the stable image representation of the faulty nonlinear system, the stability performance of the closed‐loop system is addressed, respectively. The so‐called fault‐tolerant margin is defined to evaluate the system fault‐tolerant ability. On this basis, two performance‐based FD schemes are developed aiming at detecting the system performance degradation caused by system faults. Furthermore, to recover the system stability performance, two performance‐based FTC strategies are proposed based on the information provided by the FD unit. In the end, a numerical example and a case study on the three‐tank system are given to demonstrate the proposed results.     

The design of radio frequency energy harvesting and radio frequency‐based wireless power transfer system for battery‐less self‐sustaining applications

In this paper, the RF energy harvesting system and RF‐based wireless power transfer system are proposed and designed for battery‐less self‐sustaining application. For energy harvesting, the designed antenna array improves the received RF power effectively and also can harvest RF energy in multi‐frequency bands. For wireless power transfer, the proposed helical antenna realizes the system design in miniaturization. Subsequently, the T shape LC matching network are designed between the antenna and the rectifying circuit to obtain more power transmission. The measured results show that the proposed Wi‐Fi rectifier and 433 MHz rectifier offer a maximum conversion efficiency of 66.8% and 76% in case of the input power is ?3 dBm and 0 dBm, respectively. Finally, the performance of the RF‐based wireless power transfer system and RF energy harvesting system are attested by experimentally measurement, the measured results indicate that these systems can be used to power electronic.     

Triangular norm‐based cuts and possibility characteristics of triangular intuitionistic fuzzy numbers for decision making

Triangular intuitionistic fuzzy numbers (TIFNs) is one of the useful tools to manage the fuzziness and vagueness in expressing decision data and solving decision making problems. In this paper, triangular norm (t‐norm) based cuts of TIFNs are developed to synthesize the membership and nonmembership functions in describing the cut sets, then the possibility characteristics of TIFNs, i.e., the possibility mean, the possibility variance, and the possibility mean‐standard deviation ratio, are given. Thereby, on the ground of the possibility mean‐standard deviation ratio, a ranking method of TIFNs is introduced. With these elements, an approach to multiple attributes decision making (MADM) is proposed and illustrated by a numerical example. It is shown that the approach to MADM comprehensively considers both the membership and nonmembership functions and can lead to objective and reasonable results.     

Design and measurement‐based characterization of a K‐band metalens for wideband oblique‐incident spherical‐plane wave conversion

In this article, a wideband spherical‐plane wave conversion metalens (WSPCM) working in the K‐band is designed. The WSPCM consists of metamaterial elements with gradient transmission phases, which can transform the oblique‐incident spherical wave to the plane wave propagating along the direction from the source to the center of the metalens. First, a five‐layer metamaterial element with gradient transmission phase is designed using the Computer Simulation Technology software. Then, a metamaterial wedge consists of eight metamaterial elements with 30° phase gradient (that can deflect the incident plane wave by 30°) is designed to verify the phase modulation characteristic of the metamaterial element. Afterwards, a metalens is designed according to the digitized phase distribution of the dielectric lens. Finally, the electric field distribution of the emitted wave at different frequencies and different source locations (ie, oblique‐incident angles) is studied. The design is validated through simulations and measurements.     

Thermal management of edge‐lit wide color gamut backlight for LCD using red laser diodes and cyan LEDs

The color gamut is one of the critical parameters that dictate the image quality of displays. The liquid crystal displays using white color light‐emitting diodes (LEDs) as the backlight, though having been widely employed recently, are not very satisfactory in terms of their color gamut because of the broad spectrum inherent to white LEDs. This prompted the authors to develop improved liquid crystal displays using an edge‐lit wide color gamut backlight that used red laser diodes and cyan LEDs. Generating laser beams with high color purity, the laser diodes are light sources with a significant effect on expanding the color gamut. However, laser diodes, red ones in particular, have unfavorable thermal characteristics. To cope with this shortcoming, the authors clearly defined the restrictive criteria for laying out two kinds of light source on the edge‐lit backlight and made a prototype 55‐type laser backlight for performance evaluation.