铁电液晶显示器记忆特性的Pspice可视化分析

从简洁的铁电液晶SmC^*相力学模型出发，开发了铁电液晶显示器（FLCD）的Pspice可视化系统；通过引入多种激励源，控制激励信号的幅值、脉宽、占空比和取样参数，对FLCD的驱动阈值、状态翻转、透射率、响应时间和记忆行为进行了实时仿真。分析结果表明，系统已理想地拟合了相关报道的实验结果，并显示出良好的记忆和存储性能。本方法将有助于光电混合集成系统的计算机辅助设计研究。     

Analysis of colorimetric system under foggy, thermal and electrical conditions with /

Human perception of an object is modeled in and simulated in . A colorimetric package incorporating CIE color representation standards is defined in . The colorimetric system under foggy, thermal, and electrical conditions is considered and analyzed as a multi-technological system when the light source is perceived to the eyes of people. Our / translator compiles models which reference the package. The results of this work can be useful for the pilots of an aircraft guided by runway display systems after landing or before taking-off under severe conditions.     

Design Considerations Between Color Gamut and Brightness for Multi-Primary Color Displays

Color displays show a vivid colorful image by combination of three or above primary colors on every individual pixel. Brightness of color displays, however, strongly restricts the color gamut of displays. From the color mixing theory, the area of color gamut on the color coordination would shrink smaller when brightness grows up. At the maximal brightness, displays can show one system white point only. The difficulties how to obtain the maximal brightness under an assigned color point or color gamut have been a key issue for display manufacturers. The paper proposes a theory to analyze the relation between brightness and color gamut based on the multi-primary color display. Simulations estimate the boundary of color gamut of multi-primary color displays under required brightness which had been proved by experimental results of tri-primary color display. The theory can be applied on the color temperature (CT) design which experimental results show the fact that a display apparatus with higher color temperature could sacrifice brightness less compared to one with lower color temperature when color temperature of the display image needs to change. The theory provides a design guideline for optimization between color gamut, color temperature and brightness on multi-primary color displays     

The matrix converter drive performance under abnormal input voltage conditions

The matrix converter (MC) is a direct frequency conversion device with high input power quality and regeneration capability. As a device without energy storage elements, it has higher power density than pulse-width modulation (PWM) inverter drives. However, for the same reason, the AC line side disturbances can degrade its performance and reliability. In this paper, the behavior of the MC drive under abnormal input line voltage conditions has been investigated. A technique to eliminate the input current distortion due to the input voltage unbalance has been developed and its feasibility proven via computer simulations and laboratory experiments. The power line failure behavior has also been investigated and the rapid restarting capability of the MC drive has been demonstrated via laboratory experiments.     

True color 1024×768 microdisplay with analog in-pixelpulsewidth modulation and retinal averaging offset correction

A liquid-crystal-on-silicon microdisplay based on a 1024×768 two-dimensional pixel array fabricated in a digital 0.35-μm CMOS process displays images with a color depth of 8 bits per color. The pixel pitch is 12 μm and the total chip area is 214 mm². Pixel brightness is controlled by modulating the pulsewidth of the pixel voltage drive signal with an in-pixel analog pulsewidth modulation (PWM) circuit which utilizes human optic nerve spatio-temporal averaging to eliminate comparator offset. The 16 million transistor chip displays images at a maximum rate of 85 Hz and has a power dissipation of 200 mW from a single 3.3-V supply     

Carbazole-based polymers as hosts for solution-processed organic light-emitting diodes: Simplicity,efficacy

Polymer light emitting diodes (PLEDs) have attracted a great deal of interest within academia and industry because of their potential applications in flat panel displays and solid-state lighting technologies. The solution processability of polymers offers the advantages of simple and mild fabrication conditions enabling to cut cost and produce large area displays. Among all polymeric hosts under investigation, carbazole-based materials benefit from the wide bandgap of carbazole as well as its remarkable thermal, photochemical and chemical stability. Especially, the relatively high triplet energy level of carbazole makes it an appealing candidate to design hosts for wide bandgap triplet emitters such as blue dopants. In this review, an overview of all carbazole-based polymeric hosts reported to date is presented. Noticeably, easiness of synthesis has been an aspect largely developed to access to these polymeric structures.     

A CDMA InGaP/GaAs-HBT MMIC Power Amplifier Module Operating With a Low Reference Voltage of 2.4 V

This paper describes circuit design and measurement results of our newly developed InGaP/GaAs-HBT MMIC power amplifier (PA) module which can operate with 2.4-V low reference and low supply voltages of its on-chip bias circuits. To achieve the low-reference voltage operation, the following two new circuit design techniques are incorporated into the power amplifier: 1) AC-coupled, divided power stage configuration with two different kinds of bias feeding (voltage and current drive and only current drive) and 2) successful implementation of a diode linearizer built in the power stage. Theses two techniques allow the PA to offer smooth output transfer characteristics over a wide temperature range. Measurement results done under the conditions of 900 MHz, a 3.5-V collector voltage for power stage, and 2.4-V reference and collector voltages for the bias circuits show that the PA module meets J-/W-CDMA power and distortion requirements sufficiently over a wide temperature range from -10degC to 90degC while keeping a low quiescent current of less than 65 mA. For J-CDMA modulation, the module can deliver a 27.5-dBm output power (P_out), a 40% PAE, and a -50-dBc ACPR, while a 28-dBm P_out, a 42% PAE, and a -42-dBc ACLR are achieved for W-CDMA modulation.     

Liquid-crystal display prospects in perspective

The advantages of dynamic scattering liquid-crystal displays--extremely low power consumption, flexibility of size and format, color choice, and washout immunity--are not obtained without cost. Long life requires ac drive and hermetic packaging. The optical characteristics of dynamic scattering make it difficult to design a display that utilizes the liquid-crystal panel effectively under a variety of lighting conditions. Multiplexed drive is cumbersome at best, so cost of drive electronics for more than about four digits is higher than with competing display technologies. The development of twisted nematic displays will reduce drive costs and improve appearance although the changes will not be revolutionary. The large multiplexing capability or color variability of the alterable birefringence effect is offset by prohibitive manufacturing tolerances and narrow field of view. Led by low-power digital wristwatches, liquid crystals should achieve a substantial market in applications whose requirements match unique display properties. Effective penetration of the consumer mass market will await improved field-effect devices and reductions in semiconductor packaging costs.     

Gallium phosphide monolithic display with low drive power

A gallium phosphide monolithic numeric display with seven segments has been developed by a mesa-etching technique. Internal absorption of red emission is small so that optical isolation is very difficult in monolithic-type displays. This obstacle has been overcome by sufficiently deep mesa-etching in hot aqua regia, using a stable SiO2film as a mask. Luminance and optical isolation of segments are found to be largely dependent on the configuration of the rear contacts and have been much improved by the effective combination of a highly reflective contact and an absorbing contact. Completed devices with a digit size of 3.1 mm high and 1.7 mm wide are operated at only 10 mA per digit with a luminance of 100 fL. The ratio of the luminance of the excited and unexcited segments is as high as 85:1 in the dark.     

A simulation-based multi-objective design optimization of electronic packages under thermal cycling and bending

In this study, a simulation-based multi-objective design optimization methodology was developed for improving electronic packaging reliability. It was demonstrated using a generic model of an electronic package on a printed wiring board. The objective for the optimization was to improve the reliability of solder joints under both thermal cycling and bending by optimizing a group of design parameters. A parametric finite element model was developed using ANSYS for both load conditions. To improve the numerical efficiency of the optimization, a multi-quadric response surface method was implemented to approximate the response of finite element simulations for each loading condition. Subsequently, the multi-objective optimization of solder joint reliability was implemented using a Minmax principle on all response surfaces and a differential evolution algorithm as optimal search engine, which is capable of finding global minimum when local minima exist. Our study demonstrated that the reliability of the solder joints is significantly improved for this given generic model of electronic package. The proposed methodology can be effectively used in improving the reliability of electronic packages.     

Voltage‐Dependent Multicolor Electroluminescent Device Based on Halide Perovskite and Chalcogenide Quantum‐Dots Emitters

Electroluminescent devices based on metal halide perovskites have attracted extensive attention owing to their high external quantum efficiency, excellent color purity, and inexpensive solution process. So far, extensive efforts have been made to improve the efficiency of the monochromatic perovskite light‐emitting diodes (LEDs). However, multicolor perovskite‐based LEDs are seldom studied. Here, an individual device capable of multicolor emission in response to the passage of external electric bias is demonstrated. With the rational design of the energy band alignment and control of the carrier transport property, color‐tunable electroluminescent devices based on inorganic halide perovskite and chalcogenide quantum‐dots are fabricated with a wide color tuning range, high color reversibility, and ultrafast color switching. The mechanism of chromaticity tuning is investigated and is explained by the shift of the exciton recombination zone with the driving voltage. The presented work will impact scientific communities by encouraging the manufacture of cost‐effective, high‐resolution, and full‐color displays and human‐centric lighting.     

A novel a-Si:H AMOLED pixel circuit based on short-term stress stability of a-Si:H TFTs

This letter presents a novel pixel circuit for hydrogenated amorphous silicon (a-Si:H) active matrix organic light-emitting diode displays employing the short-term stress stability characteristics of a-Si:H thin film transistors (TFTs). The pixel circuit uses a programming TFT that is under stress during the programming cycle and unstressed during the drive cycle. The threshold voltage shift (V/sub T/-shift) of the TFT under these conditions is negligible. The programming TFT in turn regulates the current of the drive TFT, and the pixel current therefore becomes independent of the threshold voltage of the drive TFT.     

一种新型单偏振片反射式液晶显示器的设计

提出一种新型单偏振片反射式液晶显示器的设计方案。采用共面转换模式并在液晶和反射板之间加入四分之一光延迟膜。通过使用参数空间表示法优化选择器件参数,获得了高反射率、低色散和宽视角的常白、常黑反射式显示模式。     

An advanced permanent magnet motor drive system for battery-poweredelectric vehicles

Availability of high-energy neodymium-iron-boron (Nd-Fe-B) permanent magnet (PM) material has focused attention on the use of the PM synchronous motor (PMSM) drive for electric vehicles (EVs). A new Nd-Fe-B PMSM is proposed for the drive system, which possesses high power density and high efficiency, resulting in greater energy and space savings. The design and optimization of the motor employs finite element analysis and computer graphics. Increasingly, a new PWM inverter algorithm is developed for the drive system, which can handle the nonconstant battery voltage source. An efficiency optimizing control is adopted to further improve the energy utilization of the drive system. Both the control strategy and the PWM generation are implemented in a single-chip microcontroller. As a result, the motor drive achieves high power density, high efficiency, and compactness. A prototype of the 3.2 kW battery-powered drive system has been designed and built for an experimental mini-EV     

Active-Matrix Amorphous-Silicon TFTs Arrays at 180$^circhboxC$on Clear Plastic and Glass Substrates for Organic Light-Emitting Displays

An amorphous-silicon thin-film transistor (TFT) process with a 180$^circhboxC$maximum temperature using plasma-enhanced chemical vapor deposition has been developed on both novel clear polymer and glass substrates. The gate leakage current, threshold voltage, mobility, and on/off ratio of the TFTs are comparable with those of standard TFTs on glass with deposition temperature of 300$^circhboxC$–350$^circhboxC$. Active-matrix pixel circuits for organic light-emitting displays (LEDs) on both glass and clear plastic substrates were fabricated with these TFTs. Leakage current in the switching TFT is low enough to allow data storage for video graphics array timings. The pixels provide suitable drive current for bright displays at a modest drive voltage. Test active matrices with integrated polymer LEDs on glass showed good pixel uniformity, behaved electrically as expected for the TFT characteristics, and were as bright as 1500$hboxcd/hboxm^2$.     

Development of an implantable motor-driven assist pump system

A motor-driven artificial pump and its transcutaneous energy transmission (TET) system have been developed. The artificial pump consists of a high-speed dc brushless motor driving a ball screw and magnetic coupling mechanism between the blood pump and ball screw. The ball screw transfers high-speed rotary motion into low-speed rectilinear motion by a single component. Magnetic coupling enables active blood filling without applying an excess negative pressure to the pump. The transcutaneous transformer is formed from a pair of concave/convex ferrite cores. This design minimizes lateral motion of the external core. Information on motor voltage is transmitted through the skin by infrared pulses. The motor voltage is regulated by controlling the duty ratio of the square pulse supplied to the primary coil. Pump flow of 5.6 l/min was obtained with a mean outlet pressure of 100 mmHg at a drive rate of 100 bpm under preload of 15 mmHg. The performance of synchronous pumping has been very satisfactory. Continuous pumping was maintained by the backup battery in the case of interruption of TET. 24 W were transmitted by TET system with 78 percent of efficiency. Temperature rise of the internal core was 0.2 C. The developed system is promising as an implantable assist pump system.     

Improved 40-inch plasma display for wall-hanging HDTV receiver

A new 40-inch-diagonal color dc plasma display panel (cell pitch: 0.65 mm, 800×1340 cells) with both a resistor-in-cell structure and a phosphor screen on the side wall and bottom of the cell has been developed through the improvement on the large-area panel fabrication technologies. Stable HDTV pictures have been experimentally reproduced on a compact display using the new panel and pulse memory drive circuits. The peak white luminance is 150 cd/m². The lifetime of the 40-inch panel is expected to be over 30,000 hours, judging from the results obtained using a medium-sized panel under the same conditions     

Improved Multilevel Hysteresis Current Regulation and Capacitor Voltage Balancing Schemes for Flying Capacitor Multilevel Inverter

This paper focuses on the development of multilevel hysteresis current regulation strategies. Two such strategies have been discussed and some modifications in their control tasks have been proposed to achieve more reliable and improved performance. In general, the multiband concept has been used while making the proposals. The hysteresis band size considerations have also been presented by taking into account the desired and existing system conditions. The proposed modulation schemes have been applied to a five-level flying-capacitor inverter, whose operation under hysteresis current control mode is much less established. A new method of flying-capacitor voltage balancing is proposed which ensures balanced flying-capacitor voltages and, at the same time, maintains the desired current profile. It uses a time-based approach for controlling the capacitor voltages and achieves appreciable voltage spectrum under wide range of load power factor conditions. The performance of the proposed strategies is confirmed through both simulation and experimental investigations.     

Charge pump design for high-voltage biasing applications in piezoelectric-based miniaturized robots

Fully autonomous piezoelectric-based miniaturized robots usually have a high-voltage biasing system that provides the required voltage levels to drive properly their piezoelectric actuators. In this paper a novel on-board biasing system based on the cascade connection of three full-custom charge pump ICs is presented. Simulated and experimental results show that the proposed biasing system is capable to obtain a regulated output voltage up to 20 V from a 3.3 V battery and deliver successfully up to 120 mW of power. Moreover, a novel approach in the steady-state analysis of the two-phase voltage doubler (which is the core of the designed charge pump IC) has been developed in order to have a tool capable to provide a full understanding of the steady-state voltage doubler’s behavior while at the same time accelerate and simplify the design process of such circuit. Simulated results show that the proposed mathematical model is more accurate than already developed models. The design of the charge pump IC has been implemented using a commercial 0.7 μm Bipolar-CMOS-DMOS (BCD) technology.     

An analytic and accurate model for the threshold voltage of short channel MOSFETs in VLSI

Based on the two-dimensional Poisson equation, the surface potential distribution along the surface channel of a MOSFET has been analytically derived by assuming negligible source and drain junction depths and its minimum potential is then used to determine the threshold voltage. The existence of a minimum surface potential point along the channel of a MOSFET under an applied drain bias is consistent with the numerical results of the two-dimensional analysis. The effects of finite source and drain junction depths have been elegantly included by modifying the depletion capacitance under the gate and the resulted threshold voltage model has been compared to the results of the two-dimensional numerical analysis. It has been shown that excellent agreement between these results has been obtained for wide ranges of substrate doping, gate oxide thickness, channel length (< 1 μm), substrate bias, and drain voltage. Moreover, comparisons between the developed model and the existing experimental data have been made and good agreement has been obtained. The major advantages of the developed model are that no iterations and no adjustable fitting parameters are required. Therefore, this simple and accurate threshold voltage model will become a useful design tool for ultra short channel MOSFETs in future VLSI implementation.