Printable Semiconductors for Backplane TFTs of Flexible OLED Displays

Studies on printable semiconductors and technologies have increased rapidly over recent decades, pioneering novel applications in many fields, such as energy, sensing, logic circuits, and information displays. The newest display technologies are already turning to metal oxide semiconductors, i.e., indium gallium zinc oxide, for the improvements needed to drive active matrix organic light‐emitting diodes. Convenience and portability will be realized with flexible and wearable displays in the future. This report summarizes recent progress on the development of solution‐processed thin film transistors, especially those deposited at low temperatures for next‐generation flexible smart displays. The first part provides an overview on the history and current status of displays. Then, recent advances in state‐of‐the‐art solution‐processed transistors based on different semiconductors are presented, including metal oxides, organic materials, perovskites, and carbon nanotubes. Finally, conclusions are drawn and the remaining challenges and future perspectives are discussed.     

利用FPGA的全彩OLED显示器控制电路

根据有机发光二极管(OLED)的特性,利用解码模块和FPGA控制模块,设计OLED视频动态图像驱动控制电路。介绍了如何采用FPGA实现OLED视频显示控制电路的方法,分析了电路中各个模块的作用及整个电路的工作过程。从组成框图、硬件设计以及软件流程等几方面介绍了该OLED的驱动电路,给出了硬件接口电路图。其中,FPGA由硬件描述语言(VerilogHDL)设计了控制电路,从DVI接口获取动态图像,获得了能实时动态显示的3.8cm(1.5in)128×(128×3)全彩色PM-OLED显示屏显示。     

OLED点阵驱动电路设计及OLED驱动特性研究

设计了一种方便测试OLED显示屏特性的驱动电路。用此驱动电路研究了与驱动方式相关的(OLED显示屏特性即“串扰”、老化、击穿等，观测到与OLED“形成过程”相对应的“恢复过程”。实验结果表明．通过对驱动电路采取适当的措施，能够减轻“串扰”和击穿对显示屏造成的影响，并延长显示屏的使用寿命。     

串联电容补偿线路距离保护研究

随着大容量远距离输电的发展,串联电容补偿技术在超高压、远距离输电中得到了广泛应用。文中介绍了串联电容补偿装置的构成、工作原理,以及等效模型的不同工作方式,分析了MOV的工作特性。串联电容补偿技术是一项成熟的技术,通过串联电容补偿线路感抗,缩短交流传输的电气距离,降低线路输送损耗,改善线路的电压质量,提高线路传输功率,更加合理地分布输送功率,提高系统的动态稳定和静态稳定性。     

有机电致发光产品的研发现状

有机电致发光器件(OLED)具有驱动电压低、主动发光等优势,在平板显示领域引起了广泛的关注。本文介绍了近年来有机电致发光产品的研发状况,并展望了OLED的商业前景。     

OLED电视的发展潜力和应用前景

2007年12月份索尼公司推出了第一款可用于商品化的OLED电视,此项创举轰动一时。此后他们持续致力于研究改进,文章将对索尼公司在大尺寸AMOLED电视上的研发成果和量产化进程做一详细介绍。     

一种新颖的激光驱动器芯片温度补偿电路

基于对激光二极管(LD)输出光功率与流过其上的电流及温度变化关系的分析,研究了激光驱动器芯片温度补偿电路的补偿原理和实现方案,提出了一种简单新颖的称之为温控电流开关的电路,通过片外编程对输出调制电流的温度补偿起点以及补偿力度进行调节.仿真结果显示3.3V工作电压下该电路调制电流的温度补偿斜率可从400 ppm/℃到 2×104 ppm/℃变化,调制电流的温度补偿起点可从20 ℃到75 ℃变化,从而能够灵活地满足不同激光二极管的不同特性的要求.     

External Compensation of Nonuniform Electrical Characteristics of Thin-Film Transistors and Degradation of OLED Devices in AMOLED Displays

The variation of electrical characteristics of polycrystalline-silicon thin-film transistor (TFT) and degradation of organic light-emitting-diode (OLED) device cause nonuniform intensity of luminance and image sticking in active-matrix OLED (AMOLED) displays. An external compensation method that senses and compensates variations of threshold voltage and mobility of TFTs and degradation of OLED device is proposed. The effect of the external compensation method on AMOLED pixel is experimentally verified by measuring the luminance of OLEDs and the electrical characteristics of TFTs in AMOLED pixels.      

Method of Measuring Ultralow Water Vapor Permeation for OLED Displays

It is well known that proper encapsulation is crucial for the lifetime of organic LED (OLED) displays. With the development of better and better barrier coatings and perimeter seals, it has now become very desirable to be able to precisely measure the rate of water vapor and oxygen permeation through barrier coatings and perimeter sealing. This paper demonstrates a new permeation measurement method that uses tritium-containing water (HTO) as tracer materials. The theoretical detection limit is 2.4/spl times/10/sup -7/ g/(m/sup 2//spl middot/day).     

Mirrored OLED pixel circuit for threshold voltage and mobility compensation with IGZO TFTs

In this paper, pixel circuit using mirroring structure with Indium–Gallium–Zinc oxide (IGZO) thin film transistors (TFTs) for active matrix organic light emitting diode (AMOLED) display is proposed. This pixel circuit consists of only four TFTs, and one capacitor. Due to the mirroring structure, characteristic of the driving TFT can be precisely sensed by the sensing TFT, which is deployed in a discharging path for gate electrode of the driving TFT. This discharging process is strongly dependent on threshold voltage (V_T) and effective mobility of the sensing TFT. Circuit operating details are discussed, and compensation effects for threshold voltage shift and mobility variations are verified through numerical derivation and SPICE simulations. Furthermore, compared with conventional schematics, the proposed pixel circuit might have much simplified external driving circuits, and it is a promising alternative solution of high performance AMOLED display.     

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$hboxcd/hboxm^2$.     

用于OLED驱动电路的振荡器设计

有机发光二极管(OLED)在不同的工作温度下发光亮度不同,严重影响显示效果。为解决这一问题,需要在驱动芯片中设计温度传感器,实时采样温度信息来调整光亮度。利用带隙基准原理设计了一种输出信号的频率与绝对温度成线性关系的振荡器。通过带隙基准电源产生与绝对温度成正比例的电流,使用该电流对电容充放电以实现信号的振荡。采用CSMC 0.18μm CMOS工艺对电路仿真,电源电压设置为1.8 V,TT标准工艺角,仿真温度设置为0℃时,输出信号频率为3.447 MHz。温度每升高1℃,输出信号的频率增加16 k Hz,可以为OLED驱动电路提供精确的温度信息。     

Predicting Method of Leakage Current in Multiple-Gate Amorphous Silicon TFTs for Active-Matrix Electrophoretic Displays

The large off-state drain–source leakage current of the thin-film transistor (TFT) in active-matrix electrophoretic display (AMEPD) may cause severe crosstalk and long pixel refresh time. Multiple-gate amorphous silicon TFT (a-Si TFT) is a common use to overcome this issue. In this paper, we show that the leakage current of multiple-gate a-Si TFT can be computed from the $I$–$V$ characteristics of a single TFT by an analytical current model. The predicted leakage currents show good agreement with the expected values in SPICE simulation. This model is also applicable for the multiple-gate a-Si TFTs used in other high voltage driven devices.      

AMOLED电流镜像像素电路的稳定性分析

a—Si：HTFT在长时间施加直流栅偏压下将导致晶体管闽值电压漂移,造成OLED的发光亮度下降,影响其使用寿命。而多管的像素电路设计可以补偿或消除阂值电压的漂移。本文分析了电流控制电流镜像像素电路的工作原理。结合a—Si：HTFT阈值漂移模型仿真了电路在长时间工作下阈值漂移对驱动电流稳定性的影响,并提出了相应的解决办法。研究结果表明合理的像素电路设计可以有效改善驱动电流的稳定性。     

用于器件描述和电路仿真的新型多晶硅TFT直流模型

提出一种新型的多晶硅薄膜晶体管电流-电压物理模型.考虑了陷阱态密度的V形指数分布,运用Lambert W函数推出了表面势的显式求解方法,大大提高了运算效率,在电路仿真中发挥了重要作用.基于指数的陷阱态密度和计算的表面势,描述了亚阈值区和强反型区的漏电流特性.推导了完整、统一的漏电流表达式,包括翘曲效应.在很广的沟道长度范围和工作区内,模型和实验数据一致.     

OLED评估电路的设计与应用

利用OLED显示器,温度传感器和单片机设计了一种实现控制和显示数字温度的电路。首先分析系统中三种主要芯片的基本结构和功能,然后从硬件和软件两个方面阐述系统的实现方法．最后得到精确的实验数据,为进一步研究OLED显示器的应用打下了基础。     

用于器件描述和电路仿真的新型多晶硅TFT直流模型

提出一种新型的多晶硅薄膜晶体管电流-电压物理模型，考虑了陷阱态密度的V形指数分布,运用Lambert W函数推出了表面势的显式求解方法,大大提高了运算效率,在电路仿真中发挥了重要作用，基于指数的陷阱态密度和计算的表面势,描述了亚阈值区和强反型区的漏电流特性。推导了完整、统一的漏电流表达式,包括翘曲效应，在很广的沟道长度范围和工作区内,模型和实验数据一致。     

用于OLEDoS微显示的电路设计

本文描述了用于OLED－on-Silicon微显的几种新型电路模块的设计问题，这些模块包括用于降低功耗的带门D触发器，具有最小尖刺噪声的电流模式DAC，所设计的象素单元对器件和工艺的差异不敏感，并具有较大的输出范围，文中展示了两种用上述模块制造的倒置OLED的微型显示样机。     

一种微型OLED显示屏驱动接口电路

介绍了一种采用OLED技术的微型显示屏驱动接口电路的实现。根据实际系统性能要求与指标,从硬件和软件两个方面对驱动电路进行了设计,硬件电路体积为20mm×27mm,兼容NTSC和PAL制式,标称功耗为300mW;软件包实现显示初始化,软件IIC接口,组合键盘扫描等功能,同时可以方便地进行在线升级和维护。阐释了系统的硬件构成和软件流程图;最后介绍了实际的测试结果和应用。