Parallel Addressing Scheme for Voltage-Programmed Active-Matrix OLED Displays

This paper presents a novel parallel addressing scheme for voltage-programmed active-matrix organic light-emitting diode (OLED) displays which provides high precision recovery of the threshold voltage shift. As a result, the uniformity over the panel is significantly improved. In addition, a new pixel circuit is presented that is capable of providing a predictably higher current as the pixel ages, so as to compensate for the OLED luminance degradation     

OLED显示开发的最新进展

１小分子ＯＬＥＤ［１］ 日本先锋公司（Ｐｉｏｎｅｅｒ）附属的东北Ｐｉｏｎｅｅｒ正在生产６４ × ２５６像素的多色ＯＬＥＤ显示屏,月产３０ ０００块,生产线费用仅为２８．２千万美元（地点设在米泽）。先锋公司还推出了全色１３．２ｃｍ（５．２ｉｎ）,对角线Ｑｕａｒｔｅｒ－ＶＧＡ无源矩阵ＯＬＥＤ显示,像素间距为０．１１ｍｍ。这种全色显示屏是通过移动掩膜板逐渐形成红、绿和蓝发光色材料而成的。１９９９年９月,美国柯达公司与日本三洋公司研制出世界第一个有源矩阵ＯＬＥＤ全色显示器。显示器为６．１ｃｍ（２．４ｉｎ）,…     

平板显示器中的OLED

随着最新平板显示技术的大量涌现和不断完善．使得平板显示的应用和市场进一步向难以预测的多元化方向发展。目前，由于OLED技术的日臻成熟和快速产业化．使得原有的平板显示的均衡将被打破。文章从技术、器件性能、应用和市场前景方面着重分析同OLED可能发生竞争的主要对手LCD(液晶显示器)与OLED的相应情况．并对平板显示技术的发展进行了分析预测。     

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。     

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。     

用于场发射显示器的火山口型场发射阴极

介绍一种国内外研究的用于场发射显示器的火山口型场发射阴极,它相对于尖锥型场发射阴极来说，具有制作方法简单，制作成本更低，发射一致性更好，更适合大规模工业化生产。但不足之处是发射电流密度太小和有较大的栅极电流。文章详细介绍了火山口型场发射阴极的制作过程，分析并测试了其发射性能以及转移到玻璃基底上的制作方法。最后还介绍了火山口型场发射阴极的改进型-跑道型场发射阴极。     

OLED显示器热带雨林环境适应性研究

为开展OLED显示器在热带雨林气候条件下的环境适应性研究,将OLED显示器置于西双版纳试验站进行库内自然暴露试验,并定期对样品进行观察和检测.经过一年的暴露试验,OLED显示器表面出现针孔、黑点和膜层脱落等现象,以及发光面积减小和亮度降低等性能衰减变化.研究发现,OLED显示器在热带雨林环境中长期受温度、湿度等环境因素的交变应力作用,其密封性遭到破坏,外界氧气、水汽等进入显示器内部,最终导致OLED显示器失效.因此,要想进一步提高OLED显示器在热带雨林环境中的使用寿命,关键在于改善OLED显示器的密封性.     

显示器件大面积闪烁视觉生理基础与改善方法

在目前显示器件(如CRT,PDP)中,大面积闪烁的问题日益引起人们的关注.本文首先讨论了闪烁的视觉生理基础和临界闪烁频率的分析手段,给出了大面积闪烁程度的量化计算模型,并在此基础上提出了常用显示器件减小闪烁的方法,实验效果明显.     

先进LCD和OLED显示对测试精度和灵敏度提出更高要求

新型平板显示技术,包括从非晶硅和低温多晶硅(LTPS)有源阵列LCD(AMLCD)平板显示到新出现的有机LED及其他技术在内的多项新型技术,势必将催生附加值更高的产品.不过,它们需要效率更高的测试,而相应的仪器和系统必须能提供更高的测试吞吐量和精度.     

用于大面积显示的低成本纳米管场发射显示器

我们验证了一个显示视频图像的阴极阵列,它基于6in对角线、QVGA分辨率的碳纳米管,采用了简单的低成本器件结构。该纳米管是利用选择性化学汽相沉积法生长在特定位置上的,对净化阴极具有良好的可控性。该器件结构只需要三个低分辩率的掩膜工序,开关电压为50V。此外,我们的器件设计为较长的显示寿命创造了条件。在一个较小的全熔接密封的试验显示器上,我们已经记录了超过3000小时的寿命,而电流仅下降了20%。     

Improved Transient Current Feedforward Output Buffer for Fast and Compact Active-Matrix OLED Column Drivers

An improved transient current feedforward driver is designed for compact implementation and low-power consumption by adopting the demultiplexing operation of the proposed driver based on the fast driving speed of 6 mus for the panel load of 6 kOmega/40 pF, which is equivalent to that of extended-graphic-array active-matrix organic light-emitting diode displays. The driver has the structural advantages of simple frequency compensation and low-power consumption, which come from the elimination of an internal operational transconductance amplifier (OTA). The chip implementation confers that the area of the driver is 32.5 times217 mum², and the power consumption is 6.5 muA for each channel.     

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.      

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$hboxcd/hboxm^2$.     

a-Si:H-TFT阈值电压漂移机理及其在驱动OLED显示中的补偿设计

分析了a—Si：H—TFT阈值电压漂移的机理，即分析了栅偏应力下电荷注入到SiNx：H栅绝缘层和a—Si：H中亚稳态的产生对TFT阈值电压漂移的影响。根据非晶硅中亚稳态产生的特点，并针对驱动OLED的两管a—Si：H—TFT像素电路，提出了一种通过对数据信号时序的重新设计来补偿周值电压漂移的方法，即在数据信号间加插一个与数据信号极性相反的补偿信号。通过这种正负交替的信号，使驱动管TFT中由亚稳态造成的阈值电压漂移始终保持在一个动态平衡的过程，来实现驱动OLED电流稳定的目的。     

Large Power Increase Enabled by High-Q Diamond-Loaded Cavities for Terahertz Gyrotrons

Journal of Infrared, Millimeter, and Terahertz Waves - A new operation scheme is proposed to enable large increase in output power of terahertz gyrotrons. In this scheme, the gyrotron operates in...     

Large Mode Area Fibers for High Power Applications

We review our recent work toward designing large mode area fibers for high power applications. We show that appropriately designed doped multimode fibers can be used to provide robust single-mode output when used in fiber laser cavities. Single-mode (SM) fiber mode field diameters of ∼ 35 μm are demonstrated with record SM pulse energies of 0.5 mJ at 1550 nm with a repetition rate of 200 Hz. Energies approaching 1 mJ are obtained with a slight compromise in mode quality. A modification in the laser cavity results in a passively modelocked laser giving femtosecond pulses with nanojoule energies.     

Power Dissipation in Multi-Line Addressed Liquid-Crystal Displays

Power dissipation in the driver circuit of liquid-crystal display is analyzed when the display is scanned with a multi-line addressing (MLA) technique that is based on Rademacher functions. We have considered the binary addressing technique (BAT), hybrid addressing technique (HAT), and improved HAT (IHAT) to obtain, the extreme as well as the average, power dissipation in the driver circuit. Closed-form expression for power dissipation is also obtained for these techniques; when the number of transitions in the addressing waveforms is forced to be independent of the state of the pixels by introducing duty cycle in select and data pulses. An improvement in the brightness uniformity can be achieved among pixels that are driven to the same state without increasing the average power dissipation by introducing duty cycle in the addressing waveforms.     

一种电力专用SOC的低功耗小面积ADPLL设计

智能电网电弧检测片上系统(SOC)芯片需要高性能的锁相环为其提供各种频率的时钟.设计了一种面积小、功耗低、输出频率范围大且锁定精度高的全部基于数字标准单元的全数字锁相环(ADPLL).该ADPLL基于环形结构的全新的数控振荡器(DCO)设计,通过控制与反相器并联的三态缓冲器的导通数量控制反相器电流进行频率粗调,使DCO具有1.2～2.6 GHz的调节范围.通过控制与反相器输出端并联逻辑门的导通数量控制其负载电容进行频率细调,并通过基于夹逼原理的控制字搜索算法找到DCO的最佳控制字.仿真结果表明,ADPLL锁定后输出时钟的均方根周期抖动控制在3 ps以内,并且其在55 nm CMOS工艺下的面积仅为60 μm×60 μm,功耗为1 mW左右.     

一种低温漂低功耗的带隙基准源的设计

设计一种低温漂低功耗的带隙基准结构,在传统带隙基准核心电路结构上增加一对PNP管,两个双极型晶体管叠加的结构减小了运放的失调电压对输出电压的影响,降低了基准电压的温度失调系数.电路设计与仿真基于CSMC0.5μm CMOS工艺,经流片,测得室温下带隙基准输出电压为1.326 65 V,在-40～+85℃范围内的温度系数为2.563 ppm/℃;在3.3 V电源电压下,整个电路的功耗仅为2.81μW;在2～4 V之间的电源调整率为206.95 ppm.     

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.