多晶硅TFT有源OLED两管像素电路的研究

在采用精确的模型基础上,利用AIM-Spice软件对有源OLED poly-Si薄膜晶体管(TFT)驱动电路和1×4矩阵电路进行分析研究。最后得到合理的电路参数,使OLED能够达到一定的显示亮度要求。在每帧时间内维持电流恒定,并且在时变的灰度信号作用下能够良好地跟踪响应,最大程度上消除了TFT的一些非线性特性对OLED驱动电流的影响。为OLED显示器像素驱动电路的设计、参数选取、性能分析等提供依据。     

一种有源有机发光显示屏(AM-OLED)驱动电路的设计

介绍一种有源有机发光显示屏(AM-OLED)的驱动电路的设计方法。像素驱动电路采用常用的两管电路结构,依据此像素驱动电路,提出一种利用多晶硅TFT将部分外围驱动电路集成于衬底的设计方法和电路结构。采用互补的多晶硅TFT管设计屏上移位寄存器,传输门等模块,将部分外围驱动电路集成于OLED显示屏的衬底上,极大地减小了数据信号线的数目,降低了屏内信号线布线和屏外驱动电路的复杂程度。进一步讨论了利用复杂可编程逻辑器件(CPLD)设计驱动AM-OLED显示屏专用集成芯片的设计方案。     

非晶InGaZnO薄膜晶体管驱动OLED像素电路的仿真研究

为解决非晶InGaZnO薄膜晶体管(a-IGZO TFT)因其阈值电压漂移而导致的OLED电流衰减的问题,本文研究了基于a-IGZO TFT的有源矩阵有机发光显示(AMOLED)像素电路的阈值电压补偿问题。利用实验室制备的a-IGZO TFT器件进行参数提取后建立的SPICE仿真模型并进行仿真计算,对电压驱动型2T1C和4T1C的像素电路进行稳定性的比较研究,证明了4T1C电路对阈值漂移有非常好的补偿效果,并指出增加存储电容值和驱动TFT的宽长比可有效提高OLED电流的保持能力。     

用液晶驱动芯片驱动有机发光显示屏的设计

应用TFT液晶驱动芯片设计了一个TFT有机发光显示屏用的驱动电路。目前有机发光显示屏(OLED)是平板显示领域的研究热点,在研制长寿命、高稳定的器件方面取得了一定的进展,但与之配套的驱动电路还不是很成熟,而且专用芯片又价格昂贵。液晶显示器件的配套驱动芯片功能比较完善,且价格低廉,所以应用TFT液晶驱动芯片设计了TFT有机发光显示屏用的驱动电路很有实际意义。比较了TFT LCD与TFT OLED驱动原理的异同点,从原理上探讨了将TFT LCD用的驱动芯片加以改造,使其可用于驱动TFT OLED,并采用三星公司的TFT液晶驱动芯片S6C0655和S6C0671设计了一个驱动64×3×80的全彩色OLED显示屏的驱动电路。     

基于数据线控制发光的A-IGZO薄膜晶体管集成AMOLED像素电路

本文提出了一种采用铟镓锌氧化物（IGZO）薄膜晶体管（TFT）的有源矩阵有机发光二极管（AMOLED）显示器的新型补偿结构。它利用数据线关闭电源和驱动晶体管之间的控制晶体管,以抑制编程期间的泄漏电流。在所提出的电路和传统电路之间进行电路性能的比较,表明所提出的像素电路可以有效地补偿驱动晶体管的阈值电压偏移和迁移率变化。当V_TH飘移2 V和μ增加30%时,I_OLED误差率可以分别降低至小于5%和9%。此外,由于使用同时驱动方法,因此所需的最小编程时间可以被详细推导出来。所提出的像素电路的编程能力和机制已经通过FPGA平台和离散的场效应器件所证实。尽管所提出的像素电路具有非常简单的驱动结构,但它能够提高补偿精度。     

基于OLED微显示器和变形目镜的全景显示技术

全景成像在特种车辆内夜间驾驶与观察、警戒监视等应用中具有广泛的应用需求。本文提出了一种基于OLED微显示器和变形目镜的全景图像显示方法,并设计了一套全景显示实验系统,通过图像处理模块完成全景图像数据的存储、缓存、图像预处理和传输,以OLED微显示器的子像素作为显示像素进行驱动信号重编码,实现全景灰度图像的水平3倍压缩显示,最后利用变形目镜将OLED微显示器上显示的压缩图像复原,以供人眼正常观察。实验结果表明:采用现有系统搭建的变形目镜基本实现了双像素靶标条纹的亚像素分辨,并验证了本文全景显示方案的可行性。     

彩色有源OLED显示屏上像素仿真及外围驱动电路设计

有机发光二极管(Organic Light Emitting Diode,OLED)由于高对比度、高亮度、超薄、低功耗、宽视野、快响应速度等特性,日益引起人们的兴趣。通过对部分周边驱动电路集成于衬底的2英寸(5.08cm,64×3×80)有源矩阵显示屏(Active Matrix OLED,AMOLED)上像素驱动电路的仿真,确定彩色OLED显示屏维持白平衡时R、G、B三种OLED所需的驱动电压、电流等工作参数。OLED的发光亮度和电压并不是线性关系,为了维持显示屏的色彩均衡性,对图像数据编码进行校正,保证了灰阶电压与发光亮度呈线性变化。从BMP格式的文件中提取出图像数据部分,进行数据变换,生成符合INTELHEX文件格式并且满足D/A输出要求的数据文件,刻录到E²PROM中,完成外围驱动电路所需要的图像数据准备。AMOLED显示屏采用逐行扫描的显示方式,因此外围驱动电路的目的是要在行、列扫描有效的同时,为每个像素送入相应的灰阶数据。现在,OLED专用驱动芯片比较少见,而液晶驱动芯片具有集成度高,电压输出范围大等优点,尤其是其内部集成了数据移位寄存器、数据锁存器、D/A转换器等电路,所以设计了基于FPGA和TFT-LCD液晶驱动芯片的外围驱动电路,实现了AMOLED显示屏的彩色图像显示。     

PM-OLED带恒流源的驱动电路

一种带恒流源的驱动电路,能实现对小尺寸OLED屏(30 mm×38 mm)的驱动,该屏分辨率为64×56。OLED属电流型器件,对该屏采用恒流源驱动,即在每一列电极上接一个恒流源,只要保证流过每个OLED像素的电流为一常数,就能保证其亮度一致。从而可消除因ITO阳极电阻压降所引起的显示亮度不均匀性问题。其中恒流源的设计是整个驱动电路设计的重点。采用的晶体管恒流源,以晶体三极管为主要组成器件,同时采用一定的温度补偿和稳压措施,通过计算分析和实验测试改进完成设计。该恒流源驱动电路的设计较为简单、成本低、而且易于集成,在改进PM-OLED驱动电路方面作了相应的尝试。     

金属氧化物TFT阈值对LCD显示屏可靠性的影响

TFT的器件特性是影响氧化物TFT驱动的LCD显示屏良率的关键因素。本文研究了氧化物TFT的关键特性参数(阈值,稳定性)对窄边框LCD显示屏的良率和可靠性的影响。氧化物TFT阈值过负,将会导致TFT无法正常关断,而使显示屏的外围移位寄存器(VSR)电路失效。另外,在显示区域用于像素驱动的氧化物TFT的高温和背光照射下阈值持续负向漂移,最终会导致显示区域的驱动TFT漏电流过大,从而使显示屏出现串扰和残影不良。     

OLED/LCD器件中的γ校正

阐述了OLED／LCD器件中γ校正的基本原理,通过考虑人眼视觉非线性和液晶电光非线性,得到了CRT相对于OLED／LCD的灰度级亮度特性曲线。以所设计的26．4cn VGA(行反转)的TFT—LCD为例,采用源驱动器μPD16641芯片,通过γ校正电路和输入数据、灰度级和基准电压的关系,进行了实际的γ校正。得到了驱动电路中的γ校正的外部电压设定值,将设定目标值与实际驱动测定值进行了比较,从比较的结果可以看到,两者十分接近的,解决了实际的TFT液晶驱动电路中Gamma(γ)校正问题,达到了预期的设计目的,使图像的质量满足了用户的要求。     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.     

A novel methodology for photometric compensation of projection display on patterned screen

We propose a novel methodology based on the projector-camera (ProCam) system to address the photometric compensation issue for the projection display on the patterned screen.The patterned screen is treated as the combination of a perfect white screen and a color modulator.The perfect white screen is used to automatically and accurately characterize the ProCam system offline using the polynomial model,and the parameters of the color modulator can be efficiently recovered by employing only two gray images based on the linear reflectance model.The experimental results show that the color artifacts of the display image can be greatly improved with this methodology,which demonstrates its feasibility and validity in the photometric compensation.