基于a-IGZO TFT的AMOLED像素电路稳定性的仿真研究

非晶铟镓锌氧化物薄膜晶体管(a-IGZO TFT)有望在有源矩阵有机发光显示(AMOLED)像素电路中得到实际应用,但其电压偏置效应仍会引起电路特性的不稳定。本文利用实验室制备的a-IGZO TFT器件进行参数提取并建立了SPICE仿真模型,通过拟合得到了它的阈值电压随时间变化的方程。在此基础上,采用SPICE软件对基于a-IGZO TFT的2T1C和3T1C两种AMOLED像素电路的稳定性进行了比较研究,证明3T1C电路对阈值电压偏移确实存在一定的补偿效果。最后讨论了进一步改善AMOLED像素电路稳定特性的方法和实际效果。     

面向IGZO-TFT-AMOLED像素电路设计的V_(TH)检测方法研究

由于迁移率高、均匀性好、制备成本低等优势,铟镓锌氧化物薄膜晶体管(IGZO TFT)有望促成有源矩阵有机发光显示器件(AMOLED)的大规模量产。但是IGZO TFT存在阈值电压(VTH)漂移的问题,实用的AMOLED像素电路必须对VTH漂移进行补偿以实现较好的显示效果,而VTH的检测是AMOLED像素电路设计中的关键环节。本文系统研究了VTH检测方法,比较了放电法、充电法、偏置电流法补偿VTH的效果,研究了VTH检测时间和TFT寄生电容等参数的影响。研究结果表明:放电法不能精确地补偿负VTH漂移,充电法需要的VTH检测时间最长,偏置电流法能够达到的补偿精度最高。     

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。     

有源OLED两管TFT像素驱动电路的仿真研究

利用AIM-Spice对有源OLED显示器的两管TFT像素驱动电路进行了仿真分析，结果表明合理选择电路参数，能够保证OLED显示器的亮度要求，并在一帧时间里保持恒流，改变数据电压能够调整OLED显示器的灰度级；给出了电器中各类参数变化对电路性能的影响；在此基础上，得到了两管TFT像素驱动电路各参数的选择参考值。为OLED显示器像素驱动电路结构的设计、参数选取、性能分析以及版图设计等提供了依据。     

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。     

射频磁控溅射低温制备非晶铟镓锌氧薄膜晶体管

利用射频磁控溅射技术室温制备了铟镓锌氧(IGZO)薄膜,采用X射线衍射(XRD)表征薄膜的晶体结构,原子力显微镜(AFM)观察其表面形貌,分光光度计测量其透光率。结果表明:室温制备的IGZO薄膜为非晶态且薄膜表面均匀平整,可见光透射率大于80%。将室温制备的IGZO薄膜作为有源层,在低温(<200℃)条件下成功地制备了铟镓锌氧薄膜晶体管(a-IGZO TFT),获得的a-IGZO-TFT器件的场效应迁移率大于6.0 cm2.V-1.s-1,开关比约为107,阈值电压为1.2 V,亚阈值摆幅(S)约为0.9 V/dec,偏压应力测试a-IGZO TFT阈值电压随时间向右漂移。     

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。     

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。     

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.     

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.     

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.     

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.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.