LED背光源现况与展望

现阶段,LED被广泛地应用到中小尺寸背光源中,大尺寸TV背光源也由原来的CCFL向LED转变。LED背光源的优势有低能耗、无汞环保、超薄化结构设计、高色彩饱和度、高品质画面显示,其应用领域广阔,几乎涵盖了中小尺寸、大尺寸显示应用领域。文章介绍了国内外LED背光源的标准体系建立情况,并根据当前产业面临的困难提出大尺寸LED背光源的发展方向。     

Noise effect on Grover algorithm

The decoherence effect on Grover algorithm has been studied numerically through a noise modelled by a depolarizing channel. Two types of error are introduced characterizing the qubit time evolution and gate application, so the noise is directly related to the quantum network construction. The numerical simulation concludes an exponential damping law for the successive probability of the maxima as time increases. We have obtained an allowed-error law for the algorithm: the error threshold for the allowed noise behaves as ε_th(N) ∼1/N^1.1 (N being the size of the data set). As the power of N is almost one, we consider the Grover algorithm as robust to a certain extent against decoherence. This law also provides an absolute threshold: if the free evolution error is greater than 0.043, Grover algorithm does not work for any number of qubits affected by the present error model. The improvement in the probability of success, in the case of two qubits has been illustrated by using a fault-tolerant encoding of the initial state by means of the [[7,1,3]] quantum code.     

Study on the optical limiting properties of the mixed liquid of carbon black suspensions and green tea solution by multi-pulse laser

The optical limiting properties of the mixed liquid of carbon black suspensions (CBS) and green tea solution were studied by using an 8 ns laser pulse at 532\,nm. The optical limiting effects of the CBS and mixed liquid have been compared between 5 and 10\,Hz repetition frequencies with nanosecond laser pulse. The experimental results indicate that the optical limiting threshold of the sample with the incidence laser at 10\,Hz repetition frequency is lower than at 5\,Hz repetition frequency. The possible reasons for the influence of the repetition frequency on the samples are discussed. And by observing the optical radiant distributions when the laser pulse passing through different samples, a possible mechanism for the observed effects is suggested. At the same time, the result shows that the optical limiting of CBS is the dominant factor to optical limiting of the mixed liquid.     

Copyright protection in digital museum based on digital holography and discrete wavelet transform

A new method to protect the copyright of digital museum based on digital holography is proposed. The Fresnel hologram of watermark image is embedded in the object to be protected through discrete wavelet transform （DWT）. After the watermark detection, the copyright information appears in the reconstructed hologram. With the higher redundancy feature in the hologram, the proposed technique can actually survive several kinds of image processing. Experimental results prove that the presented method has good robustness in image protection.     

用于KDP晶体保护的AF2400-SiO2疏水光学薄膜

在惯性约束聚变(ICF)装置中大量使用具有变频特性的水溶性磷酸二氢钾(KDP)类晶体材料。在KDP晶体上镀制薄膜材料成为保护KDP晶体的有效措施。以正硅酸乙酯(TEOS)为原料,采用溶胶-凝胶法和提拉方式制备膜厚λ/4的增透膜,再采用具有高憎水特性、高透射率、低折射率的氟聚合物AF2400在FC-75的可溶解特性,在SiO2增透膜上旋涂AF2400防潮膜。对薄膜的表面形貌、疏水性能、光学性能和抗激光损伤阈值等进行了测试。结果显示,AF2400-SiO2复合光学薄膜表面平整,折射率为1.21,疏水角可以达到110°~120°,抗激光损伤阈值为19.5 J/cm2,是性能优良的疏水光学薄膜,可用于三倍频晶体KDP的保护。     

低压差电压调整器中热保护电路的设计

针对常见电压调整器芯片由于热保护电路高温端性能的限制,导致调整器在较高工作温度下输出电压稳定性变坏的缺点,提出一种可用于低压差电压调整器的高性能热保护电路的设计。通过改进热保护电路的电路结构及版图设计,在保证热保护电路的关断精度达到±0.5℃的同时,改善了电压调整器高温段的输出电压稳定性。用Spectre对电路进行仿真的结果表明,采用该热保护电路的电压调整器在0℃～150℃范围内的输出电压精度保持在0.5%之内,输出电压的温漂达17.5ppm/℃。此外,设计的热保护电路结构简单,占用芯片面积小,可在双极型或BCD(BipolarCMOSDMOS)工艺下实现,应用于多种电源管理芯片设计中。     

XD3407过流保护模块的电路设计

同步降压型DC/DC稳压器XD3407具有使用方便、性能稳定、价格低廉等优点,因此在掌上型个人电脑、蜂窝电话、无线与DSL调制解调器、数码相机和便携式媒体播放器等便携式电子产品领域得到了广泛的应用。主要介绍了XD3407的基本功能和特点,提出了XD3407过流保护模块的电路设计原理、设计分析、计算,并用HSpice软件对结果进行了仿真验证。     

电动自行车用无刷直流电动机辅助功能控制系统研究

研究电动自行车用无刷直流电动机辅助功能控制系统,提出如何利用脉宽调制PWM和综合译码控制来实现电动自行车无刷直流电动机的电子刹车、欠压保护、过加速防抖动、堵转保护、巡航及1∶1助力等辅助功能。实车试验表明该系统能有效地改善电动自行车的舒适性、安全性。     

功率集成电路中的高压电源和地之间的ESD保护

重点讨论了应用于功率集成电路的高压电源和地之间的一种采用动态检测电路的ESD保护电路,介绍了他的电路结构和工作原理,利用HSpice软件对其在ESD脉冲和正常工作2种情况下的功能进行了仿真,并模拟了保护电路中各器件的尺寸对电路性能的影响。仿真结果证明这种保护电路能满足ESD保护的要求,实际流水结果通过了4 kV HBM测试。