MAX6951型LED驱动器及其应用

MAX6950/6951是Maxim公司推出的串行接口LED显示驱动器,内部集成16进制译码器和亮度控制器.介绍MAX6951的结构特点、工作原理及与LPC2214型ARM微控制器配合使用的软硬件实现.     

多位LED串行显示电路设计与应用

74HC595A芯片具有串行输入、并行输出功能,利用该集成电路可设计多位LED(发光二极管)串行显示电路。文中介绍了利用该芯片设计的12位LED串行显示电路,详细说明了该电路的工作原理及编程思路,并给出了参考程序。该电路只占用单片机3根口线,较并行显示方式极大地节省了系统资源,已在实际系统中得到应用。     

虚拟标准显色设备——跨网络色彩重现的新方案

随着网络的普及和多媒体应用的增长,彩色的传输和真实重现日益受到重视.虽然基于ICC的色彩管理提供了色彩复制与传递机制,但是这些技术仍存在增加系统开销、设备特性信息传递困难、不同色彩管理系统难以混合等问题.本文提出了"虚拟标准显色设备"的概念,较好地解决了跨网络、跨平台的色彩重现问题.实验结果证明了这种方法的有效性.     

脉冲氙灯用截紫外石英玻璃管性能的研究

研究了不同CeO2浓度掺铈石英玻璃的光谱性能和机械强度，制备了几种不同杂质(CeO2，Al2O3，TiO2)含量的掺铈石英玻璃管，并且这些掺铈石英玻璃管用相同的工艺研制成大功率脉冲氙灯。对掺铈石英玻璃管的光谱性能、机械性能和热学性能进行了测试，并测试了脉冲氙灯放电的极限负载能量。通过对比实验表明，掺入适量的CeO2等杂质的掺铈石英玻璃管可以吸收氙等离子体的320nm左右的近紫外辐射，改善脉冲氙灯的辐射光谱。但CeO2等杂质的掺入降低了掺铈石英玻璃管的机械强度，导致掺铈石英玻璃管脉冲氙灯的极限负载能量比纯石英玻璃管脉冲氙灯有差距，影响了掺铈石英玻璃管脉冲氙灯的使用寿命。因此，有必要研制一种既能吸收氙等离子体的320nm左右的紫外辐射，又具有高强度的脉冲氙灯管壁材料。     

Investigation on the stress behavior of cellulose acetate and the development of highly moisture‐resistant optical films for display devices

An optical film with high optical anisotropy was prepared by the stretching of a cellulose acetate film and the consequential orienting of a retardation‐enhancing additive. The change in retardation in response to moisture absorption was explored and it was found that the degree of the retardation variation is strongly related to the stretching temperature. Stress generated by the stretching and its relaxation was systematically investigated to elucidate the effect of stretching temperature on the irreversible change in retardation upon moisture absorption. The results show that the magnitude of releasable stress plays an important role in controlling changes in optical properties. In addition, the difference in the deformation behavior between glassy and rubbery states should be taken into account in the development of a moisture‐resistant optical film. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1470–1478     

Fabrication of photoluminescent liquid crystal device using an in situ self-assembled molecular layer of a pyrene derivative

An in situ self-assembled molecular layer of 1-pyrenesulfonic acid sodium salt as an alignment agent was formed on indium tin oxide substrates for vertically aligning liquid crystals (LCs). The thus-aligned LCs exhibited uniform vertical alignment under crossed polarisers. The electro-optical characteristic of the LC cell fabricated using this method exhibited better performance than those of conventional LC cells with a polyimide alignment layer. Because the proposed alignment method is a simple one and involves low concentrations of the alignment agent (0.05 wt%), it is highly cost-effective. Further, the pyrene derivative, when mixed with LCs, exhibited photoluminescence (PL) under ultraviolet light. Given that the proposed method resulted in highly vertically aligned LCs and the alignment agent exhibited PL, the method should find wide use in the fabrication of colour-filter-free LC displays.     

Real-time sensing and three-dimensional display of far outdoor scenes based on asymmetric integral imaging

A new asymmetric integral imaging (AII) system for real-time pickup and three-dimensional (3-D) display of far outdoor scenes based on dynamic-pixel-mapping (DPM) is proposed. DPM is a digital process to transform the elemental images captured with a lens array into the perspective-variant object images (POIs) whose structures are matched with those of display lenses, where the orders of pixels in each POI are reversely mapped, and then capture a set of virtual elemental images (EIs) at the specific depth planes from the back-propagated POIs. This DPM enables an asymmetrical use of pickup and display lens arrays, allowing the long-ranged pickup of far outdoor scenes and their resolution-enhanced 3-D reconstruction. Experiments with a pair of pickup and display lens arrays whose pitches and focal lengths are given by 7.5 mm, 30 mm and 1.2 mm, 8 mm, respectively, show that the effective pickup-range and resolution of the proposed system have been increased up to 6 m and 1600×1600 pixels, respectively, from 0.064 m and 480×480 pixels of the conventional systems employing the same pickup and display lens arrays. In addition, experiments with an implemented test bed confirms that the proposed system can provide real-time 3-D images in 25 frames per second.     

Miniaturized structures based on color centers in lithium fluoride: Optical properties and applications

Research activities concerned with color centers in alkali halide films started recently. The use of versatile, well-assessed, and low-cost fabrication techniques consisting of physical vapor deposition of Lithium Fluoride (LiF) films combined with direct writing lithographic processes allows the realization of miniaturized structures, like broad-band emitters, channel waveguides, optical microcavities and point-light sources emitting in the visible spectral range. Promising results have been obtained in the generation, amplification and waveguiding of visible light in LiF treated by low energy electron beams, where the efficient formation of stable primary and aggregate color centers also induces a local modification of the refractive index. A brief overview of the investigated optical properties is presented together with a short discussion about their perspectives of applications in optoelectronics.