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21.
本文给出了一个快速高效且易于实现的信道响应估计算法。对本算法的一系列仿真,将证明基于该算法的自适应均衡具有低SNR门限,能对付大幅度(包括0dB的付径)付径的特点。由于该算法占用的硬件资源很少,尤其适用于数字电视地面广播中的VSB(残留边带调制)接收机。  相似文献   
22.
A high performance white light emitter diode (LED) driver based on boost converter with novel single-wire serial-pulse digital dimming (SWSP) is proposed. The driver uses external serial programmed pulses and internal clock to simplify brightness control. By embedding a 5-bit digital analog converter (DAC) into the driver, wide dimming range is achieved. Moreover, a new dynamic slope compensation circuit is presented and other key circuits of the driver are optimized to get higher efficiency and fast transition response. A practical circuit is implemented with 0.6 um bipolar complementary-metal-oxide-semiconductor double-diffused-metal-oxide-semiconductor (BCD) technology. The simulation results show that the driver can provide both wide output current from 1.3 mA to 42 mA with 32-level digital dimming and higher efficiency up to 83% while it works at 1 MHz switching frequency with the input voltage variation from 2.7 V to 5.5 V.  相似文献   
23.
64 cm FS彩色显像管白场品位的提高   总被引:1,自引:0,他引:1  
通过对64cmFS彩管白场的测试及分析,确定提高白场色度及亮度比是提高整管白场品位的关键.经过对涂屏工艺条件的优化,对曝光台主透镜曲面及荫罩槽宽的优化设计,使该管型白场品位低下的顽疾得到明显改善。  相似文献   
24.
针对PCB制程中防焊退洗出现的品质问题,从退洗原因、退洗设备构成、退洗物料配制、工艺参数选取等方面,结合实际工作中的生产跟进分析,制定完善的控制方法,预防及保证返工产品性能满足客户需求,减少PCB的报废。  相似文献   
25.
Despite their merits of high efficiency and environmental friendliness, phosphor based white organic light-emitting diodes (WOLEDs) for commercial applications still face tough challenges of efficiency roll-off and color stability. Herein, we fabricated high-efficiency phosphor WOLEDs with extremely low roll-off and stable white emission by employing mixed spacer layer between the two complementary emissions as well as mixed host in the orange layer. The strategic exciton management in our proposed device structure greatly balanced the transport of charge carriers due to the excellent exciton manipulation of the mixed spacer, and significantly suppressed the exciton quenching owing to the extended exciton recombination region, which significantly minimized the efficiency roll-off of the fabricated WOLEDs. The resulting phosphor WOLED exhibited the maximum current efficiency (CE) and power efficiency (PE) of 47.5 cd A−1 and 44.7 lm W−1, respectively, and the CE still had 43.1 cd A−1 at 5000 cd m−2, showing a suppressed efficiency roll-off of only 9.2%. Additionally, the device achieved fairly stable spectra over a wide range of luminance with suitable CIE coordinates for indoor lighting and outdoor displays.  相似文献   
26.
Down-conversion structure white organic light-emitting diodes (WOLEDs), in which white light is generated by a blue emission organic light-emitting diodes (OLEDs) in combination with a color conversion layer (CCL) outside the substrate, has attracted extensive interest due to its significant advantages in low cost and stabilized white-light emissions. However, low color-conversion efficiency of CCL is still a bottleneck for the performance improvement of down-conversion WOLEDs. Here, we demonstrate an approach to enhance the color-conversion efficiency of CCL-WOLEDs by localized surface plasmon resonance (LSPR) effect. In this approach, a blend of Ag nanoparticles and polyvinyl alcohol (PVA) is solution-deposited between the blue organic light emitting diodes and color-conversion layer. Based on the LSPR effect of this modified structure, the color conversion efficiency has improved 32%, from 45.4% to 60%, resulting a 14.4% enhancement of the current efficiency, from 9.73 cd/A to 11.14 cd/A. Our work provides a simple and low-cost way to enhance the performance of down-conversion WOLEDs, which highlights its potential in illumination applications.  相似文献   
27.
We report on efficient solution-processed phosphorescent white polymer light-emitting diodes (WPLEDs) with tunable color-correlated temperature (CCT) and color rendering index (CRI), through rationally controlling the composition of the emission layer (EML) based on a near-infrared (NIR)-emitting dinuclear cyclometalated platinum (II) complex bridged with NˆS anionic ligand, named (niq)2Pt2(μ-C8PhOXT)2 (Pt-1, in which PhOXT is 5-(phenyl-1,3,4-oxadiazole)-2-thiol, niq is 1-naphthylisoquinolinato), a sky-blue emitter iridium (III) bis[(4,6-di-fluorophenyl)-pyridinato-N,C2] (picolinate) (FIrpic), and a yellow emitter bis[2-(thieno[3,2-c]pyridin-4-yl)phenyl]iridium(III)(acetylacetonato) (PO-01). One of the best three-color WPLEDs shows a CCT of 3246 K as well as an excellent high CRI of 87, which are greatly beneficial in reducing deep-blue light damage and simultaneously meet the requirement for good color reproduction. Meanwhile, the relevant WPLED also achieves a maximum current efficiency of 12.1 cd/A, corresponding to an external quantum efficiency of 10.6%. This work presents an effective approach through rational combination of sky-blue, yellow, and NIR emitters towards high-performance solution-processable WPLEDs with a physiologically-friendly CCT and a high CRI.  相似文献   
28.
Greenish yellow organic light-emitting diodes (GYOLEDs) have steadily attracted researcher's attention since they are important to our life. However, their performance significantly lags behind compared with the three primary colors based OLEDs. Herein, for the first time, an ideal host-guest system has been demonstrated to accomplish high-performance phosphorescent GYOLEDs, where the guest concentration is as low as 2%. The GYOLED exhibits a forward-viewing power efficiency of 57.0 lm/W at 1000 cd/m2, which is the highest among GYOLEDs. Besides, extremely low efficiency roll-off and voltages are achieved. The origin of the high performance is unveiled and it is found that the combined mechanisms of host-guest energy transfer and direct exciton formation on the guest are effective to furnish the greenish yellow emission. Then, by dint of this ideal host-guest system, a simplified but high-performance hybrid white OLED (WOLED) has been developed. The WOLED can exhibit an ultrahigh color rendering index (CRI) of 92, a maximum total efficiency of 27.5 lm/W and a low turn-on voltage of 2.5 V (1 cd/m2), unlocking a novel avenue to simultaneously achieve simplified structure, ultrahigh CRI (>90), high efficiency and low voltage.  相似文献   
29.
AlGaAs/AlAs体系DBR的MOCVD生长及表征   总被引:1,自引:2,他引:1  
设计并利用MOCVD在(311)GaAs衬底上生长了12.5个周期的Al0.6Ga0.4As/AlAs黄绿光分布式Bragg反射(DBR)体系,测量了白光反光谱及其外延片峰值波长分布,反射率90%以上,波长不均匀性在1.0%以下;利用了X射线双晶衍射对其进行结构表征,580nm波长DBR结构周期为84.5nm。  相似文献   
30.
We report on the spectral tunability of white light by localized surface plasmon (LSP) effect in a colour converting hybrid device made of CdSe/ZnS quantum dots (QDs) integrated on InGaN/GaN blue light-emitting diodes (LEDs). Silver (Ag) nanoparticles (NPs) are mixed with QDs for generating LSP effect. When the plasmon absorption of Ag NPs is synchronized to the QW emission at 448 nm, the NPs selectively absorb the blue light and subsequently enhance the QD emission. Using this energy transfer scheme, the (xy) chromaticity coordinates of the hybrid white LED was tuned from (0.32, 0.17) to (0.43, 0.26), and thereby generated warm white light emission with correlated colour temperature (CCT) around 1800 K. Moreover, a 47% enhancement in the external quantum efficiency (EQE) was realized.  相似文献   
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