Research on High S/P of Phosphor-type White LED with High Color Temperature

对于白光照明而言,显色指数(CRI)和暗视觉下光通量与明视觉下光通量的比值(S/P)是衡量白光光源质量的两个重要参数。CRI反映的是待测光源下物体色彩还原能力;而S/P值越高的光源下人眼视物越清晰,对节能也具有一定作用。一般而言,这两个参数越高越好;然而在实际中,两者是一对矛盾体。当前的大部分白光光源的S/P值普遍低于2.5。白光发光二极管(LED)具有光谱可调特性,因此可以通过优化光谱,在满足一定的CRI下获得更高的S/P值。首先模拟光谱,然后通过计算机编程调节光谱峰值波长、相对光强度等光谱参数,最终获得高色温(6 500 K)下高S/P值光谱,对于节能照明光源设计具有重要参考价值。For white light illumination, color rendering index(CRI) and scotopic/photopic(S/P) ratio are twocritical parameters to evaluate the quality of white light source. The CRI is introduced to describe the color fidelityof objects under tested light sources. Under light sources with higher S/P values, human eyes can see more clearly,and it also has a certain effect on energy saving. In general, the higher is the values of the two parameters, the quali-ty of the illumination effect is better. However, there is a trade-off between them. The S/P value of most of the cur-rent white light sources is generally less than 2.5. White light emitting diode(LED) has spectrum adjustment charac-teristic, so higher S/P value is obtained under the condition of meeting the certain CRI through optimizing spectrum.Firstly, LED spectrum is simulated, and then spectrum parameters such as spectrum peak wavelength and relativelight intensity are adjusted through computer programming. Finally, high S/P value spectrum under the high colortemperature of 6 500 K is obtained, which has an important reference value for energy-saving illumination lightingsource design.中德国际科技合作项目(2015DFG62190

Optimized Algorithm for Determining Dominant Wavelength of LED

从发光二极管主波长的定义出发,比较分析了计算发光二极管主波长的3种方法,并提出了一种优化的计算方法。先将色品图划分为10个区域,再结合线性插值运算,可以减少运算次数、提高寻找速度,简化了求主波长的计算过程,同时使主波长计算结果的精确度优于0.1 nm。A novel algorithm to determine the dominant wavelength of LED is proposed based on the definition of dominant wavelength and the comparisons of three conventional calculation methods.To realize this algorithm,the CIE1931-xy Chromaticity Diagram is divided into 10 different regions within the wavelength range from 380.0?nm to 780.0?nm with a resolution of 1.0?nm,then the linear interpolation is implemented to locate the dominant wavelength with a resolution as precise as 0.1?nm.This algorithm not only very facilitates the calculation speed to determine the dominant wavelength of LED,but also increases the resolution precision.国家863计划“半导体照明工程”重大项目(2006AA03A175);; 福建省重点科技项目(2006H0092);; 厦门大学科技创新项目(XDKJCX20051011

海西对台光电产业产学研合作现状及趋势

海峡西岸对台光电产业产学研合作是两岸科技界高度重视的一项重点工程,在两岸政策的引导下,在市场需求及产业界、学术界的共同推动下,合作领域越发广泛,合作交流的形式和渠道不断拓宽,带动两岸科技进步及经济发展。本文着重分析了两岸光电产业的发展现状和海西对台光电产业产学研合作现状、趋势,阐明了合作机制及相应的目标与重点、方式等。在此基础上提出了海峡西岸经济区对台光电产业合作的策略及对两岸光电产业良性发展的建议。福建省科技计划项目（2016R0091）;福建省高等教育教学改革研究项目（JAS151398）

Color Matching of RGB-LEDs Based on Dichotomy

研究如何快速、精确地匹配三基色rgb的比例得到任意颜色的光具有重要意义.提出一种结构简单易于实现的rgb-lEdS配色模型,通过振幅调制电流来改变三基色lEd辐射功率,从而调节各基色在混合色中的亮度比例,使得rgb-lEdS能够匹配到任意颜色.同时给出使用该模型进行配色的精确度评价指标.在此模型基础上提出一种基于二分法的rgb配色算法,使得混合颜色的色品坐标能够快速、精确地匹配到指定范围.仿真实验证明了算法的正确性和有效性.该算法收敛速度快,配色精确度高,具有很高的实用价值.The way to match the ratio of RGB trichromatic lights to get arbitrary color of light quickly and accurately is of great significance.An easily realizable RGB-LEDs color matching model with simple structure was proposed.An arbitrary color can be matched by changing trichromatic LED radiation power in the way of current amplitude modulation,which in turn adjusts the proportion of each color′s luminous intensity.At the same time,an accuracy evaluation indicator for color matching model was given.Based on the model,a dichotomy algorithm of RGB color matching is employed so that the chromaticity coordinates of mixed color can be quickly matched to a specified scope.The simulation results prove the correctness and validity of the algorithm.This algorithm has a high value in practical application for its rapid convergence and high precision color matching.863半导体照明工程重大专项(2006AA03A175);福建省重大专项(2006H0092);福建省自然科学基金(2008J0030

Investigation on The Circadian Action Factor of RGB White LEDs

采用司辰节律因子模型,通过计算三基色白光LED光源在不同工作电流下的司辰节律因子,对可调色温的三基色白光LED光源进行非视觉效应研究。为了获取与自然光非视觉效应类似的LED白光,建立了司辰节律因子和相关色温分别相对于工作电流的关系模型,从而已知自然光的司辰节律因子和相关色温,就可以确定三基色LED的工作电流。通过测试一天内不同时刻的自然光光谱,根据上述模型推算出了三基色LED的工作电流。在所推算的三基色电流下,测试了白光LED光谱参数并计算了相应的司辰节律因子。与自然光司辰节律因子的对比结果表明,理论值和实验值的误差在1.1%以内,证实该方法具有可行性。本文所呈现的方法对于利用三基色白光LED模拟自然光具有一定的指导意义。The circadian action factor( CAF) model was adopted to study the non-visual biological effects for the three-primary color-tunable white LEDs by calculating CAFs at various driving currents. In order to obtain the white light similar to the natural light according to non-visual biological effects,the models of CAF versus current and CCT versus current were generated. Therefore,the driving currents of three-primary LEDs could be determined after the CAF and the CCT of the natural light were known. Based on aforementioned models,and after the natural light at different times in a day was tested,the driving currents of three-primary LEDs were deduced. Then,driven by these currents,white LEDs were tested and their CAFs were calculated. A comparison between calculated values and experimental counterparts shows that the difference lies within 1. 1%,suggesting the feasibility of this approach. This work appears meaningful for mimicking the natural light by using three-primary white LEDs.科技部国际合作项目(2015DFG62190);; 国家自然科学基金(61504112);; 福建省产学合作重大专项(2013H6024);; 福建省自然科学基金(2016R0091);; 科技部港澳台科技合作专项(2015DFT10120)资助项

Testing System of Phosphor Excited by Blue LED Based on Integral Sphere

为尽可能反映荧光粉在实际工作条件下的发光性质,准确测量荧光粉的发光性能,提出了一种基于积分球的荧光粉发光性能测试系统。该系统采用蓝光lEd作为激发光源,配置有TEC控温系统对光源有效实施控温,可提供持续稳定的激发荧光粉发光。采用出光筒控制光源方向和积分球收集光线,能有效防止能量损失,提高测试的精确性。通过实验得到了不同强度蓝光激发下的荧光粉光谱功率分布以及发光效能、量子效率、光转换效率等参数的变化规律。随着驱动电流的增大,由于蓝光芯片内量子限制斯塔克效应,从而导致蓝光峰值波长出现小幅度的蓝移。三种效率在小电流下基本呈线性下降趋势,且在大电流下趋于平缓。实验结果表明,该系统及方法可以有效地评价实际lEd芯片工作状态下的荧光粉发光性能。A testing system for phosphor luminous characteristics based on integral sphere is proposed so as to show luminous characteristics of phosphor at actual operation circumstances and measure its luminous characteristics accurately.Blue LED is used as an excited source in the system.TEC temperature control system is used to control the temperature of the source effectively.And continuous and stable excited light is provided to excite phosphor illumining.Energy loss is prevented effectively and testing accuracy is enhanced for the direction of source controlled by a light tube and light ray collected by integral sphere.Based on experiments,spectrum power distributions of phosphor excited by blue light with difference light strength and variation rules of parameters such as luminous efficiency,quantum efficiency and light conversion efficiency are got.With the increasing of driving current,a small blue shift appears in blue light peak wavelength for quantum confined Stark effect in blue light chip.Three kinds of efficiency almost show linear decline trend at low current and then approach to constant at high current.Experimental results show that luminous characteristics of phosphor on real LED chip at operation state can be evaluated effectively by the system and method.国家自然科学基金项目(11104230); 福建省重点科技项目(2011H6025;2012H0039

Research on voltage-temperature coefficient of high power light-emitting diodes

理论上详细分析了LED正向电压随温度变化的物理机理,并在大的电流范围(0.1~200 mA)和温度范围(60~350 K)内,对AlGaInPI、nGaN材料系功率型LED正向电压随温度的变化关系进行了系统的实验研究。发现在恒定电流下,两者的变化关系可分为高温区和低温区两段。在高温区两者为线性反比关系,并且电压温度系数与正向电流有关,在低温区正向电压随温度减小而突然急剧增大。理论很好地解释了实验结果。The physical mechanism of the forward voltage as a function of the junction temperature in light-emitting diodes(LEDs) was analyzed in detail.And experimental investigation was carried out systematically on the relationship between the forward voltage and the junction temperature in AlGaInP and InGaN high-power LEDs over wide current range(0.1-200 mA) and temperature range(60-350 K).It is discovered that at a constant current,the relationship may be divided into two segments,i.e.in the high temperature region,a linear inverse relationship exists between them and the voltage-temperature coefficient is closely relevant with forward current;while in low temperature region,forward voltage increases drastically as the junction temperature decreases.The experimental results is in good agreement with the theory.国家“863”半导体照明工程资助项目(2006AA03A175);; 福建省重大专项资助项目(2006H0092,2008J0030);; 厦门市重大项目(3502Z20061004

Time-resolved PL Spectra Study of Ordered Ga_(0.52)In_(0.48)P Alloys

【中文摘要】 在室温和低温液氮下 ,研究了有序和无序 Ga0 .52 In0 .4 8P的时间分辨发光谱。对实验结果的拟合表明 ,有序 Ga0 .52 In0 .4 8P的发光呈双指数规律衰退。其中快过程对应着有序区域上载流子的复合 ,慢过程则对应着有序区域和无序区域的空间分离中心上载流子的复合。无序 Ga0 .52 In0 .4 8P的发光在室温下呈单指数规律衰退。同时从低温下的时间分辨发光谱还可以看出有序样品的发光峰随着延迟时间的变长而蓝移 ,说明低温下在有序 Ga0 .52In0 .4 8P中存在着载流子从无序区域到有序区域的转移 【英文摘要】 The time resolved photoluminescence(TRPL) spectra of ordered and disordered Ga 0.52 In 0.48 P alloys grown by MOVPE were investigated.The least square fitting of the luminescence decay spectra of ordered alloys shows that there exist two exponential processes:The short lifetime process was corresponding to the high energy peak in PL spectra which is attributed to the recombination of the carriers in the ordered domains and the long lifetime process was corresponding to the low energy peak in the P...国家自然科学基金 (编号:69776011); 福建省自然科学基金 (编号:A9910004和 A0110007

Exciton-Phonon Coupling of NN_3 Center in Heavily Nitrogen Doped GaP

通过光致发光谱研究了在 1 9～ 4 8K范围内掺氮浓度为 0 .1 2 %时的 Ga PN的 NN3束缚激子与声子的耦合 .直接计算了 NN3束缚激子的 L O,TO和 TA声子伴线的黄昆因子 S,除了 L O声子外 ,得到了 TO和 TA声子伴线的S因子在该温度范围内对温度的依赖关系 .计算表明 ,NN3的 L O,TO和 TA声子的 S因子均与温度无关 ,说明NN3的 L O,TO和 TA声子伴线与它们的零声子线具有相同的温度依赖关系 ,符合黄昆的多声子光跃迁理论Under heavy nitrogen doping,due to the “concentration quenching” effect,the full spectrum of the NN 3 center is revealed without the interference from the spectra of other higher energy centers.This investigation offers a direct proof for that all the phonon replicas are the phonon sidebands governed by the Huang Rhys’ multiphonon optical transition theory.国家自然科学基金 (批准号 :60 2 760 0 2 );; 厦门大学预研基金 (批准号 :Y0 70 0 5 )资助项目~

Thermal characteristic analysis of high-power LEDs by structure functions

运用电学法测量功率型lEd冷却瞬态温度曲线,通过数学方法将其转化为积分和微分结构函数来分析器件各区域的热阻和热容,结果发现,各层材料的测量值与理论值基本一致。1μS的瞬态数据采集精度和高的重复性保证了实验结果的准确性和可靠性,运用这种方法比较了3种不同金属芯印刷电路板(MCPCb)对功率型lEd的散热效果,贝格斯Al基板散热性能最好,AnTAl基板次之,普通Al基板最差。研究表明,利用结构函数分析功率型lEd的热特性是一种强有力的方法。The cooling transient temperature curves of high-power LEDs are measured by electritical method.The cumulative and differential structure functions are extracted from these curves to analyse thermal resistances and thermal capacitances of all regimes of high-power LEDs with numeric computational method.It is found out that calculated and measured values of various materials are essentially conformable.The sampling resolution of 1 μs of transient data and high repetition assure the veracity and reliability of experimental result.Subsequently,thermal conduction capabilities of three different metal core printed circuit boards(MCPCBs) with high-power LEDs are compared by this method,and it is discovered that bergquist′s MCPCB has the best thermal conduction capability,ANT′s MCPCB takes second place,and the common MCPCB is the worst.So the structure functions are powerful tools for thermal characteristic analysis of high-power LEDs.国家“863”计划资助项目(2006AA03A175);福建省科技项目(2006H0092;2008J0030);厦门市重大专项资助项目(3502Z20061004