InGaN基高压LED和传统大功率LED的发光效率比较

主要从三个不同角度探究并分析了基于In Ga N材料的高压LED的发光效率优于传统大功率LED的原因。为了保证实验结论的可靠性,文中所采用的实验样品具有相同的芯片尺寸和材料以及相同的封装结构。经过大量的实验证明,更均匀的电流分布和小芯片间隙的出光,使得高压LED的发光效率优于传统大功率LED。结果显示,在相同的1 W输入功率下,高压LED的发光效率比传统大功率LED高大约4.5%。     

大功率LED照明灯具的光学及散热技术的研究

大功率LED照明灯具的光学及散热技术主要通过研发一种大功率LED照明灯具通过对LED模组的内部结构、发光特性、散热特性及电源连接控制等方面的研究,优化大功率LED生产工艺,改进现有生产的技术不足,研发出具有大照射角度、高散热长寿命的大功率LED灯具,降低了生产成本,提高大功率LED灯具的可靠性,提高其光学品质和光输出效率。     

10W COB集成LED光源的性能分析

随着发光二极管(LED)的发光效率、寿命、可靠性等性能的逐步提高,特别是大功率LED的发展备受人们关注,已经开始作为光源应用于普通照明领域中。但是大功率LED的散热问题是阻碍其迅速发展和推广普及的难题之一。从光色电热等性能方面,详细介绍了10W COB集成LED光源的研究进展,通过封装材料的选择和封装工艺的改善,可以有效改善LED的热阻性能,实测器件热阻值Rth=4.6K/W。     

大功率LED散热问题的探讨

大功率LED得以广泛应用,主要由于其寿命长、体积小、电转化效率以及高色温等特点。但是在LED的推广应用中,高效稳定的散热问题成为了重要阻碍。本文着重对大功率LED的散热问题进行了探讨。     

基于多串变压器LLC控制的LED驱动电路设计

和高压钠灯、节能灯等传统灯具相比,大功率LED照明系统更加节能、环保,且具有更长的寿命,在室外照明和其他高功率场合具有很大的潜力。传统的大功率LED照明驱动电路由AC/DC变换器和多个恒流DC/DC变换器构成。为了提高效率和可靠性,文章提出一种适合于大功率LED照明驱动的新型多串变压器LLC谐振变换器,该变换器基于磁平衡技术驱动多串LED负载,以UCC25710作为控制芯片制作了一款100 W的LED驱动电路。实验结果表明该电路结构简单、工作可靠、具有更高的效率。     

大功率LED照明灯具的配光与散热的研究

本文通过对大功率LED照明灯具的配光与散热的研究,了解大功率LED照明灯具的使用寿命、光输出定向性、大功率LED灯珠的发光效率、散热系数等相关参数。对本公司现有的大功率LEDN明灯具产品的一次配光、二次配光、大功率LED灯珠散热进行了改进设计。大功率LED照明灯芯片加速老化、工作寿命减短等问题,因此散热是制约其发展的一个至关重要的因素。本文介绍了目前广泛运用的大功率LED灯散热技术、散热产品以及热分析工具,应用ANSYS软件针对一款大功率LED进行了热分析,求得各个部分的温度场分布,巴超出了结温的最大允许值。通过热分析,对该LED灯散热结构进行改进,将芯片最高温降为51．1226℃,仿真分析结果表明在允许范围之内,验证了改进方案的可行性。     

认识大功率LED

大功率LED是指拥有大额定工作电流的发光二极管。普通LED的功率一般为0．05W,工作电流为20mA,而大功率LED可以达到1W、2W,甚至数十瓦,工作电流可以是几十毫安到几百毫安不等。由于目前大功率LED受到光通量、转换效率和成本等方面的制约,决定了大功率白光LED短期内的应用主要是一些特殊领域的照明,中长期目标才是通用照明。     

一种显微镜LED光源驱动设计

大功率LED拥有寿命长、单色性好、控制灵活等优势,能够很好的服务于现代生物成像实验。文中基于LED照明和生物实验的特点,为显微镜LED光源设计针对性的驱动电路;电路采用大功率LED驱动器LT3755和boost拓扑结构,实现了电流满量程调节。通过测试不同控制电压下LED输出电流的实验,说明电路能实现较高精度和线性度的电流控制。     

大功率氮化镓基LED关键技术研究

对大功率氮化镓基LED的关键技术,尤其是大芯片LED的结构设计,p电极的选择与制备,提取效率的提高以及倒装焊技术做了重点的介绍与讨论.     

大功率氮化镓基LED关键技术研究

对大功率氮化镓基LED的关键技术,尤其是大芯片LED的结构设计,p电极的选择与制备,提取效率的提高以及倒装焊技术做了重点的介绍与讨论.     

A polymer based miniature loop heat pipe with silicon substrate and temperature sensors for high brightness light-emitting diodes

Solid State Lighting (SSL) systems, powered by light-emitting diodes (LEDs), are revolutionizing the lighting industry with energy saving and enhanced performance compared to traditional light sources. However, around 70%–80% of the electric power will still be transferred to heat. As the elevated temperature negatively affects the maximum luminous output, efficiency, light quality, reliability and the lifetime of the SSL systems, thermal management is a key design aspect for LED products. In this work, an innovative thermal management with a package, a silicon substrate with temperature sensors and a polymer based loop heat pipe (LHP) was designed, manufactured and assembled. It can supply a low and relatively stable temperature to maintain higher optical power, more luminous flux and less color shift. In a word, the novel design can provide LEDs with the efficient thermal management and temperature monitoring with reduced weight, easy fabrication, less energy consumption and better light quality.     

A General Photo-Electro-Thermal Theory for Light Emitting Diode (LED) Systems

The photometric, electrical, and thermal features of LED systems are highly dependent on one another. By considering all these factors together, it is possible to optimize the design of LED systems. This paper presents a general theory that links the photometric, electrical, and thermal behaviors of an LED system together. The theory shows that the thermal design is an indispensable part of the electrical circuit design and will strongly influence the peak luminous output of LED systems. It can be used to explain why the optimal operating power, at which maximum luminous flux is generated, may not occur at the rated power of the LEDs. This theory can be used to determine the optimal operating point for an LED system so that the maximum luminous flux can be achieved for a given thermal design. The general theory has been verified favorably by experiments using high-brightness LEDs.      

基于COB技术的LED散热性能分析

当前,散热问题已成为影响LED寿命、光效、光衰和色温等技术参数的重要因素。文章在综合分析散热技术和LED封装对散热性能影响的基础上,利用COB(板上芯片)封装技术,将LED芯片直接封装在铝基板上,研制成了一种基于COB封装技术的LED。与SMD封装LED进行比较,分析了其散热性能。分析结果表明:基于COB封装技术的LED减少了LED器件的结构热阻和接触热阻,使其具有良好的散热性能。     

两基色白光LED的光视效能的研究

光视效能的高低直接影响到光源的光效,两基色白光LED存在无数个同色异谱色,它们的光视效能值不同.通过计算确定了可合成白光的两基色的选取范围,确定了得到高光视效能的白光LED的两基色的选取范围.     

A study on the heat dissipation of high power multi-chip COB LEDs

In this study, the heat dissipation efficiencies of high power multi-chip COB (Chip-on-Board) LEDs with five different chip gaps were compared by assessing their junction temperature (T_j) and thermal resistance (R_th). Junction temperatures were measured using an IR camera and were also simulated by computational fluid dynamics (CFD) software. The effects of heat sinks with different surface areas, heat slugs made of different materials and different injection currents (different wattages) on high power LED junction temperatures are discussed. In addition, the optical characteristics of the LED, such as its lumens and luminous efficiency are evaluated. The experimental results show that a chip with a smaller gap has a higher junction temperature and more thermal resistance, and the junction temperature difference between the LEDs with the smallest and largest chip gaps is 3.12 °C. Optical performance analyses show that the LED with a larger chip gap has higher lumens and higher luminous efficiency. Thus, higher junction temperatures reduce the optical performance of high power LEDs.     

LED封装中的散热研究

文章论述了大功率LED封装中的散热问题,说明它对器件的输出功率和寿命有很大的影响,分析了小功率、大功率LED模块的封装中的散热对光效和寿命的影响。对封装及应用而言,增强它的散热能力是关键技术,指出对大功率LED和LED模块散热设计很重要,因为大功率白光LED的光效和寿命取决于其散热。目前大功率LED的重点是提高散热能力,说明封装结构和封装材料在提高大功率LED散热中的影响,LED模块的散热是未来的重点。通过选用高热导率材料可以使温度得到显著控制,重点论述了封装的关键技术,最后指出了未来LED封装技术的发展趋势。     

大功率白光LED封装设计与研究进展

封装设计、材料和结构的不断创新使发光二极管(LED)性能不断提高.从光学、热学、电学、机械、可靠性等方面,详细评述了大功率白光LED封装的设计和研究进展,并对封装材料和工艺进行了具体介绍.提出LED的封装设计应与芯片设计同时进行,并且需要对光、热、电、结构等性能统一考虑.在封装过程中,虽然材料(散热基板、荧光粉、灌封胶)选择很重要,但封装工艺(界面热阻、封装应力)对LED光效和可靠性影响也很大.     

GaN基白光LED温度特性实验研究

实验研究了恒流驱动条件下,GaN基白光LED的正向电压、发光光谱和发光效率随环境温度的变化情况.结果表明,在输入电流恒定的情况下,随着温度的升高,结电压和发光强度与温度具有良好的线性关系,并且GaN基白光LED的发光颜色总是向蓝光漂移,而小电流驱动时比大电流驱动时蓝光漂移更明显.根据实验结果,分析了器件的最佳额定工作电流.

Abstract：

Under a constant driving current, the changes of the forward voltage, emission spectrum and luminous efficiency of GaN-based White LEDs with the ambient temperature are studied experimentally. It is found that the forward voltage and the luminous intensity depend on the temperature linearly with constant injection current, and luminous colors of GaN-based White LEDs always shift towards blue. And the blue shift with low driving current is more obvious than that with high driving current. According to the results, the best rated operating current of GaN-based white LEDs is discussed.     

Correlated Color Temperature Tunable Multi-chip Light Emitting Diodes Light Source Design

One of the methods to derive white light from light emitting diodes（LEDs） is the multi-chip white LED technology, which mixes the light from red, green and blue LEDs. Introduced is an optimal algorithm for the spectrum design of the multi-chip white LEDs in this paper. It optimizes the selection of single color LEDs and drive current controlling, so that the multi-chip white LED achieves the target correlated color temperature （CCT）, as well as high luminous efficacy and good color rendering. A CCT tunable LED light source with four high-power LEDs is realized based on the above optimal design. Test results show that it maintains satisfactory color rendering and stable luminous efficacy across the whole CCT tuning range. Finally, discussed are the design improvement and the prospect of the future applications of the CCT tunable LED light source.     

Calculation of LED modules for highway lighting

The calculated distributions of the highway illuminance provided by light-emitting diode (LED) modules that can be used in available supports and arms are presented. Different variants of the arms with LEDs characterized by various luminous intensity curves and emission angles of 10 to 100° are investigated. Rotation of LEDs with various luminous fluxes at a luminous efficiency of 100 lm/W is also considered.