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The Effect of Package Structure on the Light Extraction Efficiency of Near-Ultraviolet LED
摘要： The near-ultraviolet high-power LED, with five package structures, is designed and fabricated. The efficiency of electric conversion to light (EECL) of various package structures is measured, and the EECL is used to characterize the light extraction efficiency (LEE) of the package structure. By analyzing the Fresnel loss (FNL) and total inner reflection loss (TIRL) of light at different interfaces, the experimental results are explained qualitatively. When approximate spherical lens is used, filling silica gel between chip and lens can improve the LEE. The EECL of the device can reach 66.84%, which is higher than that of bare chip by 55.10%. In planar packaging, the EECL of the device is lower than that of the bare chip, whether or not it is filled with silica gel. After filling with silica gel, a new TIRL is produced at the final interface of the device, and the EECL of the device is even lower, which is only 37.14%. The experimental results show that when the LED chip adopts graphic substrate and surface microstructure to improve the LEE, the traditional coating of silica gel (or epoxy) and other materials on the chip surface may not improve the LEE of the device. If the introduction of the silica gel layer leads to a new total inner reflection interface, it will result in a significant decrease in LEE of the device. When a layer, such as silica gel, does not result in a new total reflection interface, the FNL and TIRL of the chip surface can be effectively reduced, and the LEE of the LED device can be improved.
关键词： total inner reflection loss,package structure,near-ultraviolet LED,Fresnel loss,light extraction efficiency
更新于2025-09-11 14:15:04
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[IEEE 2018 10th International Conference on Advanced Infocomm Technology (ICAIT) - Stockholm, Sweden (2018.8.12-2018.8.15)] 2018 10th International Conference on Advanced Infocomm Technology (ICAIT) - Exploring Evolution of Patent Litigation and Licensing Strategy: The Case of Philips's Light Emitting Diodes (LED) Patents
摘要： LED lighting has received considerable attention due to high energy efficiency, high intensity of brightness, high reliability, low radiated heat, long life span and negligible UV rays. As time goes by, some powerful and invincible patents which had been used as litigation weapons by patent giants are expired. These patent giants changed their strategies to revamp their businesses by earning licensing revenue or releasing some of their patents. This study conducts patent litigation and IP competitiveness analysis to explore Philips’s patent portfolio, identify prospective and valuable litigated patents, and illustrate its litigation /licensing strategy. Visualizations of overall research results and IP implications can benefit policy maker, LED leaders and followers such as China, Taiwan and Korea-based companies in the post oligopoly era.
关键词： patent licensing,patent litigation,patent competitiveness,Light Emitting Diodes (LED)
更新于2025-09-11 14:15:04
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Engineering cation vacancies to improve the luminescence properties of Ca <sub/>14</sub> Al <sub/>10</sub> Zn <sub/>6</sub> O <sub/>35</sub> : Mn <sup>4+</sup> phosphors for LED plant lamp
摘要： In the recent years, Mn4+-doped phosphors for indoor plant cultivation have received extensive concern owing to the far-red emission that can match well with the absorption spectra of plant pigments. Whereas, many Mn4+-doped phosphors still face some challenges such as poor light efficiency and low thermal stability. It is an effective way to resolve these problems via cation vacancies engineering. Herein, the Ca14-xAl10Zn6-yO35: Mn4+ phosphors are successfully synthesized by combustion method. The luminescence intensity of Ca14-xAl10Zn6-yO35: Mn4+ phosphor is enhanced through engineering Ca2+ and Zn2+ vacancies according to the charge compensation mechanism. The optimal content of each of Ca2+ and Zn2+ vacancies is equal to be 0.3. Furthermore, the defect formation is accompanied with lattice distortion, which plays a vital role in driving the excited phonon traps to reduce the energy loss by non-radiation transitions. Therefore, the thermal stability of Ca14-xAl10Zn6-yO35: Mn4+ phosphor is also improved via engineering cation vacancies. In addition, the Ca14-xAl10Zn6-yO35: Mn4+ phosphors can be effectively excited by blue light and it exhibits far-red emission due to the Mn4+ spin-forbidden 2E→4A2 transition. The results suggest that the Ca14-xAl10Zn6-yO35: Mn4+ phosphors can have a tremendous potential in indoor plant cultivation.
关键词： defects,cation vacancies,LED plant lighting,phosphors,charge compensation
更新于2025-09-11 14:15:04
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Optimization of LED Lighting for Clinical Settings
摘要： The advent of the LED light source has promoted the concept of human-centric lighting (HCL). The LED has also been responsible for increases in the electrical e?ciency of lighting systems, coupled with recent improvements in their colour properties. We have found that it is also possible to create a lit environment with enhanced clinical attributes by providing a source spectrum that meets the requirements of the Cyanosis Observation Index (COI). This paper describes the use of a di?erential evolution (DE) algorithm for the spectral design of a mixed LED light source capable of meeting COI recommendations as well as HCL performance criteria.
关键词： differential evolution algorithm,Cyanosis Observation Index,LED lighting,human-centric lighting,spectral design
更新于2025-09-11 14:15:04
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Selected Scattering on Quasi-Ordered Hexagonal Close-Packed Al Nanodents for Tunable Output of White LEDs
摘要： Quasi-ordered hexagonal close-packed Al nanodents, with depths of 30 nm and top-diameters of 300 nm prepared by electrochemical anodizing, are used to manage the output spectrum of white Light Emitting Diodes (LEDs). Signi?cant short wavelength light, with a peak of 450 nm, displays signi?cant scattering enhancements on these Al nanodents with the increment of the angle of the incidence, while long wavelength light, with a peak of 550 nm, shows weaker scattering on Al nanodents with the increment of theincidence angle. Near-?eld and far-?eld simulations reveal the e?ect of light coupling in the holes of Al nanodents on the selected scattering. This work could provide a striking new way to make use of cheap white LEDs.
关键词： Al nanodents,nanomaterials,selected light scattering,white LED
更新于2025-09-11 14:15:04
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Narrowing Linewidth of Wavelength-Swept Active Mode Locking Laser Based on Cross Gain Modulation
摘要： South Korea’s Rural Development Administration embarked on the Korean Programs on International Agriculture (KOPIA) in six developing countries for agricultural development assistance in 2009, and the programs were undertaken in 21 countries in 2018. The purposes of the KOPIA are to introduce new agricultural technologies by cooperative research and development, and to extend developed technologies to farmers and agricultural businesses. In this paper, the economic e?ects of the KOPIA are estimated in 23 recipient countries in terms of their production and value-added inducement e?ect. In doing so, the inter-industry relation analysis method is used with an input-output table for each country from the Eora multi-region input-output (Eora MRIO) database. From the analysis between 2009 and 2017, the production inducement e?ect (PIE) by the KOPIA in the 23 countries is estimated to total US$99 million, accounting for 1.7 times its total budget of US$58.9 million, and the value-added inducement e?ect (VIE) in the 13 countries is estimated to total US$23.9 million. More importantly, the PIE and VIE continue to be higher in some countries, and the annual VIE tends to increase in most of the countries. These ?ndings imply that the research-led KOPIA has contributed to agricultural development and further economic growth through inter-industrial relations in the recipients.
关键词： Korean Programs on International Agriculture,Agricultural Development Assistance,Research-led Agricultural Development,O?cial Development Assistance,South Korea’s Rural Development Administration
更新于2025-09-11 14:15:04
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Study on Modulation Bandwidth and Light Extraction Efficiency of Flip-Chip Light-Emitting Diode with Photonic Crystals
摘要： In this study, the photonic crystal structure is employed to increase both the light extraction e?ciency and the modulation bandwidth of ?ip-chip GaN-based light-emitting diodes (LEDs). The ?nite di?erence time domain method is utilized to investigate the in?uence of structure of photonic crystals on the Purcell factor and light extraction e?ciency of ?ip-chip GaN-based LEDs. Simulation results show that the modulation bandwidth is estimated to be 202 MHz at current densities of 1000 A/cm2. The experimental result of modulation bandwidth is in accord with the simulation. The optical f-3dB of the device achieves 212 MHz at current densities of 1000 A/cm2 and up to 285 MHz at current densities of 2000 A/cm2. This design of photonic crystal ?ip-chip LED has the potential for applications in high-frequency visible light communication.
关键词： Purcell e?ect,photonic crystals,light extraction e?ciency,?ip-chip LED,visible light communication
更新于2025-09-11 14:15:04
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Value Retention Options in Circular Economy: Issues and Challenges of LED Lamp Preprocessing
摘要： The Circular Economy is gaining recognition for its attention to increasing material circularity by proposing a set of value retention options, and organizing business, institutions, and policies for their implementation. Light emitting diode (LED) lamp recycling is becoming increasingly important due to their growing market share and precious metal content. Instead of the current shredding approach, this study applied higher value retention options, such as testing for the functionality of the bulb at the product level, manual disassembly to reuse parts at the component level, and automatic disassembly for industrial scale reuse. This study ?nds that the e?ort that is needed to implement higher value retention options (such as reuse) requires a new form of secondary business, wider networks of recycling chains, and favorable policies. It also shows that about 50% of the lamp waste stream is still functioning and economically attractive if they are remarketed. However, the demand-pull market conditions seem to be missing. For manual disassembly, the output fractions are cleaner, but it is not economically feasible due to high labor cost. On the other hand, automatic disassembly does not produce cleaner fractions due to wide design variability. Thus, this study suggests that shifting from shredding-focused-resource recovery to reuse-based-resource circularity requires a comprehensive framework that simultaneously encourages secondary market formation, collaboration between manufacturers, recyclers and companies, and the formulation of favorable reuse policies. This study applies insights from circular economy principles to LED lamp recycling, and it also contributes to the latter by identifying challenges and possible solutions.
关键词： circular economy,light emitting diode (LED) lamp,value retention options,disassembly,recycling
更新于2025-09-11 14:15:04
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LED Boost Driver Topologies for Low Voltage DC Distribution Systems in Smart Structured Buildings
摘要： Most of the loads connected to the existing AC distribution system operate with low voltage DC power. Hence, there is a requirement to convert AC into DC power. Often there are many inefficiencies associated with AC to DC power conversion. To enhance the energy conservation, low voltage DC distribution system (LVDCDS) is suggested in this paper. Forty percent of the total power consumed in India is by lighting loads which make use of DC power. LVDCDS is an ideal choice to power lighting loads in residential and commercial buildings. This paper presents a detailed study of four different single stage, interleaved, non-isolated light emitting diode (LED) drivers for lighting load. All the topologies are developed in hardware and tested experimentally with controller implementation to provide a constant power of 70 W to power LED lights in the campus building. The installation cost, payback period, and energy savings for the converters connected to LVDCDS are analyzed and discussed in particular.
关键词： digital controller,LED boost drivers,energy savings,energy efficient building
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Micro-LED Waveguide for Fluorescence Applications
摘要： A micro-LED-coupled multimode slab waveguide is reported for fluorescence sensing. The device consists of a 1-dimensional micro-LED array coupled to a sub-mm polymeric slab for evanescent excitation of fluorescent analytes present on the surface. Proof-principle detection of semiconductor nanocrystals down to 0.2 pM/cm2 is demonstrated.
关键词： fluorescence,quantum dots,GaN,LED
更新于2025-09-11 14:15:04