Thermal management is one of the key technologies for high-power Light emitting diode(LED)entering into the general illuminating field.Successful thermal management depends on optimal packaging structure and selected ...Thermal management is one of the key technologies for high-power Light emitting diode(LED)entering into the general illuminating field.Successful thermal management depends on optimal packaging structure and selected packaging materials.In this paper,the aluminum is employed as a substrate of LED,3×3 array chips are placed on the substrate,heat dissipation performance is simulated using finite element analysis(FEA)software,analyzed are the influences on the temperature of the chip with different convection coefficient,and optical properties are simulated using optical analysis software.The results show that the packaging structure can not only effectually improve the thermal performance of high-power LED array but also increase the light extraction efficiency.展开更多
In order to study the role of printed circuit board(PCB)in high-power LED heat dissipation,a simple model of high-power LED lamp was designed.According to this lamp model,some thermal performances such as thermal resi...In order to study the role of printed circuit board(PCB)in high-power LED heat dissipation,a simple model of high-power LED lamp was designed.According to this lamp model,some thermal performances such as thermal resistances of four types of PCB and the changes of LED junction temperature were tested under three different working currents.The obtained results indicate that LED junction temperature can not be lowered significantly with the decreasing thermal resistance of PCB.However,PCB with low thermal resistance can be matched with smaller volume heat sink,so it is hopeful to reduce the size,weight and cost of LED lamp.展开更多
The Rwandan State-run Energy Water and Sanitation Authority Company (EWSA) is rapidly increasing the number of population having access to electrical power energy. 30% of electrical energy is used in lighting. The inc...The Rwandan State-run Energy Water and Sanitation Authority Company (EWSA) is rapidly increasing the number of population having access to electrical power energy. 30% of electrical energy is used in lighting. The incandescent bulbs, compact fluorescent lamp bulbs as well as fluorescent tubes are mostly used to convert electrical energy into light. The said light sources have many disadvantages such as excessive power consumption leading to giant bills of electricity, short life span leading to continuous replacement of lamps, and emission of CO2. Application of light-emitting diode (LED) lamps in lighting in long term suppresses the aforementioned problems resulting into saving of money that will be used for running new small investments.展开更多
As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated hy a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is ...As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated hy a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is used as the primary source for exciting fluorescent material such as cerium doped yttrium aluminum garnet with the formula Y3Al2O12 ： Ce^3＋ （in short： YAG ： Ce^3＋ ）. The matching of the spectrum of the blue LED chips and the YAG ： Ce^3＋ yellow phosphor is studied to improve the conversion efficiency. The packaging methods and manufacturing processes for high power single chip-white LEDs are introduced. The uniformity of the output white light is investigated. Based on the characteristics of the high power white LEDs, some approaches and processes are suggested to improve the light uniformity when they are fabricated. The effectiveness of those approaches on the improvement of LEDs is discussed in detail and some interesting conclusions are also presented.展开更多
To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with a fan is proposed. In the experiment, the LEDs array of 18 W composed of 6 LEDs of 3 W is used and the room temperature...To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with a fan is proposed. In the experiment, the LEDs array of 18 W composed of 6 LEDs of 3 W is used and the room temperature is 26oC. Results show that the temperature of the substrate of LEDs reaches 62oC without the fan, however, it reaches only 32oC when the best cooling condition appears. The temperature of the LEDs decreases by 30oC since the heat produced by LEDs is transferred rapidly by the fan. The experiment demonstrates that the cooling system with the fan has good performance.展开更多
The purpose of this paper is to present a methodology for optimizing the geometry of the LED （light emitting diode） secondary lens. The research objective is to uniform the illumination distribution on a target plan...The purpose of this paper is to present a methodology for optimizing the geometry of the LED （light emitting diode） secondary lens. The research objective is to uniform the illumination distribution on a target plane for nonimaging application. In order to achieve this, a software that simulates ray tracing is used, in conjunction with a heuristic process for enhancing the optimized parameters that form the geometry of the LED secondary lens. Spherical lenses was opted for optimization due to its lower manufacture complexity.展开更多
通过对BPZ 220/5 W JA55型阳光球泡灯进行额定功率下40℃和60℃温度应力加速寿命实验,分析了该款LED球泡灯的失效机理.通过推导激活能计算公式,建立了计算光衰激活能的理论模型,给出了测试LED球泡灯光衰激活能方法.通过实验测定该款球...通过对BPZ 220/5 W JA55型阳光球泡灯进行额定功率下40℃和60℃温度应力加速寿命实验,分析了该款LED球泡灯的失效机理.通过推导激活能计算公式,建立了计算光衰激活能的理论模型,给出了测试LED球泡灯光衰激活能方法.通过实验测定该款球泡灯的光衰激活能数值为0.67 eV.展开更多
In order to meet the requirements of indoor illumination, a LED daylight lamp model was designed, it can replace traditional fluorescent lamp without insteading additional power supply establishment. The optical prope...In order to meet the requirements of indoor illumination, a LED daylight lamp model was designed, it can replace traditional fluorescent lamp without insteading additional power supply establishment. The optical properties of the model were simulated using optical analysis software. Its luminous efficiency is about 30.4 lm/W, and the illuminance is about 38 lux when the distance is 1.5 m between the center of the model and measured spot. With the theoretically-optimized design of LED model, experiments based on the results of the optimal simulation in the laboratory were conducted to verify the performance of the proposed LED model, it reaches a power factor of about 0.8 at 6 W. The simulation results are very similar with the measured values. It is testified that simulative method is one of the effective tools for LED lighting optical design.展开更多
Achieving a high color rendering index(CRI)and luminous stability in single-structured Ce:Y_(3)Al_(5)O_(12)(Ce:YAG)phosphor ceramics(PCs)is crucial for high-power white light-emitting diodes or laser diodes(LEDs/LDs)....Achieving a high color rendering index(CRI)and luminous stability in single-structured Ce:Y_(3)Al_(5)O_(12)(Ce:YAG)phosphor ceramics(PCs)is crucial for high-power white light-emitting diodes or laser diodes(LEDs/LDs).However,cyan valleys and insufficient amounts of the red component in the Ce:YAG emission spectra significantly limit their real applications.In this work,a series of Ce,Mn:Y_(3)(Al,Sc)_(2)Al_(3)O_(12)(Ce,Mn:YSAG)PCs were fabricated by vacuum sintering,and efficient spectral regulation was realized for full-color lighting.The cyan valley was filled by the blueshifted emission peak of Ce^(3+)via Sc^(3+)doping.The orange‒red emission at approximately 580 nm was effectively supplemented via Mn^(2+)doping.In particular,CRI of Ce,Mn:YSAG increased from 56.4 to 85.8,a 52%increase compared with that of Ce:YAG under high-power LED excitation,and the operating temperature was stable at approximately 50℃for long working time.Moreover,CRI of 80.9 could still be obtained for PC-based white LDs.These results indicated that Ce,Mn:YSAG PC,which has excellent CRI and luminous stability,is an extremely promising color convertor for high-power white LEDs/LDs.展开更多
基金Key Scientific and Technological Research Projects of Henan Province(072102240027)Dr Foundation of Henan Polytechnic University(648602)Postgraduate Degree Thesis Innovation Foundation of Henan Polytechnic University(644005)
文摘Thermal management is one of the key technologies for high-power Light emitting diode(LED)entering into the general illuminating field.Successful thermal management depends on optimal packaging structure and selected packaging materials.In this paper,the aluminum is employed as a substrate of LED,3×3 array chips are placed on the substrate,heat dissipation performance is simulated using finite element analysis(FEA)software,analyzed are the influences on the temperature of the chip with different convection coefficient,and optical properties are simulated using optical analysis software.The results show that the packaging structure can not only effectually improve the thermal performance of high-power LED array but also increase the light extraction efficiency.
基金Special Fund Project of Science and Technology Innovation of Dongli District(21090302)Research Projectof Applied Basic and Front Technologies of Tianjin(10JCZDJC15400)
文摘In order to study the role of printed circuit board(PCB)in high-power LED heat dissipation,a simple model of high-power LED lamp was designed.According to this lamp model,some thermal performances such as thermal resistances of four types of PCB and the changes of LED junction temperature were tested under three different working currents.The obtained results indicate that LED junction temperature can not be lowered significantly with the decreasing thermal resistance of PCB.However,PCB with low thermal resistance can be matched with smaller volume heat sink,so it is hopeful to reduce the size,weight and cost of LED lamp.
文摘The Rwandan State-run Energy Water and Sanitation Authority Company (EWSA) is rapidly increasing the number of population having access to electrical power energy. 30% of electrical energy is used in lighting. The incandescent bulbs, compact fluorescent lamp bulbs as well as fluorescent tubes are mostly used to convert electrical energy into light. The said light sources have many disadvantages such as excessive power consumption leading to giant bills of electricity, short life span leading to continuous replacement of lamps, and emission of CO2. Application of light-emitting diode (LED) lamps in lighting in long term suppresses the aforementioned problems resulting into saving of money that will be used for running new small investments.
基金"863"Project from Ministry of Science & Technology of China(2006AA03A116)
文摘As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated hy a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is used as the primary source for exciting fluorescent material such as cerium doped yttrium aluminum garnet with the formula Y3Al2O12 ： Ce^3＋ （in short： YAG ： Ce^3＋ ）. The matching of the spectrum of the blue LED chips and the YAG ： Ce^3＋ yellow phosphor is studied to improve the conversion efficiency. The packaging methods and manufacturing processes for high power single chip-white LEDs are introduced. The uniformity of the output white light is investigated. Based on the characteristics of the high power white LEDs, some approaches and processes are suggested to improve the light uniformity when they are fabricated. The effectiveness of those approaches on the improvement of LEDs is discussed in detail and some interesting conclusions are also presented.
文摘To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with a fan is proposed. In the experiment, the LEDs array of 18 W composed of 6 LEDs of 3 W is used and the room temperature is 26oC. Results show that the temperature of the substrate of LEDs reaches 62oC without the fan, however, it reaches only 32oC when the best cooling condition appears. The temperature of the LEDs decreases by 30oC since the heat produced by LEDs is transferred rapidly by the fan. The experiment demonstrates that the cooling system with the fan has good performance.
文摘The purpose of this paper is to present a methodology for optimizing the geometry of the LED （light emitting diode） secondary lens. The research objective is to uniform the illumination distribution on a target plane for nonimaging application. In order to achieve this, a software that simulates ray tracing is used, in conjunction with a heuristic process for enhancing the optimized parameters that form the geometry of the LED secondary lens. Spherical lenses was opted for optimization due to its lower manufacture complexity.
基金Key Scientific and Technological Research Projects of Henan Province(072102240027) Doctor Foundationof Henan Polytechnic University(648602)Postgraduate Degree Thesis Innovation Foundation of Henan Polytechnic University(644005)
文摘In order to meet the requirements of indoor illumination, a LED daylight lamp model was designed, it can replace traditional fluorescent lamp without insteading additional power supply establishment. The optical properties of the model were simulated using optical analysis software. Its luminous efficiency is about 30.4 lm/W, and the illuminance is about 38 lux when the distance is 1.5 m between the center of the model and measured spot. With the theoretically-optimized design of LED model, experiments based on the results of the optimal simulation in the laboratory were conducted to verify the performance of the proposed LED model, it reaches a power factor of about 0.8 at 6 W. The simulation results are very similar with the measured values. It is testified that simulative method is one of the effective tools for LED lighting optical design.
基金financially supported by the National Key R&D Program of China(No.2021YFB3501700)the National Natural Science Foundation of China(Nos.52202135,61975070,and 52302141)+4 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),the International S&T Cooperation Program of Jiangsu Province(No.BZ2023007)the Key R&D Project of Jiangsu Province(Nos.BE2023050 and BE2021040)Natural Science Foundation of Jiangsu Province(No.BK20221226)the Special Project for Technology Innovation of Xuzhou City(Nos.KC23380,KC21379,KC22461,and KC22497)the Open Project of State Key Laboratory of Crystal Materials(No.KF2205).
文摘Achieving a high color rendering index(CRI)and luminous stability in single-structured Ce:Y_(3)Al_(5)O_(12)(Ce:YAG)phosphor ceramics(PCs)is crucial for high-power white light-emitting diodes or laser diodes(LEDs/LDs).However,cyan valleys and insufficient amounts of the red component in the Ce:YAG emission spectra significantly limit their real applications.In this work,a series of Ce,Mn:Y_(3)(Al,Sc)_(2)Al_(3)O_(12)(Ce,Mn:YSAG)PCs were fabricated by vacuum sintering,and efficient spectral regulation was realized for full-color lighting.The cyan valley was filled by the blueshifted emission peak of Ce^(3+)via Sc^(3+)doping.The orange‒red emission at approximately 580 nm was effectively supplemented via Mn^(2+)doping.In particular,CRI of Ce,Mn:YSAG increased from 56.4 to 85.8,a 52%increase compared with that of Ce:YAG under high-power LED excitation,and the operating temperature was stable at approximately 50℃for long working time.Moreover,CRI of 80.9 could still be obtained for PC-based white LDs.These results indicated that Ce,Mn:YSAG PC,which has excellent CRI and luminous stability,is an extremely promising color convertor for high-power white LEDs/LDs.
