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High Voltage, Low Current High-Power Multichannel LEDs LLC Driver by Stacking Single-Ended Rectifiers with Balancing Capacitors
摘要： In this paper, a new LLC converter for series-connected, high-voltage LEDs is proposed. The proposed LLC converter consists of two stacked, single-ended recti?ers and one balancing capacitor, to compensate for the current deviation of two individual LED strings. The proposed LLC LED driver can use a diode with low voltage stress, even if the secondary LED is connected in series to have a high driving voltage. In addition, even if several series-connected LEDs are changed into two-stacked structures, the balancing capacitor can compensate for the current deviation of the two separated LEDs, as well as the di?erence in leakage inductance of the two stacked single-ended recti?ers. The balancing capacitor can be made equal to the voltage tolerance of the stacked, single-ended recti?er diodes. The proposed circuit can be easily extended to a series channel LED driver circuit, without increasing the voltage stress. To verify the characteristics and operation of the proposed LLC LED driver, a 260W high-power LED driver is implemented.
关键词： high-power LED light,stacked single-end recti?er,balancing capacitor,LLC LED driver
更新于2025-09-23 15:19:57
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Handbook of Smart Photocatalytic Materials || Sustainable photocatalytic porcelain gr??s slabs active under LED light for indoor depollution and bacteria reduction
摘要： The photocatalytic performances of TiO2-based and doped Ag-TiO2-based porcelain grés ceramic tiles as self-cleaning materials developed by digital printing process were investigated. The photoactive tiles coated with doped Ag-TiO2 K1077 showed better photocatalytic efficiency than tiles coated with TiO2 K1077 for the degradation of NOx and ethanol due to the better light absorption and higher electron–hole pairs separation caused by Ag nanoparticles. The total mineralization of EtOH to CO2 was proved. The photoactive tiles also exhibited an excellent efficiency for the densification of E. coli and S. aureus. These experimental data manifested the efficient and durable water and air treatment/densification using Ag-TiO2-based porcelain grés ceramic tiles, which may be significant to future use as self-cleaning materials.
关键词： LED light,bacteria reduction,porcelain grés ceramic tiles,photocatalytic,depollution,Ag-TiO2,TiO2,self-cleaning
更新于2025-09-23 15:19:57
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Application of Response Surface Methodology to Evaluate Photodynamic Inactivation Mediated by Eosin Y and 530 nm LED against Staphylococcus aureus
摘要： Photodynamic antimicrobial chemotherapy (PAC) is an efficient tool for inactivating microorganisms. This technique is a good approach to inactivate the foodborne microorganisms, which are responsible for one of the major public health concerns worldwide—the foodborne diseases. In this work, response surface methodology (RSM) was used to evaluate the interaction of Eosin Y (EOS) concentration and irradiation time on Staphylococcus aureus counts and a sequence of designed experiments to model the combined effect of each factor on the response. A second-order polynomial empirical model was developed to describe the relationship between EOS concentration and irradiation time. The results showed that the derived model could predict the combined influences of these factors on S. aureus counts. The agreement between predictions and experimental observations (R2 adj = 0.9159, p = 0.000034) was also observed. The significant terms in the model were the linear negative effect of photosensitizer (PS) concentration, followed by the linear negative effect of irradiation time, and the quadratic negative effect of PS concentration. The highest reductions in S. aureus counts were observed when applying a light dose of 9.98 J/cm2 (498 nM of EOS and 10 min. irradiation). The ability of the evaluated model to predict the photoinactivation of S. aureus was successfully validated. Therefore, the use of RSM combined with PAC is a promising approach to inactivate foodborne pathogens.
关键词： photodynamic inactivation,xanthene dye,foodborne pathogen,green LED light,mathematical model
更新于2025-09-23 15:19:57
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Red shift properties, crystal field theory and nephelauxetic effect on Mn4+-doped SrMgAl10-yGayO17 red phosphor for plant growth LED light
摘要： The discovery of novel Mn4+-doped oxide red phosphor with suitable spectrum for plant growth is a hot issue in the recent years due to the characteristic red photoluminescence of 2Eg → 4A2 transition in Mn4+ ions. Generally, the emission position of Mn4+ is hard to tune because of specific crystal field in most phosphors. In this work, tunable luminescence property with obvious red shift in the spectra is observed in the Mn4+-doped SrMgAl10-yGayO17 red phosphor via simple substitution of Ga3+ for Al3+, and crystal field theory and nephelauxetic effect are employed to explain this phenomenon. Meanwhile, the Ga3+ dopant changes the shape of the spectra because Ga3+ dopant guides the replacement site of Mn4+ and changes the luminescence center. Improved emission intensity is obtained because appropriate Ga3+ doping leads to larger band gap and reduces non-radiative transitions. Phosphor-converted LED (pc-LED) devices fabricated with blue chip (470 nm) and the as-obtained SrMgAl10-yGayO17:1.0%Mn4+ phosphors emit bright blue and red light, which fit the absorption regions of plant pigments well, thus SrMgAl10-yGayO17:Mn4+ phosphor can be a candidate for plant growth LED light.
关键词： crystal field theory,SrMgAl10-yGayO17:Mn4+,plant growth LED light,red shift,nephelauxetic effect
更新于2025-09-23 15:19:57
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High-Speed Light Signal Transmitters for Optical Communication Based on Ultraviolet Radiation
摘要： A light signal transmitter based on ultraviolet radiation is realized on GaN-on-silicon platform. The light signal transmitter with ultra-small active area is fabricated by a double-etching process. The absolute value of negative junction capacitance of transmitter is as low as the pF (picofarads) scale in positive bias voltage. Small capacitance is bene?cial to improve the communication performance of a transmitter. The dominant EL (electroluminescence) peak of transmitter is located at about 380 nm in the ultraviolet range. With the increase of the current, the dominant peak of transmitter remains stable and the light output power is lineally modulated. A free-space data transmission test in the ultraviolet range with 250 Mbps was conducted to indicate a promising high-speed optical communication capability of a light signal transmitter in the ultraviolet range.
关键词： LED (light emitting diode),GaN,ultraviolet,optical communication
更新于2025-09-23 15:19:57
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Brain Photobiomodulation—Preliminary Results from Regional Cerebral Oximetry and Thermal Imaging
摘要： A new piece of equipment for LED (light emitting diode) brain photobiomodulation is introduced. Preliminary results from regional cerebral oxygen saturation and from thermography are shown before, during and after stimulation. The procedure offers a new way to quantify the biological effects of a possible innovative therapeutic method. However further measurements are absolutely necessary.
关键词： stroke,brain,LED (light emitting diode) stimulation,photobiomodulation,regional cerebral oxygen saturation,LED helmet,mental diseases,light therapy,wavelength,dementia,thermal imaging
更新于2025-09-19 17:15:36
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Development of Narrow Band LED Sources and Their Application to Dermatology
摘要： 半導体を用いた LED を光源とし，バンドパスフィルタを用いて超狭帯域光を得る技術を開発した．この光源をヒトの毛髪再生に応用し，有効な臨床結果を得ることができた．また超狭帯域 LED 照射が人の毛乳頭細胞を刺激し，mRNA の発現や蛋白生成が生じる事が分子生物学的に示された．更に皮膚深達度が高い超狭帯域赤色 LED 光照射が毛成長に有効であることがマウスの実験や，又培養ヒト毛乳頭細胞を用いた実験から分子メカニズムモデルが示された．逆に皮膚深達度が浅い超狭帯域緑色 LED 光照射は，創傷治癒に有効であった．このように，LED を光源とした超狭帯域光は，更に上述の研究を深化させるとともに，新たな光医学融合分野を発展させ新産業を開拓していくものと期待している．
关键词： Hair growth,Laser diode (LD),Human dermal papilla cells,Narrow-band LED (NB-LED),Light source,m-RNA,Wound healing,Band-pass filter
更新于2025-09-19 17:13:59
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[IEEE 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Shenzhen, China (2019.11.25-2019.11.27)] 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Effects of LED Light Color and Intensity on Feather Pecking and Fear Responses of Layer Breeders in Natural Mating Colony Cages
摘要： Natural mating colony cages for layer breeders have become commonplace for layer breeders in China. However, feather pecking (FP) and cannibalism are prominent in this system. The objective of this study was to investigate the effects of 4 LED light colors (white: WL, red: RL, yellow-orange: YO, blue-green: BG) with 2 light intensities for each color on FP, plumage condition, cannibalism, fear, and stress. A total of 32 identical cages were used for the 8 treatments (4 replicates for each treatment). For both light intensities, hens in RL had a lowest frequency of severe FP, whereas hens in WL had a highest frequency of severe FP. Hens in RL and BG had a better plumage condition than in WL and YO. Compared with RL and BG, hens in WL and YO had a significant longer TI duration. Hens in RL had a higher concentration of 5-HT, a lower concentration of CORT, and a lower heterophil to lymphocyte ratio than WL and YO. Furthermore, RL could significantly reduce mortality from cannibalism. Overall, hens treated with RL and low light intensity showed a lower frequency of severe FP, less damaged plumage, were less fearful, and lower physiological indicators of stress, and had reduced mortality from cannibalism. Transforming the light color to red or dimming the light could be regarded as an effectively method to reduce the risk of FP and alleviate the fear responses of layer breeder.
关键词： LED light color,natural mating colony cages,layer breeders,light intensity,fear responses,feather pecking
更新于2025-09-19 17:13:59
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Fabrication of vessel–like biochar–based heterojunction photocatalyst Bi2S3/BiOBr/BC for diclofenac removal under visible LED light irradiation: Mechanistic investigation and intermediates analysis
摘要： In this work, a novel, economical and effective vessel–like biochar–based photocatalyst Bi2S3/BiOBr/BC was synthesized by a facile one–pot solvothermal method for the first time. A series of characterization analyses demonstrated the successful preparation of photocatalyst Bi2S3/BiOBr/BC. Furthermore, diclofenac (DCF) as the target contaminant was applied to elucidate the enhanced photocatalytic performance (93.65%, 40 min) under energy–saving visible LED light irradiation. Comparison experiments among different photocatalysts and photoelectrochemical tests results illustrated that excellent photocatalytic performance of Bi2S3/BiOBr/BC 10% might be attributed to the electrons transfer of biochar and higher charge separation efficiency of heterojunction structure. Besides, lower electrical energy per order value indicated photocatalyst/visible LED light system was more energy–saving. Proper photocatalyst dosage (0.6 g/L) and relatively acidic water environment (pH=5.0) would be beneficial to DCF photodegrdation by Bi2S3/BiOBr/BC. Good reusability and stability of Bi2S3/BiOBr/BC were verified via five consecutive recycle experiments. Furthermore, the role of active species was determined through trapping experiments and ·O2– and h+ dominated the photodegradation reaction to mineralize DCF molecules. Eleven main intermediates and four possible photodegradation pathways were proposed by HRMS analysis. Accordingly, photocatalyst Bi2S3/BiOBr/BC would provide potential technical support for emerging pollutant removal in water matrix.
关键词： Diclofenac,Photocatalytic mechanism,Bi2S3/BiOBr/BC,Visible LED light,Degradation pathway
更新于2025-09-19 17:13:59
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[IEEE 2019 Innovations in Power and Advanced Computing Technologies (i-PACT) - Vellore, India (2019.3.22-2019.3.23)] 2019 Innovations in Power and Advanced Computing Technologies (i-PACT) - A Novel Switched Capacitor based High Gain Boost Converter with efficient MPPT controller for LED Lighting Applications
摘要： The paper proposed a novel switched capacitor based high gain quadratic DC-DC boost converter with Perturb & Observe MPPT (Maximum Power Point Tracking) controller. The converter configuration is appropriate to be employed in fuel cell and solar photovoltaic systems. The presented converter topology is designed with solar powered switched capacitor based voltage lift technique to provide high voltage conversion ratio. Due to variable atmospheric conditions it’s very difficult to provide constant output to the LED (Light Emitting Diode) load. Even small change in the characteristics of LED that will effect to damage the load. Hence P&O (Perturb & Observe) MPPT controller is applying for the designed converter configuration in order to produce stable output with high gain under variable weather conditions. Due to high step up gain and symmetrical configuration of the circuit topology, the stress voltage across the power semiconductor devices is low. Hence, the metal oxide semiconductor field-effect transistor gives high performance with low ON state resistance. The design cost of the circuit is reduces because of using low voltage rating diodes. Also reverse recovery and conduction losses are low which improves the power conversion and efficiency of the converter. The principle of operation and steady state analysis of the circuit topology are conferred in detail. Finally a simulation experiment of proposed converter with 120Watts of LED load is simulated and verified with theoretical analysis.
关键词： High voltage conversion ratio,Switched Capacitor,LED (Light Emitting Diode),PWM (Pulse Width Modulation) control,MPPT(Maximum Power Point Tracking),SMPS (Switched Mode Power Supplies),P&O (Perturb &Observe)
更新于2025-09-19 17:13:59