scholarly journals Failure Analysis of Some Commercial Spotlights Based on Light Emitting Diodes

Electronics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 48
Author(s):  
Wei Zhong ◽  
Thomas Walther
Keyword(s):  
Integrated Circuit ◽  
Light Emitting Diode ◽  
Light Output ◽  
Open Circuit ◽  
Constant Current ◽  
Current Output ◽  
Light Emitting ◽  
Catastrophic Failures ◽  
Drive Circuit

The failure mechanism of two commercial light-emitting diode (LED)-based spotlights with GU10 form factor is analyzed. Through component testing and comparison to nominal values as well as to simulations, it is found that the cause of both device failures is related to damaged components within the drive circuits rather than the LEDs themselves. Both LED heads work as normal when connected to an external direct current (DC) source. The results show that the lack of light output of one spotlight is related to the open circuit caused by damaged resistors and inductors in its drive circuit, while the flickering of the other is related to the malfunction of the integrated circuit providing constant current output. Therefore, improving the quality of the LED drive circuits is considered the most effective way for manufacturers to reduce catastrophic failures of LED spotlights.

The Design of High Power LED Headlamp

2013 ◽  
Vol 423-426 ◽  
pp. 2098-2103
Author(s):  
Wen Lin Chen ◽  
Zhen An ◽  
Chao Qun Xiang ◽  
Chen Yang Liu ◽  
Li Na Hao
Keyword(s):  
High Power ◽  
Heat Dissipation ◽  
Light Emitting Diode ◽  
Current Drive ◽  
Constant Current ◽  
Light Emitting ◽  
High Power Led ◽  
Drive Circuit ◽  
Led Headlamp ◽  
The Stability

With the continuous development of LED(Light-Emitting Diode) manufacturing technology, the high power white LED is gradually applied in the field of all kinds of lighting .But with working time increasing of LED chips, their junctions temperature continue increasing, which lead to decrease light-emitting efficiency and reliability of LED chip, and even be failure. According to the serious heating of LED chip, this paper has been designed a fin-type aluminum radiator panels using Pro/E software. A LED constant current drive circuit is designed by using LTC3783 chip. With the ANSYS software, thermal analysis was carried out on the fin-type aluminum radiator panels, and eventually the mode of high power LED headlamps is determined. The stability of the LED constant current drive circuit is verified through experiments. The LED headlamps of 90W worked for ten hours, and the results of the experiments showed that the LED chip junctions temperature measured are less than 75°Cso we can solve heat dissipation of high power LED headlamps effectively.

scholarly journals Increased Plant Quality, Greenhouse Productivity and Energy Efficiency with Broad-Spectrum LED Systems: A Case Study for Thyme (Thymus vulgaris L.)

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 960
Author(s):  
Jenny Manuela Tabbert ◽  
Hartwig Schulz ◽  
Andrea Krähmer
Keyword(s):  
Broad Spectrum ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Thymus Vulgaris ◽  
Light Spectrum ◽  
Light Emitting ◽  
Biomass Yields ◽  
Lighting Systems

A light-emitting diode (LED) system covering plant-receptive wavebands from ultraviolet to far-red radiation (360 to 760 nm, “white” light spectrum) was investigated for greenhouse productions of Thymus vulgaris L. Biomass yields and amounts of terpenoids were examined, and the lights’ productivity and electrical efficiency were determined. All results were compared to two conventionally used light fixture types (high-pressure sodium lamps (HPS) and fluorescent lights (FL)) under naturally low irradiation conditions during fall and winter in Berlin, Germany. Under LED, development of Thymus vulgaris L. was highly accelerated resulting in distinct fresh yield increases per square meter by 43% and 82.4% compared to HPS and FL, respectively. Dry yields per square meter also increased by 43.1% and 88.6% under LED compared to the HPS and FL lighting systems. While composition of terpenoids remained unaffected, their quantity per gram of leaf dry matter significantly increased under LED and HPS as compared to FL. Further, the power consumption calculations revealed energy savings of 31.3% and 20.1% for LED and FL, respectively, compared to HPS. In conclusion, the implementation of a broad-spectrum LED system has tremendous potential for increasing quantity and quality of Thymus vulgaris L. during naturally insufficient light conditions while significantly reducing energy consumption.

Self Powered Flexible Electronics Based on Self Poled “Ferroelectretic” Nanogenerator

MRS Advances ◽  
2016 ◽  
Vol 1 (45) ◽  
pp. 3083-3088 ◽  
Author(s):  
Sujoy Kumar Ghosh ◽  
Dipankar Mandal
Keyword(s):  
Composite Film ◽  
Flexible Electronics ◽  
Light Emitting Diode ◽  
Open Circuit ◽  
Pvdf Film ◽  
Light Emitting ◽  
Single Finger ◽  
Finger Touch ◽  
Self Powered ◽  
Pure Pvdf

ABSTRACTA ferroelectric nanogenerator without any electric poling treatment has been realized by incorporation of ytterbium (Yb) salt incorporated porous PVDF composite film. The composite film compose of electroactive β- and γ-phases, demonstrates higher dielectric and ferroelectric polarization responses than pure PVDF film. The 3 V of open circuit voltage with 0.47 µW/cm2 power density was generated by the nanogenerator upon single finger touch. It can also operate capacitor and light emitting diode without any subsidiary batteries.

Image quality of a novel light-emitting diode (LED)-illuminated colonoscope

Endoscopy ◽  
2016 ◽  
Vol 48 (10) ◽  
pp. 934-938 ◽  
Author(s):  
Sho Sasaki ◽  
Jun Nishikawa ◽  
Hideo Yanai ◽  
Munetaka Nakamura ◽  
Junichi Nishimura ◽  
...  
Keyword(s):  
Image Quality ◽  
Light Emitting Diode ◽  
Light Emitting

scholarly journals A 3 W High-Voltage Single-Chip Green Light-Emitting Diode with Multiple-Cells Network

2015 ◽  
Vol 2015 ◽  
pp. 1-4 ◽  
Author(s):  
W. Wang ◽  
Y. Cai ◽  
Y. B. Zhang ◽  
H. J. Huang ◽  
W. Huang ◽  
...  
Keyword(s):  
High Voltage ◽  
Light Emitting Diode ◽  
Light Output ◽  
Green Light ◽  
Current Crowding ◽  
Single Chip ◽  
Light Output Power ◽  
Large Area ◽  
Light Emitting ◽  
Multiple Cells

A parallel and series network structure was introduced into the design of the high-voltage single-chip (HV-SC) light-emitting diode to inhibit the effect of current crowding and to improve the yield. Using such a design, a6.6×5 mm2large area LED chip of 24 parallel stages was demonstrated with 3 W light output power (LOP) at the current of 500 mA. The forward voltage was measured to be 83 V with the same current injection, corresponding to 3.5 V for a single stage. The LED chip’s average thermal resistance was identified to be 0.28 K/W by using infrared thermography analysis.

scholarly journals ZnO Microcrystals for Light Emitting Diode and Photovoltaic Applications with Integration on Flexible Substrates

2009 ◽  
Vol 1192 ◽  
Author(s):  
Jesse J Cole ◽  
Heiko Jacobs
Keyword(s):  
Flexible Electronics ◽  
Light Emitting Diode ◽  
Flexible Substrate ◽  
Oxygen Plasma Treatment ◽  
Near Band Edge ◽  
Transfer Printing ◽  
Light Emitting ◽  
Integration Approach ◽  
Photovoltaic Applications

AbstractWe report a new integration approach to produce arrays of ZnO microcrystals for optoelectronic and photovoltaic applications. Demonstrated applications are n-ZnO/p-GaN heterojunction LEDs and photovoltaic cells. The integration process uses an oxygen plasma treatment in combination with a photoresist pattern on Magnesium doped GaN substrates to define a narrow sub-100nm width nucleation region. ZnO is synthesized in the defined areas by a hydrothermal technique using zinc acetate and hexamethylenetetramine precursors. Nucleation is followed by lateral epitaxial overgrowth producing single crystal disks of ZnO. The process provides control over the dimension and location of the ZnO crystals. The quality of the patterned ZnO is high; the commonly observed defect related emission in the electroluminescence spectra is suppressed and a single near-band-edge UV peak is observed. Transfer printing of the ZnO microcrystals onto a flexible substrate is also demonstrated in the context of transparent flexible electronics.

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