An Investigation Into the Optothermal Behavior of a High Power Red Light Emitting Diode: Impact of an Optical Path

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Ahmet Mete Muslu ◽  
Burak Ozluk ◽  
Mehmet Arik
Keyword(s):  
Computational Models ◽  
Red Light ◽  
Monochromatic Light ◽  
Junction Temperature ◽  
Normal Operation ◽  
Imaging Method ◽  
Light Emitting ◽  
Wide Range ◽  
Red Led ◽  
The Impact

Abstract Monochromatic light emitting diodes (LEDs) are getting more attention day by day for a very wide range of applications such as general lighting, signage, automotive lighting, display, water purification, and skin imaging. While they are taking place in a large number of applications, thermal challenges associated with the operation of LEDs have become a significant issue to address since their performance is greatly affected by thermal conditions. Thus, this study focuses on identifying thermal, optical, and electrical characteristics of an AlGaInP-based red LED considering the impact of the LED dome on the chip performance. The junction temperature measurement results obtained with forward voltage change method were validated with thermal imaging method (TIM) and computational models. It was observed that the LED dome may critically affect the thermal, optical, and electrical behaviors of the LED chip. In fact, a 3.7% increase in junction temperature and a 6.1% drop in optical conversion efficiency were found at the normal operation of the red LED after the LED dome was removed. The results were also compared with a blue LED, and lower junction temperatures were measured for the red LED at each driving current. The difference in junction temperature became even more noticeable at higher driving currents. Results have shown a good agreement between three different methods with a maximum variation of 6.9%.

scholarly journals LED Rail Signals: Full Hardware Realization of Apparatus with Independent Intensity by Temperature Changes

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1291
Author(s):  
Giuseppe Schirripa Schirripa Spagnolo ◽  
Fabio Leccese
Keyword(s):  
Temperature Sensor ◽  
Energy Efficient ◽  
Light Emitting Diode ◽  
Junction Temperature ◽  
Light Emitting ◽  
Temperature Changes ◽  
Wide Range ◽  
International Regulations ◽  
Long Lifetime ◽  
Set Up

Nowadays, signal lights are made using light-emitting diode arrays (LEDs). These devices are extremely energy efficient and have a very long lifetime. Unfortunately, especially for yellow/amber LEDs, the intensity of the light is closely related to the junction temperature. This makes it difficult to design signal lights to be used in naval, road, railway, and aeronautical sectors, capable of fully respecting national and international regulations. Furthermore, the limitations prescribed by the standards must be respected in a wide range of temperature variations. In other words, in the signaling apparatuses, a system that varies the light intensity emitted according to the operating temperature is useful/necessary. In this paper, we propose a simple and effective solution. In order to adjust the intensity of the light emitted by the LEDs, we use an LED identical to those used to emit light as a temperature sensor. The proposed system was created and tested in the laboratory. As the same device as the ones to be controlled is used as the temperature sensor, the system is very stable and easy to set up.

scholarly journals Critical Photoperiod and Optimal Quality of Night Interruption Light for Runner Induction in June-Bearing Strawberries

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1996
Author(s):  
Yali Li ◽  
Jie Xiao ◽  
Jiangtao Hu ◽  
Byoung Ryong Jeong
Keyword(s):  
Red Light ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light Emitting ◽  
Red Led ◽  
Critical Photoperiod ◽  
Closed Walk ◽  
White Light Emitting Diodes ◽  
Optimal Quality

The optimal photoperiod and light quality for runner induction in strawberries ‘Sulhyang’ and ‘Maehyang’ were investigated. Two experiments were carried out in a semi-closed walk-in growth chamber with 25/15 °C day/night temperatures and a light intensity of 250 μmol·m–2·s–1photosynthetic photon flux density (PPFD) provided from white light-emitting diodes (LEDs). In the first experiment, plants were treated with a photoperiod of either 12, 14, 16, 18, 20, or 22 h In the second experiment, a total of 4 h of night interruption (NI) light at an intensity of 70 μmol·m–2·s–1PPFD provided from either red, blue, green, white, or far-red LED in addition to 11 h short day (SD). The results showed that both ‘Sulhyang’ and ‘Maehyang’ produced runners when a photoperiod was longer than 16 h, and the number of runners induced positively correlated with the length of photoperiod. However, the plant growth, contents of chlorophyll, sugar and starch, and Fv/Fo decreased in a 22 h photoperiod. All qualities of the NI light, especially red light, significantly increased the number of runners and daughter plants induced per plant as compared with those in the SD treatment in both cultivars. In a conclusion, a photoperiod between 16 and 20 h and NI light, especially red NI light, can be used for quality runner induction in both ‘Sulhyang’ and ‘Maehyang’.

Fundamentals and Applications of Red Light-Emitting Diodes (LEDs) In Vitro Plant Growth on Tomato Lycopersicon esculentum Mill

2019 ◽  
Vol 805 ◽  
pp. 141-145
Author(s):  
Nguyen Phuc Thien
Keyword(s):  
Lycopersicon Esculentum ◽  
Plant Growth ◽  
Significant Influence ◽  
Growth And Development ◽  
Red Light ◽  
Light Emitting ◽  
Red Led ◽  
In Vitro Plant ◽  
Normal Light

The aim of these studies was mainly to investigate the effects of monochromatic LEDs applied singly on the in vitro plant growth and morphogenesis. Various morphological and physiological parameters are considered that influence the growth and development of plants in vitro under red LED light as compared to those under normal light. Upon exposure to LED, in vitro-raised plants have shown significant improvements in growth and morphogenesis. In particular, red and blue lights, either alone or in combination, have a significant influence on plant growth. The present study gives an overview of the fundamentals of LEDs and describes their effects on in vitro plant growth and morphogenesis and their future potentials. The main objective of this study was to carry out line and combing ability of plant growth on tomato.

Syntheses, crystal structures and photoluminescence properties of Ca9Y(PO4)5(SiO4)F1.5O0.25:Ln3+ (Ln3+ = Eu3+/Tb3+/Dy3+/Sm3+) phosphors for near-UV white LEDs

RSC Advances ◽  
2016 ◽  
Vol 6 (95) ◽  
pp. 92371-92377 ◽  
Author(s):  
Man Liu ◽  
Wei Lü ◽  
Jiansheng Huo ◽  
Baiqi Shao ◽  
Yang Feng ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Red Light ◽  
Photoluminescence Properties ◽  
Light Emitting ◽  
White Leds ◽  
Red Led

We report red light-emitting Ca9Y(PO4)5(SiO4)F1.5O0.25:Eu3+/Sm3+ phosphors for the fabrication of red LED devices.

scholarly journals Growth and Bioactive Compound Synthesis in Cultivated Lettuce Subject to Light-quality Changes

HortScience ◽  
2017 ◽  
Vol 52 (4) ◽  
pp. 584-591 ◽  
Author(s):  
Ki-Ho Son ◽  
Jin-Hui Lee ◽  
Youngjae Oh ◽  
Daeil Kim ◽  
Myung-Min Oh ◽  
...  
Keyword(s):  
Blue Light ◽  
Bioactive Compounds ◽  
Light Quality ◽  
Red Light ◽  
Monochromatic Light ◽  
Bioactive Compound ◽  
Light Emitting ◽  
Compound Synthesis ◽  
Plant Factory ◽  
Ferulic Acids

This study aimed to determine the effect of changes in light quality on the improvement of growth and bioactive compound synthesis in red-leaf lettuce (Lactuca sativa L. ‘Sunmang’) grown in a plant factory with electrical lighting. Lettuce seedlings were subjected to 12 light treatments combining five lighting sources: red (R; 655 nm), blue (B; 456 nm), and different ratios of red and blue light combined with three light-emitting diodes [LEDs (R9B1, R8B2, and R6B4)]. Treatments were divided into control (continuous irradiation of each light source for 4 weeks), monochromatic (changing from R to B at 1, 2, or 3 weeks after the onset of the experiments), and combined (changing from R9B1 to R8B2 or R6B4 at 2 or 3 weeks after the onset of the experiments). Growth and photosynthetic rates of lettuce increased with increasing ratios of red light, whereas chlorophyll and antioxidant phenolic content decreased with increasing ratios of red light. Individual phenolic compounds, including chlorogenic, caffeic, chicoric, and ferulic acids, and kaempferol, showed a similar trend to that of total phenolics. Moreover, transcript levels of phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) genes were rapidly upregulated by changing light quality from red to blue. Although the concentration of bioactive compounds in lettuce leaves enhanced with blue light, their contents per lettuce plant were more directly affected by red light, suggesting that biomass as well as bioactive compounds’ accumulation should be considered to enhance phytochemical production. In addition, results suggested that growth and antioxidant phenolic compound synthesis were more sensitive to monochromatic light than to combined light variations. In conclusion, the adjustment of light quality at a specific growth stage should be considered as a strategic tool for improving crop yield, nutritional quality, or both in a plant factory with electrical lighting.

scholarly journals Calcium Tungstate Doped with Rare Earth Ions Synthesized at Low Temperatures for Photoactive Composite and Anti-Counterfeiting Applications

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1214
Author(s):  
Soung-Soo Yi ◽  
Jae-Yong Jung
Keyword(s):  
Rare Earth ◽  
Light Emission ◽  
Red Light ◽  
Blue Emission ◽  
Xrd Analysis ◽  
Rare Earth Ions ◽  
Precipitation Method ◽  
Calcium Tungstate ◽  
Light Emitting ◽  
Wide Range

A precursor was prepared using a co-precipitation method to synthesize crystalline calcium tungstate. The prepared precursor was dried in an oven at 80 °C for 18 h. The dried powders, prepared without a heat treatment process, were observed in XRD analysis to be a crystalline CaWO4 phase, confirming that the synthesis of crystalline CaWO4 is possible even at low temperature. To use this crystalline CaWO4 as a light emitting material, rare earth ions were added when preparing the precursor. The CaWO4 powders doped with terbium (Tb3+) and europium (Eu3+) ions, respectively, were also observed to be crystalline in XRD analysis. The luminescence of the undoped CaWO4 sample exhibited a wide range of 300 ~ 600 nm and blue emission with a central peak of 420 nm. The Tb3+-doped sample showed green light emission at 488, 545, 585, and 620 nm, and the Eu3+-doped sample showed red light emission at 592, 614, 651, and 699 nm. Blue, green, and red CaWO4 powders with various luminescence properties were mixed with glass powder and heat-treated at 600 °C to fabricate a blue luminescent PiG disk. In addition, a flexible green and red light-emitting composite was prepared by mixing it with a silicone-based polymer. An anti-counterfeiting application was prepared by using the phosphor in an ink, which could not be identified with the naked eye but can be identified under UV light.

scholarly journals Effect of Light-Emitting Diode (Led) Light on the Gene Expression Related With Ascorbate Biosynthesis and Metabolism in Broccoli Florets

2017 ◽  
Vol 2 (6) ◽  
pp. 529
Author(s):  
Chandra Kurnia Setiawan ◽  
Supriyadi Supriyadi ◽  
Umar Santoso ◽  
Gang Ma ◽  
Masaya Kato
Keyword(s):  
Gene Expression ◽  
Chlorophyll Content ◽  
Mrna Level ◽  
Red Light ◽  
Light Treatment ◽  
Rt Pcr ◽  
Light Emitting ◽  
Led Light ◽  
Red Led ◽  
Effect Of Light

Ascorbate is one of the most abundant soluble antioxidants in the plant. Multiple functions of ascorbate in photo protection have been proposed, including scavenging of reactive oxygen species generated by oxygen photoreduction and photorespiration. There is still unclear information relation to LED light with Ascorbate biosynthesis and metabolism, yellowing, chlorophyll content, and ethylene production in broccoli florets. The effect of light-emitting diodes (LED) light on ascorbate (AsA) biosynthesis and metabolism in broccoli (Brassica oleracea L. var. Italica) cultivar “Ryokurei” were studied using red (660 nm), blue (470 nm) and white LED lights as the light source and also no light treatment as the control. Gene expression involved in the biosynthesis and metabolism of AsA, AsA content, color, chlorophyll content and ethylene production rate on the postharvest broccoli were observed in 4 days. The result showed that after two days, red light treatment significantly (p < 0,05) delayed the decrease of ascorbate content. The result was supported by observations using Real-Time Quantitative RT-PCR showed that red light treatment can suppress mRNA level of BO-APX1, BO-APX2, and BO-sAPX on the third day. Observation of BO-GLDH mRNA level was increased in the third-day exposure of red LED light. Therefore red LED light showed up-regulated AsA biosynthesis transcriptional level. Enzymes which possibility responsible for AsA metabolism and biosynthesis in a row were Ascorbate Peroxide (APX) and L-Galactono-1,4-Lactone Dehydrogenase (GLDH). The regulation of this gene expression might contribute to the suppression of AsA reduction by red LED light treatment in broccoli. Red LED also showed suppression of yellowing and decline the chlorophyll content in postharvest broccoli florets. Keywords: ascorbate, LED; broccoli; gene expression; real-time quantitative RT-PCR.

Design and Construction of a Machine to Evaluate the Forces in Roller Chain Drives

1992 ◽  
Author(s):  
James C. Conwell ◽  
Glen E. Johnson ◽  
S. W. Peterson
Keyword(s):  
Experimental Investigation ◽  
Impact Force ◽  
Normal Operation ◽  
Test Machine ◽  
Chain Drive ◽  
Roller Chain ◽  
Wide Range ◽  
The Impact ◽  
Chain Drives ◽  
Design And Construction

Abstract In this article, a brief history of chain drives is presented, and the design and construction of a machine to investigate chain drive force phenomena is discussed. The new test machine allows the measurement of the impact force between a roller and the sprocket during “seating” and it can also be used to measure the forces that exist in the link sides plates during normal operation (including start-up and shut down conditions). Data can be obtained for a wide range of chain loads and speeds. Two companion papers (“Experimental Investigation of the Impact Force that Occurs When a Roller Seats on the Sprocket During Normal Operation of a Roller Chain Drive” and “Experimental Investigation of the Forces in a Link Side Plate During Normal Operation of a Roller Chain Drive”, both presented at this conference) describe experiments that have been completed with this test machine.

Experimental Investigation of the Forces in a Link Side Plate During Normal Operation of a Roller Chain Drive

1992 ◽  
Author(s):  
James C. Conwell ◽  
Glen E. Johnson ◽  
S. W. Peterson
Keyword(s):  
Experimental Investigation ◽  
Unit Length ◽  
Linear Chain ◽  
Normal Operation ◽  
Test Machine ◽  
Side Plate ◽  
Inertia Effects ◽  
Roller Chain ◽  
Wide Range ◽  
The Impact

Abstract The fluctuation in the tension of a chain link during normal operation is very likely the root cause of chain stretch and fatigue in roller chain drives. In this paper we present the results from a recent experimental investigation of this tension variation phenomenon. The experimental procedure is described, and data are presented for a wide range of initial tensions, transmitted loads, and chain speeds. At low speeds, the data give reasonable agreement with previously published theoretical models for quasi-static load distribution. However, at higher speeds (where inertia effects are more significant) the experimental results indicate that quasi-static models do not provide an adequate explanation. The differences are noted and discussed. An empirical equation for “tight side” chain tension is presented in terms of torque transmitted, sprocket pitch radius, mass per unit length of chain, and linear chain speed. This paper is accompanied by companion papers that describe the design and construction of the test machine and the measurement of the impact force as a roller seats on the sprocket.

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