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- 摘要
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- 实验方案
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Tunable Chromaticity and High Color Rendering Index of WLEDs with CaAlSiN <sub/>3</sub> :Eu <sup>2+</sup> and YAG:Ce <sup>3+</sup> Dual Phosphora??ina??silicaa??glass
摘要： Phosphors-in-glass (PiG), which serves as a potential bi-replacement of both phosphors and organic encapsulants in high-power white light-emitting diodes (WLEDs), has captured much attention due to its high thermal stability and excellent luminescent properties. However, due to the high temperature-sensitivity and the chemical reactions between phosphors with glass matrix, a variety of phosphors, especially red phosphors could be hardly dispersed into the glass without thermal quenching and decomposition, which greatly limits the improvement of color rendering index and chromaticity tunability of the WLEDs. In this study, adopting the mesoporous silica (FDU-12) and commercial phosphors as raw materials, the phosphors-in-silica-glasses (PiSGs) embedded with red phosphor CaAlSiN3:Eu2+ and yellow phosphor YAG:Ce3+ have been successfully prepared at low sintering temperature (950 ?C) and short preparation time (10 min) using spark plasma sintering. Owing to the well preservation of the originally emissive properties of the embedded phosphors, the warm WLEDs with tunable chromaticity and exhibited a superior performance with LE of 133 lm/W, CCT of 3970 K and CRI of 81 were fabricated by encapsulating the as-prepared PiSGs on the blue chips. Moreover, the PiSG composite exhibits a high thermal conductivity up to 1.6 W/m·K.
关键词： white light-emitting diodes,phosphor in silica glass,tunable chromaticity,mesoporous silica
更新于2025-09-23 15:21:01
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[IEEE 2018 International Conference on Platform Technology and Service (PlatCon) - Jeju (2018.1.29-2018.1.31)] 2018 International Conference on Platform Technology and Service (PlatCon) - Classification of Daytime and Night Based on Intensity and Chromaticity in RGB Color Image
摘要： Classification of daytime and night in the color image is a very important task in image processing based on color images acquired from CCTV. Also, weather classification must be performed before performing image processing such as weather report, shadow removal and fog detection. In this paper, we proposed the classification, whether a color image is daytime or night. We first set the range of pixels in the gray level image from 0 to 50, from 51 and over 101, and we estimated each range as daytime, evening and night. In the first step, it is estimated based on the intensity and chromaticity of the image. If the classification result based on the intensity and chromaticity image is the same, the process is terminated. Otherwise, the k-means segmentation is used in the second step to determine the final classification. Some experiments are conducted so as to verify the proposed method, and the classification is well performed. The execution time results up to the first step are about 0.31 seconds on average, and the execution up to the second step is changed according to the resolution of the image.
关键词： daytime and night,k-means segmentation,intensity,classification,chromaticity
更新于2025-09-19 17:15:36
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Structure, thermal stability and chromaticity investigation of TiB2 based high temperature solar selective absorbing coatings
摘要： Transition metal titanium diboride (TiB2) is a promising material for the solar selective absorbing coatings due to its favorable spectral selectivity and thermal stability. In this research, spectrally selective TiB2/Al2O3 tandem absorber is deposited on stainless steel (SS), which exhibits a high solar absorptance (αs = 0.93) and a low thermal emissivity (ε = 0.11). In this tandem absorber, the TiB2 acts as the main absorber layer and the Al2O3 acts as an antire?ection layer. The tandem absorber coating is systematically characterized by ultra-high resolution scanning electron microscope (SEM), UV–vis-NIR spectrophotometer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Micro-Raman techniques. The thermal stability in vacuum of the SS/TiB2/Al2O3 tandem absorber coatings is investigated in the temperature range of 400–800 °C for 2 h and 100 h, respectively. SEM and Raman spectra indicate that the change of surface morphology and chemical composition for the coating result in the degradation of optical performance. With the di?erent annealed temperature, the SS/TiB2/Al2O3 tandem absorber coatings exhibit di?erent color, which is further investigated using chromaticity diagram.
关键词： Chromaticity,Titanium boride,Structure,Thermal stability,Solar selective absorbing coatings
更新于2025-09-19 17:15:36
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Fuzzy Logic Vehicle Positioning System Based on Chromaticity and Frequency Components of LED Illumination
摘要： Given their wide applicability, vehicle positioning systems are being actively studied currently. As the conventional global positioning system (GPS) cannot determine the vehicle position inside tunnels and other GPS-shaded areas, we propose to improve vehicle positioning using a fuzzy logic system that can retrieve the position of a moving vehicle in such areas. The proposed system analyzes the chromaticity and frequency components of active LED illumination, which is being commonly installed at locations like inside tunnels. We verify the system performance in a test environment that resembles a tunnel. As the proposed method uses the chromaticity and frequency of LED lights for vehicle positioning, it is suitable for areas where GPS reception is poor or unavailable.
关键词： GPS-shaded areas,Chromaticity,vehicle positioning system
更新于2025-09-19 17:13:59
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Hue‐ and Chromaticity‐Based Exploration of Surface Complexation‐Induced Tunable Emission from Non‐Luminescent Quantum Dots
摘要： Herein we report the use of a hue parameter of HSV (Hue, Saturation and Value) color space—in combination with chromaticity color coordinates—for exploring the complexation-induced luminescence color changes, ranging from blue to green to yellow to white, from a non-luminescent Fe-doped ZnS quantum dot (QD). Importantly, the surface complexation reaction helped a presynthesized non-luminescent Fe-doped ZnS QD to glow with different luminescence colors (such as blue, cyan, green, greenish-yellow, yellow) by virtue of the formation of various luminescent inorganic complexes (using different external organic ligands), while the simultaneous blue- and yellow-emitting complex formation on the surface of non-luminescent Fe-doped ZnS QD led to the generation of white light emission, with a hue mean value of 85 and a chromaticity of (0.28,0.33). Furthermore, the surface complexation-assisted incorporation of luminescence properties to a non-luminescent QD not only overcomes their restricted luminescence-based applications such as light-emitting, biological and sensing applications but also bring newer avenues towards unravelling the surface chemistry between QDs and inorganic complexes and the advantage of having an inorganic complex with QD for their aforementioned useful applications.
关键词： quantum dots,inorganic complexes,photoluminescence,hue,chromaticity,white light emission
更新于2025-09-19 17:13:59
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Supplemental intracanopy far-red radiation to red LED light improves fruit quality attributes of greenhouse tomatoes
摘要： Off-season greenhouse tomatoes have a poor reputation relative to their in-season, field-grown counterparts. Previously, we reported that supplemental intracanopy far-red (700–800 nm, FR) radiation in addition to red (600–700 nm, R) light with light-emitting diodes (LEDs) significantly decreased fruit water content compared to R LEDs alone and high-pressure sodium (HPS) lamps, the most common supplemental lighting used in commercial greenhouses. We hypothesize that supplemental R + FR LEDs during production improves fruit quality attributes (i.e., physicochemical properties, mineral concentrations, and sensory properties) in greenhouse tomatoes compared to R LEDs and HPS lamps. Both intracanopy LED lights increased fruit yield and biomass compared to HPS lamps. R LEDs increased dry matter ratio and improved overall physicochemical proprieties such as total soluble solids (TSS), titratable acidity (TA), and pH; however, R + FR LEDs had more significant effects on all measured attributes than did R LEDs. Similarly, R LEDs increased potassium, magnesium, and calcium content in whole fruit by 30, 74, and 40% compared to HPS lamps, and the addition of FR to R LEDs further increased sodium (Na) content and concentration. Consumer sensory panelists rated higher for sensory attributes (aroma, sweetness, acidity, and texture) of R + FR LED-supplemented tomatoes on a hedonic scale compared to R LED-supplemented ones. Importantly, HPS lamp-supplemented tomatoes had the least desirable quality attributes even when compared at the same ripe stage as LED-supplemented ones. Energy use efficiency (EUE) was not different between R + FR LEDs and R LEDs, which was 5 times higher than that of HPS lamps. Our results demonstrate for the first time that fruit quality attributes of greenhouse tomatoes can be improved by supplemental intracanopy lighting with R + FR LEDs to a degree that consumer panelists could perceive the differences. Therefore, we conclude that supplemental R + FR LEDs is indispensable for improving fruit quality of greenhouse tomatoes during off-season production.
关键词： Sensory evaluation,Electricity consumption,Hydroponics,Mineral nutrients,Solanum lycopersicum,Chromaticity,Intracanopy lighting
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Distributed Computing, VLSI, Electrical Circuits and Robotics (DISCOVER) - Manipal, India (2019.8.11-2019.8.12)] 2019 IEEE International Conference on Distributed Computing, VLSI, Electrical Circuits and Robotics (DISCOVER) - Improvement of health and well-being of human beings using tunable white LEDs
摘要： With the introduction of the International Telecommunication Union—Radiocommunication Sector (ITU-R) Recommendation BT.2020 (Rec. 2020) color space for ultrahigh de?nition television, the development of wide-gamut displays has become a high priority. To measure the relative gamut sizes of wide-gamut displays, it is herein proposed that the International Commission on Illumination (CIE) 1931 xy chromaticity diagram be used as a practical single metric rather than the nominally perceptually uniform CIE 1976 u'v' chromaticity diagram because of the high correlations between the Rec. 2020 gamut area-coverage ratios in the xy diagram and the volume-coverage ratios in the CIE 1976 L*a*b* and CIE 1976 L*u*v* color spaces. This paper explains why using the perceptually nonuniform xy diagram is counterintuitively appropriate to measure display gamut sizes by presenting a quantitative analysis of the gamut coverage in terms of hue. The argument is made that performing planimetry in the u'v' diagram, whose perceptual uniformity is valid only when the luminance is constant, does not yield accurate display gamut sizes, because the magenta region area is overestimated and the yellow region area is underestimated. Furthermore, some limitations on the use of planimetry for measuring display gamut sizes of multiprimary displays are discussed, and the color light output standard is proposed as a complement to practical planimetry using the xy diagram.
关键词： ultrahigh de?nition television,display gamut size,Chromaticity diagram,Recommendation ITU-R BT.2020,planimetry,wide color gamut
更新于2025-09-16 10:30:52
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Temporal Luminescence of Broadband Light-Emitting Diodes and Their Use for Generating Customizable White Light
摘要： Broadband visible light-emitting diodes (LEDs) are now being used for applications where high-quality tunable light is needed. These LEDs are based on phosphors with wide emission bands (full width at half maximum, FWHM, of 70 nm or more). We describe the time-dependent characteristics of light emission from such devices. We found time lags in both luminescence buildup and decay as the broadband red, green and white LEDs are pumped by square pump photon flux. The reasons for such delays are photon percolation in phosphor/light scatterer blends and luminescence persistence due to defects in phosphors. The latter part of the paper describes a setup for combining light from phosphor-based red and green broadband LEDs with that of a band-edge emission blue LED to produce white light. It is shown that the chromaticity of white light can be changed stably by changing the frequency/duty cycle of PWM waveforms that are used for controlling red, green and blue LEDs. We also introduce a new LED drive scheme where PWM signals are converted to steady DC levels before driving LEDs. The setup described here enables the generation of full-spectrum white light with electrically controllable chromaticity.
关键词： light-emitting diodes,pulse width modulation,phosphors,color mixing,Chromaticity
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing ADVANCES IN BASIC SCIENCE (ICABS 2019) - Bahal, India (7–9 February 2019)] ADVANCES IN BASIC SCIENCE (ICABS 2019) - Photoluminescence and chromaticity properties of CdSe nanobeads made by a complexing agent assisted hydrothermal method for LEDs and laser applications
摘要： CdSe nanosbeads have been synthesized using a complexing agent assisted hydrothermal method. It is found that the presence of complexing agent (Oleic acid) plays a key role in the formation of nanobeads. The structural, morphological and optical properties of CdSe nanoparticles have been investigated. The obtained nanobeads of cadmium selenide are of wurtzite structure. It is inferred that the nucleation and agglomeration of nuclei is a major reason of the formation of nanobeads. The optical results show the obtained band gap is blue shifted from the bulk value and the photoluminescence and chromaticity spectrum show that the prepared CdSe nanobeads are yellowish green color emitters and useful for yellowish green LEDs and lasers.
关键词： chromaticity,nanobeads,CdSe,LEDs,luminescence,solvothermal route
更新于2025-09-11 14:15:04
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P‐15.3: The Importance of Centroid Wavelength for the Image Quality Evaluation of Laser Displays
摘要： The accuracy of a measurement method for the chromaticity and photometric quantity of laser displays using centroid wavelengths was experimentally verified. This method allows more accurate optical evaluation of laser displays in principle than the method using peak wavelengths which has been commonly known in the laser industry.
关键词： Chromaticity,Tristimulus Values,Peak Wavelength,Colorimetry,Laser,Laser Display,Radiometric Quantity,Centroid Wavelength,Photometric Quantity,Photometry
更新于2025-09-11 14:15:04