Evaluation of Color Rendering Index for LED and Fluorescent Light Sources

2015 ◽  
Vol 731 ◽  
pp. 22-26
Author(s):  
Huan Jiang ◽  
Min Huang ◽  
Fu Song Yang ◽  
Yu Liu
Keyword(s):  
Light Emitting Diode ◽  
Fluorescent Light ◽  
Light Sources ◽  
Light Emitting ◽  
Led Light ◽  
Color Science ◽  
Color Rendering Index ◽  
Different Color ◽  
Color Rendering

In order to assess the performances of different color rendering index (Ra, CRI, CQS, nCRI, R96a). The LED (light-emitting diode), fluorescent light sources and 30 printed color samples were used in our experiment. 20 observers were organized to carry out the color preference experiment, the visual data were accumulated to test the performances of the light sources and the results indicated that existing color rendering index have some deficiencies to assess the quality of the light source, which were needed to be modified for the theory of color science and industry application. The new CQS additional scales were calculated and the improvements were still insufficient for the LED light sources.

Reliability of High-Power Light Emitting Diode Attached With Different Thermal Interface Materials

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Xin Li ◽  
Xu Chen ◽  
Guo-Quan Lu
Keyword(s):  
High Power ◽  
Heat Dissipation ◽  
Light Emitting Diode ◽  
Temperature Cycling ◽  
Fluorescent Light ◽  
Light Sources ◽  
Light Emitting ◽  
Die Attach ◽  
Nanosilver Paste ◽  
Interconnection Material

As a solid electroluminescent source, white light emitting diode (LED) has entered a practical stage and become an alternative to replace incandescent and fluorescent light sources. However, due to the increasing integration and miniaturization of LED chips, heat flux inside the chip is also increasing, which puts the packaging into the position to meet higher requirements of heat dissipation. In this study, a new interconnection material—nanosilver paste is used for the LED chip packaging to pursue a better optical performance, since high thermal conductivity of this material can help improve the efficiency of heat dissipation for the LED chip. The bonding ability of this new die-attach material is evaluated by their bonding strength. Moreover, high-power LED modules connected with nanosilver paste, Sn3Ag0.5Cu solder, and silver epoxy are aged under hygrothermal aging and temperature cycling tests. The performances of these LED modules are tested at different aging time. The results show that LED modules sintered with nanosilver paste have the best performance and stability.

scholarly journals Gd3Li3Te2O12:U6+,Eu3+: A Tunable Red Emitting Garnet Showing Efficient U6+ to Eu3+ Energy Transfer at Room Temperature

Inorganics ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 84
Author(s):  
David Böhnisch ◽  
Juri Rosenboom ◽  
Thomas Jansen ◽  
Thomas Jüstel
Keyword(s):  
Energy Transfer ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Fluorescent Light ◽  
Light Sources ◽  
Light Emitting ◽  
Emission Lifetime ◽  
Uv Reflectance ◽  
Inorganic Composition ◽  
Color Rendering

Since the invention of fluorescent light sources, there is strong interest in Eu3+ activated phosphors as they are able to provide a high color rendering index (CRI) and luminous efficacy, which will also hold for phosphor converted light emitting diodes. Due to an efficient U6+ to Eu3+ energy transfer in Gd3Li3Te2O12:U6+,Eu3+, this inorganic composition shows red photoluminescence peaking at 611 nm. That means Eu3+ photoluminescence can be nicely sensitized via excitation into the U6+ excitation bands. Therefore, photoluminescence properties, such as temperature dependent emission and emission lifetime measurements, are presented. Charge transfer bands were investigated in detail. Additionally, density functional theory calculations reveal the band structure of the pure, i.e., non-doped host material. Obtained theoretical results were evaluated experimentally by the aid of diffuse UV reflectance spectroscopy.

Efficient very-high color rendering index organic light-emitting diode

2011 ◽  
Vol 12 (5) ◽  
pp. 865-868 ◽  
Author(s):  
Jwo-Huei Jou ◽  
Shih-Ming Shen ◽  
Chuen-Ren Lin ◽  
Yi-Shan Wang ◽  
Yi-Chieh Chou ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light ◽  
Color Rendering Index ◽  
Color Rendering ◽  
Very High

High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

2015 ◽  
Vol 24 (5) ◽  
pp. 057802 ◽  
Author(s):  
Yan-Qin Miao ◽  
Zhi-Xiang Gao ◽  
Ai-Qin Zhang ◽  
Yuan-Hao Li ◽  
Hua Wang ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light ◽  
Color Rendering Index ◽  
Color Rendering

The Color Mixing White-Light LEDs

2013 ◽  
Vol 378 ◽  
pp. 440-443
Author(s):  
Chiu Jung Yang ◽  
Chien Sheng Huang ◽  
Chih Wei Chen ◽  
Po Wen Chen
Keyword(s):  
White Light ◽  
Light Emitting Diode ◽  
Optical Power ◽  
Integrating Sphere ◽  
Light Spectrum ◽  
Light Emitting ◽  
Driver Circuit ◽  
Color Mixing ◽  
Color Rendering

Thepaperis discussedin coloruniformity study.The experiment divided into two steps in this study,first is modules design and simulation. Second is fabrication and measurement.After measure the LEDs property, calculating the ratio of each colored LEDs by using Grassmanns Law,modeling by Solidworks, and simulating the front study by optical software TracePro.Using four-color mixing with self-developed formula to avoid the present white light emitting diode patent, and the four-color grains are Red, Green, Blue and adding Y to modify the overall quality of the mixed light.The phosphorproduceSteabler-Wronsk hardly in the high temperatureas compared tofour-color mixing.Using four-color mixing to producehigher color rendering index than yellow phosphor.Series-parallel array of grain arrangement adopted to achieve the high demand for uniformity, while simplifying the design conditions by a certain current instead of the general mixed light-driven complex driver circuit,the completion of the mixing module using integrating sphere, light spectrum on the spectrophotometer, optical power, color coordinates values, such as mixing uniformity measurements.The chromaticity coordinates errors after complete results of the mixing module measurement and simulation can be controlled under (0.01x, 0.01y).

High color rendering index single phase white light emitting phosphors based on Tb3+/Sm3+ co-doped CePO4 nanocrystals: the role of Tb3+ as a bridge between Ce3+ and Sm3+

2019 ◽  
Vol 43 (44) ◽  
pp. 17367-17382 ◽  
Author(s):  
Sisira S. ◽  
Linju Ann Jacob ◽  
Kamal P. Mani ◽  
Biju P. R. ◽  
N. V. Unnikrishnan ◽  
...  
Keyword(s):  
White Light ◽  
Single Phase ◽  
Color Temperature ◽  
Light Emitting ◽  
Chromaticity Coordinates ◽  
Color Rendering Index ◽  
Cie Chromaticity ◽  
Color Rendering

Single phase white light emitting CePO4 nanocrystals doped with Tb3+ and Sm3+ were synthesized. The quality of white light is characterized by CIE chromaticity coordinates, color temperature, color rendering index and quantum yield.

scholarly journals A Practical Method to Design Reflector-Based Light-Emitting Diode Luminaire for General Lighting

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Jinren Yan
Keyword(s):  
Light Emitting Diode ◽  
Spherical Surface ◽  
Target Surface ◽  
Practical Method ◽  
Optical Simulation ◽  
Light Sources ◽  
Aspheric Surface ◽  
Light Emitting ◽  
Led Light ◽  
Spherical Reflector

A reflector-based light-emitting diode (LED) luminaire structure that can achieve a large cut-off angle for general lighting is presented in this work. The proposed lighting unit mainly consists of a spherical reflector and a primary packaging lens that contains an aspheric surface and a spherical surface. The light rays emitted from the LED light source are well controlled by the spherical reflector and the aspheric surface of the lens for the purpose of obtaining a uniform illumination on the target surface. Both the ideal Lambertian LED and non-Lambertian LED light sources were employed to validate the proposed structure and the performance of the designed lighting units was analyzed by optical simulation. The results show that the light utilization efficiencies and the estimated uniformities are 92.96% and 91.11% for ideal Lambertian LED-based lighting unit and 93.31% and 91.64% for non-Lambertian LED-based lighting unit, respectively. Further analysis shows that the tolerances of horizontal, vertical, and rotational deviation of the both lighting units were about 2.0 mm, 1.0 mm, and 1.0°, respectively.

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