Multifunctional integrating sphere setup for luminous flux measurements of light emitting diodes

2010 ◽  
Vol 81 (2) ◽  
pp. 023102 ◽  
Author(s):  
Tuomas Poikonen ◽  
Pasi Manninen ◽  
Petri Kärhä ◽  
Erkki Ikonen
Keyword(s):  
Light Emitting Diodes ◽  
Luminous Flux ◽  
Integrating Sphere ◽  
Light Emitting ◽  
Flux Measurements

ACCURATE MEASUREMENT OF ULTRAVIOLET LIGHT-EMITTING DIODES

2021 ◽  
Author(s):  
C. Yuqin Zong ◽  
Cameron Miller
Keyword(s):  
Ultraviolet Light ◽  
Light Emitting Diodes ◽  
Luminous Flux ◽  
Junction Temperature ◽  
Integrating Sphere ◽  
Light Emitting ◽  
Type D ◽  
Uv Led ◽  
Uv Leds ◽  
Ultraviolet Light Emitting Diodes

We have developed a new calibration capability for 200 nm to 400 nm ultraviolet light-emitting diodes (UV LEDs) using a Type D gonio-spectroradiometer. The recently-introduced mean differential continuous pulse (M-DCP) method is used to overcome the measurement difficulty associated with the initial forward voltage, VF, anomaly of a UV LED, which makes it impossible to use VF to infer junction temperature, TJ, during pulsed operation. The new measurement facility was validated indirectly by comparing the measured total luminous flux of a white LED with that measured using the NIST’s 2.5 m absolute integrating sphere. The expanded calibration uncertainty for the total radiant flux is approximately 2 % to 3 % (k = 2) depending the wavelength of the UV LED.

Novel fiber-based integrating sphere for luminous flux measurements

2006 ◽  
Vol 77 (6) ◽  
pp. 063102 ◽  
Author(s):  
Martin Szylowski ◽  
Michele Mossman ◽  
David Barclay ◽  
Lorne Whitehead
Keyword(s):  
Luminous Flux ◽  
Integrating Sphere ◽  
Flux Measurements

Model Predictive Control for Luminous Flux Tracking in Light-Emitting Diodes

2017 ◽  
Vol 25 (2) ◽  
pp. 695-703 ◽  
Author(s):  
Silvio Baccari ◽  
Francesco Vasca ◽  
Massimo Tipaldi ◽  
Luigi Iannelli
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Light Emitting Diodes ◽  
Luminous Flux ◽  
Light Emitting

Performance of chip-on-board and surface-mounted high-power LED luminaires at different relative humidities and temperatures

2018 ◽  
Vol 51 (8) ◽  
pp. 1249-1262
Author(s):  
D Raul ◽  
K Ghosh
Keyword(s):  
Light Emitting Diodes ◽  
Luminous Flux ◽  
Light Sources ◽  
Ambient Conditions ◽  
Light Emitting ◽  
Tropical Conditions ◽  
Temperature Ageing ◽  
Lighting Systems ◽  
State Device ◽  
Solid State Device

In today's world, light-emitting diodes are quickly replacing conventional light sources, both indoors and outdoors. Being a solid-state device, adverse ambient conditions such as high temperature and humidity lead to its poor performances, light quality and longevity. In outdoor applications, exposure to high ambient temperature during daytime, even when the lamp power is off, causes the lamp performance to deteriorate. In tropical countries, the environmental temperature in most of the days is higher than 25℃ and sometimes reaches 50℃. Here, the humidity varies between 30% and 80% and frequently over 80%. Thus, the reliability of the light emitting diodes is a question that needs a thorough study. In line with this, in this study, an effort has been made through an experiment. Here, commercially available surface-mounted device and chip-on-board-based light-emitting diodes are tested through an environmental chamber, and their measured illuminance values were observed by varying the relative humidity. Then, the temperature ageing or stress was set at 60℃ on the above types of light-emitting diodes at power off condition for 6000 hours and after that its luminous flux and spectral distribution were observed. The degradation observed under these conditions may guide designers and manufacturers to upgrade their lighting systems to make them fit for tropical conditions.

Assessment of Lumen Degradation and Remaining Life of Light-Emitting Diodes Using Physics-Based Indicators and Particle Filter

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Pradeep Lall ◽  
Hao Zhang
Keyword(s):  
Solid State ◽  
Particle Filter ◽  
Luminous Flux ◽  
Remaining Useful Life ◽  
Integrating Sphere ◽  
Harsh Environment ◽  
Forward Voltage ◽  
Acceptable Error ◽  
Light Emitting ◽  
Forward Current

The development of light-emitting diode (LED) technology has resulted in widespread solid state lighting (SSL) use in consumer and industrial applications. Previous researchers have shown that LEDs from the same manufacturer and operating under same use-condition may have significantly different degradation behavior. Applications of LEDs to safety critical and harsh environment applications necessitate the characterization of failure mechanisms and modes. This paper focuses on a prognostic health management (PHM) method based on the measurement of forward voltage and forward current of bare LED under harsh environment. In this paper, experiments have been done on single LEDs subjected to combined temperature–humidity environment of 85 °C, 85% relative humidity. Pulse width modulation (PWM) control method has been employed to drive the bare LED in order to reduce the heat effect caused by forward current and high frequency (300 Hz). A data acquisition system has been used to measure the peak forward voltage and forward current. Test to failure (luminous flux drops to 70%) data has been measured to study the effects of high temperature and humid environment loadings on the bare LEDs. A solid state cooling method with a Peltier cooler has been used to control the temperature of the LED in the integrating sphere when taking the measurement of luminous flux. The shift of forward voltage forward current curve and lumen degradation has been recorded to help build the failure model and predict the remaining useful life (RUL). Particle filter has been employed to assess the RUL of the bare LED. Model predictions of RUL have been correlated with experimental data. Results show that prediction of RUL of LEDs, made by the particle filter model, works with acceptable error-bounds. The presented method can be employed to predict the failure of LED caused by thermal and humid stresses.

The characteristic analysis of continuous light diodes

2021 ◽  
pp. 2150247
Author(s):  
I. T. Huseynov
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Light Flux ◽  
Continuous Light ◽  
Luminous Flux ◽  
Characteristic Analysis ◽  
Light Emitting ◽  
White Leds ◽  
Composite Solution ◽  
White Light Emitting Diodes

Photoluminescence (PL) spectra, light flux, color temperatures and color coordinates of white light emitting diodes that are based on CaGa2S4:Eu[Formula: see text]–CaS:Eu[Formula: see text] composite solution and industrial phosphor were analyzed. The study was carried out continuously for a 1000 h with two white LEDs which based on an exciting InGaN wavelength of 450 nm with a power of 10 W. Luminous flux and color temperatures were investigated during 200, 400, 600, 800 and 1000 h. All experiments were carried out for both CaGa2S4:Eu[Formula: see text]–CaS:Eu[Formula: see text] and industrial phosphor and comparatively analyzed. Consequently, the application perspectives of CaGa2S4:Eu[Formula: see text]–CaS:Eu[Formula: see text] composite solution in the white LEDs technologies are presented.

Optimization Spectrum of White Light Emitting Diodes Based on Correlated Color Temperature and Luminous Flux

2015 ◽  
Vol 44 (10) ◽  
pp. 1030001
Author(s):  
黄马连 HUANG Ma-lian ◽  
陈焕庭 CHEN Huan-ting ◽  
周小方 ZHOU Xiao-fang ◽  
蔡嘉毅 CAI Jia-yi ◽  
周锦荣 ZHOU Jin-rong ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Luminous Flux ◽  
Color Temperature ◽  
Light Emitting ◽  
White Light Emitting Diodes
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