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.

LED Lumen Degradation and Remaining Life Under Exposure to Temperature and Humidity

2013 ◽  
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 ◽  
Forward Current ◽  
Useful Life

The development of light-emitting diode (LED) technology has resulted in widespread solid state lighting 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 (300Hz). A data acquisition system has been used to measure the peak forward voltage and forward current. Test to failure (luminous flux drops to 70 percent) 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. Particle filter has been employed to assess the remaining useful life (RUL) of the bare LED. Model predictions of RUL have been correlated with experimental data. Results show that prediction of remaining useful life 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.

Assessment of Lumen Degradation and Remaining Life of LEDs Using Particle Filter

2013 ◽  
Author(s):  
Pradeep Lall ◽  
Hao Zhang ◽  
Lynn Davis
Keyword(s):  
Solid State ◽  
Particle Filter ◽  
Luminous Flux ◽  
Remaining Useful Life ◽  
Integrating Sphere ◽  
Harsh Environment ◽  
Forward Voltage ◽  
Acceptable Error ◽  
Forward Current ◽  
Useful Life

The development of light-emitting diode (LED) technology has resulted in widespread solid state lighting 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 (300Hz). A data acquisition system has been used to measure the peak forward voltage and forward current. Test to failure (luminous flux drops to 70 percent) 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. Particle filter has been employed to assess the remaining useful life (RUL) of the bare LED. Model predictions of RUL have been correlated with experimental data. Results show that prediction of remaining useful life 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.

Prognostics Health Management Model for LED Package Failure Under Contaminated Environment

2015 ◽  
Author(s):  
Pradeep Lall ◽  
Hao Zhang ◽  
Lynn Davis
Keyword(s):  
Health Management ◽  
Luminous Flux ◽  
The State ◽  
Remaining Useful Life ◽  
Integrating Sphere ◽  
State Estimator ◽  
Acceptable Error ◽  
Color Shift ◽  
Useful Life ◽  
The Impact

The reliability consideration of LED products includes both luminous flux drop and color shift. Previous research either talks about luminous maintenance or color shift, because luminous flux degradation usually takes very long time to observe. In this paper, the impact of a VOC (volatile organic compound) contaminated luminous flux and color stability are examined. As a result, both luminous degradation and color shift had been recorded in a short time. Test samples are white, phosphor-converted, high-power LED packages. Absolute radiant flux is measured with integrating sphere system to calculate the luminous flux. Luminous flux degradation and color shift distance were plotted versus aging time to show the degradation pattern. A prognostic health management (PHM) method based on the state variables and state estimator have been proposed in this paper. In this PHM framework, unscented kalman filter (UKF) was deployed as the carrier of all states. During the estimation process, third order dynamic transfer function was used to implement the PHM framework. Both of the luminous flux and color shift distance have been used as the state variable with the same PHM framework to exam the robustness of the method. Predicted remaining useful life is calculated at every measurement point to compare with the tested remaining useful life. The result shows that state estimator can be used as the method for the PHM of LED degradation with respect to both luminous flux and color shift distance. The prediction of remaining useful life of LED package, made by the states estimator and data driven approach, falls in the acceptable error-bounds (20%) after a short training of the estimator.

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.

scholarly journals An Investigation of Catastrophic Failure in Solid-State Lamps Exposed to Harsh Environment Operational Conditions

2015 ◽  
Author(s):  
Pradeep Lall ◽  
Peter Sakalaukus ◽  
Lynn Davis
Keyword(s):  
Solid State ◽  
Applied Voltage ◽  
Color Space ◽  
Thermal Quenching ◽  
Junction Temperature ◽  
Color Temperature ◽  
Integrating Sphere ◽  
Harsh Environment ◽  
Contributing Factors ◽  
Operational Conditions

Today’s lighting technology is steadily becoming more energy efficient and less toxic to the environment since the passing of the Energy Independence and Security Act of 2007 (EISA) [1]. EISA has mandated a higher energy efficiency standard for lighting products and the phase out of the common incandescent lamp. This has led lighting manufacturers to pursue solid-state lighting (SSL) technologies for consumer lighting applications. However, two major roadblocks are hindering the transition process to SSL lamps: cost and quality. In order to cut cost, manufactures are moving towards cheaper packaging materials and a variety of package architecture construction techniques which may potentially erode the quality of the lamp and reduce its survivability in everyday applications. Typically, SSL lamps are given product lifetimes of over twenty years based off of the IES TM-21-11 lighting standard which does not include moisture effects or large operational temperatures [2]. A group of recently released off-the-shelf lamps have undergone a steady-state temperature humidity bias life test of 85°C/85%RH (85/85) to investigate the reliability in harsh environment applications. The lack of accelerated test methods for lamps to assess reliability prior to introduction into the marketplace does not exist in literature. There is a need for SSL physics based models for the assessment and prediction of a lamp’s lifetime which is being spearheaded by the DOE [3]. In order to be fully accepted in the marketplace, SSL lamps must be able to perform similarly to incandescent lamps in these environments, as well as live up to the lifetime claims of manufacturers. A lamp’s package architecture must be designed with performance factors in mind, as well as address some of the known and published package related failure mechanisms, such as carbonization of the encapsulant material, delamination, encapsulant yellowing, lens cracking, and phosphor thermal quenching [4]. Each failure mechanism produces the similar failure mode of lumen degradation predominately due to two contributing factors: high junction temperature and moisture ingress. The current state-of-the-art has focused on individual areas of the lamp, such as the LED chip, substrate material, electrical driver design and thermal management techniques. [5] – [16] Looking at the lamp as a whole is a novel approach and has not been seen before in literature. This work followed the JEDEC standard JESD22-A101C of 85/85 with a one hour interval of applied voltage followed by a one hour interval of no applied voltage [17]. This test was performed continuously for each SSL lamp until it became nonoperational, i.e. did not turn on. Periodically, photometric measurements were taken following the IES LM-79-08 standard at room temperature using an integrating sphere, a spectrometer, and lighting software. The overall health of the SSL lamps was assed using the relative luminous flux (RLF), correlated color temperature (CCT) and the color difference (Δu′v′) using the Euclidean distance of the CIE 1976 color space coordinates. Finally, a Weibull analysis was completed to compare the characteristic lifetime of the SSL lamp to the actual rated lifetime. An important result from this work shows that the rated lifetime does not come close to the actual lifetime when the SSL lamps are used in a harsh humid environment which is fairly common in outdoor applications across the U.S. Also, the photometric results are presented for the entire lifetime of each SSL lamp under test.

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

scholarly journals Preparation and Inverstigation of MEH-PPV Films Used for White Light Emitting Diodes

2011 ◽  
Vol 21 (2) ◽  
pp. 153
Author(s):  
Nguyen Nang Dinh ◽  
Do Ngoc Chung ◽  
Nguyen Phuong Hoai Nam ◽  
Pham Hong Duong
Keyword(s):  
White Light ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Emission Spectra ◽  
Luminous Flux ◽  
Heat Treatment Condition ◽  
Integrating Sphere ◽  
Light Emitting ◽  
Treatment Conditions ◽  
White Light Emitting Diodes

With the aim to prepare white Light Emitting Diode (WLED), the conjugate polymer films like (Poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) were investigated. Spectroscopic (absorption and emission) spectra of the MEH-PPV films showed that this polymer is suitable for casting onto the chips of the blue InGaN LED to make WLED. The luminous flux measured on the WLEDs in the integrating sphere proved that the white light emission can be obtained from the combination of inorganic LED and conjugate (MEH-PPV) polymers with an optimal thickness and a high quality. The aging process of MEH-PPV films was found to be strongly dependent post-treatment conditions. Reasonable heat treatment condition for the MEH-PPV polymers was suggested as in vacuum of 5×10-2 Pa at a temperature of 120°C in, for 2 hous.

Calculating luminous flux radiated to a camera lens via high dynamic range photogrammetry

2020 ◽  
pp. 147715352092144
Author(s):  
RM Poling ◽  
H Cai
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Luminous Flux ◽  
Integrating Sphere ◽  
Remote Measurement ◽  
Imaging Method ◽  
Light Emitting ◽  
Camera Lens ◽  
High Dynamic ◽  
Test Scenarios

A camera-aided method of using high dynamic range photogrammetry was developed to calculate luminous flux radiated to the camera lens from an environment or its subareas, with per-pixel contributions from visible light-emitting sources, objects, and reflective surfaces. A series of equations were derived to calculate the luminous flux with valid sub-divisibility and additivity. A pilot study was first conducted, followed by a laboratory experiment using an integrating sphere to improve and validate this high dynamic range imaging method with a measurement error of 5.6%. This method was then tested in a real office space to estimate ‘visible’ luminous flux arriving at the camera lens simulating a typical view of 30 office users under four different test scenarios (fluorescent vs. LED lighting, with vs. without access to lighting controls). The luminous flux retrieved from each of a total of 120 high dynamic range images was checked with the illuminance measured at the camera lens. This camera-aided method for remote measurement of luminous flux was proven valid and useful for lighting practice and research. Further investigations on this method are necessary to overcome several limitations and issues of the present study.

scholarly journals Study of Temperature Effect on Luminous Flux of High Power Chip on Board Light Emitting Diode

2014 ◽  
Vol 24 (3) ◽  
pp. 267
Author(s):  
Cao Xuan Quan ◽  
Vu Khanh Xuan ◽  
Luu Thi Lan Anh ◽  
Vo Thach Son
Keyword(s):  
Solid State ◽  
Temperature Effect ◽  
Measurement System ◽  
High Power ◽  
Light Emitting Diode ◽  
Flux Measurement ◽  
Luminous Flux ◽  
Light Emitting

High power chip on board light emitting diode (HPCOBLED) are a promising solid state light technology for a variety of lighting applications. In this study, we studied temperature effect on luminous flux of HPCOBLED using VMI-PR-001 system of Vietnam Metrology Institute. The results according to the temperature Tc is increasing, luminous flux reduced. Especially HPCOBLED is larger power, decreasing luminous flux is larger. Reason of this is chance power.   HPCOBLED model describes the temperature affection on luminous flux of HPCOBLED. The results of HPCOBLED model matched with that measured by the luminous flux measurement system (VMI-PR-001, Vietnam).

Absolute Luminous Flux and Quantum Yield of Sm3+-Doped Cadmium-Aluminum-Silicate Glasses under the Pumping of Blue Light Emitting Diode

2013 ◽  
Vol 275-277 ◽  
pp. 1974-1977 ◽  
Author(s):  
Yu Lei ◽  
Fang Fang Fu ◽  
Li Zheng ◽  
Zhi Qiang Wang ◽  
Xin Zhao ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Blue Light ◽  
Optical Radiation ◽  
Light Emitting Diode ◽  
Luminous Flux ◽  
Silicate Glasses ◽  
Integrating Sphere ◽  
Aluminum Silicate ◽  
Light Emitting ◽  
Ccd Detector

Absolute luminous flux and quantum yield for multichannel transition emissions have been determined in samarium ion (Sm3+)-doped cadmium-aluminum-silicate (CAS) glasses under the pumping of blue light emitting diode (LED) using an integrating sphere of 30 cm diameter, which connected to a CCD detector with a 400 μm-core optical fiber. The radiant flux and luminous flux for the visible transition emissions (550–750 nm) of Sm3+under the blue LED excitation were solved to be 123 μW and 32 mlm, respectively, which occupied 1.51% and 7.16% of the whole. The total quantum yield of the visible fluorescence of Sm3+has been calculated to be 2.52%. Investigation on optical radiation parameters for multichannel visible transition emissions of Sm3+in CAS glasses provides a reference in developing luminescence and display materials.

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