Modeling Spectra of Low-Power SMD LEDs as a Function of Ambient Temperature

Raypah, Muna E.; Devarajan, Mutharasu; Sulaiman, Fauziah

doi:10.1109/ted.2017.2656862

Cited by 18 publications

(11 citation statements)

References 28 publications

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“…The electrons subsequently recombine in the active region and cause photon emissions. We find a carrier recombination temperature which is not consistent with the junction temperature, particularly at higher junction temperatures [6][7][8][9][10][11][12]. This effect is larger than previously noted [10,13].…”

contrasting

confidence: 94%

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Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias

Orem¹,

Vogt

Graham

et al. 2018

Electronics

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This study was launched to demonstrate that LEDs at zero bias show recombination photon emissions, and to check the models for the same. A method for measuring the light emission for a LED near zero bias is presented. A large reverse bias sufficient to suppress detectable emissions is assumed. The bias voltage between ‘large reverse’ and our target voltage is modulated, and the difference measured. The measured emissions found are consistent with the Shockley diode equation. The spectrum near zero bias can be measured and characterized. It shows LED behavior that is substantially different from other typical measurements, and suggests a violation of Kirchhoff’s Law.

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contrasting

confidence: 94%

“…In Section 3.2, we noted that the high energy tail is not consistent with the measured temperature [6][7][8][9][10][11][12]. For 201 • C, the best fit exponent is roughly 1.4× the measured temperature.…”

Section: Analysis Of Properties Of Recombinationmentioning

confidence: 85%

Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias

Orem¹,

Vogt

Graham

et al. 2018

Electronics

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“…As the working temperature increases or as time goes by, the peak wavelengths and FWHMs of LEDs and camera responsivities shift (Zhang JJ et al 2013;Raypah et al 2017). The robustness of reflectance estimation under small variations of the optimal projector spectra and camera responsivities, important for stable reflectance estimation accuracy in practical applications, was therefore investigated.…”

Section: Robustness Of Optimal System Functions Under Small Parameter Shiftsmentioning

confidence: 99%

Improved and Robust Spectral Reflectance Estimation

Zhang

Meuret

Xiang-guo

et al. 2020

LEUKOS

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Accurately estimating spectral reflectance functions from color camera images is a hot research subject that demonstrates tremendous potential for illuminating engineering and computer vision applications. However, the impact of the illumination spectrum and camera responsivity (system functions) to the estimation accuracy has not been systematically studied so far, nor the impact of 'training' spectral reflectance set. In this study, a dual imaging reflectance optimization system is used based on a neural network and optimal system functions that are resp. trained and optimized using several sample sets. Simulations showed that such optimal systems, trained and optimized with the IES TM30 spectral reflectance set, can have a substantially higher estimation accuracy compared to 'real' systems composed of commercially available projector spectra and camera responsivities and that they are sufficiently robust under small changes in system function peak wavelength and spectral width due to changes in working temperature or with passing time. An analysis of the impact of the specific sample set database adopted for neural net training on estimation accuracy showed that training with the IES set results in good and stable performance, even for other sample sets and different illumination spectra. Training with the spectrally uniform IES spectral reflectance set is therefore advised for general purpose, high-accuracy reflectance estimation systems. A comparison with a state-ofthe-art method shows that the proposed method has a higher color prediction accuracy and a significantly shorter running time for realistic images with high resolution.

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“…Just as it is important to ensure that the temperature of the devices is kept within limits, it is also of importance to ensure the heat generation in the device doesn't significantly increase the ambient temperature. This is due to the fact that the LED optical output is significantly affected by the temperature as presented in [4,5]. In [5] the optical output was while altering the ambient temperature.…”

Section: Package Thermal Designmentioning

confidence: 99%

“…This is due to the fact that the LED optical output is significantly affected by the temperature as presented in [4,5]. In [5] the optical output was while altering the ambient temperature. The results show that the higher the ambient temperature the higher the number of non-radiative recombination of carriers and subsequently diminishing the light intensity [6,7].…”

Section: Package Thermal Designmentioning

confidence: 99%

Chip-on-board assembly of 800V Si L-IGBTs for high performance ultra-compact LED drivers

Aliyu

Mouawad

Castellazzi

et al. 2017

2017 29th International Symposium on Power Semiconductor Devices and IC's (ISPSD)

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Abstract-This paper presents a novel chip on board assembly design for an integrated power switch, based on high power density 800V silicon lateral insulated-gate bipolar transistor (Si LIGBT) technology. LIGBTs offer much higher current densities (5-10X), significantly lower leakage currents, and lower parasitic device capacitances and, gate charge compared to conventional vertical MOSFETs commonly used in LED drivers. The higher voltage ratings offered (up to 1kV), the development of high voltage interconnection between parallel IGBTs, self-isolated nature and absence of termination region unlike in a vertical MOSFET makes these devices ideal for ultracompact, low bill of materials (BOM) count LED drives. Chip onboard LIGBTs also offer significant advantages over MOSFETs due to high ambient temperatures seen on most of the LED lamps as the LIGBTs on-state losses increase only marginally with temperature. The design is based on a built-in reliability approach which focuses on a compact LED driver as a case-study of a cost-sensitive large volume production item.

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Modeling Spectra of Low-Power SMD LEDs as a Function of Ambient Temperature

Cited by 18 publications

References 28 publications

Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias

Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias

Improved and Robust Spectral Reflectance Estimation

Chip-on-board assembly of 800V Si L-IGBTs for high performance ultra-compact LED drivers

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