Analysis of the far-field region of LEDs

Sun, Ching Cherng; Chien, Wei Ting; Moreno, Iván; Hsieh, Chih Ching; Lo, Yu Chih

doi:10.1364/oe.17.013918

Cited by 81 publications

(35 citation statements)

References 16 publications

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“…4. The components of r i (t) include a random noise (denoted by w i ), whose distribution is determined by (7), and in the faulty case, a fault signal (denoted by ϕ i ); i.e.…”

Section: Diagnostic Methodsmentioning

confidence: 99%

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Automatic diagnosis and control of distributed solid state lighting systems

Dong¹,

Driel²,

Zhang³

2011

Opt. Express

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This paper describes a new design concept of automatically diagnosing and compensating LED degradations in distributed solid state lighting (SSL) systems. A failed LED may significantly reduce the overall illumination level, and destroy the uniform illumination distribution achieved by a nominal system. To our knowledge, an automatic scheme to compensate LED degradations has not yet been seen in the literature, which requires a diagnostic step followed by control reconfigurations. The main challenge in diagnosing LED degradations lies in the usually unsatisfactory observability in a distributed SSL system, because the LED light output is usually not individually measured. In this work, we tackle this difficulty by using pulse width modulated (PWM) drive currents with a unique fundamental frequency assigned to each LED. Signal processing methods are applied in estimating the individual illumination flux of each LED. Statistical tests are developed to diagnose the degradation of LEDs. Duty cycle of the drive current signal to each LED is re-optimized once a fault is detected, in order to compensate the destruction of the uniform illumination pattern by the failed LED.

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“…4. The components of r i (t) include a random noise (denoted by w i ), whose distribution is determined by (7), and in the faulty case, a fault signal (denoted by ϕ i ); i.e.…”

Section: Diagnostic Methodsmentioning

confidence: 99%

“…Recent research in the literature mainly focuses on analyzing the illumination distribution of a group of LEDs [4][5][6][7]. A group of LEDs are usually required to achieve a uniform illumination pattern [4,6,8].…”

Section: Introductionmentioning

confidence: 99%

Automatic diagnosis and control of distributed solid state lighting systems

Dong¹,

Driel²,

Zhang³

2011

Opt. Express

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“…LIDCs show that the maximum intensity of a HP-LED is distributed about the angle of 45 [21,22]. HPLEDs were installed on a calculated distance (about 6e8 cm far) from the inner edge of photoreactor, in a way that their radiated intensity is smoothly and maximum distributed around the center of the cylinder mouth.…”

Section: Design and Preparation Of A Hp-led Photoreactormentioning

confidence: 99%

The improvement of photocatalytic processes: Design of a photoreactor using high-power LEDs

Khademalrasool

Farbod

Talebzadeh

2016

Journal of Science: Advanced Materials and Devices

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Keywords:Fluorescent lamp photoreactor High-power LED photoreactor Photocatalytic water purification Reactive blue dye Zinc oxide nanoparticle a b s t r a c t This paper is an attempt to survey the benefits of a well-designed photoreactor containing just 6 ultraviolet UV high power light emitting diodes (HP-LEDs) each one with the power of 1 W (totally 6 W) and the wavelength of 365 nm HP-LEDs as an efficient irradiation source for photocatalytic studies. However we have been reported an experiment just with the 365 nm LEDs, but the other LEDs were predicted for other experiments like green photocatalytic experiments. We installed diodes with respect to the luminescence intensity distribution curves (LIDCs) or intensity patterns. In this order, the efficiency of the UV-HP-LEDs in a HP-LED photoreactor (HPLED-PhR) was compared with the efficiency of the traditional UV lamps that are extensively used in photocatalytic processes including a set of UV HPLEDs was designed and made up and then its performance was compared with a traditional fluorescent lamp photoreactor (FL-PhR) performance. As a typical photocatalytic experiment, Zinc Oxide (ZnO) nanoparticles via co-precipitation methodwere synthesized and used as photocatalyst for purification of water polluted with the reactive blue dye (RB), under UV irradiation in two photoreactors. Results showed that the rate of the photocatalytic reaction under the UV-LEDs wastwice greater than it under the traditional fluorescent UV lamps, while the both electrical power consumption and making cost of the HPLED-PhR are less than a quarter of them for the FL-PhR.

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“…In 2008, the authors proposed and demonstrated a precise optical modeling algorithm that simulated light patterns for a light source in the midfield; the proposed model has since been applied in practice in relevant industries [33], [34], [37]. However, the modeling algorithm does not address color distribution.…”

Section: Modeling Algorithmmentioning

confidence: 99%

Precise Spatial-Color Optical Modeling in Phosphor-Converted White LEDs

Sun¹,

Chang²,

Wang³

et al. 2015

J. Display Technol.

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White light LEDs are playing a more and more important role in display in various structures. Here, a new modeling algorithm is proposed for use in phosphor-converted white light-emitting diodes (pcW-LEDs); the algorithm can be used to accurately simulate color appearances, potentially enabling optical designers to remove yellowish/bluish spots in LED lighting. The proposed modeling method was applied to simulate a pcW-LED without an encapsulation lens, and subsequently, a pcW-LED with a hemispherical lens. Both simulations accurately predicted the blue and yellow light distribution. The model was further verified by applying a total internal reflector lens to the pcW-LED. In the midfield region, the blue and yellow light distribution exhibited large variations as the observation distance changed; this varying light pattern for both the blue and yellow lights can be accurately predicted using the proposed model. The developed optical model should facilitate designing a pcW-LED that features high-quality illumination and increased color uniformity.Index Terms-Fluorescent and luminescent materials, light-emitting diodes, wavelength conversion devices.

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Analysis of the far-field region of LEDs

Cited by 81 publications

References 16 publications

Automatic diagnosis and control of distributed solid state lighting systems

Automatic diagnosis and control of distributed solid state lighting systems

The improvement of photocatalytic processes: Design of a photoreactor using high-power LEDs

Precise Spatial-Color Optical Modeling in Phosphor-Converted White LEDs

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