Ring Remote Phosphor Structure for Phosphor-Converted White LEDs

Lin, Ming Chang; Ying, Shang-Ping; Lin, Mingyao; Tai, Kuang-Yu; Tai, Sheng-Chieh; Liu, Chih-Hsuan; Chen, Jyh Chen; Sun, Ching-Cherng

doi:10.1109/lpt.2010.2043088

Cited by 60 publications

(26 citation statements)

References 10 publications

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“…However, more than half of the light re-emitted from the phosphor transfers backward to the absorptive LED chip, the configuration of conventional pcLED would get a low luminous efficiency [3], [4]. Remote-phosphor LEDs with phosphor layer away from the chip have been demonstrated in previous studies to improve the luminous efficiency of pcLEDs [5]- [13]. Nevertheless, there is still a large probability of light from the remote phosphor being reflected by the reflector cup and absorbed by the LED chip.…”

Section: Inverted-cone-lens Encapsulant With Gradientmentioning

confidence: 99%

Inverted-Cone-Lens Encapsulant With Gradient Surface for Ring-Remote-Phosphor Structure

Lin¹,

Ying²,

Lin³

et al. 2014

IEEE Trans. Device Mater. Relib.

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The ordinary ring-remote-phosphor structure consisting of an inverted-cone-lens encapsulant and a surrounding ring-remote-phosphor layer reduces the probability of the backward light from the phosphor layer to the absorptive lightemitting diode (LED) chip and then increases the package extraction efficiency. However, some of the blue light emitting from the LED chip impinges on the inverted-cone-lens surface and then escapes without hitting the ring-remote-phosphor layer. The blue light leakage from the inverted-cone-lens surface is a serious problem for the ring-remote-phosphor structure devices in use, because it will lower the actual illumination effects and result in discomfort for the eyes. In this paper, we discuss the predominant factors of the blue light leakage from the inverted-cone-lens surface and propose an improve ring-remote-phosphor structure that utilizes an inverted-cone-lens encapsulant with gradient surface to decrease the blue light leakage. Ray-tracing simulations are performed to analyze the blue light leakages from the ordinary and improved inverted-cone-lens encapsulants in the ring-remotephosphor structures. The simulation results show that the improved inverted-cone-lens encapsulants get almost no blue light leakage from the inverted-cone-lens surface directly and then lessen the discomfort for the eyes. Our results further demonstrate that the improved ring-remote-phosphor structure device will have higher angular color uniformity than the ordinary one.Index Terms-Blue light leakage, inverted-cone-lens encapsulant with gradient surface, phosphor-converted white lightemitting diodes (LEDs), ring-remote-phosphor structure.

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Section: Inverted-cone-lens Encapsulant With Gradientmentioning

confidence: 99%

Inverted-Cone-Lens Encapsulant With Gradient Surface for Ring-Remote-Phosphor Structure

Lin¹,

Ying²,

Lin³

et al. 2014

IEEE Trans. Device Mater. Relib.

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“…This allows for optimization of reflective and refractive elements in the optical system. Recently, remote phosphor white light emitting diodes (LEDs) have become an important new light source [16][17][18][19][20]. In a remote phosphor configuration, white light is created by combining the emission of blue LEDs and a wavelength conversion element, positioned at a distance of the LED.…”

Section: Introductionmentioning

confidence: 99%

“…Simulations with two wavelengths are frequently used, with one wavelength representing the blue light from the LED and one wavelength representing the yellow emission from the remote phosphor converter [18][19][20]. In the case of multiple fluorescent materials or materials exhibiting a spectral overlap between excitation and emission spectra (typically the case for QDs), full spectrum simulations are required, especially for the prediction of colour characteristics [24].…”

Section: Introductionmentioning

confidence: 99%

Taking the spectral overlap between excitation and emission spectra of fluorescent materials into account with Monte Carlo simulations

et al. 2014

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Monte Carlo ray tracing is an important simulation tool in applications where fluorescence is present, e.g. in bio-medical applications and in the design of luminaires and luminescent solar concentrators. A frequently used ray tracing procedure for fluorescence is the 'dual stage' approach. In this approach, first, all sources are traced through the system and the rays absorbed in the fluorescent components are stored. Next, the emission from the fluorescent components is traced. This approach does not allow for subsequent re-absorption and re-emission effects in fluorescent materials with a spectral overlap between excitation and emission spectra.In this work, a 'multi stage' ray tracing procedure for the simulation of luminescence is presented. Herein, wavelengths are traced from short to long separately and no distinction is made regarding the origin of emission (either a fluorescent component or a source). The presented approach can be easily implemented in existing commercial ray tracing software thus reducing the programming efforts for the new ray tracing algorithm and taking advantage of the strength of the selected ray tracing package concerning the modelling of complex geometrical systems.Both techniques are compared to investigate the influence of the selected ray tracing approach on the efficiency and colour prediction of a remote phosphor LED module.

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“…For reducing the light trapped in the LED chip and improving the efficiency of white LED, remote phosphor coating in which phosphor layer is away from the LED chip was proposal [8][9][10][11]. Furthermore, this LED structure can low the temperature of phosphor layer and enhance the color characteristic stability, because of less heat transfers from the LED chip to phosphor layer [12].…”

Section: Introductionmentioning

confidence: 99%

Angular color uniformity improvement for phosphor-converted white light-emitting diodes by optimizing remote coating phosphor geometry

Zheng

et al. 2012

2012 13th International Conference on Electronic Packaging Technology &Amp; High Density Packaging

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Angular color uniformity (ACU) of a king of popular remote phosphor coating LED packaging with spherical phosphor shape with uniform thickness was invested by the Monte Carlo ray tracing method. The simulation results indicate the yellowish ring can't be avoided under uniform phosphor thickness in angular range of 0°-180°. The optimized phosphor geometry was proposed whose thickness gradually reduces from the center to the edge. The optimized phosphor geometry can improve ACU 45%, compared with the initial uniform thickness phosphor layer.

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Ring Remote Phosphor Structure for Phosphor-Converted White LEDs

Cited by 60 publications

References 10 publications

Inverted-Cone-Lens Encapsulant With Gradient Surface for Ring-Remote-Phosphor Structure

Inverted-Cone-Lens Encapsulant With Gradient Surface for Ring-Remote-Phosphor Structure

Taking the spectral overlap between excitation and emission spectra of fluorescent materials into account with Monte Carlo simulations

Angular color uniformity improvement for phosphor-converted white light-emitting diodes by optimizing remote coating phosphor geometry

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