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A new “heatsink-less” LED based T8 retrofit design is proposed in this study. The lamp consisted of light emitting elements directly attached on a flexible substrate. The substrate is mount on to the inner wall of a full cylindrical glass tube. The design is intended to simplify the lamp construction. However, since the metal-based heat sink is eliminated, the thermal design is a concern. Finite element...
A new “heatsink-less” LED based T8 retrofit design is proposed in this study. The lamp consisted of light emitting elements directly attached on a flexible substrate. The substrate is mount on to the inner wall of a full cylindrical glass tube. The design is intended to simplify the lamp construction. However, since the metal-based heat sink is eliminated, the thermal design is a concern. Finite element...
In this study, gel glass containing yellow, green and orange phosphors is fabricated via sol-gel process. Effects of different temperatures on condensation time of the sol and density of the gel glass are investigated. The gel glass is detected to confirm micro structure by SEM. The phosphors are well dispersed in the glass without phosphor degradation. The white light is successfully observed by...
The optical characteristics of LTCeYDG applied to high-power PCWLEDs are demonstrated. The LTG powder exhibited a lower transition temperature about 567°C. The 4-wt% LTCeYDG, distribution uniformity and quantum efficiency were measured 85% and 34.5%, respectively.
We present an improved cooling for a high power density UV LED module for a wavelength of 395 nm. The module consists of 98 LED chips soldered on a thick film printed alumina substrate on an area of 2.11 cm2. We investigated cooling by a commercial water cooler as well as by a surface micro cooler developed by our own. Further we describe a technology to replace alumina by aluminum as substrate material...
Luminescent ceramics may exhibit less scattering and increase the conversion efficiency over prior phosphor layers. Recently, the great majority of the commercial white LED (light emitting diodes) modules realized white light by GaN blue chip adding yellow phosphor. Although it has relatively high quantum efficiency, but its performance degenerates obviously at high temperature, and also causes deviation...
In this paper, study of theory and technique experiment has done about noncontact fluorescence temperature detection technique. This system is particularly adapt to the temperature measurement in the rang of 0°C to130°C¡£The calibration graph was shown to be highly reproducible when the probe is temperature cycled. A change in drive current from 5 to 30mA yields a spectral shift of the peak emission...
Aiming to study dynamic mechanical properties of the transparent silicone resins for LEDs packaging and the effects of dynamic mechanical properties on the reliability of high power LEDs, dynamic mechanical analysis (DMA) has been adopted to study one silicone resin used for packaging high power white light LEDs. The viscoelastic behavior of silicone resin was obtained from multi-frequencies dynamic...
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