Improved white LEDs

Nanophosphors for White Light Leds

Useful lifetime analysis for high-power white LEDs

Keywords: Accelerated degradation test HPWLED Useful lifetime Bi-exponential model Degradation-data-driven method. a b s t r a c t An accelerated degradation test is used to analyze the useful lifetime of high-power white light-emitting diodes (HPWLEDs) as the point at which the light output declines to 70% of the initial flux in lumens, called L 70 In this study, the degradation-data-driven me...

Precise optical model of multi-chip white LEDs.

A single-chip white light LED is commonly modeled by considering the phosphor coating as a homogeneous Lambertian light source. However, this approach leads to an incorrect optical simulation of phosphor-coated multi-chip LEDs due to the presence of a previously unreported spatial distribution of emission spots across the phosphor layer. We introduce "weighting" factors based on position-depend...

Red, Green, and Blue LEDs for White Light Illumination

The rapid improvement of the white light efficacy achievable with light-emitting diodes (LEDs) opens up new opportunities in the general illumination market. An LED light source made of red, green, and blue LEDs (RGB-LEDs) can provide the unique feature of color variability, allowing the user to select the desired color point of the lamp. The white light color accuracy required in the general i...

The Mixed Blessing of Phosphor-Based White LEDs

Light-emitting diodes (LEDs), which use less energy and last longer than even compact fluorescent lights, 1 are predicted to become the leading lighting technology in the United States as incandescent bulbs are phased out. 2 But Abraham Haim, director of the Israeli Center for Interdisciplinary Studies in Chronobiology, will not bring white LEDs and other so-called short-wavelength lights into ...