LIGHT EMITTING DIODE PERFORMANCE & OPTIMIZATION

With technology paving the road for economic solutions that will reduce the amount of energy consumed, Light Emitting Diodes (LEDs) are quickly becoming a popular and the desired form of illumination. LEDs are up to ten times more efficient than incandescent lights and are double the efficiency of compact fluorescent lights (CFLs). While CFLs are comparable in efficiency, they contain mercury and produce ten times the amount of heat as an LED. Another advantage of LEDs is that they can withstand a wider range of environments. The LEDs used for household lighting produce blue light. To provide the desired white light, they are manufactured with a yellow silicone phosphor encapsulant. While the encapsulant allows for the emitting of white light, it has a few disadvantages. One in particular is that some of the light output is reduced which leads to a decrease in efficiency, and perhaps the biggest downside is the change in light output color over the lifespan of the LED. Due to the heat generated inside the LED and other environmental factors, the silicone phosphor encapsulant hardens and degrades over time. While the change in color is common among other types of light bulbs, it is more often noticed in LEDs due to their longer lifespan. The efficiency and lifespan of LEDs has been well documented. Of all of the factors that contribute to the long life and high efficiency of LEDs, the junction temperature is one of the most crucial. The junction temperature of the LiteOn 5630 LED was estimated using thermal modeling from data collected from a LabSphere Illumia® Light Measurement System. This system allows a myriad of performance data to be gathered and analyzed from nearly any light source. The results have shown that purity, efficacy, and efficiency are all related to the LED’s junction temperature. By having a clearer understanding of how external temperature and LED module design affects junction temperature, the industry will have a more accurate estimation of LED lifespan and efficacy at real world operating conditions. This research is funded by a Lamar University Office for Undergraduate Research Grant. 1