Red, green and blue LED-based white light source: implementation challenges and control design

The improvements in high power light emitting diode (LED) technology with 100+ lumens per LED chip bring solid-state lighting close to reality. Combining red, green and blue (RGB) LEDs can provide a compact white light source with unique features such as instant color variability. However, the implementation of an RGB-LED light source has numerous practical issues such as sensor placement, LED driving, control design and stability with temperature and time. This can result in lamp operation that may not meet the spatial, color maintenance and perception requirements of many applications. In this paper, we highlight the practical issues and present solutions using an RGB-LED light engine as an example. The spatial mixing, sensor placement, and control system design for the light engine are discussed and experimental results are provided.