Implementation of smartphone-based color temperature and wavelength control LED lighting system

This study proposes a smartphone-based LED lighting system to maximize efficiency by easily measuring the characteristics of artificial light currently offered, and automatically adjusting color temperature and wavelength according to an occupant’s action. Targeting the classroom environment, this study designs lighting control indicators by classifying an occupant’s action into five areas—sleep, rest, creativity/arts, language/society, and concentration/mathematics—and then by extracting and referring to color temperature and wavelength ratio according to each activity, based on previous study results and actually measured data of natural light. The system consists of a measurement module and a control module. The measurement module contains a function to convert tristrimulus values XYZ, chromaticity coordinates xy and color temperature CCT after sensing the surrounding light’s RGB data through the color sensor installed within the occupant’s smartphone. Also, by automatically controlling artificial light according to action type by the control module, the system guarantees mobility, minimizes cost, and improves an occupant’s efficiency to the fullest. To evaluate the system’s performance, the system produces detailed information of artificial light, which is currently offered, to UI, and compares the error ratio with the data collected from the measuring equipment. The system also induces a user to prevent a lighting environment harmful to health by identifying the characteristics of mixed light emitted from various lighting sources including fluorescent lamp, desk lamp, and monitor.