Power optimization under brightness and communication requirements for visible light communication based on MacAdam ellipse

Data transmission with RGB LEDs is attracting significant research interest in VLC(Visible Light Communication).We consider the power optimization under brightness and communication requirements for RGB LEDs,and model the color constraint using the MacAdam ellipse instead of a fixed point in the chromaticity diagram.Then an optimization problem is formulated to determine the transmission power consumption and the corresponding coordinates in the chromaticity diagram.We propose a novel two-step algorithm to solve the optimization problem with lower implementation complexity.Numerical results show that the proposed approach shows the same performance as the optimal solution using a brute-force method,and requires the lower power consumption using MacAdam ellipse instead of merely a fixed point in the chromaticity diagram.

A RGB LED Driving Structure and Signal Processing Based on Tone-to-Color Conversion

In order to solve the uncertainty of voice-to-color conversion in which one of the three voice features（loudness, tone, rhythm） is applied to control LED color, a linear conversion solution is proposed. And a chromaticity diagram is defined by using hue definition on hue-saturation-lightness（HSL） hue ring and the normalization of CIE xyY which is a color standard defined by International Commission on Illumination（CIE）. The chromaticity diagram shows a linear relation between pitch and color, which is referred to conversions of other physical parameters as well. Based on the solution, red（R）, green（G） and blue（B） LEDs, the driving structure of a conversion circuit is designed and set up. The results indicate that signal processing of tone-to-color conversion is effective, from 30 Hz to 3 kHz with a resolution of 10 Hz mapped to the chromaticity diagram.