Light Out-Coupling for Reflective Displays: Simple Geometrical Model, MATLAB Simulation, and Experimental Validation

Light out-coupling efficiency is a common issue for light emissive displays and devices, but is rarely discussed for reflective displays (e-Paper). The latest generation of reflective displays include light scattering particles and reflectance that is close to Lambertian (paper-like). However, this light scattering inside a reflective pixel can lead to total-internal reflection and additional light loss. This paper provides both a simple geometrical and a more detailed MATLAB simulation for calculating light out-coupling. Both approaches were found to agree with experimental results that reveal 5%-20% optical loss due to inefficient out-coupling. These out-coupling models improve the accuracy of predicting optical performance in reflective displays.