Design and Pareto solution analysis of novel alignment-free ultra-thin multi-layered diffuser film applied for mini-LED backlighting and general lighting applications

Abstract Design of a novel, alignment-free, ultra-thin multi-layered diffuser film for mini-LED backlight unit and other LED general lighting applications is presented. The ultra-thin diffuser film is inserted between the blue mini-LED array and the QD film for the backlight application. The diffuser film consists of two optical elements, a diffractive layer (DOE or a microprism-array) faced on the mini-LED side and a dielectric multi-layer stack faced on the QD film side. The diffractive layer optimally adjusts the incident angle of the lights emitted out of the mini-LED and the dielectric multi-layer stack acts as an angle-selective filter. The innovative combination of the two optical elements realizes distinct improvement of lighting efficiency and illuminance uniformity without alignment of the diffuser film with the mini-LED array. We also demonstrate the optimal design of the diffuser film using Pareto solution analysis. This method is flexibly applicable to optimally designing not only mini-LED backlight units but also various general lighting applications.