Alignment-free diffuser film composed of a multilayer dielectric and a microprism layer for mini-LED backlights

We propose a novel diffuser film structure designed for mini-LED backlights. The proposed film is composed of a multilayer dielectric and a microprism layer. The dielectric layers function as an angle filter that does not transmit blue light directly above the LED and only transmits blue light with an incident angle above a designed value. The microprism layer controls the direction of the LED light and replicates the LED lights laterally. This combination of angle filter and microprism layer makes the illuminance distribution uniform without requiring alignment between the LED chips and the diffuser film. Our proposed diffuser film provides 4× better efficiency, better uniformity than conventional films, and only 50 μm thickness.