Polarization Recycling LED Module for Pico Projector

Pico projector can display larger images based on

handheld electronic devices including mobile phone, portable multimedia players (PMPs, or MP4), PDA, GPS, and mobile TVs. Nowadays LEDs are ideal light source for the pico projection optical engine. However the optical efficiency of common LEDs can not be used adequately in pico projectors due to the undesired polarization state is absorbed, scattered, and/or blocked. In this study, a polarization recycling LED module was developed, which could convert the undesired polarization state to the desired one. In order to simplify the projection optical design and shrink the size of the projection optical system, and further enhance the optical efficiency of the projection system, this LED module integrated light recycling system and thermal dissipation structure. The light recycling system includes a reflective polarizer and a quarter wave plate (QWP). The experimental results show that the light recycling can enhance the system optical efficiency and increase output brightness of the projector system by 11.14% and increase the LED module brightness by 22.67% respectively. This paper also analyzed how to improve the utilizing efficiency of recycled light

further more.