Thermal management for LED Pico projector

Consumers love tiny handheld electronic devices, but don't love tiny displays that show only tiny images. Pico projector is a good solution. Nowadays using LEDs as the lighting source is the current mainstream for Pico projectors. In this study, the high power LED chip has a surface area of 1mm² with a total power consumption of 1.4W. If approximately 75% electrical power transfers to heat, it will contribute a high heat flux of 105 W/cm² within the LED Chip, which will cause high junction temperature (T_j). However the junction temperature of the LED chip should keep under 150°C. In this study, different heat dissipations for LED pico projector were investigated through CFD simulations. The testing results demonstrated the thermal management is available for the handheld pico projector. The results show that the reducing thermal resistance of the PCB is the most effective way to dissipate the heat generated from the LED module. When the driving current of LED is 350mA, a metal housing attached a MCPCB can dissipate the heat. When the driving current increases to 700mA, a heat sink needs to be attached to enlarge the surface area for heat dissipation. When the driving current further increases to 1000mA, the larger heat dissipation area is needed. In this paper, the effects on the junction temperature of different thermal solutions are investigated and compared by simulations and experiments.