Receiver coil built into belt for heat dissipation of watch-type smart devices

This letter proposes a novel method to promote the heat dissipation of watch-type smart devices by using receiver coils for wireless charging. It is achieved by embedding a spiral coil inside the belt. The heat dissipation effects of the proposed method on temperatures at key hot spots are clarified. The power transfer efficiency is also clarified. In watch-type smart devices, the most critical part for temperature is the underside surface of the belt, since this is the part that touches the skin for a long time. The analysis results show that the proposed method can reduce the increase in ambient temperature at the belt's underside surface by 59.7% and that its power transfer efficiency is more than 90%.