a system and its design variations using heat pump to generate useful warm and cool usages for multi functional mobile projector is exposed ; the purpose is two folds : first is to reduce the excessive heat , in order to increase the brightness ; the second is to reuse the energy , so to extend the functionalities . the key component used is silicon based heat pump , which can convert the electrical energy to heat energy . different shaped heat or cool fins are designed to match the multiple use cases . one sample implementation using digital serial interface is described in details .