Abstract: A system and its method using waste heat energy to generate useful electricity for mobile projector is revealed; the purpose are two folds: first is to reduce the excessive heat, in order to increase the brightness; the second is to recycle the energy, so to extend the working hours between the recharges. The key component used is silicon based reversible heat pump diode, which can convert the electrical energy to heat energy, or from heat energy to electrical energy. Both hydrophilic and hydrophobic coatings are used to enhance the energy converting efficiency. One sample implementation combined with standard alone battery charger is described in details.

Abstract: A system and its methods using 4D signature to verify ones' online transaction through mobile projector is disclosed for the first time; the purpose is to enhance the security of currently booming e-commence industry. By 4D, we mean a signature that is written in 3D space and 1D time. The speed and the force the writer used are all recorded in great details, and it becomes very hard to be forged. One sample implementation combined with a popular smart phone is described in details. Two mini projectors and two cameras are used in a coordinated way, with one catch even line, and the other catch odd line; and both catch the red green and blue in strictly defined time sequences. Pre-distortion, de-jitter, auto focus and background color compensation methods are also included. Finally, cloud sever is used to improve the authentication accuracy, through the data fusion.

Abstract: 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.