US Patent 9357493 Stylus power management using motion and orientation sensing

A system including an active stylus and a mobile computing device where an electronic signal emitted by the tip of the stylus that the mobile computing device uses to locate the tip is turned on and off when the stylus is not being used to save power. Whether the stylus is being used is determined based on an orientation of the stylus in comparison to an orientation of an electronic writing surface of the computing device. Difference in barometric air pressure or altitude between the stylus and mobile computing device may also be used to turn the tip signal on and off.