US Patent 8493359 Capacitive stylus for a touch screen

A system comprising a sensing device and a capacitive sense array configured to track the position of a stylus and synchronize the capacitive sense array to the stylus transmit signal. The system is configured to track the position of both a stylus and a passive touch object. The system is further configured to track the position of the stylus using self capacitance sensing and track the position of the passive touch object using mutual capacitance sensing. The system further configured to modulate the stylus transmit signal to include additional data to support additional stylus functions.