Apple has acquired a movement detection technology for the iPhone from telecoms giant BT.
US patent 6,956,564 covers sensing technology invented by Lyndsay Williams for BT in 1997, which was originally deployed in a touch-sensitive computer called SmartQuill.
SmartQuill was capable of handwriting recognition, and could be used to write documents on paper the computer would then remember and store.
As it applies to the iPhone, the patent covers the device's designation as a portable computer that's responsive to movement and produces an electrical output signal representative of such movement.
SmartQuill carried a small screen that offered different views as the device was turned around. The patent purchase could be designed to protect Apple's iPhone's movement detection sensor, which moves the screen and changes the representation offered on screen when iPhone is moved around.