US Patent 7396178 Universal pen with optical, position and/or motion sensors

A pen for marking a visible path on a surface. The pen has a marking device adapted to change one or more attributes of the visible path, and a sensing device having at least one of a position sensor for determining the position of the pen relative to the surface, a motion sensor for sensing the motion of the pen relative to the surface, and an optical sensor for sensing colors and or images on a surface. A controller in the pen is linked to the sensing device and the marking device; such that the changes to the or each attribute are derived from at least one of he relative position, the relative motion, colors, and images, sensed by the sensing device