A road map display system comprises a map memory for storing map image data, a sensor for detecting the travelling distance and travelling direction and outputting a signal representative of the angular offset between the direction of travel and an axis of a map coordinate system, an arithmetic means...http://www.google.com.au/patents/US4543572?utm_source=gb-gplus-sharePatent US4543572 - Road map display system with indications of a vehicle position and destination
