A scanning mouse has two optical navigation sensors to allow measurement of both translation and rotation of the scanning mouse. It also has an image sensor, and the ability to digitize the sensed image data. There may be a second image sensor at perpendicular to the first. A high speed digital data...http://www.google.co.uk/patents/US5994710?utm_source=gb-gplus-sharePatent US5994710 - Scanning mouse for a computer system
