A pen-type computer input device is used to move a cursor on the display of a computer system or enter data such as of figures, letters, numerals, or the like into a computer system. The pen-type computer input device includes a shank, a ball rotatably supported on the tip end of the shank, a pair of...http://www.google.co.uk/patents/US5371516?utm_source=gb-gplus-sharePatent US5371516 - Pen-type computer input device
