A pointing device employs a panel mounted at an opening in a keyboard of a computer, such as a portable computer with a hinged display screen. The panel is mounted with freedom to move in two dimensions. A knob projecting from atop the panel has an indicating pushbutton. A sensor mounted adjacent to...http://www.google.com.hk/patents/US5663747?utm_source=gb-gplus-share專利 US5663747 - Pointing device
